Giáo trình Cơ sở kỹ thuật bờ biển - PGS. TS. Vũ Minh Cát

Nội dung text: Giáo trình Cơ sở kỹ thuật bờ biển - PGS. TS. Vũ Minh Cát

1. Tr‡êng ®¹i häc thñy lîi Gi¸o tr×nh C¬ së kü thuËt bê biÓn Biªn so¹n: PGS. TS. Vò Minh C¸t HiÖu ®Ýnh: PGS. TS. Vò Thanh Ca Hμ néi, th¸ng 5 n¨m 2005
2. Lêi nãi ®Çu Víi sù t¨ng nhanh nhu cÇu sö dông ®a môc tiªu vïng ven biÓn trong nh÷ng n¨m gÇn ®©y, viÖc hiÓu s©u s¾c dßng ch¶y vïng ven bê, sãng, chuyÓn vËn bïn c¸t vμ t¸c ®éng t†¬ng hç cña c¸c nh©n tè nμy víi c¸c c«ng tr×nh lμ rÊt quan träng. MÆt kh¸c cã thÓ thÊy r»ng c¸c ho¹t ®éng kinh tÕ x· héi quan träng nhÊt ®ang diÔn ra trªn d¶i bê biÓn. ViÖt nam cã trªn 3200 km bê biÓn, hiÓu biÕt qui luËt mét c¸ch cÆn kÏ, khai th¸c vμ ph¸t triÓn bÒn v÷ng d¶i ven biÓn sÏ thóc ®Èy sù ph¸t triÓn ®Êt n†íc trong sù nghiÖp c«ng nghiÖp hãa, hiÖn ®¹i hãa. Cho ®Õn nay, viÖc nghiªn cøu d¶i bê biÓn cña n†íc ta ch†a ®†îc nhiÒu, cã rÊt nhiÒu t¸c ®éng xÊu do c¸c ho¹t ®éng kinh tÕ x· héi ®ang diÔn ra ë d¶i bê biÓn. Chóng ta ch†a cã nguån nh©n lùc cã ®Çy ®ñ kiÕn thøc ®Ó phôc vô cho c¸c ho¹t ®éng ®ang diÔn ra trªn d¶i bê biÓn. TËp bμi gi¶ng ”NhËp m«n kü thuËt bê biÓn” ®†îc viÕt lμ mét ho¹t ®éng n»m trong khu«n khæ dù ¸n :”N©ng cao n¨ng lùc ®μo t¹o ngμnh kü thuËt bê biÓn” víi môc tiªu cung cÊp kiÕn thøc cho ng†êi häc nh»m khai th¸c vμ ph¸t triÓn bÒn v÷ng d¶i ven biÓn n†íc ta. TËp bμi gi¶ng gåm 12 ch†¬ng ®†îc chia lμm 2 phÇn, phÇn I cung cÊp cho ng†êi häc nh÷ng kiÕn thøc c¬ së vÒ d¶i bê biÓn nh† qu¸ tr×nh h×nh thμnh, ph¸t triÓn cña ®†êng bê biÓn vμ c¸c thμnh t¹o cña nã, khÝ t†îng biÓn, h¶i d†¬ng häc, thñy triÒu, sãng v.v PhÇn 2 sÏ tr×nh bμy s©u h¬n vÒ h×nh th¸i, ®Þa m¹o, nhiÔm bÉn vïng ven biÓn, dßng ch¶y vμ t¸c ®éng cña c¸c nh©n tè nμy ®Õn m«i tr†êng vμ c¸c gi¶i ph¸p nh»m qu¶n lý bÒn v÷ng d¶i ven biÓn. Tμi liÖu tham kh¶o chÝnh ®Ó x©y dùng tËp bμi gi¶ng nμy lμ cuèn :”NhËp m«n kü thuËt bê biÓn” cña c¸c Gi¸o s† vμ c¸n bé gi¶ng d¹y khoa Kü thuËt D©n dông vμ §Þa kü thuËt, Tr†êng §¹i häc c«ng nghÖ Delft (Hμ lan) viÕt lÇn ®Çu n¨m 1982, ®· ®†îc n©ng cÊp, söa ch÷a, cËp nhËt nhiÒu lÇn, lμ gi¸o tr×nh chÝnh thøc gi¶ng d¹y t¹i §¹i häc c«ng nghÖ Delft . T¸c gi¶ xin ch©n thμnh c¶m ¬n GS. TS. Marcel Stive, GS. K. d’Angremond, PGS. H.J. Verhagen ®· ®äc vμ cho c¸c ý kiÕn ®ãng gãp quý b¸u cho tËp bμi gi¶ng nμy. T¸c gi¶ còng xin ch©n thμnh c¶m ¬n nhμ khoa häc Krystian Pilarczyk, ViÖn Qu¶n lý n†íc vμ c¬ së h¹ tÇng, Bé Giao th«ng c«ng chÝnh Hμ Lan; TS. Randa Hassan, Gi¶ng viªn kü thuËt bê biÓn, tr†êng quèc tÕ vÒ c¬ së h¹ tÇng, qu¶n lý n†íc vμ kü thuËt m«i tr†êng, TS. Ad J.F. van der Spek, ViÖn Khoa häc ®Þa chÊt øng dông Hμ lan ®· cung cÊp tμi liÖu vμ cã nhiÒu ý kiÕn ®ãng gãp quÝ b¸u. Cuèi cïng, xin c¶m ¬n c¸c c¸n bé thuéc Phßng Hîp t¸c quèc tÕ, §¹i häc c«ng nghÖ Delft (CICAT) ®· gióp ®ì mét c¸ch hiÖu qu¶ ®Ó t¸c gi¶ hoμn thμnh tËp bμi gi¶ng nμy. 1
3. Môc lôc C¬ së kü thuËt bê biÓn Ch‡¬ng 1: më ®Çu 1.1 Kh¸i qu¸t chung vÒ kü thuËt bê biÓn 06 1.1.1 §Þnh nghÜa 06 1.1.2 C¸c nghiªn cøu c¬ b¶n 07 1.2 C¸c thuËt ng÷ chuyªn m«n 09 1.3 C¸c ký hiÖu 40 1.4 §¬n vÞ theo hÖ SI 49 ch‡¬ng 2: Tõ sù ra ®êi cña vò trô tíi viÖc h×nh thμnh ®‡êng bê biÓn 2.1 Më ®Çu 51 2.2 Sù h×nh thμnh cña vò trô, tr¸i ®Êt, ®¹i d†¬ng vμ khÝ quyÓn 51 2.3 CÊu t¹o ®Þa chÊt cña tr¸i ®Êt 52 2.4 Ph©n lo¹i ®†êng bê theo quan ®iÓm ®Þa chÊt kiÕn t¹o 59 2.5 §†êng bê biÓn ViÖt Nam 64 Ch‡¬ng 3: khÝ hËu biÓn 3.1 Më ®Çu 74 3.2 HÖ thèng khÝ t†îng 74 3.3 Tõ khÝ t†îng ®Õn khÝ hËu 75 3.4 Chu tr×nh tuÇn hoμn n†íc 75 3.5 Bøc x¹ mÆt trêi vμ sù ph©n bè cña nhiÖt ®é 77 3.6 Hoμn l†u khÝ quyÓn - giã 82 3.7 B¶ng giã Beafort 85 ch‡¬ng 4: h¶i d‡¬ng häc 4.1 Më ®Çu 88 4.2 HÖ thèng giã 89 4.3 Vμi nÐt vÒ ®¹i d†¬ng 90 4.4 Dßng ch¶y do giã 92 4.5 §éng lùc cña dßng biÓn 93 4.6 TÝnh chÊt cña n†íc biÓn 95 4.7 Dßng mËt ®é 97 ch‡¬ng 5: Thuû triÒu 5.1 Më ®Çu 98 5.2 Nguån gèc cña thuû triÒu 99 5.3 N†íc d©ng 104 5.4 Sãng thÇn 108 5.5 Dao ®éng mùc n†íc trong hå do sù thay ®æi cña ¸p suÊt kh«ng khÝ 109 5.6 BiÓu diÔn to¸n häc vÒ thuû triÒu 110 2
4. 5.7 ChÕ ®é triÒu däc bê biÓn ViÖt Nam 117 5.8 §Þnh nghÜa c¸c mùc n†íc triÒu 119 ch‡¬ng 6: Sãng ng¾n 6.1 Sãng vμ ph©n lo¹i sãng 123 6.2 Sãng ®Òu 125 6.2.1 C¬ häc sãng 125 6.2.2 Tèc ®é truyÒn sãng 130 6.3 Sãng ven bê 133 6.3.1 Më ®Çu 133 6.3.2 HiÖu øng n†íc n«ng 133 6.3.3 Sãng khóc x¹ 134 6.3.4 Sãng vì 136 6.3.5 Sãng ph¶n x¹ 139 6.3.6 Sãng nhiÔu x¹ 140 6.3.7 HiÖn t†îng n†íc d©ng do sãng 141 6.3.8 Sãng leo 141 6.4 Ph©n bè sãng ng¾n vμ dμi h¹n (Ph©n bè sãng theo mÉu vμ tæng thÓ) 142 6.4.1 Ph©n bè sãng ng¾n h¹n (theo mÉu) 143 6.4.2 Ph©n bè sãng dμi h¹n (tæng thÓ) 146 6.4.3 C¸c øng dông cña ph©n bè sãng dμi h¹n 147 6.5 Quan tr¾c sãng 154 6.6 Dù b¸o sãng tõ tμi liÖu giã 155 6.7 Sö dông tμi liÖu ®o ®¹c sãng toμn cÇu 155 6.8 Phæ sãng 159 6.8.1 Phæ chiÒu cao sãng 159 6.8.2 Phæ h†íng sãng 160 Ch‡¬ng 7: Cöa s«ng vμ cöa vÞnh triÒu 7.1 Sù kh¸c nhau gi÷a cöa vÞnh triÒu vμ cöa s«ng 161 7.2 §Æc tÝnh cöa vÞnh triÒu 161 7.3 ChuyÓn vËn bïn c¸t/ båi l¾ng ë cöa vÞnh triÒu 164 7.4 §Èy nhanh qu¸ tr×nh båi tô 165 7.5 Cöa s«ng vïng triÒu 165 7.6 ChuyÓn ®éng cña dßng bïn 168 7.7 L¹ch triÒu lªn vμ triÒu rót 170 7.8 C¸c cöa s«ng siªu mÆn 171 Ch‡¬ng 8: C¸c kiÓu bê biÓn 8.1 Më ®Çu 173 8.2 §Æc ®iÓm bê biÓn c¸t 176 8.2.1 Vïng cöa s«ng 176 8.2.2 B·i triÒu 179 8.2.3 §ång b»ng ven biÓn 180 8.2.4 B·i biÓn 188 8.2.5 Cån c¸t, ®ôn c¸t 190 3
5. 8.2.6 §Çm ph¸ 193 8.2.7 Bê biÓn ®†îc che ch¾n 194 8.2.8 Cöa l¹ch triÒu, vÞnh triÒu 195 8.3 §†êng bê biÓn chÞu h†ëng tréi cña c¸c hÖ sinh th¸i biÓn 196 8.3.1 C¸c ®Çm n†íc mÆn 196 8.3.2 Rõng ngËp mÆn 198 8.3.3 HÖ thùc vËt sèng trªn c¸t 200 8.3.4 D¶i san h« 201 8.4 Bê biÓn ®¸ 204 8.4.1 Nguån gèc cña bê biÓn ®¸ 204 8.4.2 Bê ®¸ x©m thùc 206 8.5 C¸c d¹ng bê biÓn cña ViÖt Nam 209 8.5.1 Bê ®¸ vμ san h« 209 8.5.2 D¹ng b·i vïng cöa s«ng 209 8.5.3 D¹ng ®ång b»ng ch©u thæ 209 8.5.4 §†êng bê vïng ®Çm ph¸ 209 8.5.5 Cöa vμo vÞnh triÒu 210 8.5.6 §Çm lÇy, rõng ngËp mÆn vμ c¸c loμi cá biÓn 210 Ch‡¬ng 9: vÊn ®Ò ¤ nhiÔm vμ dßng mËt ®é 9.1 Më ®Çu 212 9.2 ¤ nhiÔm 212 9.2.1 C¸c lo¹i « nhiÔm 212 9.2.2 C¸c gi¶i ph¸p kiÓm so¸t « nhiÔm 214 9.3 Dßng mËt ®é vïng cöa s«ng 215 9.3.1 Sù thay ®æi ®é mÆn theo thuû triÒu 215 9.3.2 Nªm mÆn 217 9.3.3 HiÖn t†îng ph©n tÇng theo ph†¬ng ngang 219 9.3.4 Båi l¾ng trong s«ng 221 9.3.5 Mét sè biÖn ph¸p kiÓm so¸t dßng mËt ®é trong s«ng 222 9.4 Dßng mËt ®é trong c¶ng 224 9.4.1 Båi l¾ng trong c¶ng 232 9.4.2 Bμi to¸n thùc tÕ 232 9.4.3 Gi¶i ph¸p gi¶m ¶nh h†ëng dßng mËt ®é trong c¶ng 236 Ch‡¬ng 10: H×nh th¸i häc bê biÓn 10.1 Më ®Çu 238 10.2 C¸c qu¸ tr×nh trong vïng sãng vì 240 10.3 ChuyÓn vËn bïn c¸t 241 10.4 Sù thay ®æi vμ tr¹ng th¸i c©n b»ng cña ®†êng bê 244 10.5 TÝnh to¸n l†îng bïn c¸t ven bê 248 Ch‡¬ng 11: Qu¶n lý d¶i ven bê 11.1 Më ®Çu 250 11.2 Nh÷ng thay ®æi mang tÝnh toμn cÇu 251 11.2.1 T¨ng tr†ëng d©n sè thÕ giíi 251 4
6. 11.2.2 Sù thay ®æi khÝ hËu vμ mùc n†íc biÓn t¨ng 253 11.2.3 NhiÔm bÈn 254 11.3 C¸c hÖ thèng kinh tÕ - x· héi 255 11.4 Sù cÇn thiÕt cña bμi to¸n qu¶n lý 257 11.5 C¸c c«ng cô qu¶n lý 262 11.5.1 Träng sè c¸c quan t©m 262 11.5.2 Bμi to¸n qu¶n lý thùc tÕ 264 11.6 Chung sèng víi tù nhiªn 265 Ch‡¬ng 12: C¸c bμi to¸n thùc tÕ vμ c¸c gi¶i ph¸p b¶o vÖ 12.1 Më ®Çu 267 12.2 C¸c d¹ng xãi 267 12.2.1 Xãi do c«ng tr×nh 267 12.2.2 Xãi bê biÓn vμ ®ôn c¸t trong b·o cã n†íc d©ng 269 12.2.3 Xãi c¸c vïng ®Êt míi 270 12.2.4 Xãi cöa vÞnh triÒu 271 12.3 Gi¶i ph¸p c«ng tr×nh b¶o vÖ bê biÓn 271 12.3.1 B¶o vÖ khu vùc bÞ xãi do c«ng tr×nh 274 12.3.2 B¶o vÖ b·i biÓn vμ ®ôn c¸t khi b·o n†íc d©ng cao 276 12.3.3 B¶o vÖ c¸c vïng ®Êt míi 276 12.3.4 æn ®Þnh cöa vÞnh triÒu 277 12.4 Gi¶i ph¸p phi c«ng tr×nh 277 12.4.1 Nu«i b·i 277 12.4.2 Trång rõng ngËp mÆn 280 Tμi liÖu tham kh¶o 287 5
7. I. Giíi thiÖu chung 1.1 Kh¸i qu¸t chung vÒ kü thuËt bê biÓn 1.1.1 §Þnh nghÜa Kh«ng cã mét ®Þnh nghÜa chÝnh x¸c vÒ bê biÓn vμ vïng ven biÓn. Vïng ven biÓn phô thuéc vμo c¸c vÊn ®Ò kinh tÕ - x· héi vμ ®†îc qui ®Þnh tïy thuéc vμo mçi n†íc. Ch¼ng h¹n vïng cöa s«ng cã ®†îc xem lμ vïng ven biÓn hay kh«ng?, m«i tr†êng tù nhiªn vμ x· héi trong vïng ven biÓn mang nÐt ®Æc tr†ng g×?v.v V× vËy, trong mçi tr†êng hîp cô thÓ, sÏ cã mét ®Þnh nghÜa phï hîp nhÊt vÒ vïng ven biÓn. ë mét sè n†íc, vïng ven biÓn ®†îc x¸c ®Þnh kh¸ hÑp n»m gi÷a vïng giíi h¹n thuû triÒu lín nhÊt vμ nhá nhÊt. Tuy nhiªn, mét sè n†íc qui ®Þnh vïng ven biÓn réng h¬n, ch¼ng h¹n ®ã lμ vïng sãng ¶nh h†ëng ®Õn ®¸y biÓn ë phÝa biÓn vμ giíi h¹n xa nhÊt cña thuû triÒu biÓn vμo hÖ thèng s«ng ngßi. Mét sè n†íc kh¸c l¹i lÊy giíi h¹n vïng nμy n»m gi÷a cao ®é + 10 vμ - 10 m trªn mùc n†íc biÓn trung b×nh. §Æc ®iÓm c¬ b¶n nhÊt cña vïng ven biÓn lμ sù ¶nh h†ëng hçn hîp gi÷a m«i tr†êng biÓn vμ lôc ®Þa, gi÷a n†íc ngät vμ n†íc mÆn, bïn c¸t s«ng vμ bïn c¸t biÓn. §iÒu nμy t¹o nªn mét vïng víi mét hÖ sinh th¸i ®a d¹ng vμ lμ c¬ héi tèt cho con ng†êi. Nãi tãm l¹i, ho¹t ®éng kinh tÕ x· héi vïng ven biÓn kh¸ ®a d¹ng, ®«i khi tr¸i ng†îc nhau, trong ®ã quan träng nhÊt lμ sinh ho¹t lμng x·, nu«i trång ®¸nh b¾t thuû s¶n, n«ng nghiÖp, cÊp n†íc, vËn t¶i thñy, b¶o tån c¸c hÖ sinh th¸i tù nhiªn vμ vui ch¬i, gi¶i trÝ. ë Hμ Lan, vai trß quan träng nhÊt cña c¸c d¶i c¸t lμ b¶o vÖ c¸c vïng ®Êt phÝa trong kh«ng bÞ ngËp n†íc. Thªm vμo ®ã viÖc x©y dùng c¸c d¶i bê biÓn phôc vô nghØ m¸t còng kh«ng kÐm phÇn quan träng. Tuy nhiªn, hai ho¹t ®éng nμy th†êng m©u thuÉn víi nhau. Khi cã nhiÒu ho¹t ®éng cïng diÔn ra ®ång thêi th× tÝnh phøc t¹p sÏ t¨ng lªn. NÕu ®i s©u nghiªn cøu vïng ven biÓn th× cã thÓ s¬ ®å ho¸ theo nhiÒu c¸ch kh¸c nhau. C¸c thμnh phÇn trong hÖ thèng cã thÓ ph©n chia thμnh hai nhãm chÝnh: Tù nhiªn vμ nh©n t¹o. Nhãm nh©n t¹o chÞu sù t¸c ®éng cña con ng†êi ®†îc ®Æc tr†ng bëi c¸c hÖ thèng c¬ së h¹ tÇng, c¸c ho¹t ®éng kinh tÕ - x· héi. Cã thÓ thÊy r»ng hai hÖ thèng ®ã cã mèi liªn hÖ mËt thiÕt víi nhau vμ v× vËy ®ßi hái c¸c kü s† kü thuËt bê biÓn ph¶i cã kiÕn thøc vÒ hÖ thèng tù nhiªn vïng ven biÓn. Còng cÇn nhÊn m¹nh r»ng viÖc qu¶n lý bÒn v÷ng vïng bê lμ rÊt cÇn thiÕt. Theo dù b¸o sÏ cã h¬n 50% d©n sè sèng ë vïng ven biÓn (Vïng ven biÓn trong tr†êng hîp nμy ®†îc më réng h¬n). HÇu hÕt c¸c siªu ®« thÞ ®Òu ®†îc x©y dùng ven biÓn, ch¼ng h¹n Tokyo, Jakarta, Th†îng H¶i, Hong Kong, Bangkok, Calcutta, Bombay, New York, Buenos Aires, Los Angeles. Khi thiÕu sù c©n b»ng gi÷a c¸c qu¸ tr×nh tù nhiªn vμ x· héi ë vïng ven biÓn sÏ dÉn tíi c¸c vÊn ®Ò nh† ®ãi nghÌo, « nhiÔm vμ c¸c vÊn ®Ò x· héi kh¸c. Nãi tãm l¹i, t†¬ng lai cña thÕ giíi phÇn lín phô thuéc vμo t†¬ng lai cña vïng ven biÓn. 6
8. Tãm l¹i, kü thuËt bê biÓn lμ c¸c ho¹t ®éng kinh tÕ kü thuËt liªn quan tíi vïng ven biÓn. C¸c ho¹t ®éng ®ã bao gåm: x C¸c hÖ thèng, c¸c qu¸ tr×nh vμ ph©n tÝch c¸c vÊn ®Ò x Qu¶n lý th«ng tin vμ c¸c d÷ liÖu x HÖ thèng ho¸ vμ m« h×nh ho¸ x Qui ho¹ch, thiÕt kÕ, x©y dùng, vËn hμnh vμ qu¶n lý hÖ thèng c¬ së h¹ tÇng x HÖ thèng c¸c gi¶i ph¸p b¶o vÖ hÖ sinh th¸i tù nhiªn. X¸c ®Þnh c¸c ho¹t ®éng kü thuËt nμo trong nh÷ng t×nh huèng cô thÓ thuéc hÖ thèng bê biÓn ph¶i ®†îc nghiªn cøu lμ vÊn ®Ò rÊt quan träng. C¸c qu¸ tr×nh vïng bê biÓn ®†îc chia thμnh c¸c qu¸ tr×nh tù nhiªn ch¼ng h¹n chuyÓn ®éng cña bïn c¸t vμ c¸c qu¸ tr×nh kinh tÕ - x· héi vÝ dô qui ho¹ch vμ ph¸t triÓn kinh tÕ vïng ven biÓn. §èi víi kü s† lμm viÖc vïng ven biÓn th× viÖc nghiªn cøu c¸c qu¸ tr×nh tù nhiªn lμ träng t©m. ViÖc nghiªn cøu c¸c qu¸ tr×nh kinh tÕ – x· héi cã xu h†íng ®†îc bao gåm trong nghiªn cøu qu¶n lý tæng hîp vïng bê. §©y lμ c¸c ho¹t ®éng ®a môc tiªu, trong ®ã vai trß chñ ®éng cña kü s† bê biÓn lμ rÊt quan träng. Nh† ®· tr×nh bμy ë trªn, rÊt khã ph©n chia ranh giíi cña vïng ven biÓn. Kh«ng ph¶i ®†êng bê lμ ranh giíi ®ã. Tuy nhiªn, vËy vïng bê sÏ lμ ë ®©u? ph¶i ch¨ng ®ã lμ giíi h¹n ngoμi cña vïng thÒm lôc ®Þa? hay nã ®†îc x¸c ®Þnh phô thuéc vμo sù ph¸t triÓn cña kü thuËt?. ThËm chÝ ranh giíi trong ®Êt liÒn cßn khã x¸c ®Þnh h¬n. Mét con s«ng chi phèi bê biÓn th«ng qua l†îng bïn c¸t vËn chuyÓn ra biÓn. Sù thay ®æi chÕ ®é s«ng ngßi sÏ t¸c ®éng lËp tøc ®Õn bê biÓn. Do vËy viÖc nghiªn cøu qu¸ tr×nh bê biÓn ph¶i g¾n víi viÖc nghiªn cøu toμn bé hoÆc phÇn chñ yÕu cña l†u vùc s«ng. Hay nãi mét c¸ch kh¸c, nh÷ng lÜnh vùc mμ ng†êi kü s† bê biÓn ph¶i quan t©m rÊt réng. C¸c ho¹t ®éng kü thuËt t¸c ®éng ngμy cμng lín ®Õn bê biÓn v× c«ng nghÖ t¸c ®éng vμo c¸c qu¸ tr×nh bê biÓn ngμy cμng hiÖn ®¹i (ch¼ng h¹n dïng gi¶i ph¸p n¹o vÐt lμm thay ®æi l†îng bïn c¸t ë c¸c ®o¹n bê kh¸c nhau). §iÒu ®ã cÇn cã kiÕn thøc ngμy cμng ®Çy ®ñ vÒ qu¶n lý tæng hîp vïng bê. C¸c kh¸i niÖm vμ c¸c tõ kho¸ vÒ kü thuËt bê biÓn ch¼ng h¹n nh† ®Æt vÊn ®Ò, th«ng tin, ®o ®¹c, m« pháng, c¸c gi¶i ph¸p c«ng tr×nh nh©n t¹o vμ c¸c c¸c gi¶i ph¸p kh¸c v.v cÇn ®†îc th¶o luËn trong mét ph¹m vi réng lín h¬n. 1.1.2 C¸c nghiªn cøu c¬ b¶n Mét trong nh÷ng vÊn ®Ò c¬ b¶n mμ c¸c kü s† bê biÓn ph¶i nghiªn cøu lμ chuyÓn ®éng cña n†íc däc bê biÓn, t¸c ®éng t†¬ng hç gi÷a dßng n†íc vμ xãi båi bê vμ b·i biÓn, c¸c lùc t¹o ra do sãng, giã vμ dßng ch¶y t¸c ®éng lªn c«ng tr×nh. Mét sè vÝ dô ®¬n gi¶n sÏ tr×nh bμy trong phÇn nμy, nh÷ng vÝ dô kh¸c sÏ tr×nh bμy trong c¸c phÇn sau. Kh¶o s¸t nh÷ng nh©n tè ®ã h×nh thμnh c¬ së nghiªn cøu kü thuËt bê biÓn. Kü thuËt bê biÓn ®†îc chia thμnh hai phÇn vμ néi dung c¬ b¶n cña mçi phÇn ®†îc tr×nh bμy ë phÇn d†íi. 7
