CHNG VI

NG DNG M HNH MIKE11 CNH BO, D BO L V NGUY C NGP LT SNG TRUI, SNG B LU TNH THA THIN HU

Ths. Phm Vn Chin

i Khi tng Thuy vn khu vc Trung Trung B

TM TT

Tnh Tha Thin Hu l mt trong nhng tnh c a hnh v mng li sng phc tp nht khu vc Trung Trung B. Ch ma l ti y cng rt c lit v thng xuyn gy nh hng ln n kinh t- x hi hng nm.

Trn a bn ca tnh Tha Thin Hu, h thng sng Hng c lu vc sng ln nht. Bn cnh , cn c cc lu vc sng khc nh: sng Lu pha bc, sng Trui v sng B Lu pha nam. Hng nm, l cng thng xuyn xut hin v gy ngp lt lm nh hng n i sng dn sinh kinh t ti cc khu vc ny.

Trong nhng nm qua, tnh Tha Thin Hu c s quan tm, u t nhm hon thin, nng cao cht lng v hiu qu ca cng tc phng chng l lt trn phm vi ton Tnh. Cng vi h thng sng Hng, cc sng khc cng c quan tm, u t xy dng cng c phc v cng tc ch huy, ch o phng chng l lt, trong nhim v cnh bo, d bo l lt l mt trong nhng nhim v c ch trng u tin.

Vi s u t ca Tnh, cng tc o c, kho st v kh tng thy vn, nghin cu xy dng cng c cnh bo v d bo nguy c l lt cho sng Trui v sng B Lu c i Kh tng Thy vn khu vc Trung Trung B thc hin t nm 2008-2010. Trong , nghin cu ng dng m hnh MIKE11 d bo l, cnh bo nguy c ngp lt cho 2 sng ny t c kt qu kh quan.

ABSTRACT

Thua Thien Hue is one of the province has terrain and river network of the most complex of the central region. Every year, the flooding here is very fierce and often causes great impact on the socio-economic.On the region of Thua Thien Hue, the Huong river system has the largest river basin. Besides, there are also different river basins such as O Lau River in the north, Truoi river and Bu Lu river in the south. The flood often occurs here and causes flooding to affect the life-economic in the region every year.

In the past years, Thua Thien Hue province has the attention and investment to improve, enhance quality and efficiency of flood prevention in the province. In fact, Huong river system and other rivers have also been interested and invested construction tools for the command and direction to prevent the flood, in which the mission of the flood warning and the flood forecasting is one of the missions are interested on first.With the investment of the province, the work of measurement, survey of meteorological and research to build tools warning and forecast the risk of flooding for Truoi river and Bu Lu river have been carried out by the MID-CENTRAL REGIONAL HYDRO-METEOROLOGICAL CENTER in 2008-2010. Of which, the research applied to model MIKE11 for flood forecasting and warning of these rivers has achieved positive result.

I/ C IM MA L

1.1, c im mng li sng

Sng Trui c chiu di 20km, khong 2/3 chiu di sng chy qua vng ni v rng rm c cao 200-820m. Sng Trui c din tch lu vc khong 149km2, bao gm phn t ca huyn Nam ng v huyn Ph Lc. Chiu di v din tch lu vc rt hn ch. dc mt t v sng sui ln, lu vc hp l nhng yu t thc y nhanh qu trnh tp trung nc, truyn l. Ngoi ra, thng lu ni Diu G xy dng h cha nc Trui c dung tch 50 triu mt khi nc phc v ti rung v iu tit nc vng h lu.

Sng B Lu c chiu di 17km, din tch lu vc 118km2, dc trung bnh lu vc trn 26.1m/km. Cng tng t sng Trui, dc lu vc v dc lng sng ln, sng ngn v dc l nhng yu t thc y nhanh qu trnh tp trung nc, truyn l.

