Dac diem dong chay.
Vimg ha luu song Hong, nd'u tfnh tir Scm Tay cd nam chi luu:
Song Dudng chuye'n 26 % ddng chay ciia song Hdng vao song Thai Binh. Nga ba hai sdng d vi trf vao khoang 5 km phfa tren Ha Npi. Day la nhanh quan lrong nhat va ddng chay ciia nd chiem ty le chii yeu ciia luu lugng nude song Thai Binh.
Sdng Lupe mang 11 % ddng ehay sdng Hdng d6 vao sdng Thai Binh. Cac sdng Hdng va sdng Thai Binh lien ket vdi nhau thanh mot he thdng nhat bdi cac sdng Dudng va sdng Lupe.
Sdng Dao Nam Dinh chuyen tai 20 % ddng chay sdng H6ng vao song Day. Sdng Ninh Ca dua 8 % luu lugng song Hdng ra bidn.
Ddng chay song Hdng cung nhu nhieu song khac hang nam dao dpng liieo miia: miia lu va miia can. Ddng ehay phan phdi khdng ddu trong nam, lugng nude phdn Idn tap trung vao mua lu. Thdi gian bdt dau ed lu la thang VI, nhung doi khi lu cd the xuat hien vao cudi thang V. Thdi gian kd't thiic ciia miia lu la thang IX hoac thang X. Trong khoang bdn dd'n nam thang (thang VI-X),lugng nude miia lu chiem 75-85% lugng nude ca nam. Luu lugng dinh lu gap hang chuc Idn luu lugng nude miia can. Cac thang miia lu cd ty Id nude Ichoang 9-30%. Ty Id phan phdi lugng nude miia lii hang thang bien ddi nhieu hem miia can. Vao cac thang ddu va cudi miia lu, theo thdng kd nhieu nam thi tir 30-70 % sd nam trdn luu vuc song Hdng thang VIII la thang co lu Idn nhat. Lugng nude trong thang VIII co thd bang 15-35 % lugng nude ca nam.
Miia can thudng vao thang XI dd'n thang V. Vao thdi gian nira nam dd. sdng
ngdi cd luang nude thudng chi bdng 20-30 % lugng nude ca nam. Giai doan dau \'h
cudi miia can cd nhimg tran mua do Ichong khi cue ddi va fron ianh. ducmg dut... tuy ed lam bien dpng muc nude sdng ngdi nhung nhin chung xu the la muc nude giam dan, nhimg bidn dpng dd cd lam cho lugng nude ngay tang, eon lugng nude trung binh thang vdn nhd dudi trung bmh hang nam. Giai doan on dinh ciia miia can cd lugng ddng chay kha nhd, giai doan nay thudng keo dai ba thang (tir thang I de'n thang III). Luong ddng chay ciia ca ba thang nay cung chi bdng 7-8 % luong nude ca nam
Dong chay biin cat.
Ddng chay song Hdng trudc khi vao ddng bdng da bdt ddu bi khdng che' bdi he thdng de, che dd thuy luc ciia eac doan sdng kha phiic tap. lai tuy theo che dp muc nude ciia cac nhanh anh hudng ngugc iai ichac nhau do do tao ra che do thuy luc khdng dn dinh va lam cho ddng bim cat cung bie'n ddi rat phuc tap.
sdng Dudng va lugng bun cat phan sang song Dudng gia nhap vao song Thai Binh hang nam dat khoang 27-28 % tdng lugng biin cat ciia Ha Npi va Thugng Cat. Sau Ha Npi, sdng Hdng cdn phan luu qua song Lupe, sdng Tra Ly, sdng Dao Nam Diiih. sdng Ninh Co, nhung do didn bien dp due va luu lupng nude co su anh hudiig eiia thuy trieu va man nen cang phuc tap
Phan doan vimg cura sdng Hong.
Di thuan tien cho vide nghidn cun, chiing toi phan doan vimg cira song Hdng
theo mure do anh hudng tndu thanh bdn tidu khu ed cac che do thuy luc Ichac nhau.
Khu vuc khong chiu dnh huang trieu:
Day la khu vuc ndm tren Ha Npi " . . - . . ,
Khu vuc bi dnh huang trieu ddi chiit:
Do la khu vuc giira Ha Npi va Hung Yen, dai khoang 70 km, tren song co
nhieu bai bdi. Vao miia kiet. tai Hung Yen do rong ciia song ia 600 m dd'n 650 m va do sau tdi da tir 9 m den 10 m. Vao mira lu. khi muc nude tai Ha Noi vuat qua miic bao ddng cap ba thi dd rdng song ien den 2800 m va do sau tdi da la 13-14 m. Muc nude tai Hung Yen anh hudn chii yeu eiia ddng chay song, anh hudng ciia thuy trieu khong dang kd.
Khu vuc vira bi ddng chdy ciia sdng lan thuy trieu kiem sodt:
Khu vuc nay la doan tir Hung Yen dd'n Nam Dinh. dat khoang 45 km. Vijng nay chiu anh hudng manh me ciia lu va thuy tneu. Khi muc nude tai Ha Ndi cdn d dudi 8 m, nhutig dao dpng vd muc nude trong viing nay phan anh dao dong eiia thuy tndu tai Hdn Dau vdi thdi gian cham hon tir 5 den 8 gid. Khi muc nude tai Ha Noi giira 8 m va 10 m, anh hudng ciia ddng chay lu tang len. con anh hudng ciia thuy trieu giam di ro ret, dac bidt trong thdi gian nude len. Khi muc nude tai Ha Ndi vugt qua 10 m thi bidu dd thuy van quan sat dugc khdng cdn phan anh anh hudng ciia thuy tndu nira.
'' Day la khu vuc tir cira Ba Lat vao, dai khoang 62 km. Tai doan nay muc nude
thay ddi theo nhat tridu tai Hdn Dau, vdi thdi gian cham tir 1 den 4 gid trong khi tridu len va tir 2 de'n 6 gid khi tneu xudng. Hinh thai cira Ba Lat va cira Lach Giang thudng xuyen bien ddi lam cho anh hudng ciia thuy tridu tir bien vao luc dia luon ludn thay doi ca theo khong gian va thdi gian.
HaNoi HiJDg Y e a
Nam Dinh.
Ciia Ba Lat
Chucrng 3