9. C¶ng C¶ng ®†îc con ng†êi x©y dùng ®Ó dïng tμu thuyÒn vËn chuyÓn hμng ho¸. Khi x©y dùng c¶ng th× tÝnh thuËn tiÖn vμ kinh tÕ lμ nh÷ng vÊn ®Ò ®†îc quan t©m. Hai vÊn ®Ò nμy cÇn ®†îc xem xÐt ®ång thêi vμ sù hîp t¸c cña c¸c kiÕn tróc sù hμng h¶i vμ nh÷ng ng†êi lμm c«ng t¸c ë c¶ng sÏ gióp cho viÖc lùa chän nh÷ng vÊn ®Ò tèi †u nhÊt. §†êng vμo c¶ng th†êng ®†îc b¶o vÖ b»ng c¸c ®ª ch¾n sãng. ThiÕt kÕ lo¹i c«ng tr×nh nμy ®†îc tr×nh bμy trong m«n häc:” ThiÕt kÕ ®ª ch¾n sãng”. Còng cã rÊt nhiÒu c¶ng ®†îc x©y dùng ë cöa s«ng nªn sù h×nh thμnh b·i ngÇm vμ luång tμu vïng cöa s«ng ®†îc nghiªn cøu trong c¸c m«n kü thuËt bê biÓn vμ râ rμng m«n häc nμy cã quan hÖ mËt thiÕt víi kü thuËt trong s«ng. VÊn ®Ò ¶nh h†ëng cña dßng mËt ®é vμ sù thay ®æi nång ®é muèi theo thêi gian ¶nh h†ëng tíi qu¸ tr×nh båi l¾ng khu vùc c¶ng. ë ®©y, Dßng mËt ®é sÏ ®†îc xem xÐt trªn quan ®iÓm kü thuËt; lý thuyÕt c¬ b¶n cña dßng mËt ®é ®†îc häc kü h¬n trong m«n häc dßng mËt ®é. §Æc tÝnh cña bïn c¸t trong c¶ng vμ vïng cöa s«ng lμ vÊn ®Ò rÊt quan träng v× liªn quan tíi vÊn ®Ò n¹o vÐt vμ ¶nh h†ëng tíi h×nh th¸i ®Þa m¹o ngoμi cöa s«ng kh¸ xa. ViÖc x©y dùng c¶ng cã quan hÖ rÊt chÆt chÏ víi c¸c vÊn ®Ò h×nh th¸i bê biÓn vμ kh«ng thÓ t¸ch rêi viÖc xem xÐt mét trong hai vÊn ®Ò nμy. Mét vÊn ®Ò quan träng nhÊt cña h×nh th¸i ®Þa m¹o liªn quan tíi c¶ng lμ vÊn ®Ò båi l¾ng luång tμu vμ ¶nh h†ëng cña ®ª ch¾n sãng tíi qu¸ tr×nh thay ®æi ®†êng bê. H×nh th¸i bê biÓn Nghiªn cøu h×nh th¸i bê biÓn lμ nghiªn cøu t†¬ng t¸c gi÷a sãng, dßng ch¶y víi ®†êng bê. PhÇn lín bê biÓn lμ c¸c bê c¸t vμ nã thay ®æi rÊt lín d†íi t¸c ®éng cña sãng giã. Bê ®¸ Ýt chÞu ¶nh h†ëng cña c¸c ®iÒu kiÖn sãng giã vμ d†êng nh† liªn quan tíi c¸c nhμ ®Þa chÊt nhiÒu h¬n lμ c¸c kü s† bê biÓn. Sù biÕn ®æi cña ®†êng bê cã thμnh t¹o vËt chÊt mÞn (bïn, phï sa) còng sÏ ®†îc tr×nh bμy trong phÇn cuèi cña m«n häc nμy. PhÇn lín c¸c bê biÓn ®†îc thμnh t¹o bëi c¸t, nªn cã thÓ dù b¸o ®†îc sù thay ®æi cña ®†êng bê b»ng c¸c m« h×nh to¸n häc. Nh÷ng m« h×nh nμy sÏ ®†îc giíi thiÖu trong m«n häc. Nghiªn cøu s©u h¬n vÒ m« h×nh ®†îc tr×nh bμy trong c¸c gi¸o tr×nh vμ s¸ch liªn quan tíi vËn chuyÓn bïn c¸t ven bê. Mét c¸ch râ rμng r»ng, muèn ®¸nh gi¸ ®†îc sù thay ®æi cña ®†êng bê th× chóng ta cÇn ph¶i hiÓu c¬ chÕ chuyÓn ®éng cña n†íc biÓn d†íi t¸c ®éng cña sãng vμ c¸c ngo¹i lùc kh¸c. Do vËy, nh÷ng kiÕn thøc vÒ c¬ häc chÊt láng, thuû lùc rÊt cÇn thiÕt trong qu¸ tr×nh häc. Nh÷ng kiÕn thøc kh¸c còng cÇn thiÕt trong qu¸ tr×nh nghiªn cøu m«n häc nμy. Dßng ch¶y vïng ven biÓn chÞu ¶nh h†ëng cña thuû triÒu mμ thuû triÒu lμ mét d¹ng sãng dμi. Sãng do giã lμ lo¹i sãng ng¾n. Do vËy trong thuû lùc biÓn, cÇn ph¶i ph©n biÖt râ sãng dμi vμ sãng ng¾n. 8
10. Cho ®Õn nay, hiÓu biÕt cña con ng†êi vÒ t¸c ®éng cña sãng ng¾n lªn bê c¸t còng ch†a hoμn toμn râ rμng. ChuyÓn ®éng cña bïn c¸t ven bê vμ ngoμi kh¬i lμ nh÷ng nghiªn cøu hÕt søc quan träng khi nghiªn cøu sù thay ®æi cña bê biÓn. RÊt nhiÒu kÕt qu¶ ®· vμ ®ang nghiªn cøu nh»m c¶i thiÖn c¸c m« h×nh to¸n m« pháng vμ dù b¸o sù thay ®æi cña ®†êng bê. V× rÊt nhiÒu thay ®æi cña ®†êng bê ngoμi ý muèn cña con ng†êi, nªn c¸c c«ng tr×nh b¶o vÖ bê lμ rÊt cÇn thiÕt. C¸c c«ng tr×nh nμy, vÒ nguyªn t¾c, lμm chËm t¸c ®éng xÊu tíi bê biÓn hoÆc lμ gi÷ bê biÓn ë tr¹ng th¸i c©n b»ng. Ch¼ng h¹n, x©y dùng má hμn vu«ng gãc hoÆc song song víi ®†êng bê sÏ lμm gi¶m qu¸ tr×nh xãi lë. Mét gi¶i ph¸p kh¸c lμ chuyÓn c¸t ë nh÷ng ®o¹n bê båi ®Õn c¸c ®o¹n bê xãi. C¸c lo¹i c«ng tr×nh b¶o vÖ bê biÓn sÏ ®†îc nghiªn cøu trong c¸c m«n häc sau. Ngoμi ra, hÖ thèng ®ª ch¾n sãng, ®†êng vμo c¶ng vμ dßng ch¶y ra biÓn tõ c¸c s«ng trong néi ®Þa lμ nh÷ng nh©n tè g©y nªn sù thay ®æi cña ®†êng bê 1.2 C¸c thuËt ng÷ chuyªn m«n C¸c thuËt ng÷ nμy ®†îc dïng th†êng xuyªn trong c¸c m«n häc kü thuËt bê biÓn. Còng cÇn nhÊn m¹nh r»ng, nghÜa cña c¸c thuËt ng÷ nμy cã thÓ kh¸c víi c¸c thuËt ng÷ th†êng dïng trong cuéc sèng. Tuy nhiªn, c¸c kü s† bê biÓn còng cÇn biÕt c¸c biÖt ng÷ (ng«n ng÷ ®Þa ph†¬ng) cña c¸c lÜnh vùc kh¸c nhau thuéc kü thuËt bê biÓn. C¸c thuËt ng÷ chuyªn m«n cã thÓ t×m trªn Website: www.minvenw.nl/projects/netcoast/address/glossary.htm Abrasion Frictional erosion by material transported by wind and waves Sù mμi mßn Sù xãi mßn ma s¸t cña c¸c vËt chÊt do sãng vμ giã Abrasion platform A rock or clay platform which has been worn by the processes of abrasion ThÒm mμi mßn ThÒm ®¸ hoÆc ®Êt sÐt h×nh thμnh trong qu¸ tr×nh mμi mßn Abutment That part of the valley side against which the dam is constructed, or the approach embankment in case of bridges which may intrude some distance into the waterway Trô chèng, têng bªn Hai ®Çu thung lòng n¬i ®Æt ®Ëp (cßn gäi lμ vai ®Ëp), hoÆc lμ trô ®Çu cÇu n¬i cã ®†êng dÉn lªn cÇu Accretion The accumulation of (beach) sediment, deposited by natural fluid flow processes Båi l¾ng Qu¸ tr×nh tÝch tô bïn c¸t do dßng ch¶y Aggradation A build-up or raising of the river/sea bed due to sediment deposition Båi tô Sù n©ng lªn cña ®¸y s«ng do qu¸ tr×nh båi l¾ng bïn c¸t Alignment The course along which the centre line of a channel, canal or drain is located §êng tuyÕn Lμ ®†êng trung t©m (tim) s«ng, kªnh t†íi, tiªu Alongshore see longshore Däc bê biÓn Xem tõ longshore Alluvial plane A plain bordering a river, formed by the deposition of material eroded from areas of higher elevation Vïng ®Êt båi tÝch Vïng ®ång b»ng h×nh thμnh do c¸c vËt chÊt mμi mßn tõ vïng cao h¬n ch¶y xuèng 9
11. Altitude Vertical height of a ground or water surface above a reference level (datum) Cao ®é §é cao theo ph†¬ng th¼ng ®øng so víi mÆt chuÈn Amplitude Half of the peak-to-trough range (or height) Biªn ®é Mét nöa kho¶ng c¸ch gi÷a ch©n vμ ®Ønh liªn tiÕp Angle of repose The maximum slope (measured from the horizon) at which soils and loose materials on the banks of canals, rivers or embankments stay stable Gãc nghØ Gãc nghiªng lín nhÊt theo ®ã ®Êt ®¸ vμ c¸c vËt chÊt cã thÓ n»m æn ®Þnh trªn m¸i Anisotropic Having properties that change with changing directions Kh«ng ®¼ng híng Cã tÝnh chÊt thay ®æi khi thay ®æi h†íng trong mét m«i tr†êng Antidunes Bed forms that occur in trains and that are in phase with and strongly interact with water-surface waves Sãng c¸t Mét d¹ng h×nh th¸i ®¸y s«ng cã d¹ng h×nh sin cïng pha víi sãng trªn mÆt Apron Layer of stone, concrete or other material to protect the toe of a seawall TÊm ch¾n TÊm ®¸, tÊm bª t«ng hoÆc vËt liÖu kh¸c b¶o vÖ ch©n kÌ hoÆc t†êng ®øng Armour layer Protective layer on a breakwater or sea wall composed or Armour units Líp b¶o vÖ Líp b¶o vÖ ngoμi ®ª ch¾n sãng hoÆc t†êng ®øng Armour unit Large quarried stone or specially shaped concrete block used as primary protection against wave action TÊm b¶o vÖ Mét viªn ®¸ tù nhiªn hoÆc 1 khèi bª t«ng cã h×nh d¹ng ®Æc biÖt ®†îc sö dông nh† lμ líp chèng sãng ngoμi cïng. Artificial Supplementing the natural supply of beach material to a beach, using imported nourishment, beach material. replenishment, recharge, beach feeding Nu«i b·i Bæ sung l†îng c¸t mÊt ®i t¹i mét ®o¹n bê biÓn Asperities The three-dimensional irregularities forming the surface of an irregular stone (or rock) subject to wear and rounding during attraction MÊu gi¶m sãng MÊu cÊu t¹o trªn bÒ mÆt viªn ®¸ hoÆc khèi bª t«ng vμ bÞ mμi nh½n dÇn khi bÞ sãng ®¸nh Astronomical tide The tidal levels and character which would result from gravitational effects, e.g. of the Earth, Sun and Moon, without any atmospheric influences TriÒu thiªn v¨n Mùc n†íc vμ c¸c ®Æc tr†ng triÒu do t¸c dông cña lùc träng tr†êng cña tr¸i ®Êt, mÆt trêi vμ mÆt tr¨ng bá qua ¶nh h†ëng cña khÝ quyÓn. Atoll A ring-shaped coral reef, often carrying low sand islands, enclosing a lagoon §¶o san h« vßng D¶i san h« ngÇm cã h×nh vßng cung, th«ng th†êng ph¸t triÓn ë ®¶o Ýt c¸t vμ qu©y quanh c¸c ®Çm ph¸ Attenuation A lessening of the amplitude of a wave with distance from the origin The decrease of water particle motion with increasing depth; particle motion resulting from surface oscillatory waves attenuates rapidly with depth, and practically disappears at a depth equal to a surface wavelength Sù t¾t dÇn Sù gi¶m dÇn biªn ®é sãng theo h†íng sãng tiÕn hay sù gi¶m chuyÓn ®éng cña h¹t n†íc khi ®é s©u t¨ng dÇn; ChuyÓn ®éng cña h¹t n†íc t¹o ra do dao ®éng cña sãng bÒ mÆt gi¶m nhanh theo ®é s©u vμ hÇu nh† t¾t h¼n ë ®é s©u b»ng chiÒu dμi sãng trªn mÆt 10
12. Back-rush The seaward return of water following the up-rush of a wave Dån ngîc Dßng ch¶y ng†îc ra biÓn sau khi sãng leo lªn bê Back-shore The upper part of the active beach above the normal reach of the tides (high water), but affected by large waves occurring during a high tide PhÇn trªn bê biÓn PhÇn phÝa trªn b·i biÓn cao h¬n mùc n†íc triÒu c†êng b×nh th†êng, nh†ng chÞu ¶nh h†ëng cña sãng lín trong kú triÒu c†êng Backwater curve The longitudinal profile of the water surface in an open channel where the depth of flow has been increased by an obstruction as a weir or a dam across the channel, by increase in channel roughness, by decrease in channel width or by a decrease of the bed gradient §êng cong níc vËt §†êng mÆt n†íc däc theo kªnh cã ®é s©u t¨ng dÇn khi dßng ch¶y ch¶y qua ®Ëp do t¨ng ®é nh¸m hay gi¶m ®é réng s«ng hay gi¶m ®é dèc ®¸y s«ng Bank (1) The rising grounds bordering a lake, river or sea; of a river or channel, Bӡ designated as right or left as it would appear facing downstream (1) Gê ®Êt cao bao quanh hå, s«ng, biÓn (2) An elevation of the sea floor of large area, located on a continental (or island) shelf and over which the depth is relatively shallow but sufficient for safe navigation; a group of shoals (2) Mét vïng ®¸y biÓn réng hoÆc thÒm lôc ®Þa cã cao tr×nh cao h¬n xung quanh (3) A shallow area consisting of shifting forms of silt, sand, mud, and gravel; in this case usually used with a qualifying word such as “sandbank”, “mudbank” (4) Vïng n«ng tÝch tô bïn, c¸t, hoÆc sái; Trong tr†êng hîp nμy th†êng dïng kh¸i niÖm d¶i c¸t hoÆc d¶i bïn Bar A submerged or emerged embankment of sand, gravel, or other unconsolidated material built on the sea floor in shallow water by waves and currents in front of a river entrance or and estuary Cӗn, doi D¶i c¸t, sái hoÆc c¸c vËt chÊt ch†a cè kÕt hoμn toμn n»m ngÇm d†íi ®¸y biÓn tÝch tô l¹i (®†îc dån l¹i) do sãng vμ dßng ch¶y tr†íc cöa s«ng vμ vÞnh triÒu Barrage A barrage built across a river, comprising a series of gates which when fully open allow the flood to pass without appreciably increasing the flood level upstream of the barrage TiÕng ViÖt gäi lμ Ba C«ng tr×nh x©y dùng trªn s«ng bao gåm mét lo¹t cèng mμ khi më hoμn toμn cã thÓ Ra th¸o ®†îc n†íc lò kh«ng lμm t¨ng mùc n†íc th†îng l†u Barrier The function of a barrier is to control the water level. It consists of a combination of concrete or a steel structure with or without adjacent rockfill Vұt chҳn Chøc n¨ng cña vËt ch¾n lμ kiÓm so¸t mùc n†íc, cã thÓ lμ c«ng tr×nh bª t«ng hoÆc c«ng tr×nh thÐp cã ®æ ®¸ hoÆc kh«ng ®æ ®¸ Barrier beach A bar, essentially parallel to the shore, the crest of which is above normal high water level; also called offshore barrier and barrier island VËt ch¾n ngoμi biÓn D¶i ®Êt mμ cao tr×nh cña nã th†êng cao h¬n mùc n†íc triÒu c†êng b×nh th†êng n»m song song víi bê biÓn; mét sè tμi liÖu gäi lμ ®¶o ch¾n hoÆc nói ch¾n ngoμi kh¬i Barrier island Long island, parallel to the shore, mainly consisting of sand, on which sometimes dunes are formed, behind which intertidal flats exists §¶o ch¾n §¶o n»m song song bê biÓn chñ yÕu lμ c¸t mμ phÝa trong ®ã lμ b·i triÒu. Barrier reef A coral reef parallel to an separated from the coast by a lagoon that is too deep for coral growth; generally, barrier reefs follow the coast for long distances, and are cut through at irregular intervals by channels or passes 11