C th ni vng h lu sng Trui v B Lu c mng li sng kh phc tp, trong khi li t c s liu kh tng thy vn (KTTV) c bn nn kh c th nh gi chi tit c ch thy vn ni chung, ch l ni ring v nghin cu d bo l cho cc lu vc sng ny.

Hnh 1- Bn mng li sng sui, trm KTTV lu vc sng Trui, sng B Lu phc v nghin cu d bo l

1.2, c im ma- l

Cng nh cc lu vc sng khc thuc tnh Tha Thin Hu, ma trn lu vc sng Trui v sng B Lu ch yu do Bo, p thp nhit i (ATN), Khng kh lnh (KKL), Hi t nhit i (HTN) v mt s hnh th thi tit khc. Ma ln nht thng do Bo, ATN kt hp vi KKL gy ra.

Ma ma trn hai lu vc thng bt u vo thng 9 kt thc vo thng 12. Do s tc ng ca iu kin a hnh v hon lu kh quyn nn hnh thnh cc trung tm ma ln l: Bch M, Nam ng- Ph Lc vi lng ma nm y dao ng trong khong 3400mm n 4000mm, c nm trn 5000mm nh cc nm 1973, 1996, v nm 1999 Nam ng, c bit lng ma nm 1980 Bch M o c 8664 mm.

Mt t ma ln gy l thng ko di t 2-3 ngy, vi tng lng ma trung bnh khong 350mm.Mi nm bnh qun c 4 trn l, c nm nhiu c ti 7 trn, nh nm 1981, 1996, 1998, 2007, nm t nht l 2 trn. L thng xy ra vo thng 10, 11 chim t 89- 97%. Vo thi gian ny cng thng xut hin cc trn l ln nguy him, c bit trong nhng nm gn y s trn l ln xut hin c chiu hng gia tng.

*Sng Trui:

Bin l ca cc trn l ln nht nm ti trm Trui trung bnh l 2.75m, ln nht l 3.58m (nm 1999), nh nht l 1.72m (nm 2003).

L sng Trui c cng sut (I) l ln kh ln. Trung bnh trong mi trn, l ln vi cng sut khong 0.13m/h. Trn l c cng sut l ln trung bnh trong ton trn ln nht l 0.3m/h. Cng sut l ln bin i ch yu l do cng ma. Khi ma ln, cp tp c th lm cho l ln rt nhanh vi cng sut c th ln n gn 1m/h, nh trn l ln nht nm 1999 c cng sut l ln ln nht t n 0.83m/h

Mi trn l thng ch ko di trong vi ngy, thi gian duy tr l mc cao khng di. Thi gian l ln trung bnh trong mi trn l l 27 gi, thi gian l xung l 68 gi v thi gian c trn l trung bnh l 96 gi. Tuy nhin cng c trn l ko di ln n 6-7 ngy.

*Sng B Lu:

Sng B Lu c cng sut l ln nh hn sng Trui, do sng c lu vc nh, vng h lu chy qua vng ng bng thp, b sng c cao trnh thp nn dng chy l thng xuyn trn khi lng sng chnh gy ngp lt, nhng su ngp khng ln.

Cng sut l ln trung bnh l 0.08m/h, trn ln nht c Itb l 0.18m/h; cng sut l ln ln nht (tc thi) l 0.27m/h. Khi mc nc l ti trm Nc Ngt t t 3m tr ln, l ln chm hn, Itb ch khong 0.02m/h; ln nht l 0.07m/h. Nguyn nhn l do khi l ln cao, lng ma gim, dng chy trn b lm cho cng sut l ln gim hn.

Thi gian l ln trong mi trn l trung bnh l 30 gi, trn ln nht ko di trong 65 gi; thi gian l xung ko di hn: trung bnh l 65 gi v ln nht l 153 gi.

Vng h lu do s tc ng ca thy triu nn cao trnh l c s bin i phc tp hn. Triu cng c th lm gia tng cao trnh l ti Trui ln khong 10 n 20cm, trm Nc Ngt ln khong 15 n 25cm.

