lu vc sng hng- thi bnh

  • Published on
    25-Jun-2015

  • View
    973

  • Download
    4

Transcript

GII THIU CHUNG V H THNG LU VC SNG HNG SNG THI BNH 1 IU KIN T NHIN 1.1 V TR A L Lu vc sng Hng - sng Thi Bnh l mt lu vc sng lin quc gia chy qua 3 nc Vit Nam, Trung Quc, Lo vi tng din tch t nhin vo khong 169.000km2 v din tch lu vc ca hai sng ny trong lnh th Vit Nam vo khong 87.840km2. Chu th sng nm hon ton trong lnh th Vit Nam c din tch c tnh khong 17.000km2. Chiu da sng Hng trong lnh th Vit Nam khong 328km. Phn lu vc nm Trung quc l: 81.200 km2 chim 48% din tch ton lu vc. Phn lu vc nm Lo l: 1.100 km2 chim 0,7% din tch ton lu vc. Phn lu vc nm Vit Nam l: 87.840 km2 chim 51,3% din tch lu vc. y l con sng ln th hai (sau sng Mkng) chy qua Vit Nam ra bin ng. Sng Hng c hnh thnh t 3 sng nhnh ln l sng , sng L v sng Thao. Sng Thi Bnh cng c hnh thnh t 3 nhnh sng ln l sng Cu, sng Thng v sng Lc Nam. Hai h thng sng c ni thng vi nhau bng sng ung v sng Luc to thnh lu vc sng Hng - sng Thi Bnh. Lu vc sng Hng - sng Thi Bnh c gii hn t 20023 n 25030 v Bc v t 1000 n 107010 kinh ng. + Pha Bc gip lu vc sng Trng Giang v sng Chu Giang ca Trung Quc. + Pha Ty gip lu vc sng Mkng. + Pha Nam gip lu vc sng M. + Pha ng gip vnh Bc B. Phn lu vc sng Hng - sng Thi Bnh trn lnh th Vit Nam c v tr a l t: 20023 n 23022 v Bc v t 102010 n 107010 kinh Ty.

2

Hnh 1.1: Bn lu vc sng Hng - Thi Bnh 1.2 C IM A HNH a hnh lu vc sng Hng c hng dc chung t ty bc xung ng nam, a hnh phn ln l i ni, chia ct mnh, khong 70% din tch cao trn 500m v khong 47% din tch lu vc cao trn 1000m. cao bnh qun lu vc khong 1090m. Pha ty c cc dy ni bin gii Vit Lo, c nhiu nh cao trm 1800m nh nh Pu - Si - Lung (3076m), Pu - Den - Dinh (1886m), Pu - San - Sao (1877m). Nhng nh ni ny l ng phn nc gia h thng sng Hng vi h thng sng M Kng. Trong lu vc c dy Hong Lin Sn phn chia sng v sng Thao, c nh Phan Xi Pan cao 3143m, l nh ni cao nht nc ta. cao trung bnh lu vc ca sng ngi ln, chia ct su dn ti dc bnh qun lu vc ln, ph bin dc bnh qun lu vc t t 10% n 15%. Mt s sng rt dc nh Ngi Thia t ti 42%, Sui Sp 46,6%. a hnh lu vc sng Thi Bnh l a hnh dng i, vi cao ph bin t 50m n 150m, chim 60% din tch. Rt t nh cao vt qu 1000m. Ch c mt s nh nh Tam o c cao 1591m, Phia eng cao 1527m. Ni i trong h thng sng Thi Bnh c hng Ty bc - ng nam tn ti song song vi nhng vng cung m rng v pha Bc. ng bng sng Hng Thi bnh c tnh t Vit Tr n ca sng chim hn 70% din tch ton lu vc. a hnh thp v tng i bng phng, cao trung bnh khong 25m. Dc theo cc sng ng bng u c chia ct3

ng bng thnh nhng tng i c lp. Vng ca sng gip bin c nhiu cn ct v bi ph sa. V mt hnh thi, c th chia vng lu vc sng Hng Thi Bnh thnh nhng khu vc chnh nh sau: a) Vng thng lu Trn lu vc sng Hng c nhiu dy ni chy theo hng Ty Bc - ng Nam hoc Bc Nam phn cch gia cc lu vc: - Dy V Lng v Ai Lao c nh cao trn 3000m, ngn cch lu vc sng vi sng M Cng. - Dy Hong Lin Sn c ngn ni Phan Xi Phng cao 3142m ngn cch gia sng Thao v sng . - Dy Ty Cn Lnh c nh cao 2419m ngn cch gia sng L v sng Thao. - Cc dy Ngn Sn, Tam p c nh cao t 1000-2000m ngn cch gia Thi Bnh vi sng L. [1] Cc dy ni u c cao thp dn t Bc xung Nam v t Ty sang ng lm cho lu vc c dc chung theo hng Ty Bc - ng Nam. Phn phi cao ca lu vc sng Hng nh sau: Bng 1.1: Bng phn phi cao ca lu vc sng Hng Cao Phn Trung Quc Phn Vit Nam Tng cng 2 2 (Km ) (%) (Km ) (%) (Km2) (%) >3000 90 0,1 25 0,04 115 0,08 3000-2500 990 1,2 155 0,25 1145 0,80 2500-2000 30860 38,0 11990 9,70 42850 30,12 2000-1500 30860 38,0 11990 9,70 42850 30,12 1500-1000 30860 38,0 20570 9,70 42850 30,12 1000-500 15180 18,7 23550 3,70 35750 24,90