13. §¶o san h« D¶i san h« n»m song song víi bê biÓn mμ gi÷a chóng lμ vÞnh triÒu kh¸ s©u. Th«ng th†êng d¶i san h« ph¸t triÓn kh¸ dμi däc theo bê biÓn vμ bÞ chia c¾t t¹i nh÷ng kho¶ng c¸ch kh«ng ®Òu bëi c¸c l¹ch s©u. Bastion A massive groyne, or projecting section of seawall normally constructed with its crest above water level. Má hμn Lμ má hμn vu«ng gãc víi t†êng ®øng víi cao tr×nh ®Ønh cao h¬n mùc n†íc Bathymetry Refers to the spatial variability of levels on the seabed §é s©u cña biÓn Liªn quan tíi sù thay ®æi cao ®é ®¸y biÓn Bay A recess in the shore or an inlet of the sea between two capes or headlands, not as large as a gulf but larger than a cove; see also bight and embayment VÞnh Chç hâm vμo ë bê biÓn hoÆc cöa biÓn gi÷a 2 mòi ®Êt nh« ra, nhá h¬n gulf, nh†ng lín h¬n cove Bayou A minor sluggish waterway or estuarial creek, tributary to, or connecting other streams or bodies of water; its course is usually through lowlands or swamps, sometimes called slough Con l¹ch Mét nh¸nh s«ng nhá hoÆc con l¹ch nèi víi c¸c s«ng suèi hoÆc hå kh¸c trong vïng ®Êt thÊp h¬n hoÆc vïng ®Êt ngËp n†íc, ®«i khi gäi lμ ®Çm lÇy Beach A deposit of non-cohesive material (e.g. sand, gravel) situated on the interface between dry land and the sea (or other large expanse of water) and actively "worked" by present-day hydrodynamics processes (i.e. waves, tides and currents) and sometimes by winds B·i biÓn Vïng cÊu t¹o bëi vËt liÖu kh«ng dÝnh kÕt víi nhau (C¸t hoÆc sái) n»m gi÷a biÓn vμ ®Êt liÒn vμ chÞu t¸c ®éng m¹nh cña c¸c qu¸ tr×nh ®éng lùc biÓn (sãng, triÒu vμ dßng ch¶y) vμ giã Beach crest The point representing the limit of high tide storm wave run-up (see Fig. 1.1) §Ønh b·i §iÓm ®¸nh dÊu giíi h¹n cao nhÊt sãng leo khi triÒu cao gÆp b·o Beach face From the beach crest owl to the limit of sediment movement (see Fig. 1.1) §é réng b·i Kho¶ng c¸ch theo chiÒu ngang tõ ®Ønh b·i tíi vïng n†íc kh«ng cßn bïn c¸t chuyÓn ®éng d†íi t¸c ®éng cña sãng n÷a (®†êng sãng vì) Beach head The cliff, dune or sea wall looming the land ward limit of the active beach (see Fig. 1.1) Mòi b·i Mám ®¸, doi c¸t nh« ra biÓn Beach material Granular sediments, usually sand or shingle moved by the sea VËt chÊt b·i biÓn H¹t c¸t chuyÓn ®éng d†íi t¸c ®éng c¸c nh©n tè biÓn vμ giã Beach plan shape The shape of the beach in plan; usually shown as a contour line, combination of contour lines or recognizably features such as beach crest and/or still water line MÆt b»ng b·i H×nh d¹ng cña b·i ®†îc thÓ hiÖn b»ng c¸c ®†êng ®ång møc th«ng qua ®ã mμ ph©n biÖt ®†îc ®Ønh b·i, mùc n†íc lÆng Beach profile A cross-section taken perpendicular to a given beach contour; the profile may include the face of a dune or sea wall, extend over the backshore, across the foreshore, and seaward underwater into the nearshore zone MÆt c¾t ngang b·i MÆt c¾t vu«ng gãc víi bê biÓn cã thÓ bao gåm mÆt b·i hoÆc t†êng ®øng ®†îc tÝnh c¶ phÇn trong cïng cña b·i + b·i + Vïng n†íc n«ng Beach recharge Supplementing the natural volume of sediment on a beach, using material from elsewhere - also known as beach replenishment / nourishment / feeding Nu«i b·i Bæ sung thªm c¸t vμo b·i tõ n¬i kh¸c 12
14. Beach scarp An almost vertical slope along the beach caused by erosion by wave action; it may vary in height from a few inches to several feet, depending on wave action and the nature and composition of the beach Bê dèc b·i PhÇn bê ®øng bÞ xãi do sãng. Theo chiÒu cao nã thay ®æi tõ vμi cm ®Õn hμng mÐt phô thuéc vμo c†êng ®é sãng, thμnh phÇn vμ cÊu t¹o cña vËt chÊt b·i Beach wall A (mostly vertical) structure of masonry or concrete to protect the backshore from erosion Têng ®øng T†êng bª t«ng hoÆc tre b¶o vÖ bê biÓn Bed forms Features on a seabed (e.g. ripples and sand waves) resulting from the movement of sediment over it H×nh th¸i ®¸y H×nh th¸i cña ®¸y biÓn (gîn sãng hoÆc sãng c¸t) khi c¸c vËt chÊt ®¸y chuyÓn ®«ng d†íi t¸c ®éng cña sãng, giã t¹o ra Bed load Sediment transport mode in which individual particles either roll or slide along the bed as a shallow, mobile layer a few particle diameters deep. Bïn c¸t ®¸y H×nh thøc chuyÓn ®éng cña bïn c¸t. C¸c h¹t vËt chÊt hoÆc l¨n, nh¶y hoÆc tr†ît Bed protection A (rock) structure on the bed in order to protect the underlying bed against erosion due to current and/or wave action Líp b¶o vÖ ®¸y Líp b¶o vÖ tr¸nh xãi ®¸y d†íi t¸c ®éng cña sãng vμ dßng ch¶y Bed shear stress The way in which waves (or currents) transfer energy to the sea bed øng suÊt c¾t ®¸y C¸ch mμ sãng hoÆc dßng ch¶y truyÒn n¨ng l†îng vμo ®¸y biÓn Benefits The economic value of a scheme, usually measured in terms of the cost of damages avoided by the scheme, or the valuation of perceived amenity or environmental improvements Lîi Ých Gi¸ trÞ kinh tÕ ®†îc ®o b»ng lîi Ých mang l¹i cña hÖ thèng (cã thÓ b»ng vËt chÊt cô thÓ hoÆc gi¸ trÞ mang l¹i do c¶i thiÖn m«i tr†êng) Bench marks A permanently fixed point of known elevation; a primary bench mark is one close to a tide station to which the tide staff and tidal datum originally are referenced §iÓm chuÈn Mét ®iÓm cè ®Þnh ®†îc g¾n cao ®é ®Æt gÇn tr¹m triÒu Berm On a beach: a nearly horizontal plateau on the beach face or backshore, formed by the deposition of beach material by wave action or by means of a mechanical plant as part of a beach recharge scheme On a structure: a nearly horizontal area, often built to support or key-in an armour layer C¬ Lμ ®o¹n n»m ngang trªn mÆt b»ng do tù nhiªn t¹o ra (sãng, giã) hoÆc mÆt ph¼ng trªn c«ng tr×nh ®Ó ®Æt líp b¶o vÖ. Berm breakwater Rubble mound with horizontal berm of armour stones at about sea-side water level, which is allowed to be (re)shaped by the waves. §ª ph¸ sãng cã c¬ Lμ c«ng tr×nh ®¸ cã c¬ n»m ngang phÝa biÓn. H×nh d¹ng cña nã cã thÓ bÞ biÕn d¹ng do t¸c ®éng cña sãng. Bifurcation Location where a river separates in two or more reaches or branches (the opposite of a confluence) Ph©n lu N¬i s«ng ph©n nh¸nh (ng†îc víi hîp l†u) Bight A bend in a coastline forming an open bay; a bay formed by such a bend Chç lâm vμo Chç cong vμo h×nh thμnh vÞnh hë. Blanket A layer or layers of graded fine stones underlying a breakwater, groyne or rock embankment to prevent the natural bed material being washed away. Líp b¶o vÖ Mét líp hoÆc nhiÒu líp ®¸ ®†îc xÕp cÊp phèi trong ®ª ph¸ sãng, kÌ hoÆc má hμn gi÷ kh«ng cho vËt chÊt trong c«ng tr×nh tr«i ra ngoμi 13
15. Bluff A high steep bank or cliff Dèc ®øng Bê rÊt dèc A very rapid rise of the tide in which the advancing water presents an abrupt front of considerable height; in shallow estuaries where the range of tide is large, the Bore high water is propagated inward faster that the low water because of the greater depth at high water; if the high water overtakes the low water, an abrupt front is presented with the high water crest finally falling forward as the tide continues to advance; sometimes called eager Thӫy triӅu Bo Qu¸ tr×nh triÒu lªn rÊt nhanh t¹o ra mÆt tr†íc cã chiÒu cao ®¸ng kÓ. ë nh÷ng vïng cöa s«ng n«ng khi gÆp triÒu cã biªn ®é lín, sãng thuû triÒu d©ng tiÕn vμo bê nhanh h¬n ë vïng biÓn cã ®é s©u lín h¬n, gÆp vïng n†íc n«ng t¹i ch©n triÒu lμm ®é dèc sãng t¨ng dÇn cho tíi khi sãng ®æ trªn ®†êng tiÕn. Boulder A rounded rock on a beach, greater than 250 mm in diameter, larger than a cobble - see also gravel, shingle §¸ cuéi lín §¸ cã kÝch th†íc lín h¬n 250 mm bÞ mμi trßn do sãng vμ dßng ch¶y Boundary conditions Environmental conditions, e.g. waves, currents, drifts, etc. used as boundary input to physical or numerical models §iÒu kiÖn biªn C¸c th«ng sè nh† sãng, dßng ch¶y, dßng tr«i v.v ®†îc sö dông nh† ®Çu vμo cña c¸c m« h×nh vËt lý vμ m« h×nh sè Bound long wave Long wave directly due to the variation in set-down at the breaker line due to wave groups Sãng dμi giíi h¹n Sãng dμi ®†îc t¹o ra do thay ®æi trong qu¸ tr×nh dao ®éng t¹i ®†êng sãng vì Braided river A river type with multiple channels separated by shoals, bars and islands S«ng d¹ng d¶i lôa Mét d¹ng s«ng nhiÒu nh¸nh ph©n c¸ch víi nhau b»ng c¸c ®¶o, b·i c¸t Breaching Failure of the beach head or a dike allowing flooding by tidal action Vì HiÖn t†îng vì ®ª hoÆc c¸c c¸c ®ôn c¸t vμ n†íc biÓn trμn vμo Breaker A wave breaking on a shore, over a reef, etc.; breakers may classified into four types: Spilling breaker; bubbles and turbulent water spill down front face of the wave; the upper 25 percent of the front face may become vertical before breaking; breaking HiÖn tîng sãng vì generally across over quite a distance; Punging breaker; crest curls over air pocket; breaking is usually with a crash; smooth splash-up usually follows; Collapsing breaker; breaking occurs over lower half of wave; minimal air pocket and usually no splash-up; bubbles and foam present; Surging breaker; Wave peaks up, but bottom rushes forward from under wave, and wave slides up beach face with little or no bubble production; water surface remains almost plane except where ripples may be produced on the beachface during runback HiÖn tîng vì Sãng vì ë bê biÓn hoÆc trªn c¸c d¶i ®¸ ngÇm. HiÖn t†îng vì ®uîc chia thμnh 4 lo¹i nh† trªn Breaker depth Depth of water, relative to still water level at which waves break; also known as breaking depth or limiting depth §é s©u vì §é s©u n†íc tÝnh tõ ®¸y tíi mùc n†íc thiÕt kÕ, t¹i ®ã sãng vì; cßn gäi lμ ®é s©u sãng vì hay ®é s©u giíi h¹n Breaker index Maximum ratio of wave height to water depth in the surf zone ChØ sè vì TØ sè lín nhÊt gi÷a chiÒu cao sãng vμ ®é s©u n†íc t¹i ®iÓm sãng vì Breaker zone The zone within which waves approaching the coastline commence breaking, typically in water depths of between 5 and 10 metres (see Figure 1.1) Vïng sãng vì Vïng khi sãng tiÕn vμo bê bÞ vì t¹i khu vùc nμy b¾t ®Çu vì, th«ng th†êng ë ®é s©u tõ 5 m ®Õn 10m (xem h×nh 1.1) 14
16. Breaking Reduction in wave energy and height in the surf zone due to limited water depth HiÖn tîng vì ViÖc gi¶m n¨ng l†îng vμ chiÒu cao sãng trong vïng sãng vì do ®é s©u nhá Breakwater A structure protecting a harbour entrance, anchorage or shore area from waves §ª ph¸ sãng C«ng tr×nh b¶o vÖ ®†êng vμo c¶ng, n¬i neo ®Ëu cña tμu thuyÒn hoÆc vïng bê biÓn khi chÞu t¸c ®éng cña sãng Breastwork Vertically-faced or steeply inclined structure usually built with timber and parallel to the shoreline, at or near the beach crest, to resist erosion or mitigate against flooding C«ng tr×nh b¶o vÖ C«ng tr×nh th¼ng ®øng hoÆc gÇn thÈng ®øng th†êng lμm b»ng gç, song song víi ®†êng bê t¹i ®†êng sèng cao trªn bê chèng xãi vμ gi¶m n†íc trμn Bulkhead A structure or partition to retain or prevent sliding of the land; a secondary purpose is to protect the upland against damage from wave action V¸ch ng¨n C«ng tr×nh chèng tr†ît ®Êt vμ b¶o vÖ phÇn ®Êt trªn cao kh«ng bÞ ph¸ huû do sãng Bull nose Substantial lip or protuberance at the top of the seaward face of a wall, to deflect waves seaward Mòi hÊt sãng PhÇn nh« ra t¹i ®Ønh vÒ phÝa biÓn cña t†êng ®øng cã t¸c dông hÊt sãng vÒ phÝa biÓn Buoy A loat; especially a floating object moored to the bottom, to mark a channel, anchor, shoal, rock, etc. Phao VËt næi ®†îc neo xuèng ®¸y ®¸nh dÊu ®†êng ®i, c¸c d¶i ®¸ ngÇm, vïng n«ng Bypassing Moving beach material from the up drift to the down drift side or an obstruction to longshore-drift VËn chuyÓn c¸t tõ phÝa ®†îc båi xuèng phÝa bÞ xãi cña c«ng tr×nh c¾t ngang bê biÓn Catchment area The area which drains naturally to a particular point on a river, thus contributing to its natural discharge DiÖn tÝch lu vùc Vïng høng n†íc m†a h×nh thμnh dßng ch¶y cña mét con s«ng Caisson Concrete box-type structure Thùng chìm Lo¹i c«ng tr×nh d¹ng hép b»ng bª t«ng Chart datum The level to which both tidal levels and water depths are reduced- on most Nautical charts, this level is that of the predicted lowest astronomical tide level (LAT) Cao ®é hμng h¶i Cao ®é ®†îc chän b»ng mùc n†íc triÒu thiªn v¨n thÊp nhÊt tÝnh to¸n. Clay A fine grained, plastic, sediment with a typical grain size less than 0.004 mm. Possesses electromagnetic properties which bind the grains together to give a bulk strength or cohesion §Êt sÐt H¹t mÞn, dÎo víi cì h¹t th†êng nhá h¬n 0.004 mm, cã tÝnh chÊt ®iÖn tõ lμm cho c¸c h¹t kÕt hîp l¹i víi nhau Climate change Refers to any long-term trend in mean sea level, wave height, wind speed, drift rate etc. Thay ®æi khÝ hËu VÊn ®Ò liªn quan tíi xu thÕ t¨ng cña mùc n†íc biÓn, chiÒu cao sãng, tèc ®é giã vμ tèc ®é vËn chuyÓn cña dßng tr«i Closure depth The depth at the offshore limit of discernible bathymetric change between surveys. Practically this is the limit of the cross-shore sediment transport. §é s©u lÊp dßng Lμ ®é s©u phÝa ngoμi kh¬i cho thÊy sù thay ®æi cña ®Þa h×nh ®¸y biÓn qua c¸c kú kh¶o s¸t. Trong thùc tÕ ®©y lμ khu vùc cã vËn chuyÓn bïn c¸t theo h†íng vu«ng gãc víi bê. Coastal defence General term used to encompass both coast protection against erosion and sea defence against flooding C«ng tr×nh b¶o vÖ bê §©y lμ thuËt ng÷ chung chØ c¸c c«ng tr×nh chèng xãi bê vμ n†íc trμn 15