II/ NG DNG M HNH MIKE 11 D BO L SNG TRUI V SNG B LU

2.1, Khi qut v m hnh MIKE11

M hnh MIKE11 l m hnh thu ng lc hc mt 1 chiu, thuc h thng m hnh ton thng mi MIKE do Vin Thu lc an Mch pht trin, hin l mt m hnh tin phong vi nhiu ng dng thnh cng trn th gii.

M hnh MIKE 11 l loi m hnh ton, s dng phng trnh St. Venant, m phng dng chy trong sng, lin kt vi vng ngp l. MIKE11 c mt s u im ni tri so vi cc m hnh khc nh:

- Lin kt vi GIS.

- Kt ni vi cc m hnh thnh phn khc ca b MIKE v d nh m hnh ma ro-dng chy NAM, m hnh thu ng lc hc 2 chiu MIKE 21, ...

-Tnh ton chuyn ti cht khuych tn.

-Vn hnh cng trnh.

Nghin cu ng dng m hnh MIKE 11 trong lnh vc d bo c thc hin cho sng Hng v mt s h thng sng khc. Ngoi ra, MIKE11 cn c ng dng nhiu trong lnh vc qun l ti nguyn nc, m trng,...

2.2, ng dng m hnh MIKE11 trong d bo l sng Trui v sng B Lu

Sng Trui v sng B Lu l 2 sng rt ngn, c th ko di thi gian d kin th phi tin hnh d bo l t ma. V vy, vic ng dng m hnh MIKE11 trong d bo cn phi thc hin theo 2 giai on.

- Tnh ton dng chy thng ngun t ma (m hnh ma- dng chy),

- Din ton qu trnh lan truyn l t thng lu v h lu (m hnh thy lc).

2.2.1. Tnh ton, d bo lu lng l cho cc trm thng lu sng Trui, B Lu

Ni dung chnh ca phn ny l ng dng m hnh ma-dng chy NAM tnh ton d bo dng chy ti v tr mt ct ca ra ca cc lu vc phn thng lu sng Trui, B Lu. S liu lu lng ti cc v tr ny s l bin trn tnh ton thu lc phn h lu.

a, S tnh ton d bo l cc trm thng lu

Trn c s v v tr a l, d liu cc trm KTTV hin c v b sung, s lu vc tnh ton dng chy t ma cho m hnh c th hin trong hnh 2

Hnh 2- S li trm o ma phc v tnh ton lu lng t ma trong m hnh NAM

Vi c im v a hnh, mng li sng, sng Trui c phn chia thnh 2 lu vc con (lu vc b phn), sng B Lu chia thnh 4 lu vc tnh ton dng chy, c th ghi bng 1.

Bng 1- Cc c trng lu vc chnh sng Trui, B Lu

Lu vc sngTn lu vc b phnDin tch (km2)Mt ct ca ra

Sng TruiHoTruoi65.9

Truoi226.8Cu Mng

Sng B LuThuaLuu12.7

Tha Lu218.0

BuLu212.2

CauDap40.4Cu p

Vi mi mt lu vc b phn, qu trnh dng chy c tnh ton t ma, sau tng hp kt qu dng chy t cc lu vc ny s c ng qu trnh lu lng dng chy ti cc mt ct ca ra ca lu vc ln.

b, D liu s dng

Cc trm ma s dng tnh ton dng chy c lit k trong bng 2 v trng s ca cc trm ma c tnh theo phng php a gic Thiessen (bng 3).

S liu ma, lu lng dng chy c s dng hiu chnh m hnh l s liu ca trn ma- l:

t 1: t 4h ngy 11/10 n 19h/15/10 nm 2008,

t 2: t 1h ngy 16/10 n 19h/20/10 nm 2008,

t 3: 1h/25/10-19h/30/10 nm 2008.

