K £ T LUAN
Qua phdn tich ddnh gid tdi lifu ciia hai khu vpc ttpng dilm Nam Djnh vd Ha Tinh, chiing ta cd thi rdt ra mft s l kit lupn chung nhu sau:
Ve dieu kifn khi tupng thily hdi vdn thi cd hai viing biin dfu chju dnh hudng ciia gid miia DOng Bdc vd Tdy Nam vd diu ndm trong I bdo vdi tin suit chju dnh hudng thudng xuyen ciia bdo vd dp thip nhift ddi. Do dilu kifn dia hinh bai trade dd khd thip d cd hai vimg, ttong dilu kifn bdo kit hpp vdi trieu cudng thi df sau nude trade de khd Idn, sdng do dd cd thi tiln sdu hon vdo bd va tdc dOng trpc tilp gdy nguy hilm cho dd. Sp tdc dOng ttrpc tilp ndy ngdy cdng trd nen trim trpng ban khi tai lifu dieu tta hinh thdi cho thdy bd biin d ea hai vimg dang xdy ra hifn tupng bien lan vdi tdc dp xdi bd tir bung binh din manh. Bdi de dang ngdy mft hi thu hpp vd ttd ndn sdu hon ddn tdi sp thay doi ddng kl vd dilu kifn thiiy hdi van thilt k l dd (vi dp nhu chieu cao sdng thilt k l trade chan dd dang ngay mft tdng Idn). Do yeu tO dja hinh vd muc dp hopt dpng cao ciia bao, chidu cao nude dang ttong bdo cd the xdy ra d cd hai vimg la Idn, ridng d Hd TTnh cd thi Idn tdi ttdn 3,0 m.
Tdi lieu khdo sdt dia hinh dd cdn cho thiy hifn trang dinh de cdn dang d mile thip, pho biin tir cao trinh 3,50 - 4,50 m, rit it noi dat cao trinh 5,50 m. Nhu vay ed thi kit luan rdng lupng sdng trdn qua dd trong dilu kien bao la khd Idn vd theo ude tinh (theo phuong phdp ciia TAW-2002) thi lim lupng trdn trang binh qua de cd thd d miic 50 - > 1001/s/m tuy theo vi tri va cap dp bdo .
Kdt qua khdo sat dia chit dd yd ndn dd khu vuc biin hai vimg trpng dilm cdn cho thiy dit ddp than dd cd tinh dinh kdm (cat, cat pha) kit ciu kdm chat do dd dl bdo xdi, khdng cd khd ndng chdng nude ttdn qua dd vdo miia mua 10, can c6 hifn phap bio vf ttdnh mit On djnh khi bi bdo hda cd sdng trdn vd ddng thim. Trong khi dd dit nln dd d nhilu chO Id cac Idp dit ylu, siic khdng cit bd, do do de gay mdt dn djnh (nhu spt, ttirpt...) khi cd bao vd ttilu cudng
Nhu vpy vdi luu lupng ttdn qua dd Idn nhu hifn tai va dilu kifn dja chat ddt dip than dd vd ndn dd cd tinh thim cao, siic khang cdt bd, thi cdn co nhiing gidi
phdp hifu qua nhdm ddm bdo dinh vd mdi phia trong dd dupe bdo vf mpt cdch hifu qua, khdng bj mit dn djnh khi cd sdng ttdn qua trong bdo.
Tai lifu tham khao
Trjnh Minh Thp, 2009. Cdc thuylt minh bdo cdo dja chit khu vpc trpng ylu Nam Djnh vd Ha Tinh.
Vii Vdn Nam vd Phiing Xuan Difp, 2008. Cdc thuylt minh bdo cao dja hinh khu vpc ttpng ylu Nam Djnh vd Ha TTnh.
TAW, 2002. Technical report wave run-up and wave overtopping at dikes.
Technical Advisory Committee on Flood Defence, The Netherlands.