17. Coastal forcing The natural processes which drive coastal hydro- and morphodynamics (e.g. winds, waves, tides, etc) C¸c t¶i träng vïng bê C¸c qu¸ tr×nh tù nhiªn chi phèi c¸c qu¸ tr×nh ®éng lùc vμ h×nh th¸i biÓn (Giã, sãng, thuû triÒu v.v ) Coastal processes Collective term covering the action of natural forces on the shoreline, and near shore seabed C¸c qu¸ tr×nh bê biÓn Thuұt ngӳ tәng hӧp vӅ tác ÿӝng tӵ nhiên lên ÿѭӡng bӡ và ÿáy biӇn gҫn bӡ Coastal zone Some combination of land and sea area, delimited by taking account of one or more elements Vïng bê Sù kÕt hîp gi÷a biÓn vμ ®Êt liÒn víi c¸c ho¹t ®éng kinh tÕ x· héi trong ®ã Coastline The development of a strategic, long-term and sustainable coastal defence policy, management sometimes also called ‘shoreline management' Qu¶n lý vïng bê Ph¸t triÓn c¸c chiÕn l†îc b¶o vÖ bÒn v÷ng d¶i ven bê Coast protection Protection of the land from erosion and encroachment by the sea B¶o vÖ bê B¶o vÖ ®Êt chèng xãi mßn vμ sù tÊn c«ng cña biÓn Cobble A rounded rock on a beach, with diameter ranging from about 75 to 250 mm - see also boulder, gravel, shingle Cuéi, sái §¸ trßn trªn bê biÓn cã ®†êng kÝnh tõ 75 ®Õn 250mm. Coffer dam A temporary structure enclosing all or part of the construction area so that construction can proceed in the dry §ª quai xanh C«ng tr×nh t¹m ®†îc qu©y kÝn vμ lμm kh« ®Ó x©y dùng c«ng tr×nh chÝnh Cohesive sediment Sediment containing significant proportion of clays, the electromagnetic properties of which cause the sediment to bind together Bïn c¸t dÝnh kÕt Bïn c¸t cã tØ lÖ h¹t sÐt cao. Víi tÝnh ®iÖn tõ cao c¸c h¹t nμy cã thÓ liªn kÕt víi nhau. Combined closure Construction of a dam by means of partly the horizontal closure method and partly method the vertical closure method Confluence The junction of two or more river reaches or branches (the opposite of a bifurcation) Hîp lu §iÓm héi tô cña 2 hay nhiÒu nh¸nh s«ng (ng†îc nghÜa víi ph©n l†u) Conservation The protection of an area, or particular element within an area, whilst accepting the dynamic nature of the environment and therefore allowing change B¶o toμn, b¶o vÖ B¶o vÖ mét vïng, mét c¸ thÓ trong vïng trong khi thõa nhËn b¶n chÊt n¨ng ®éng cña tù nhiªn víi sù thay ®æi cña nã. Consolidation The gradual, slow compression of a cohesive soil due to weight acting on it, which occurs as water is driven out of the voids in the soil. Consolidation only occurs in clays or other soils of low permeability Cè kÕt, hîp nhÊt Qu¸ tr×nh nÐn chÆt c¸c h¹t kÕt dÝnh diÔn ra chËm ch¹p do träng lùc b¶n th©n. N†íc tho¸t ra trong qu¸ tr×nh nμy. Cè kÕt x¶y ra ®èi víi ®Êt sÐt vμ c¸c ®Êt cã kh¶ n¨ng thÊm n†íc yÕu Core A cylindrical sample extracted from a beach or seabed to investigate the types and depths of sediment layers An inner, often much less permeable portion of a breakwater, or barrier beach Lâi MÉu h×nh trô lÊy tõ b·i hoÆc ®¸y biÓn ®Ó x¸c ®Þnh lo¹i ®Êt vμ ®é s©u t†¬ng øng Lâi lμ phÇn cã hÖ sè thÊm nhá nhÊt trong ®ª ch¾n sãng vμ c¸c c«ng tr×nh b¶o vÖ bê Coriolis Force due to the Earth's rotation, capable of generating currents Lùc Coriolis Lùc ph¸t sinh do tr¸i ®Êt quay cã kh¶ n¨ng t¹o dßng ch¶y 16
18. Cover layer The outer layer used in a revetment system as protection against external hydraulic loads Líp b¶o vÖ Líp ngoμi cïng cña kÌ chèng l¹i t¶i träng sãng giã Crenulate An indented or wavy shoreline beach form, with the regular seaward- pointing parts §êng bê r¨ng ca låi rounded rather than sharp, as in the cuspate type Mét d¹ng ®†êng bê h×nh gîn sãng (r¨ng c†a) víi phÇn ®Ønh låi trßn Crest Highest point on a beach lace, breakwater or sea wall §Ønh §iÓm cao nhÊt trªn bê biÓn, ®ª ph¸ sãng hay t†êng ch¾n sãng Cross-shore Perpendicular to the shoreline MÆt c¾t ngang Vu«ng gãc víi ®†êng bê Crown wall Concrete superstructure on a rubble mound Têng ®Ønh C«ng tr×nh bª t«ng n»m trªn ®ª ch¾n sãng cã ch©n b»ng ®¸ héc Current Flow of water Dßng ch¶y Dßng ch¶y Current-refraction Process by which wave velocity is affected by a current Khóc x¹ do dßng ch¶y Qu¸ tr×nh mμ vËn tèc sãng bÞ ¶nh h†ëng do dßng ch¶y Cusp Seaward bulge, approximately parabolic in shape, in the beach contours. May occur singly, in the lee of an offshore bulk or island, or as one of a number of similar, approximately regularly- spaced features on a long straight beach §Ønh, chám Chç låi ra phÝa biÓn h×nh parabol, cã thÓ lμ 1 c¸i ë phÝa khuÊt sãng hoÆc nhiÒu c¸i gÇn t†¬ng tù nhau trªn bê biÓn th¼ng Cuspate Form of beach shoreline involving sharp seaward-pointing cusps (normally at regular intervals) between which the shoreline follows a smooth arc. §Ønh nhän Mét d¹ng ®†êng bê cã nh÷ng ®iÓm nhän n»m gi÷a c¸c ®o¹n bê h×nh cung ch¬n Dam Structure built in rivers or estuaries, basically to separate water at both sides and/or to retain water at one side §Ëp C«ng tr×nh x©y ch¾n ngang s«ng, gi÷ n†íc Datum Any permanent line, plane or surface used as a reference datum to which elevations are referred Mèc, mùc chuÈn C¸c ®èi t†îng trªn mÆt ®Êt sö dông ®iÓm nμy nh† møc so s¸nh Deep water Water too deep for waves to be affected by the seabed; typically taken as half the wavelength, or greater Níc s©u N†íc s©u nªn sãng kh«ng bÞ ¶nh h†ëng bëi ®¸y. Th«ng th†êng lín h¬n hoÆc b»ng nöa b†íc sãng. Deflation Erosion of dunes by wind action Xãi do giã Xãi c¸c ®ôn c¸t do giã Degradation see erosion Suy gi¶m, suy tho¸i Xem xãi mßn Density mass (in kg) per unit of volume of a substance;kg/m3 Dung träng Khèi l†îng riªng, mËt ®é. Density current Phenomenon of relative flow within water due to difference in density; the salt- water wedge is a density current when stratification occurs between identifiable flow masses Dßng mËt ®é Dßng ch¶y trong n†íc do cã sù kh¸c nhau vÒ mËt ®é; nªm mÆn lμ dßng mËt ®é khi sù ph©n tÇng x¶y ra gi÷a c¸c khèi n†íc cã mËt ®é kh¸c nhau 17
19. Depth-limited Situation in which wave generation (or wave height)is limited by water depth §é s©u giíi h¹n §é s©u t¹i ®ã viÖc t¹o sãng bÞ h¹n chÕ bëi ®é s©u n†íc Design storm Seawalls will often be designed to withstand wave attack by the extreme design storm. The severity of the storm (i.e. return period) is chosen in view of the acceptable level of risk of damage or failure. A design storm consist of a design wave condition, a design water level and a duration. B·o thiÕt kÕ T†êng ®øng th†êng ®†îc thiÕt kÕ chèng chÞu ®†îc søc ph¸ ho¹i cña b·o thiÕt kÕ . Chu kú lÆp l¹i ®†îc chän dùa trªn quan ®iÓm thõa nhËn møc rñi ro x¸c ®Þnh. B·o thiÕt kÕ bao gåm sãng thiÕt kÕ, mùc n†íc vμ thêi ®o¹n thiÕt kÕ. Design wave Usually an extreme wave condition with a specified return period used in the design condition of coastal works §iÒu kiÖn sãng thiÕt Th«ng th†êng ®iÒu kiÖn sãng cùc h¹n víi chu kú lÆp l¹i x¸c ®Þnh ®†îc sö dông kÕ trong thiÕt kÕ c«ng tr×nh bê biÓn Detached breakwater A breakwater without any constructed connection to the shore §ª ph¸ sãng t¸ch rêi C«ng tr×nh ph¸ sãng t¸ch rêi khái bê biÓn Diffraction Process affecting wave propagation, by which wave energy is radiated normal to the direction of wave propagation into the lee of an island or breakwater NhiÔu x¹ Qu¸ tr×nh t¸c ®éng lªn sù truyÒn sãng theo ®ã n¨ng l†îng sãng bÞ ph¸t x¹ vu«ng gãc víi h†íng truyÒn sãng vμo phÝa khuÊt sãng cña ®¶o hoÆc ®ª ph¸ sãng. Diffraction coefficient Ratio of diffracted wave height to deep water wave height HÖ sè nhiÔu x¹ TØ sè gi÷a chiÒu cao sãng nhiÔu x¹ so víi chiÒu cao sãng n†íc s©u Dike Sometimes written as dyke; earth structure along sea or river in order to protect littoral lands from flooding by high water; dikes along rivers are sometimes called levees §ª Cã thÓ viÕt Dyke lμ c«ng tr×nh ®Êt däc theo s«ng hoÆc bê biÓn ®Ó b¶o vÖ c¸c vïng ®Êt duyªn h¶i bÞ n†íc trμn. §ª däc s«ng cßn gäi lμ levees Discharge The volume of water per unit of time flowing along a pipe or channel Lu lîng ThÓ tÝch n†íc trªn mét ®¬n vÞ thêi gian ch¶y qua mÆt c¾t ngang s«ng hay èng Ditch A long and small channel to convey water for irrigation or drainage R·nh Lμ kªnh nhá, dμi chuyÓn n†íc t†íi hoÆc tiªu Diversion channel A waterway used to divert water from its natural course. The term is generally applied to a temporary arrangement e.g. to by-pass water around a dam site during construction Kªnh chuyÓn níc Kªnh sö dông chuyÓn n†íc sang l†u vùc kh¸c. Kh¸i niÖm nμy còng ®†îc dïng nh† lμ c«ng tr×nh t¹m chuyÓn n†íc ra h†íng kh¸c ®Ó thi c«ng Diurnal Literally ‘of the day’, but here meaning having a period or a ‘tidal day’, i.e. about 24.8 hours Mét ngμy ®ªm NghÜa thËt lμ ngμy. ë ®©y cã nghÜa chØ nhËt triÒu víi t=24.8 giê Downdrift In the direction of the next long shore transport of beach material Tr«i xu«i Theo h†íng chuyÓn ®éng cña vËt chÊt ®¸y däc theo bê biÓn Drowned flow see sub-critical flow Ch¶y ªm Dßng ch¶y d†íi ph©n giíi Drying beach That part of the beach which is uncovered by water (e.g. at low tide). Sometimes referred to as 'sub-aerial' beach B·i biÓn kh« PhÇn b·i kh«ng cã n†íc, cßn gäi lμ 'sub-aerial' beach 18
20. Dunes Accumulations of windblown sand on the backshore, usually in the form of small hills or ridges, stabilized by vegetation or control structure A type of bed form indicating significant sediment transport over a sandy seabed §ôn c¸t C¸t tÝch tô do giã phÝa trong mÐp n†íc. tån t¹i d†íi d¹ng c¸c nói c¸t nhá ®†îc cè ®Þnh bëi líp c©y cèi hoÆc c«ng tr×nh khèng chÕ Durability The ability of a rock to retain its physical and mechanical properties (i.e. resist degradation) in engineering service. TÝnh bÒn, l©u bÒn Kh¶ n¨ng b¶o tån c¸c tÝnh chÊt c¬ lý cña ®Êt ®¸ (chèng l¹i ph¸ huû) trong kü thuËt Duration The length of time a wind blows at a particular speed and from the same direction during the generation of storm waves Thêi kho¶ng Kho¶ng thêi gian giã thæi víi tèc ®é x¸c ®Þnh theo 1 h†íng x¸c ®Þnh trong qu¸ tr×nh t¹o sãng Dyke see dike Dynamic equilibrium Short term morphological changes that do not affect the morphology over a long period C©n b»ng ®éng Sù thay ®æi h×nh th¸i tøc thêi kh«ng ¶nh h†ëng tíi ®Þa m¹o trong thêi kho¶ng dμi Dynamic viscosity In fluid dynamics, the ratio between the shear stress acting along any plane between neighbouring fluid elements and the rate of deformation of the velocity gradient perpendicular to this plane §é nhít ®éng lùc Trong ®éng lùc häc chÊt láng, tØ sè gi÷a lùc c¾t t¸c ®éng lªn mét mÆt bÊt kú gi÷a c¸c phÇn tö chÊt láng vμ tèc ®é biÕn d¹ng cña gradient vËn tèc theo h†íng vu«ng gãc víi mÆt ph¼ng ®ã Ebb Period when tide level is falling; often taken to mean the ebb current which occurs during this period Níc rót Thêi kú n†íc triÒu xuèng thÊp víi sù xuÊt hiÖn dßng triÒu rót Ebb current Seaward movement of water along a tidal channel Dßng rót ChuyÓn ®éng h†íng ra biÓn cña dßng n†íc däc theo l¹ch triÒu Eddy A vortex type motion of water flowing partly opposite to the main current Xo¸y ChuyÓn ®éng xo¸y cña n†íc víi 1 phÇn ng†îc víi h†íng cña dßng ch¶y chÝnh Edge waves Waves which mainly exist shoreward of the breaker line, and propagate along the shore. They are generated by the incident waves, their amplitude is a maximum at the shoreline and diminishes rapidly in a seaward direction Sãng biªn Sãng tån t¹i chñ yÕu phÝa trong ®†êng sãng vì vμ truyÒn däc theo ®†êng bê. Nã ®†îc t¹o ra do sãng tíi, biªn ®é cña nã lín nhÊt t¹i ®†êng mÐp n†íc vμ gi¶m nhanh ra phÝa ngoμi Embankment Fill material, usually earth or rock, placed with sloping sides and with a length greater than its height. Usually an embankment is wider than a dike §ª ch©n réng C«ng tr×nh ®Êt hoÆc ®¸ cã m¸i nghiªng, th†êng cã ch©n réng h¬n ®ª th«ng th†êng Epifauna Animals living in the sediment surface or on the surface of other plants or animals HÖ ®éng vËt mÆt ®¸y §éng vËt sèng trªn c¸t, trªn c¬ thÓ ®éng vËt, thùc vËt kh¸c Erosion The wearing away of material by the action of natural forces. Xãi mßn Röa tr«i vËt chÊt bëi c¸c t¸c nh©n tù nhiªn. Event An occurrence meeting specified conditions, e.g. damage, a threshold wave height or a threshold water level Trêng hîp, kh¶ ViÖc x¶y ra trong ®iÒu kiÖn cô thÓ. VÝ dô tæn thÊt, chiÒu cao sãng, mùc n†íc tíi h¹n n¨ng, sù kiÖn 19