Bng 2- Cc trm ma c s dng tnh ton d bo lu lng cho cc trm thng ngun sng Trui, B Lu

Lu vc sngTn lu vc b phnDin tch (km2)Trm ma s dng

Sng TruiHoTruoi65.9Nam ng, Cu Mng, Cu p

Truoi226.8Cu Mng

Sng B LuThuaLuu12.7Cu p

Tha Lu218.0Cu p, Trui

BuLu212.2Cu p, Nc Ngt

CauDap40.4Cu p

Vai tr ca cc trm ma i vi kt qu tnh ton dng chy c th hin qua cc h s tnh ton bng phng php Thiessen (bng 3)

Bng 3- Trng s (Thiessen) ca cc trm ma cho thng ngun sng Trui, BLu

Lu vcTrm ma

Nam ngCu MngCu pTruiNc Ngt

HOTRUOI0.2810.5790.1400.0000.000

BULU20.0000.0000.7910.0000.209

THUALUU20.0000.0000.5810.0000.419

TRUOI2_CAUMANG0.0001.0000.0000.0000.000

CAUDAP0.0000.0001.0000.0000.000

THUALUU0.0000.0001.0000.0000.000

Chy m hnh v hiu chnh thng s. Kt qu tnh ton qu trnh lu lng l thc o v tnh ton bng m hnh NAM c trnh by cc hnh 3 n 8.

Hnh 3- Lu lng l thc o v tnh ton lu vc sng Trui ti Cu Mng, t ngy 10-13/10/2008Hnh 4- Lu lng l thc o v tnh ton lu vc sng B Lu ti Cu p, t ngy 12-13/10/2008

Hnh 5- Lu lng l thc o v tnh ton lu vc sng Trui ti Cu Mng, t ngy 16-18/10/2008Hnh 6- Lu lng l thc o v tnh ton sng B Lu ti Cu p t 16-18/10/2008

Sai s gia lu lng tnh ton v thc o trong bc hiu chnh m hnh c nh gi theo ch s Nash-Sutcliffe.

Bng 4- Kt qu hiu chnh v kim nghim m hnh ma - dng chy

Lu vcTn trmCh s Nash

Lu vc sng TruiCu Mng92%

Lu vc sng B LuCu p87%

2.2.2, ng dng m hnh thy lc MIKE11 din ton, d bo l h lu

a, S din ton thu lc l h lu

Cc sng c th hin trong s tnh thy lc bao gm: Sng Trui, sng B Lu gm 2 nhnh Nc Ngt v B Lu. S tnh c trnh by trong hnh 7.

b,iu kin bin

Bin trn:

Bin trn l qu trnh lu lng gi (Q~t) ti 3 trm thy vn:

Trm Cu Mng trn sng Trui,

Trm Cu p trn sng B Lu, nhnh Nc Ngt,

im Tha Lu trn sng B Lu, nhnh Tha Lu,

Bin di:

Bin di l qu trnh mc nc triu ti m Cu Hai v Cnh Dng.

Cc trm thy vn c s liu c dng trong tnh ton thu lc c trnh by trong bng 5.

Hnh 7- S tnh ton thu lc- d bo l sng Trui, B Lu

Bng 5- S liu ca cc trm thy vn c dng trong m hnh

TTTn trmSngS liuMc ch

1Cu MngTruiQ,HBin trn

2Cu pNc NgtQ,HBin trn

3Tha LuTha LuQBin trn

4TruiTruiHHiu chnh, kim nghim

5Nc NgtNc NgtHHiu chnh, kim nghim

6Thn ngTruiHBin di

7Cnh DngB LuHBin di

c, Hiu chnh thng s m hnh din ton l

S liu thy vn bao gm mc nc v lu lng quan trc ti cc trm thu vn trn lu vc c dng trong hiu chnh m hnh.