21. Exponential A model probability distribution distribution Mét d¹ng ph©n bè x¸c suÊt Ph©n bè hμm mò Extreme The value expected to be exceeded once, on average, in a given (long) period of time Cùc h¹n (cùc trÞ) Gi¸ trÞ v†ît qu¸ trung b×nh trong mét thêi kú x¸c ®Þnh nμo ®ã Facing A coating of a different material, masonry or brick, for architectural or protection purposes, e.g. stonework facing, brickwork facing (concrete dam) or an impervious coating on the upstream slope of a dam MÆt ngoμi Líp ngoμi lμm b»ng c¸c vËt liÖu kh¸c nhau theo quan ®iÓm kiÕn tróc Fetch Distance over which a wind acts to produce waves - also termed fetch length §μ giã Kho¶ng c¸ch mμ giã t¸c ®éng g©y sãng. Cßn gäi lμ chiÒu dμi ®μ giã Fetch-limited Situation in which wave energy (or wave height) is limited by the size of the wave generation area (fetch) §μ giã giíi h¹n T×nh tr¹ng n¨ng l†îng sãng (chiÒu cao sãng) bÞ h¹n chÕ do chiÒu dμi vïng t¹o sãng Filter Intermediate layer, preventing fine materials of an underlayer from being washed through the voids of an upper layer TÇng läc Líp b¶o vÖ c¸c vËt chÊt mÞn kh«ng bÞ röa tr«i th«ng qua c¸c lç rçng Flaws Discontinuities and voids within a piece of rock. VÕt nøt, chç r¹n T×nh tr¹ng kh«ng liªn tôc vμ cã lç hæng trong ®¸ Flood Period when tide level is rising; often taken to mean the flood current which occurs during this period A flow beyond the carrying capacity of a channel Lò lôt Thêi kú triÒu lªn t†¬ng øng víi dßng triÒu lªn. Dßng ch¶y qu¸ lín so víi kh¶ n¨ng dÉn cña kªnh. Flood current Landward movement of water along a tidal channel Dßng triÒu lªn Dßng ch¶y h†íng vμo ®Êt liÒn trong l¹ch triÒu. Flood gate A gravity outlet fitted with vertically-hinged doors, opening if the inner water level is higher than the outer water level, so that drainage takes place during low water Cèng ng¨n triÒu TÊm ch¾n n†íc trôc ®øng cã thÓ më khi mùc n†íc trong ®ång cao h¬n ngoμi s«ng ®Ó th¸o n†íc ra lîi dông mùc n†íc thÊp ngoμi s«ng Flood mark Proof of any kind on the shoreline used to determine the highest level attained by the water surface during the flood (note: the height of the flood mark usually includes the wave run-up) VÕt triÒu cao nhÊt DÊu ®¸nh lªn vËt bÊt kú trªn bê biÓn x¸c ®Þnh mùc n†íc triÒu cao nhÊt (th«ng th†êng bao gåm c¶ sãng leo) Flood plain The area within the flood embankments or within the flood dikes (in Europe often called winterbed) Vòng chøa lò DiÖn tÝch n»m ngoμi hoÆc trong ®ª (Ch©u ¢u gäi lμ winterbed) Flood routing The attenuating effect of storage on a river-flood passing through a valley by reason of a feature acting as control (e.g. a reservoir with a spillway capacity less than the flood inflow, or the widening or narrowing of a valley) §êng th¸o lò Lμm gi¶m l†îng lò trong hå chøa víi viÖc th¸o qua mét vïng tròng khi n¨ng lùc th¸o cña ®Ëp trμn kh«ng ®¸p øng Flood wall, splash Wall, retired from the seaward edge of the seawall crest, to prevent water from wall flowing onto the land behind Têng ch¾n T†êng chèng n†íc trμn vμo c¸c vïng ®Êt phÝa sau 20
22. Flow regime Combinations of river discharge and corresponding water levels and their respective (yearly or seasonally) averaged values and characteristic fluctuations around these values ChÕ ®é ch¶y C¸c ®Æc tr†ng nh† l†u l†îng, mùc n†íc mïa, n¨m vμ sù dao ®éng cña nã Forecasting Prediction of conditions expected to occur in the near future, up to about two days ahead Dù b¸o Dù b¸o c¸i cã thÓ x¶y ra trong t†¬ng lai víi thêi kho¶ng tèi ®a lμ 2 ngμy Foreshore An intertidal area below highest tide level and above lowest tide level (see Figure 1.1) B·i biÓn DiÖn tÝch b·i n»m gi÷a mùc n†íc triÒu cao nhÊt vμ thÊp nhÊt (xem h×nh 1.1) Freeboard The height of the crest of a structure above the still water level §é cao gia cêng §Ønh c«ng tr×nh lÊy thªm ë trªn cao ®é thiÕt kÕ Free flow A flow through a canal or over a structure which is not affected by the level of the tail water Ch¶y tù do Dßng ch¶y trong s«ng hay qua c«ng tr×nh kh«ng bÞ ¶nh h†ëng cña mùc n†íc h¹ l†u Friction Process by which energy is lost through shear stress Ma s¸t Qu¸ tr×nh n¨ng l†îng bÞ tiªu hao do øng suÊt c¾t Friction factor Factor used to represent the roughness of the sea bed HÖ sè ma s¸t HÖ sè ®†îc sö dông ®Ó biÓu diÔn ®é nh¸m cña ®¸y s«ng Frontager Person or persons owning, and often living in, property immediately land ward of the beach Ng†êi hoÆc nhãm ng†êi sèng ngay trªn bê biÓn, tμi s¶n cña hä n»m ngay ë d¶i ®Êt cËn kÒ víi biÓn Froude number A dimensionless number representing the ratio of inertia forces and gravity forces acting upon water and making it possible to distinguish between sub-critical and super-critical flow (Fr2 = v2/gh) HÖ sè b»ng tØ sè gi÷a lùc qu¸n tÝnh vμ träng lùc t¸c dông lªn khèi n†íc. Dïng hÖ sè nμy ®Ó ph©n biÖt tr¹ng th¸i ch¶y xiÕt vμ ch¶y ªm. Fully-developed sea A wave condition which cannot grow further without an increase in wind speed - also fully-arisen sea Møc ph¸t triÓn hoμn Sãng ph¸t triÓn ®Õn møc ®é lín nhÊt kh«ng thÓ t¨ng thªm ®†îc n÷a trõ khi tèc ®é chØnh giã t¨ng lªn. Function In management: generally a listing of activities or responsibilities, which an organization is empowered or authorized to carry out; in practice an organizations may not carry out all of these at any one particular period Chøc n¨ng Trong qu¶n lý: Chuçi c¸c ho¹t ®éng hoÆc tr¸ch nhiÖm mμ mét c¬ quan hay tæ chøc ph¶i thùc hiÖn. Trong thùc tÕ, mét tæ chøc cã thÓ kh«ng thùc hiÖn tÊt c¶ c«ng viÖc ë mét thêi kú nhÊt ®Þnh nμo ®ã Gabion Steel wire-mesh basket to hold stones or crushed rock to protect a bank or bottom from erosion Rä ®¸ Lång b»ng s¾t hoÆc thÐp cho ®¸ vμo trong b¶o vÖ bê hoÆc ®¸y s«ng. Gate Adjustable barrier across a channel, which can be moved to regulate the flow and/or the level of water Cöa ThiÕt bÞ chÆn ngang kªnh ®Ó ®iÒu tiÕt dßng ch¶y Gauge Device for measuring the water level relative to a datum Thíc níc, tr¹m ®o ThiÕt bÞ ®Ó ®o mùc n†íc 21
23. mùc níc Geotextile A synthetic fabric which may be woven or non-woven used as a filter V¶i ®Þa kü thuËt Lo¹i v¶i dÖt hoÆc kh«ng dÖt lμm viÖc nh† mét tÇng läc GIS Geographical Information System. A database of information which is geographically orientated, usually with an associated visualization system HÖ thèng th«ng tin Mét hÖ th«ng tin mμ c¬ së d÷ liÖu thu thËp th†êng liªn quan tíi hÖ thèng nghe nh×n ®Þa lý Gradient a measure of slope (soil- or water-surface) in meters of rise or fall per meter of horizontal distance more general, a change of a value per unit of distance, e.g. the gradient in longshore transport causes erosion or accretion §é ®èc, §é nghiªng Lμ tØ sè gi÷a chiÒu cao (m) so víi kho¶ng c¸ch ngang t†¬ng øng (m) Grading Distribution, with regard to size or weight, of individual stones within a bulk volume; heavy, light and fine grading are distinguished CÊp phèi h¹t Ph©n bè (cì h¹t hoÆc khèi l†îng) cña mét mÉu ®Êt ®¸ trong mét thÓ tÝch x¸c ®Þnh. Gradual closure Method in which the final closure gap in a dam is closed gradually either by the method vertical or horizontal closure method; this in contradiction with a sudden closure Ph¬ng ph¸p lÊp Ph†¬ng ph¸p lÊp dÇn theo líp, nh†ng ®Õn giai ®o¹n cuèi lÊp theo ph†¬ng th¼ng dßng theo líp ®øng hoÆc ngang. Ph†¬ng ph¸p nμy ®èi lËp víi ph†¬ng ph¸p chÆn dßng tøc thêi Granular filter A band of granular material which is incorporated in an embankment, dam, dike, or bottom protection and is graded so as to allow seepage to flow across or down the filter zone without causing the migration of the material adjacent to the filter TÇng läc th«ng Líp ®¸ ®Æt trong kÌ, m¸i ®ª, th©n ®Ëp theo mét cÊp phèi nhÊt ®Þnh cho phÐp n†íc thêng thÊm qua nh†ng c¸c h¹t ®Êt phÝa trong kh«ng thÓ tho¸t ra. Gravel Beach material, coarser than sand but finer than pebbles (2-4 mm diameter) Sái VËt chÊt trªn b·i biÓn cã kÝch th†íc lín h¬n c¸t, nh†ng nhá h¬n cuéi (d = 2-4mm) Group velocity The speed of wave energy propagation. Half the wave phase velocity in deep water, but virtually the same in shallow water Tèc ®é nhãm Tèc ®é truyÒn n¨ng l†îng sãng b»ng 0.5 tèc ®é sãng n†íc s©u vμ b»ng tèc ®é trong n†íc n«ng. Groyne Narrow, roughly shore-normal structure built to reduce longshore currents, and/or to trap and retain beach material. Most groynes are of timber or rock, and extend from a sea wall, or the backshore, well onto the foreshore and rarely even further offshore. In the USA and historic-ally called a groin Má hμn C«ng tr×nh lμm gi¶m dßng ven bê vμ gi÷ c¸t ë bê biÓn. HÇu hÕt c¸c má hμn lμm b»ng gç hoÆc ®¸ víi gèc má hμn tõ bê hoÆc t†êng ®øng v†¬n ra biÓn. Groyne bay The beach compartment between two groynes Vïng b·i gi÷a má hμn Vïng b·i n»m gi÷a 2 má hμn Gumbel distribution A model probability distribution, commonly used in wind and water level analysis Ph©n bè Gumbel Mét lo¹i hμm ph©n bè x¸c suÊt dïng ®Ó ph©n tÝch giã vμ mùc n†íc Habitat the natural home of a plant or animal M«i trêng sèng N¬i sèng tù nhiªn cña ®éng hoÆc thùc vËt Hard defences General term applied to impermeable coastal defense structures of concrete, timber, B¶o vÖ cøng steel, masonry, etc, which reflect a high proportion of incident wave energy, ft. soft defences Kh¸i niÖm chung cña c¸c c«ng tr×nh b¶o vÖ bê biÓn kh«ng thÊm b»ng thÐp, bª tßn hoÆc gç. Nã ph¶n x¹ phÇn lín n¨ng l†îng sãng ®Õn so víi gi¶i ph¸p b¶o vÖ mÒm 22
24. Head Seaward end of breakwater or dam §Çu §Çu phÝa biÓn cña ®Ëp ph¸ (ch¾n) sãng hoÆc ®ª, ®Ëp Headwater level The level of water in the reservoir Mùc níc thîng lu Mùc n†íc trong hå chøa Hindcasting In wave prediction, the retrospective forecasting of waves using measured wind information Dù b¸o theo tμi liÖu Mét ph†¬ng ph¸p dù b¸o phôc håi sãng sö dông tμi liÖu giã quan tr¾c tõ tr†íc. quan tr¾c Historic event Extreme analysis based on hindcasting typically ten events over a period of 100 analysis years Ph©n tÝch c¸c sè liÖu Ph©n tÝch cùc h¹n dùa trªn Ýt nhÊt 10 sè liÖu lÞch sö trong vßng 100 n¨m. lÞch sö Horizontal closure Construction of a dam by dumping the materials from one or both banks, thus method constricting the channel progressively laterally until the dam is closed. This method is also known as end dumping and point tipping Ph¬ng ph¸p chÆn Ph†¬ng ph¸p x©y dùng ®Ëp b»ng c¸ch ®æ ®Êt ®¸ tõ 2 bê vμ gi÷a s«ng cho ®Õn khi dßng theo ph¬ng lÊp kÝn. Ph†¬ng ph¸p nμy cßn ®†îc gäi lμ ph†¬ng ph¸p chÆn ®iÓm ngang Hurricane A tropical cyclone with wind of 75 mph (120 km/hr or 65 knots) or greater in which winds tend to spiral inward towards a core of low pressure; hurricanes occur especially in the western Atlantic, are usually accompanied by rain, thunder and lightning, and sometimes move into temperate latitudes. In south-east Asia these cyclones are usually called typhoons B·o (c¸ch gäi cña c¸c Xo¸y thuËn nhiÖt ®íi víi tèc ®é giã > = 120 km/giê. Giã xo¸y vμo t©m. Xo¸y x¶y ra níc B¾c Mü) ë §¹i t©y d†¬ng th†êng kÌm theo m†a, sÊm sÐt. Vïng §«ng nam ¸ gäi lμ b·o. Hydraulic radius quotient of the wetted cross-sectional area and the wetted perimeter B¸n kÝnh thuû lùc TØ sè gi÷a diÖn tÝch †ít vμ chu vi †ít Incident wave Wave moving landward Sãng tíi (®Õn) Sãng chuyÓn ®éng vμo bê Infauna Animals living in the sediment §éng vËt sèng trong bïn c¸t Infragravity waves Waves with periods above about 30 seconds generated by wave groups breaking in the surf zone Sãng ngo¹i träng lùc Sãng víi chu kú kho¶ng 30s t¹o ra bëi nhãm sãng vì ë vïng sãng vì Inshore Areas where waves are transformed by interaction with the sea bed GÇn bê Vïng sãng chÞu ¶nh h†ëng ma s¸t ®¸y biÓn Internal erosion The formation of voids within soil or soft rock caused by the mechanical or chemical removal of material by seepage Xãi néi t¹i H×nh thμnh lç rçng trong ®Êt ®¸ do c¸c qu¸ tr×nh c¬ häc hoÆc ho¸ häc khi n†íc thÊm qua Intertidal The zone between the high and low water marks Vïng triÒu Vïng giíi h¹n gi÷a mùc n†íc triÒu cao nhÊt vμ thÊp nhÊt Irregular waves Waves with random wave periods (and in practice, also heights), which are typical Sãng kh«ng ®Òu for natural wind-induced waves Sãng cã chu kú ngÉu nhiªn do giã tù nhiªn g©y ra Isobath Line connecting points of equal depth, a seabed contour §êng ®¼ng trÞ §†êng ®¼ng s©u hoÆc ®¼ng cao ®é ®¸y biÓn 23