S liu thc o ca 3 trn l nm 2008 c dng hiu chnh m hnh. Kt qu so snh gia s liu thc o v kt qu tnh ton hiu chnh m hnh ca cc trm Trui (S. Trui) v trm Nc Ngt (S. B Lu) c trnh by trong hnh 8 n hnh 11. Nhn chung qu trnh l tnh ton c hnh dng tng t nh qu trnh l thc o. Tuy mt s gi cn c sai s tng i ln nhng khng nhiu v thng nm nhng gi l bin i ln- xung nhanh.

Kt qu phn tch sai s tnh ton hiu chnh m hnh c trnh by trong bng 6. Qua so snh, c th thy kt qu tnh ton kh ph hp vi ti liu thc o. Mc hiu qu ca m hnh t gi tr xp x 80%. Sai s tuyt i trung bnh ti trm Trui (sng Trui) ch c 0.13m v ti trm Nc Ngt (sng B Lu) l 0.09m. Tuy nhin sai s tuyt i phn nc thp- chn l ln, xung cng cn kh ln.

Hnh 8- Kt qu tnh ton hiu chnh m hnh MIKE11 (HD) trm Trui- sng Trui, t ngy 10-12/10/2008Hnh 9- Kt qu tnh ton hiu chnh m hnh MIKE11 (HD) trm Nc Ngt- sng B Lu, t ngy 10-12/10/2008

Hnh 10- Kt qu tnh ton hiu chnh m hnh MIKE11 (HD) trm Trui- sng Trui, t ngy, t ngy 24-26/10/2008Hnh 11- Kt qu tnh ton hiu chnh m hnh MIKE11 (HD) trm Nc Ngt- sng B Lu, t ngy 24-26/10/2008

Bng 6- Phn tch hiu qu v sai s ca hiu chnh m hnhTTTrm kim nghimMc hiu qu ca m hnh

(%)Sai s tuyt i trung bnh

(m)Sai s tuyt i ln nht (m)

1Trui810.130.44

2Nc Ngt800.090.25

d, Kim nghim kt qu d bo

S dng lng ma vi thi on 6 gi quan trc ti 5 trm trong ma l nm 2010: Cu Mng, Cu p, Trui, Nc Nt v Nam ng, tnh ton d bo dng chy bng m hnh NAM v din ton thy lc- lan truyn l v h du bng m hnh thy lc MIKE11. Kt qu tnh ton 2 trn l nh sau ( hnh 12-15).

Hnh 12- Qu trnh l thc o v tnh ton bng m hnh MIKE11 sng Trui, t ngy 3-6/11/2010Hnh 13- Qu trnh l thc o v tnh ton bng m hnh MIKE11 sng B Lu, t ngy 3-6/11/2010

Hnh 14- Qu trnh l thc o v tnh ton bng m hnh MIKE11 sng Trui, t ngy 15-17/11/2010Hnh 15- Qu trnh l thc o v tnh ton bng m hnh MIKE11 sng B Lu, t ngy 15-17/11/2010

Nh vy, kt qu kim nghim d bo l sng Trui v sng B Lu bng m hnh MIKE11 cho thy qu trnh l tnh ton tng i ph hp vi gi tr thc o. Trn l t ngy 3-6/11 c sai s gia tnh ton v thc o nh hn trn l t 15-17/11/2010. Tuy nhin, qu trnh l tnh ton mt s thi im cn c s bin i khc bit vi thc th nh trong trn l ngy 3-6/11 trn sng B Lu. Nguyn nhn l do y l trn l nh, qu trnh mc nc l rt khng n nh do s tc ng ca lng ma cc b.

nh gi mc m bo cn c theo sai s cho php i vi sng Trui l 0.29m, sng B Lu l 0.22m th mc m bo ca m hnh d bo i vi 2 trn l trn nh sau (bng 7).