25. Isopachyte Line connecting points on the seabed with an equal depth of sediment §êng ®¼ng ®é dμy §†êng nèi c¸c ®iÓm ®¸y biÓn cã cïng ®é dμy trÇm tÝch Joint probability The probability of two (or more) things occurring together X¸c suÊt liªn hîp X¸c suÊt cña hai hoÆc nhiÒu sù kiÖn x¶y ra ®ång thêi Joint probability Function specifying the joint distribution of two (or more) variables density Hμm ph©n bè x¸c Hμm biÓu diÔn ph©n bè liªn hîp cña hai hay nhiÒu biÕn suÊt liªn hîp Joint return period Average period of time between occurrences of a given joint probability event Chu kú lÆp l¹i liªn Kho¶ng thêi gian trung b×nh khi x¶y ra sù kiÖn víi x¸c suÊt liªn hîp hîp JONSWAP spectrum Wave spectrum typical of growing deep water waves Phæ JONSWAP Phæ ®Æc tr†ng sãng n†íc s©u ®ang ph¸t triÓn Kinematic viscosity The dynamic viscosity divided by the fluid density Nhít ®éng häc TØ sè gi÷a hÖ sè nhít ®éng lùc vμ mËt ®é cña chÊt láng Levee river dike Mét tªn gäi kh¸c cña ®ª (river dike) Limit of storm A position, typically a maximum water depth of 8 to 10 metres, often identifiable erosion on surveys by a break (i.e. sudden change) in slope of the bed Giíi h¹n xãi do b·o Lμ hè xãi cã chiÒu s©u tíi 8 - 10m, thÓ hiÖn b»ng sù thay ®æi ®ét ngét ®é dèc ®¸y. Lining A coating of atsphaltic concrete, concrete or impervious geotextile to provide watertightness, to prevent erosion or to reduce friction of a canal, tunnel or shaft Líp b¶o vÖ Líp ¸o b»ng bª t«ng atsphalt, bª t«ng th†êng hoÆc v¶i ®Þa kü thuËt kh«ng thÊm ®Ó chèng xãi hoÆc gi¶m ma s¸t ®¸y kªnh hoÆc mÆt trong cña ®†êng hÇm Littoral Of or pertaining to the shore Duyªn h¶i, ven biÓn Vïng ven bê biÓn Littoral drift The movement of beach material in the littoral zone by waves and currents. Includes movement parallel (long shore drift) and sometimes also perpendicular (cross-shore transport) to the shore VËt tr«i d¹t ven biÓn ChuyÓn ®éng cña c¸c vËt tr«i næi ven biÓn do sãng hoÆc dßng ch¶y bao gåm c¶ chuyÓn ®éng däc bê vμ vu«ng gãc víi bê Littoral transport see littoral drift ChuyÓn ®éng ven biÓn Xem littoral drift Littoral zone Beach plus surf zone Vïng duyªn h¶i Bao gåm bê biÓn ®Õn giíi h¹n sãng vì Locally generated Waves generated within the immediate vicinity, say within 50 km, of the point of waves interest Sãng ®Þa ph¬ng Sãng ®†îc t¹o ra lËn cËn ®iÓm nghiªn cøu víi kho¶ng c¸ch tèi ®a lμ 50 km Lock Structure with 2 doors and a chamber to allow ships to sail from a channel section with high water to a channel section with lower water and vice-versa ¢u thuyÒn C«ng tr×nh cã 2 cöa cho tμu thuyÒn chuyÓn vËn tõ n¬i n†íc cao tíi n¬i n†íc thÊp vμ ng†îc l¹i Log-normal A model probability distribution; a distribution where not the events, but the logs of distribution the events are normal distributed Ph©n bè log chuÈn Lμ mét d¹ng ph©n bè x¸c suÊt mμ loga cña sù kiÖn tu©n theo ph©n bè chuÈn 24
26. Long-crested random Random waves with variable heights and periods but a single direction waves Sãng ngÉu nhiªn ®Ønh Sãng cã chiÒu cao vμ chu kú ngÉu nhiªn nh†ng h†íng kh«ng ®æi dμi Longshore Parallel and close to the coastline Däc bê Song song víi ®†êng bê Longshore bar Bar running approximately parallel to the shoreline B·i c¸t ch¹y däc bê B·i c¸t gÇn nh† song song víi ®†êng bê Longshore drift Movement of (beach) sediments approximately parallel to the coastline Dßng bïn c¸t däc bê ChuyÓn ®éng cña bïn c¸t gÇn nh† song song víi ®†êng bê Long waves Waves with periods above about 30 seconds generated by wave groups breaking in the surf zone Sãng dμi Sãng cã chu kú kho¶ng 30 s ®†îc t¹o ra bëi nhãm sãng vì ë vïng sãng vì Macro-tidal Tidal range greater than 4 m TriÒu cùc lín Biªn ®é triÒu lín h¬n 4 m Mach-stem wave Higher-than-normal wave generated when waves strike a structure at an oblique angle. Sãng h×nh lìi m¸c Sãng cã chiÒu cao h¬n sãng th«ng th†êng khi nã ®Ëp vμo c«ng tr×nh víi h†íng xiªn Managed retreat The deliberate setting back of the existing line of defence in order to obtain engineering and/or environmental advantages - also referred to as managed landward realignment C¶i t¹o cã qu¶n lý Lïi mét c¸ch cã chñ ®éng ®†êng bê hiÖn t¹i ®Ó ®¹t ®Õn mét vÊn ®Ò kü thuËt hoÆc m«i tr†êng. Marginal probability The probability of a single variable in the context of a joint probability analysis X¸c suÊt biªn X¸c suÊt cña mét biÕn ®¬n trong ph¹m vi ph©n tÝch x¸c suÊt liªn hîp Marginal return The return period of a single variable in the context of a joint probability analysis period Chu kú biªn Chu kú lÆp l¹i cña mét biÕn ®¬n trong ph¹m vi ph©n tÝch x¸c suÊt liªn hîp Mattress A blanket of brushwood or bamboo, poles, geotextile and reed lashed together to Th¶m, nÖm, ®Öm protect a shoreline, embankment or river/sea bed against erosion Bã c©y, que, cäc, v¶i ®Þa kü thuËt liªn kÕt víi nhau ®Ó b¶o vÖ bê, m¸i hoÆc ®¸y s«ng Mean wave period The mean of all individual waves in an observation interval of approximately half an hour. In case of a Rayleigh-distribution 63% of the significant wave height Chu kú sãng trung Gi¸ trÞ trung b×nh cña tÊt c¶ c¸c con sãng trong kho¶ng 30 phót quan tr¾c. Víi ph©n b×nh bè Rayleigh, chiÒu cao sãng trung b×nh b»ng 63% chiÒu cao sãng hiÖu qu¶. Meandering A single channel having a pattern of successive deviations in alignment which results in a more or less sinusoidal course Uèn khóc Sù thay ®æi cña dßng s«ng theo d¹ng h×nh sin nh×n trªn trôc s«ng Meso-tidal Tidal range between 2 m and 4 m TriÒu trung b×nh §é lín triÒu tõ 2 ®Õn 4 m Micro-tidal Tidal range less than 2 m TriÒu nhá §é lín triÒu nhá h¬n 2 m Monochromatic A series of waves, each of which has the same wave period. waves Sãng ®¬n Lμ tËp hîp sãng cã chu kú gièng nhau 25
27. Morphologically A single wave condition producing the same next longshore wave condition drift as averaged a given proportion of the annual wave climate Trung b×nh ®Þa m¹o Sãng ®¬n t¹o nªn dßng bïn c¸t däc bê theo mét tØ lÖ x¸c ®Þnh cña sãng trong n¨m Morphology River/estuary/lake/seabed form and its change with time. §Þa m¹o D¹ng s«ng, cöa s«ng, hå, ®¸y biÓn vμ sù thay ®æi cña nã theo thêi gian Mud flat An area of fine silt usually exposed at low tide but covered at high tide, occurring in sheltered estuaries or behind shingle bars or sand spits B·i lÇy, b·i bïn Mét vïng thμnh t¹o bëi c¸c h¹t mÞn, næi lªn khi triÒu kÐm, nh†ng bÞ ngËp khi triÒu cao, th†êng n»m trong c¸c vÞnh n†íc n«ng, c¸c vïng sau ®¶o ch¾n, cån c¸t Nearshore The zone which extends from the swash zone to the position marking the start of the offshore zone, typically at water depths of the order or 20 m (see Figure 1.1) GÇn bê (vïng thÒm Vïng ®†îc giíi h¹n tõ bê ®Õn khu vùc ngoμi kh¬i, th«ng th†êng ë ®é s©u kho¶ng 20 lôc ®Þa) m (xem h×nh 1.1) Ness Roughly triangular promontory of land jutting into the sea, often consisting of mobile material, i.e. a beach form Mòi ®Êt h×nh tam gi¸c ®Ønh h†íng ra biÓn cÊu thμnh bëi c¸c vËt liÖu dÔ di chuyÓn Numerical modeling Refers to analysis of coastal processes using computational models M« h×nh sè Liªn quan tíi viÖc ph©n tÝch qu¸ tr×nh thay ®æi vïng ven biÓn sö dông m« h×nh sè Objective A management statement reflecting values or desired outcomes related to a vision of the future; (a function is simply a statement of an activity; an objective indicates the intention to achieve an outcome from the performance of the activity and should have both qualitative and quantitative attributes) Môc tiªu C«ng bè vÒ mÆt qu¶n lý ph¶n ¸nh b»ng gi¸ trÞ hoÆc mét kÕt qu¶ mong muèn x¶y ra trong t†¬ng lai; (Chøc n¨ng chØ thÓ hiÖn 1 ho¹t ®éng, môc tiªu lμ kÕt qu¶ ®¹t ®†îc tõ c¸c ho¹t ®éng ®ã c¶ vÒ l†îng vμ chÊt) Offshore The zone beyond the nearshore zone where sediment motion induced by waves alone effectively ceases and where the influence of the sea bed on wave action is small in comparison with the effect of wind (Figure 1.1) Ngoμi kh¬i Vïng ngoμi thÒm lôc ®Þa, ë ®©y bïn c¸t chuyÓn ®éng chØ do sãng vμ ¶nh h†ëng cña ®¸y tíi sãng kh«ng ®¸ng kÓ so víi ¶nh h†ëng cña giã (xem h×nh 1.1) Offshore breakwater A breakwater built towards the seaward limit of the littoral zone, parallel (or nearly parallel) to the shore §Ëp ph¸ sãng ngoμi §Ëp x©y dùng ngoμi xa gÇn song song víi ®†êng bê kh¬i Operational The construction, maintenance and day-to-day activities, associated with beach management §iÒu hμnh C¸c ho¹t ®éng nh† x©y dùng, b¶o d†ìng vμ c¸c ho¹t ®éng cã liªn quan tíi qu¶n lý bê biÓn hμng ngμy Orthogonal (wave In a wave refraction/diffraction diagram, a line drawn perpendicular to the wave ray) crest §êng trùc giao Trong gi¶n ®å sãng khóc x¹/ph¶n x¹, nã lμ ®†êng vu«ng gãc víi ®Ønh sãng Outlet An opening through which water can be freely discharged under controlled conditions from a reservoir or polder to the river or sea for a particular purpose\ Cöa ra Lμ mét kho¶ng kh«ng n†íc ch¶y tù do tõ hå tù nhiªn, hå chøa ra s«ng, biÓn v× mét môc ®Ých cô thÓ. Overtopping Water carried over the top of a coastal defense due to wave run-up exceeding the crest height Níc trμn ®Ønh N†íc v†ît qua ®Ønh c«ng tr×nh khi sãng leo v†ît qua ®Ønh c«ng tr×nh 26
28. Overwash The effect of waves overtopping a coastal defense, often carrying sediment land wards which is then lost to the beach system Níc trμn mang theo Sãng v†ît qua ®Ønh c¸c c«ng tr×nh b¶o vÖ vμ th†êng mang theo bïn c¸t ë b·i biÓn bïn c¸t vμo ®Êt liÒn Parapet Solid wall at crest of seawall projecting above deck level. Lan can (têng ®Ønh) T†êng cøng lμm thªm trªn ®Ønh cña t†êng ®øng Peak period The wave period determined by the inverse of the frequency at which the wave energy spectrum reaches its maximum Chu kú ®Ønh Lμ gi¸ trÞ ng†îc cña tÇn sè t¹i ®iÓm cùc ®¹i cña phæ n¨ng l†îng sãng Peaks over threshold Refers to the maximum value of a variable during each excursion above a threshold (POT) value §Ønh phÝa trªn Liªn quan tíi gi¸ trÞ lín nhÊt v†ît qua gi¸ trÞ giíi h¹n ngìng giíi h¹n Pebbles Beach material usually well-rounded and between about 4 mm to 75 mm diameter Cuéi, sái VËt chÊt b·i biÓn d¹ng h×nh trßn cã ®†êng kÝnh tõ 4 - 75 mm Perennial stream A stream that flows continuously throughout the year Dßng ch¶y thêng Dßng ch¶y tån t¹i th†êng xuyªn trong n¨m xuyªn Permeability The property of bulk material (sand, crushed rock, soft rock in situ) which permit TÝnh thÊm movement of water through its pores §ã lμ tÝnh chÊt cña ®Êt ®¸ (c¸t, ®¸) ngoμi hiÖn tr†êng cho phÐp n†íc vËn chuyÓn qua c¸c khe rçng Persistence of storms The duration of sea states above some severity threshold (e.g. wave height) Thêi gian b·o Thêi gian mμ mÆt biÓn chÞu ¶nh h†ëng cña nh÷ng con sãng rÊt lín Phase velocity The velocity at which a wave crest propagates, ft group velocity VËn tèc Pha VËn tèc chuyÓn ®éng cña ®Ønh sãng Phreatic level Upper surface of an unconfined aquifer (e.g. the top sand layer in a dike)at which the pressure in the groundwater is equal to atmospheric pressure Mùc níc kh«ng ¸p Mùc n†íc tån t¹i trong tÇng chøa n†íc kh«ng ¸p, t¹i ®ã ¸p suÊt trong n†íc ngÇm b»ng ¸p suÊt khÝ quyÓn Physical modelling Refers to the investigation of coastal processes using a scaled model M« h×nh vËt lý Liªn quan tíi nghiªn cøu c¸c qu¸ tr×nh ven biÓn b»ng m« h×nh tØ lÖ Pierson-Moskowitz Wave spectrum typical of fully-developed deep water waves spectrum Phæ Phæ sãng ngoμi n†íc s©u khi ph¸t triÓn tíi giíi h¹n hoμn chØnh Pierson-Moskowitz Piezometric surface The level within (or above) a soil stratum at which the pore-pressure is zero Mùc thuû ¸p §é cao phÝa trªn mÆt chuÈn t¹i ®ã ¸p suÊt lç rçng b»ng kh«ng Piping Erosion of closed flow channels (tunnels) by the passage of water through soil; flow underneath structures, carrying subsoil particles, may endanger the stability of the structure Xói ngҫm Xãi thμnh c¸c dßng trong ®Êt hoÆc d†íi c«ng tr×nh mang theo ®Êt g©y bÊt æn ®Þnh cho c«ng tr×nh Pitching Squared masonry, precast blocks or block-shaped natural stones (e.g. basaltic columns) laid in a regular fashion with dry or filled joints on the river/sea side of an embankment, dike, or dam as a protection against wave and ice action Kè lát mái C¸c tÊm bª t«ng lμm thñ c«ng, bª t«ng ®óc s½n, ®¸ tù nhiªn cã h×nh khèi (Khèi bazan) ®Æt rêi r¹c hoÆc ngo»m víi nhau ®Æt trªn m¸i dèc cña ®ª s«ng/ biÓn chèng sãng 27
29. Pocket Beach A beach, usually small, between two headlands B·i biÓn n»m gi÷a hai mòi ®Êt Polder A tract of low land, reclaimed from marshland, the sea or an other body of water, by endiking it. In a polder, runoff is controlled by sluicing or pumping, and the watertable is controlled and independent of the watertable in the adjacent areas §Êt lÊn biÓn D¶i ®Êt thÊp ®†îc c¶i t¹o tõ ®Çm lÇy hoÆc v©y quanh c¸c vïng n†íc b»ng hÖ thèng ®ª. Trong vïng ®Êt lÊn biÓn, dßng ch¶y ®†îc khèng chÕ b»ng hÖ thèng cèng tiªu hoÆc tr¹m b¬m. Mùc n†íc ®†îc kiÓm so¸t vμ ®éc lËp víi c¸c vïng xung quanh. Pore pressure The interstitial pressure of water within a mass of soil or rock ¸p lùc lç rçng ¸p suÊt khe rçng trong ®Êt, ®¸ Porosity Percentage of the total volume of a soil not occupied by solid particles by air and/or water §é rçng PhÇn tr¨m lç rçng so víi thÓ tÝch mÉu ®Êt Preservation Static protection of an area or element, attempting to perpetuate the existence of a given 'state' B¶o tån Gi÷ nguyªn mét tr¹ng th¸i nμo ®ã. Probability The chance that a prescribed event will occur, represented by a number (p) in the range 0<p<1. It can be estimated empirically from the relative frequency (i.e. the number of times the particular event occurs, divided by the total count of all events in the class considered) X¸c suÊt Lμ c¬ héi cña mét biÕn cè nμo ®ã cã thÓ x¶y ra; TrÞ sè cña nã 0<p<1. Nã ®†îc x¸c ®Þnh b»ng thùc nghiÖm lμ tÇn sè sè lÇn x¶y ra biÕn cè trong tæng sè lÇn lμm thùc nghiÖm Probability density Function specifying the distribution of a variable Hμm ph©n bè x¸c Hμm x¸c ®Þnh ph©n bè cña mét biÕn x¸c ®Þnh suÊt Profile of storms Refers to the persistence of storms coupled with the rate of change of sea state (e.g. wave height) within the storms Hå s¬ trËn b·o Liªn quan ®Õn thêi gian b·o vμ tr¹ng th¸i mÆt biÓn (chiÒu cao sãng) trong c¬n b·o Prototype The actual structure or condition being simulated in a model VËt mÉu C«ng tr×nh thùc hoÆc ®†îc m« pháng trªn m« h×nh Quarry Site where natural rock stone is mined. Má ®¸ N¬i khai th¸c vμ xay ®¸ Quarry run Waste of generally small material, in a quarry, left after selection of larger grading PhÇn th¶i ra khi xay ®¸ vμ ®· lÊy ®i cÊp phèi lín Random waves The laboratory simulation of irregular sea states that occur in nature Sãng ngÉu nhiªn M« pháng trong phßng thÝ nghiÖm sãng ngÉu nhiªn thùc Rayleigh distribution A model probability distribution, commonly used in analysis of waves Ph©n bè Rayleigh Ph©n bè x¸c suÊt ®†îc sö dông trong ph©n tÝch sãng Reef A ridge of rock or other material lying just below the surface of the sea Bãi ÿá ngҫm Lӟp ÿá hoһc các loҥi vұt liӋu rҳn nҵm ngay dѭӟi mһt nѭӟc biӇn Reef breakwater Rubble mound of single-sized stones with a crest at or below sea level which is allowed to be (re)shaped by the waves Ĉұp chҳn sóng ngҫm Ĉұp chҳn bҵng ÿá có ÿӍnh bҵng hoһc thҩp hѫn mӵc nѭӟc biӇn và hình dҥng thay ÿәi do tác ÿӝng cӫa sóng 28