Bng 7-nh gi mc m bo (%) ca m hnh d bo l sng Trui v sng B Lu

Sng

Thi gian d boTruiB Lu

3-6/11/20119492

15-17/11/20119081

Trung bnh92.086.5

III/ NG DNG MIKE11-GIS CNH BO NGP LT

M hnh MIKE11 thc hin cc tnh ton thy vn, thy lc cho ra cc gi tr mc nc, lu lng ti cc mt ct ca sng Trui, B Lu, sau nhng gi tr ny c a ln bn tng ng vi v tr trong khng gian ca mi mt ct, t xc nh din v su ngp lt gy ra bi mi trn l bng m hnh MIKE11- GIS.

Tm tt cc bc xy dng bn ngp lt c trnh by trong s di y.

Hnh 16- S ng dng MIKE11- GIS trong cnh bo ngp lt

Kt qu cnh bo nguy c ngp lt cho 2 lu vc sng trong trn l thng 10/2008 c th hin hnh 17, 18.

Hnh 17-Bn nguy c ngp lt lu vc sng Trui khi mc nc l ti Trui l ln n 3.0m Hnh 18-Bn nguy c ngp lt lu vc sng B Lu khi l ti trm Nc Ngt ln n 2.5m

IV/ KT LUN V KIN NGH

Sng Trui v sng B Lu l nhng sng nh thuc khu vc pha nam tnh Tha Thin Hu. Vng h lu 2 sng ny l vng ng bng nh hp, c a hnh rt thp v thng xuyn b ngp trong ma ma- l. Nghin cu ng dng m hnh MIKE11 d bo l v cnh bo nguy c ngp lt cho 2 sng ny t c kt qu kh quan. Ngoi mng li trm KTTV c Nh nc u t, Tnh cn u t xy dng b sung mt s trm o ma, mc nc c iu kin ng dng m hnh ny trong d bo tc nghip phc v cng tc ch huy, ch o phng trnh l lt cho a phng.

Khu vc Trung Trung B cn nhiu h thng sng cha c nghin cu ng dng cng ngh ny trong d bo l, ngh Trung tm KTTV Quc gia tip tc c s quan tm u t pht trin mng li trm quan trc, kho st, nghin cu ng dng cc cng ngh cao trong d bo l v ngp lt.

TAI LIU THAM KHAO

[1] Nguyn Hu Khi, Nguyn Thanh Sn (2003), M hnh ton Thu vn, Nxb i hc Quc gia H Ni, H Ni.

[2] S Khoa hc v Cng ngh tnh Tha Thin- Hu (2004), c im Kh hu- Thu vn tnh Tha Thin- Hu, Nxb Thun Ho, Tha Thin- Hu.

[3] Nguyn Vn Tun, on Quyt Trung, Bi Vn c (2003), D bo thy vn, Nxb i hc Quc gia H Ni.

[4] y ban nhn dn tnh Tha Thin Hu, (2005), a ch Tha Thin Hu, Nxb khoa hc x hi.[5] Vin Kh tng Thu vn (2002), Bo co mc nghin cu cc phng n d bo l v cnh bo ngp lt lu vc sng Hng, H Ni.

Bin ng

m Cu Hai

S. Nc Ngt

S. B Lu

S. Trui

Trm TV Trui

Trm TV Nc Ngt

Thn ng

Cu Mng

Cu p

Tha Lu

Cnh Dng

-Nhp file kt qu ca MIKE 11

-To file mc nc dng TIN

-To li bn ngp lt

-To 1 project mi

-Nhn d liu v s thy lc, mt ct t MIKE11-GIS

-B sung thng tin v cc cng trnh v s liu v dng chy

-Tnh ton thy vn, thy lc

-To mng li sng sui (s thy lc)

-To v xut s liu mt ct

-Nhp d liu v a hnh

-To bn a hnh (TIN)

-To cc lp ng hoc vng xc nh cc cha, , ng giao thng

-Hiu chnh cao

Bn cnh bo nguy c ngp lt

Xc nh din ngp lt

FM module

X l mt ct ngang

Chy MIKE 11

To file u vo cho m hnh MIKE 11

Modun x l a hnh

DEM Module

Khi ng MIKE11-GIS

PAGE 4