30. Reflected wave That part of an incident wave that is returned (reflected) seaward when a wave Sóng phҧn xҥ impinges on a beach, seawall or other reflecting surface Phҫn sóng ÿӃn bӏ hҳt trӣ lҥi khi ÿánh vào bӡ, tѭӡng ÿӭng Refraction coefficient Ratio of refracted wave height to deep water wave height HӋ sӕ khúc xҥ TӍ sӕ giӳa chiӅu cao cӫa sóng sau khi bӏ khúc xҥ và sóng ngoài nѭӟc sâu Refraction (of water The process by which the direction of a wave moving in shallow water at an angle waves) to the contours is changed so that the wave crests tend to become more aligned with Khúc xҥ those contours Quá trình làm cho hѭӟng sóng thay ÿәi khi ÿi vào nѭӟc nông vӟi xu thӃÿӍnh sóng có xu thӃ song song vӟi các ÿѭӡng ÿӗng mӭc Refurbishment, Restoring the structure to its original function and level of protection renovation Phөc hӗi các chӭc năng và mӭc ÿӝ bҧo vӋ cӫa công trình Cung cҩp và ÿәi mӟi Rehabilitation Renovation or upgrading. Nâng cҩp Ĉәi mӟi hoһc nâng cҩp Regular waves Waves with a single height, period and direction Sóng ÿӅu Sóng có chiӅu cao, chu kǤ và hѭӟng không ÿәi Reservoir An artificial lake, basin or tank in which a large quantity of water can be stored Hӗ chӭa Là hӗ nhân tҥo chӭa mӝt lѭӧng nѭӟc ÿáng kӇ Residual (water level) The components of water level not attributable to astronomical effects Mӵc nѭӟc thӭ cҩp Thành phҫn mӵc nѭӟc không thuӝc tác ÿӝng thiên văn gây ra Retention water level For a reservoir with a fixed overflow sill it is the lowest crest level of that sill. In case there is a movable gate, it is the highest operational level of that gate (excluding provisions of flood surcharge, like emergency spillways) Mӵc nѭӟc giӳ trong Ĉӕi vӟi hӗ chӭa có ngѭӥng tràn cӕÿӏnh thì mӵc nѭӟc này tѭѫng ӭng vӟi mӵc nѭӟc hӗ thҩp nhҩt trên ngѭӥng. Nhѭng vӟi ngѭӥng tràn di ÿӝng, thì mӵc nѭӟc thay ÿәi theo vӏ trí ngѭӥng tràn (Không phҧi là tràn xҧ lNJ) Return period Average period of time between occurrences of a given event Thӡi kǤ lһp lҥi Là thӡi khoҧng trung bình mà mӝt hiӋn tѭӧng nào ÿó lһp lҥi mӝt lҫn Revetment (slope A sloping surface of stone, concrete or other material used to protect an protection) embankment, natural coast or shoreline against erosion Bҧo vӋ mái Lӟp ÿá, bê tông hoһc vұt liӋu khác bҧo vӋ mái ÿê, bãi tӵ nhiên chӕng xói mòn Reynolds number dimensionless number, ratio between the inertia and the viscous forces for pipes Re = vD/v, for open channels Re = vR/v (D = Diameter, R = hydraulic radius) Sӕ Reynolds Là sӕ không thӭ nguyên, tӍ sӕ giӳa lӵc quán tính và lӵc nhӟt. Vӟi ӕng Re = vD/v, vӟi kênh hӣ Re = vR/v (D = ÿѭӡng kính, R = bán kính thӫy lӵc) Rip current Jet-like seaward-going current normal to the shoreline associated with wave-induced longshore currents Dòng hѭӟng ra biӇn vuông góc vӟi bӡ có quan hӋ vӟi dòng ven bӡ do sóng Rip-rap Wide-graded quarry stone normally used as a protective layer to prevent erosion. Ĉá ÿә Ĉá có nhiӅu ÿѭӡng kính khác nhau, thѭӡng ÿә thành lӟp dày ÿӇ chӕng xói River training Any configuration constructed in a stream or placed on, adjacent to or in the structure vicinity of a stream bank that is intended to deflect currents, induce sediment deposition, induce scour, or in some other way alter the flow and sediment regimes 29
31. of the river Công trình chӍnh trӏ Là mӝt hình thӭc công trình ÿһt trên sông có tác dөng hѭӟng dòng chҧy ra xa bӡ, sông tăng cѭӡng bӗi , giҧm xói hay nói mӝt cách khác là làm thay ÿәi chӃÿӝ dòng chҧy và bùn cát cӫa sông ngòi Risk analysis Assessment of the total risk due to all possible environmental inputs and all possible mechanisms Phân tích rӫi ro Ĉánh giá tәng rӫi ro do thiên nhiên và các hoҥt ÿӝng khác gây ra Rock weathering Physical and mineralogical decay processes in rock brought about by exposure to climatic conditions either at the present time or in the geological past Phong hóa ÿá Là quá trình phá hӫy các khoáng vұt trong ÿá do ÿiӅu kiӋn thӡi tiӃt trong quá trình tiӃn hóa cӫa lӏch sӱÿӏa chҩt Rockfill dam A dam in which more than 50% of the total volume comprises compacted or dumped pervious natural or crushed stone Ĉұp ÿá ÿә Là ÿұp có trên 50% vұt liӋu sӱ dөng là ÿá trӝn lүn vӟi ÿá nhӓ và các vұt liӋu khác và ÿѭӧc ÿҫm nén. Rubble-mound A mound of random-shaped and random-placed stones structure Công trình bҵng ÿá Công trình bҵng ÿá ÿә ngүu nhiên Runnel Channels on a beach, usually running approximately shore-parallel and separated by beach ridges Dòng sông chҥy song Ĉoҥn sông chҧy gҫn song song vӟi bӡ biӇn và bӏ chһn bӣi các ÿөn cát song vӟi bӡ biӇn Run-up, run-down The upper and lower levels reached by a wave on a beach or coastal structure. relative to still-water level Sóng leo, sóng rút Là mӵc nѭӟc dâng lên và rút ÿi cӫa mӝt con sóng vào bӡ hoһc mái ÿê so vӟi mӵc nѭӟc tƭnh Salinity The content of totally dissolved solids in water, expressed in PPM or in mg/l Ĉӝ mһn Nӗng ÿӝ cӫa chҩt hòa tan trong nѭӟc tính băng PPM hoһc mg/l Salient Coastal formation of beach material developed by wave refraction and diffraction and long shore drift comprising of a bulge in the coastline towards an offshore island or breakwater, but not connected to it as in the case of a tombolo - see also ness, cusp MNJi nhô Phҫn ÿӏa mҥo phát triӇn do sóng khúc xҥ và phҧn xҥ, dòng chҧy dӑc bӡ hình thành bao gӗm ÿoҥn mNJi nhô hѭӟng ra các ÿҧo hoһc ÿұp phá sóng phía ngoài biӇn, nhѭng chѭa nӕi vӟi chúng nhѭ trѭӡng hӧp tombolo Sand Sediment particles mainly or quartz, with a diameter of between 0.062 mm and 2 mm, generally classified as fine, medium, coarse or very coarse Cát Hҥt có thành phҫn chӫ yӃu là thҥch anh vӟi ÿѭӡng kính tӯ 0.062 mm ÿӃn 2 mm và ÿѭӧc gӑi là cát mӏn, trung bình, thô hoһc rҩt thô Scatter diagram A two-dimensional histogram showing the joint probability density of two variables within a data sample BiӇu ÿӗ phân bӕ BiӇu ÿӗ 2 chiӅu biӇu diӉn hàm phân bӕ xác suҩt liên hӧp cӫa 2 biӃn Scour protection Protection against erosion of the seabed in front of the toe. Sea defences Works to Bҧo vӋ hӕ xói prevent or alleviate flooding by the sea. Bҧo vӋ chӕng xói chân công trình và các công trình chӕng nѭӟc tràn ven biӇn 30
32. Sea defences Works to prevent or alleviate flooding by the sea Công trình bҧo vӋ bӡ Là các công trình chӕng sóng, nѭӟc tràn vùng ven biӇn Sea level rise The long-term trend in mean sea level Nѭӟc biӇn dâng Xu thӃ ngày càng dâng cao cӫa nѭӟc biӇn Seawall Solid coastal defence structure built parallel to the coastline Tѭӡng ÿӭng Công trình cӭng bҧo vӋÿѭӧc xây dӵng dӑc bӡ biӇn Secular changes Long-term changes in sea level. Sӵ thay ÿәi dài hҥn Sӵ thay ÿәi dài hҥn mӵc nѭӟc biӇn Sediment Particulate matter derived from rock, minerals or bioclastic debris Bùn cát Các hҥt hình thành tӯ khoáng vұt, ÿá và xác sinh vұt Sediment cell In the context or a strategic approach to coastal management, a length of coastline in which interruptions to the movement of sand or shingle along the beaches or near shore sea bed do not significantly affect beaches in the adjacent lengths of coastline Ô cát Trên quan ÿiӇm quҧn lý bӡ biӇn, ÿoҥn bӡ tҥi ÿó ngăn quá trình chuyӇn ÿӝng liên tөc cӫa bùn cát hoһc ÿáy biӇn gҫn bӡ không gây ҧnh hѭӣng ÿáng kӇÿӃn các ÿoҥn bӡ lân cұn Sediment sink Point or area at which beach material is irretrievably lost from a coastal cell, such as an estuary, or a deep channel in the seabed Mҩt cát ĈiӇm hoһc khu vӵc mà vұt chҩt bãi bӏ mҩt liên tөc chҷng hҥn khu vӵc cӱa sông hoһc luӗng tàu Sediment source Point or area on a coast from which beach material arises, such as an eroding cliff, or river mouth Nguӗn bùn cát ĈiӇm hoһc khu vӵc trên bӡ biӇn, là nguӗn cung cҩp cát cho mӝt vùng bãi nào ÿó. Seepage The movement of water through small cracks, pores, interstices, out of a body of surface of subsurface water. The loss of water by infiltration from a canal, reservoir or other body of water or from a field. It is generally expressed as flow volume per unit of time Thҩm ChuyӇn ÿӝng cӫa nѭӟc qua các khe nӭt nҿ cӫa ÿҩt ÿá. Ĉây là hiӋn tѭӧng mҩt nѭӟc qua kênh, hӗ chӭa hoһc trên mһt ruӝng. Seiche Standing wave oscillation in an effectively closed body of water (e.g. a harbour basin) Dao ÿӝng mӵc nѭӟc Sóng ÿӭng hình thành trong hӗ hoһc các vùng nѭӟc kín (chҷng hҥn trong cҧng) trong hӗ Semi-diurnal Having a period of half a tidal day, i.e. 12.4 hours Bán nhұt triӅu Dao ÿӝng vӟi chu kǤ 12.4 giӡ cӫa thӫy triӅu Sequencing of storms Refers to the temporal distribution of storms and therefore how they are grouped Thӭ tӵ cӫa bão Liên quan ÿӃn phân bӕ thӡi gian cӫa bão Shallow water Water of such depth that surface waves are noticeably attested by bottom topography. Typically this implies a water depth equivalent to less than half the wavelength Nѭӟc nông Tҥi ÿӝ sâu này, sóng bӏҧnh hѭӣng bӣi ÿáy, tѭѫng ӭng vӟi ÿӝ sâu nѭӟc nhӓ hѫn nӱa bѭӟc sóng Shingle A loose term for coarse beach material, a mixture of gravel, pebbles and larger material, often well-rounded and of hard rock, e.g. chert, flint etc. Cuӝi sӓi Là dҥng hӛn hӧp cӫa cuӝi, sӓi vӟi ÿѭӡng kính khá lӟn và có hình dҥng gҫn tròn do tác dөng lâu ngày cӫa sóng nѭӟc 31
33. Shoaling Decrease in water depth. The transformation of wave profile as they propagate inshore HiӋu ӭng nѭӟc nông HiӋn tѭӧng giҧm ÿӝ sâu nѭӟc. BiӃn ÿәi hình dҥng sóng khi ÿi vào gҫn bӡ Shoaling coefficient Ratio of shoaled wave height to deep water wave height HӋ sӕ nѭӟc nông TӍ sӕ giӳa chiӅu cao sóng khi ÿi vào nѭӟc nông và chiӅu cao sóng ngoài nѭӟc sâu Shoreline One characteristic of the coast. Poorly defined but essentially the interface between land and sea Ĉѭӡng bӡ Mӝt khái niӋm cѫ bҧn phân ÿӏnh giӳa ÿҩt liӅn và biӇn Shoreline The development of strategic, long-term and sustainable coastal defense policy management within a sediment cell Quҧn lý ÿѭӡng bӡ Phát triӇn các chính sách bҧo vӋ ÿѭӡng bӡәn ÿӏnh lâu dài theo các ô cát Shore normal A line at right-angles to the contours in the surf zone Ĉѭӡng vuông góc Là ÿѭӡng vuông góc vӟi các ÿѭӡng ÿӗng mӭc trong vùng sóng vӥ Short-crested random Random waves with variable heights, periods and directions waves Sóng ngүu nhiên ÿӍnh Sóng ngүu nhiên có hѭӟng, chu kǤ và chiӅu cao thay ÿәi ngҳn Significant wave The average height of the highest one third of the waves in a given sea state height ChiӅu cao sóng hiӋu ChiӅu cao trung bình cӫa 1/3 sӕ con sóng tѭѫng ӭng vӟi mӝt ÿiӅu kiӋn thӡi tiӃt xác quҧ ÿӏnh Sill A submerged structure across a river to control the water level upstream The crest of a spillway Ngѭӥng (ÿӍnh) công Là công trình ngang sông ngұp dѭӟi nѭӟc ÿӇ khӕng chӃ mӵc nѭӟc hoһc ÿӍnh cӫa trình ÿұp tràn Silt Sediment particles with a grain size between 0.004 mm and 0.062 mm, i.e. coarser than clay particles but finer than sand Hҥt mӏn Hҥt có ÿѭӡng kính 0.004 mm ÿӃn 0.062 mm lӟn hѫn hҥt sét nhѭng nhӓ hѫn hҥt cát Slope Inclination, e.g. 1:2 means 1 vertical to 2 horizontal Mái dӕc Mһt có ÿӝ nghiêng Slope protection see revetment Bҧo vӋ mái Xem Revetment Sluice A structure containing a gate to control the flow of water from one area to another Cӕng Là công trình khi có cӱa khӕng chӃ dòng chҧy Soft defences Usually refers to beaches (natural or designed) but may also relate to energy-absorbing beach-control structures, including those constructed of rock, where these are used to control or redirect coastal processes rather than opposing or preventing them Giҧi pháp bҧo vӋ Thông thѭӡng liên quan ÿӃn các giҧi pháp giҧm hoһc hҩp thө năng lѭӧng sóng bao mӅm gӗm các công trình có xu thӃ phù hӧp vӟi các quá trình tӵ nhiên mà không ÿӕi ÿҫu vӟi nó Sorting of sediment Sediment is well-sorted when it has a distribution with a small standard deviation (i.e. all grains have more-or-less the same size); sediment is poorly sorted when the standard deviation is large Tính ÿӗng ÿӅu cao Bùn cát ÿѭӧc xem là lӵa chӑn tӕt khi các hҥt tѭѫng ÿӕi bҵng nhau (Ĉѭӡng kính hҥt 32
34. cӫa bùn cát gҫn bҵng nhau và khi càng có nhiӅu loҥi ÿѭӡng kính nghƭa là kém ÿӗng ÿӅu Spillway A structure over or through a dam for discharging flood flows Ĉұp tràn Là công trình tháo lNJ Spit A long narrow accumulation of sand or shingle, lying generally in line with the coast, with one end attached to the land the other projecting into the sea or across the mouth of an estuary - see also ness MNJi ÿҩt Sӵ tích tө cӫa cát hoһc sӓi thông thѭӡng nҵm song song vӟi ÿѭӡng bӡ, nhѭng 1 ÿҫu nӕi vӟi ÿҩt liӅn còn ÿҫu kia hѭӟng ra biӇn, ÿôi khi cҳt qua cӱa sông. Spur-dike see Groyne Ĉê mӓ hàn Xem ÿê biӇn S-slope breakwater Rubble mound with gentle slope around still-water level and steeper slopes above and below. Ĉê phá sóng mái kiӇu Là ÿұp ÿá ÿә có mái khá thoҧi xung quanh mӵc nѭӟc tƭnh và mái dӕc hѫn ӣ trên và chӳ S dѭӟi mӵc ÿó Standard of service The adequacy of defense measured in terms of the return period (years) of the event which causes a critical condition (e.g. breaching, overtopping) to be reached Tiêu chuҭn thiӃt kӃ Công trình ÿӫ bӅn dѭӟi dҥng chu kǤ lһp lҥi (năm) khi gһp ÿiӅu kiӋn thiӃt kӃ (chҷng hҥn ÿiӅu kiӋn bӏ vӥ hay nѭӟc tràn) Stationary process A process in which the mean statistical properties do not vary with time. Quá trình dӯng Quá trình có các ÿһc trѭng thӕng kê không thay ÿәi theo thӡi gian Still-water level Water level that would exist in the absence of waves (SWL) Mӵc nѭӟc tƭnh thiӃt Mӵc nѭӟc xét trong ÿiӅu kiӋn không có sóng kӃ Storm-surge A surge caused by a storm Nѭӟc dâng do bão Nѭӟc dâng do bão gây ra Strand line An accumulation of debris (e.g. seaweed, driftwood and litter) cast up onto a beach, and lying along the limit of wave up rush Khu vӵc rác biӇn bám Sӵ tích tө cӫa các mҧnh vӥ (cӓ biӇn, vұt trôi nәi ) ӣ khu vӵc xung quanh dҧi sóng leo và sóng rút Sub-critical The flow condition above a dam by which the tail-water level influences the upstream head. The discharge is a function of upstream and downstream head. Also called submerged flow, submodular flow, or drowned flow Trҥng thái êm Là ÿiӅu kiӋn dòng chҧy hҥ lѭu ҧnh hѭӣng tӟi trҥng thái chҧy ӣ thѭӧng lѭu. Lѭu lѭӧng là hàm sӕ cӫa cҧ mӵc nѭӟc thѭӧng và hҥ lѭu. Stochastic Having random variation in statistics. Ngүu nhiên Sӵ thay ÿәi ngүu nhiên Sub-aerial beach That part of the beach which is uncovered by water (e.g. at low tide sometimes referred to as ‘drying beach' Vùng bãi không ngұp Phҫn bãi không ngұp nѭӟc (tӭc là ӣ mӵc nѭӟc triӅu thҩp gӑi là bãi khô) nѭӟc Sub-critical flow Flow for which the Froude number is less than unity; surface disturbances can travel upstream Trҥng thái chҧy êm Trҥng thái chҧy có Fr < 1; Trҥng thái rӕi trên mһt lan truyӅn dҫn lên thѭӧng lѭu Sub-tidal beach The part or the beach (where it exists) which extends from low water out to the approximate limit of storm erosion. The latter is typically located at a maximum 33
35. water depth of 8 to 10 metres and is often identifiable on surveys by a break in the slope of the bed Bãi nҵm dѭӟi mӵc Ĉoҥn bӡ tính tӯ mӵc nѭӟc triӅu thҩp nhҩt ÿӃn vùng chӏu ҧnh hѭӣng xói do nѭӟc nѭӟc triӅu dâng. Vùng này có thӇ phát triӇn ÿӃn ÿӝ sâu 8 - 10 m và ÿѭӧc xác ÿӏnh trên hiӋn trѭӡng bҵng sӵ thay ÿәi ÿӝt ngӝt cӫa ÿӝ dӕc ÿáy. Sudden closure Method in which the final closure gap in a dam is closed suddenly, usually with the method use of large sluice caissons; this in contradiction with a gradual closure Phѭѫng pháp hҥp Phѭѫng pháp hҥp long trong giai ÿoҥn cuӕi quá trình hӧp long. Thông thѭӡng long tӭc thӡi ngѭӡi ta dùng thùng chìm loҥi lӟn. Ĉây là phѭѫng pháp trái ngѭӧc vӟi giҧi pháp hҥp long tӯ tӯ. Super-critical flow Flow for which the Froude number is greater than unity; surface disturbances will not travel upstream Dòng chҧy xiӃt Dòng chҧy có Fr > 1, nhiӉu ÿӝng mһt nѭӟc không lan truyӅn lên thѭӧng lѭu Surf-beat Independent long wave caused by reflection of bound long wave Sóng va ÿұp Sóng dài riêng rӁ tҥo ra do phҧn xҥ cӫa sóng dài nhҧy Surf zone The zone of wave action extending from the water line (which varies with tide, surge, set-up, etc.) out to the most seaward point of the zone (breaker zone) at which waves approaching the coastline commence breaking, typically in water depths of between 5 to 10 metres (Figure 1.2) Vùng sóng vӥ Vùng ÿѭӧc giӟi hҥn tӯ mép nѭӟc (Thay ÿәi theo mӵc nѭӟc thӫy triӅu, nѭӟc dâng) ÿӃn ÿiӇm tҥi ÿó sóng bҳt ÿҫu bӏ vӥ khi ÿi vào bӡ , thông thѭӡng ӣÿӝ sâu tӯ 5-10m Surge Changes in water level as a result of meteorological forcing (wind, high or low barometric pressure) causing a difference between the recorded water level and that predicted using harmonic analysis, may be positive or negative Nѭӟc dâng Sӵ thay ÿәi mӵc nѭӟc là kӃt quҧ cӫa các lӵc khí tѭӧng (gió, thay ÿәi áp suҩt) Suspended load A mode of sediment transport in which the particles are supported, and carried along by the fluid Phù sa lѫ lӱng Là trҥng thái chuyӇn ÿӝng mà các hҥt bùn ÿѭӧc chuyӇn ÿӝng lѫ lӱng trong chҩt lӓng Swash zone The zone of wave action on the beach, which moves as water levels vary, extending from the limit of run-down to the limit of run-up (see Figure 1.2) Vùng sóng vӛ Vùng sóng tác ÿӝng lên vùng bӡ dѭӟi dҥng dao ÿӝng mӵc nѭӟc nҵm giӳa nѭӟc nѭӟc sóng leo và sóng rút. Swell (waves) Remotely wind-generated waves. Swell characteristically exhibits a more regular and longer period and has longer crests than locally generated waves Sóng lӯng Sóng tҥo bӣi gió hình thành tӯ xa. Sóng lӯng ÿѭӧc thӇ hiӋn bӣi tính ÿiӅu hòa và chu kǤ lӟn, ÿӍnh sóng bҽt hѫn sóng ÿӏa phѭѫng Typhoon Tropical cyclone with winds of 75 mph (120 km/hr or 65 knots) in the western pacific, in which winds tend to spiral inward toward a core of low pressure; usually accompanied by rain, thunder and lightning. In the western Atlantic these cyclones are called hurricanes. Bão Xoáy thuұn nhiӋt ÿӟi vӟi tӕc ÿӝ gió 120 km/hr ӣ tây thái bình dѭѫng vӟi gió xoáy hѭӟng vào tâm. Bão thѭӡng kèm theo mѭa, sҩm, chӟp. ӢĈҥi tây dѭѫng có tên là hurricanes Tail-water level The water downstream of a dam or sill Mӵc nѭӟc hҥ lѭu Mӵc nѭӟc hҥ lѭu ÿұp 34
36. Thalweg The locus of the deepest points in a valley at successive cross-sections Mһt cҳt dӑc Ĉѭӡng nӕi ÿiӇm sâu nhҩt trong thung lNJng xét trên mһt căt dӑc Threshold of motion The point at which the forces imposed on a sediment particle overcome its inertia and it starts to move Ngѭӥng chuyӇn ÿӝng ĈiӇm tҥi ÿó tәng hӧp lӵc lên hҥt cát làm cho nó bҳt ÿҫu chuyӇn ÿӝng Tidal current The movement of water associated with the rise and fall of the tides Dòng triӅu Dòng chҧy hình thành do dao dӝng mӵc nѭӟc triӅu Tidal prism Volume of water that flows into a tidal channel and out again during a complete tide, excluding any upland discharges Khӕi nѭӟc triӅu Khӕi nѭӟc chuyӇn ÿӝng vào, ra vӏnh triӅu trong mӝt chu kǤ triӅu Tidal range Vertical difference in high and low water level once decoupled from the water level residuals Ĉӝ lӟn triӅu Chênh lӋch theo chiӅu thҷng ÿӭng mӵc nѭӟc triӅu lӟn nhҩt và nhӓ nhҩt trong mӝt chu kǤ triӅu Tidal river That part of a river where the water level is influenced by the tide Vùng sông ҧnh hѭӣng Ĉoҥn sông chӏu ҧnh hѭӣng cӫa thӫy triӅu triӅu Tidal wave The rise and fall in water level due to the passage of the tide Sóng triӅu Thay ÿәi cӫa mӵc nѭӟc do chuyӇn ÿӝng cӫa thӫy triӅu Tide The periodic rise and fall in the level of the water in oceans and seas; the result of gravitational attraction of the sun and moon Thӫy triӅu Dao ÿӝng có chu kǤ cӫa mӵc nѭӟc ngoài biӇn dѭӟi tác dөng lӵc hút cӫa mһt trăng và mһt trӡi. Tide gate see flood gate Cӱa kiӇm soát thӫy Xem flood gate triӅu và nѭӟc dâng Tides Highest astronomical tide (HAT), lowest astronomical tide (LAT): the highest and lowest levels, respectively, which can be predicted to occur under average meteorological conditions. Those levels will not be reached every year. HAT and LAT are not the extreme levels which can be reached, as storm surges may cause considerably higher and lower levels to occur. Các loҥi mӵc nѭӟc Mӵc nѭӟc triӅu thiên văn lӟn nhҩt (HAT), Mӵc nѭӟc triӅu thiên văn nhӓ nhҩt triӅu (LAT): là mӵc nѭӟc lӟn nhҩt và nhӓ nhҩt có thӇ dӵ báo ÿѭӧc trong ÿiӅu kiӋn khí tѭӧng bình thѭӡng. Mӵc nѭӟc này không phҧi xuҩt hiӋn hàng năm. HAT và LAT không phҧi là mӵc nѭӟc cӵc ÿҥi, vì vұy nѭӟc dâng do bão có thӇ tҥo ra mӵc nѭӟc cao hѫn hoһc thҩp hѫn. Mean high water springs (MHWS), mean low water springs (MLWS): the height of mean high water springs is the average throughout a year of the heights of two successive high waters during those periods of 24 hours (approximately once a fortnight) when the range of the tide is greatest. The height of mean low water springs is the average height obtained by the two successive low waters during the same periods. Mӵc nѭӟc lӟn nhҩt trung bình (MHWS), mӵc nѭӟc nhӓ nhҩt trung bình (MLWS): là giá trӏ trung bình cӫa mӵc nѭӟc triӅu lӟn nhҩt (nhӓ nhҩt) cӫa kǤ triӅu cѭӡng trong thӡi ÿoҥn quan trҳc là 1 năm; 35
37. Mean high water neaps (MHWN), mean low water neaps (MHWN): the height of mean high water nears is the average of the heights throughout the year of two successive high waters during those periods of 24 hours (approximately once a fortnight) when the range of the tide is least. The height of mean low water nears is the average height obtained by the two successive low waters during the same periods. Mӵc nѭӟc cao trung bình (MHW), thҩp trung bình (MLW) thӡi kǤ triӅu kém: là giá trӏ trung bình cao nhҩt (thҩp nhҩt) cӫa ÿӍnh triӅu (chân triӅu) trong thӡi kǤ triӅu kém Mean high water (MHW), mean low water (MLW): the arithmetic mean of the published values of mean high/low water springs and mean high/low water neaps. Mӵc nѭӟc triӅu trung bình cao (MHW) và thҩp (LMW) là giá trӏ bình quân sӕ hӑc cӫa mӵc nѭӟc ÿӍnh triӅu lӟn nhҩt và mӵc nѭӟc chân triӅu thҩp nhҩt. TMA spectrum Wave spectrum typical of growing seas in limited water depths Phә sóng khi sóng phát triӇn trên biӇn có ÿӝ sâu hҥn chӃ Toe Lowest part of sea- and portside breakwater slope, generally forming the transition to the seabed. Chân Phҫn thҩp nhҩt cӫa mái phía biӇn hoһc ÿê chҳn sóng, là ÿoҥn nӕi tiӃp vӟi ÿáy biӇn Tombolo Coastal formation of beach material developed by refraction, diffraction and longshore drift to form a 'neck' connecting a coast to an offshore island or breakwater (see also salient) Là mӝt dҥng ÿӏa mҥo phát triӇn do quá trình phҧn xҥ, khúc xҥ, dòng ven tích tө hình thành các doi cát nӕi bӡ biӇn vӟi các ÿҧo hay ÿұp chҳn sóng ngoài khѫi Training wall A wall built to confine or guide the flow over the downstream face of an overflow dam or in a channel Tѭӡng chӍnh trӏ Là tѭӡng xây ÿӇ chһn hoһc hҥn chӃ dòng chҧy không vѭӧt ra ngoài phҥm vi ÿó vӟi mөc ÿích chӍnh trӏ uӕn nҳn dòng sông. Updrift The direction opposite to that of the predominant longshore movement of beach material Dòng trôi ngѭӧc Là hѭӟng ngѭӧc lҥi vӟi hѭӟng chӫÿҥo cӫa vұt chҩt ven bӡ Upgrading Improved performance against certain criteria Nâng cҩp Tăng cѭӡng chӭc năng làm viӋc theo mӝt tiêu chuҭn xác ÿӏnh Up-rush The landward return of water following the back-rush of a wave Ĉҭy ngѭӧc Nѭӟc trào lên khi sóng rút xuӕng Wash load Part of the suspended load with particle sizes smaller than chez found in the bed; it is in near-permanent suspension and transported without deposition; the amount of wash load transported through a reach does not depend on the transport capacity of the flow; the load is expressed in mass or volume per unit of time Bùn cát lѫ lӱng Là các vұt chҩt lѫ lӱng có kích thѭӟc nhӓ hѫn bùn cát ÿáy tӗn tҥi thѭӡng xuyên và di chuyӇn cùng dòng nѭӟc. Tәng lѭӧng bùn cát lѫ lӱng gҫn ÿáy trên mӝt ÿoҥn sông không phө thuӝc vào vұn tӕc dong chҧy. Ĉѫn vӏ kg/s hoһc m3/s. Water depth Distance between the seabed and the still water level Ĉӝ sâu nѭӟc Khoҧng cách thҷng ÿӭng tӯÿáy ÿӃn mһt nѭӟc tƭnh Water level Elevation of still water level relative to some datum Mӵc nѭӟc Cao ÿӝ cӫa mӵc nѭӟc tƭnh so vӟi chuҭn 36