Nghien cufu & Trao d6i
LU VA VIEC Dy BAO LU TREN S O N G MA B A N G IVIO HINH NAM -MIKE11
ThS. Hoang Thj Nguyet Minh
Trudng Cao dang Tdi nguyen vd Mdi trudng Hd Ndi KS. Nguyin Ngoc Ha
Trung tdm Quy hoach vd Diiu tra tdi nguyen nude
T
^n luu vue sdng Ma, nam nao cung eo lu a vung ha du va thudng do su td hap lu giCra sdng Ma va sdng Chu va cung ed khi ed ea su td hap vdi triiu cudng. Trong 45-50 nam gin day tai Giang da xiy ra nhiiu tran lu Idn la do td hap glCea lu Idn tren sdng Ma va sdng Chu, ddng chii y nhit la lu nam 1962 va lu nam 1980., • •..,.
Lu Idn thudng lam vd de, gay itng lijt a nhiiu nai, lam thiet hai Idn vi ngudi vd tdi san cua nhan dan vd thiet hai dd eo thi duac giam nhe han niu viee du bao la ehinh xde cung nhu viee canh bao sdm han di CO cae bien phap phdng tranh.
Do vay, viee xay dung eae phuang an du bao lu la ein thiit. Cho din nay, viee du bdo lu tren song thudng duac thue hien bang phuang phap muc nude tuang irng, viee du bdo lu theo md hinh tren sdng Ma duac duac irng dung edn rit han ehi.
1. Tong quan ve he thong song
Luu vuc sdng Ma nim trong khu vuc khi hau nhiet ddi, gid mua, phdn hod theo vung rd ret: vung thugng nguin nim trong vung thdi tiit khi hau Tay Bie-Bie Bd cd miia mua den sdm vd kit thue sdm hon viing Trung Bd, vung sdng Chu nam trong vung thdi tiit khi hdu Bde Trung Bd, ed mua mua din mudn vd kit thuc mudn hon Bie Bd 15- 20 ngdy vd viing trung vd ha luu sdng Ma Id vung giao luu khi hdu giua Bde Bd vd Bde Trung Bd, ed miia mua mang nhiiu sic thdi cua ehi dp mua Bie Bd, miia mua bat diu tu thdng V vd kit thue vdo thdng XI.
Tam mua Idn nhit tren luu vue Id Thudng Xudn, tam mua nhd Id thung lung huyen sdng Md, Son La vd viing Hua-Phan thudc Ldo. Lugng mua binh
quan tren luu vue biin doi tU 1100 mm/ndm din 1860 mm/ndm. Tong lugng mua miia mua chiim tu 65 - 70% ting lugng mua nam vd ting lugng mua mua khd ehi chiim tu 30 - 35%.
Trong nam thudng cd tdi 3-4 dgt mua Idn tu 300mm trd len do bao gay ra, cdch nhau tu 5 - 7 ngdy va mdi trdn mua thudng tap trung trong 3- 4 ngdy liin. Net ddc biet tren luu vue sdng Md Id khi mua Idn d viing thugng ngudn thi tren luu vuc sdng Chu khdng ed mua hoac mua nhd vd khi mua Idn d thugng nguon sdng Chu thi phia sdng Ma khdng mua hoac mua it. Nhung khi ed bao do bd true tiip thi mua Idn se dien ra tren todn bd luu vuc, gdy nen lu Idn tren ca hd thong sdng nhu ede ndm:1927, 1962, 1989, 1996 vd 2007.
Ngudi phan bien: Bui Dire Long
Nghidn cufu & Trao doi
Bao d luu vue sdng Md thudng xuit hien chdm hon Bie Bd tu 15 - 20 ngdy Theo sd lieu thing ke tu 1954 din 2000 trong s i 140 con bao do bd vao Bie Trung Bd ed tdi 67 con bao do bd vdo luu vuc sdng Ma chiim 47,8% vdi sue gid tU cip VIII din cip XII khi gid giat tren cip XII (Vmgx ^ ^0 m/s).
Miia lu tren sdng Ma thudng bit diu, kit thue cham hon mua mua 1 thdng: thudng Id tU 6 din thdng 10 tren sdng Ma vd tu thdng 7 din thdng 11 tren sdng Chu (chdm 1 thdng so vdi sdng Ma).
Trong miia lu, ba thdng ed lugng lu Idn nhit trong nam thudng Id ede thdng 8, 9 vd 10, chiim tU 55,5% tong lugng lu trong nam (tren sdng Ma) din 54% (tren sdng Chu). Thdng cd lu Idn nhit tren sdng Ma thudng Id thdng 9 vdi tong lugng lu chiim tU 40,8% tong lugng ddng chay nam (Cam Thuy) din 45,7% (Xd Ld) Id thdng ed mua do bao. Thdng cd lu Idn nhit tren sdng Chu lai thudng Id thdng 9 va ehi chiim 38,7% (Xudn Khanh), it hon so vdi ddng chinh sdng Ma.
Luu lugng lu Idn nhit vd md dun ddng chay trung binh nhiiu nam tren sdng Ma tai Xa Ld dat 1.470m^/s vd 0,227m^/s.km2; tai Cim Thuy tren sdng Ma dat 3.100m3/s vd 0,177m3/s.km2; tai Cu-a Dat tren sdng Chu dat 2.330m3/s vd 0,378m3/s.km2; tai Lang Chdnh tren sdng Am dat 558m3/s vd 1.78 m^/s.km^; tai Vu Ban tren sdng Budi dat 1.060 m3/s vd1,20m3/s.km2.
Lu Idn xay ra d ha du sdng thudng do to hgp lu eua lu tren sdng Ma, sdng Chu vd ed khi ed ca trieu cudng. Theo s i lieu quan trie, trong 40-45 nam gin ddy cd 14 nam lu Idn nhit tai Gidng Id do to hgp lu eua sdng Ma vd sdng Chu gdy nen. Trong dd, ddng chu y nhdt Id cdc trdn lu:
- Lu nam 1962 Id lu to hgp bit Igi nhit giu-a lu trdn sdng Chu, sdng Ma, sdng Am lam eho mue nude lu ha du taj Gidng len rit eao, dat 7,48 m.
,., - Lu nam 1980 Id lu trdn lu do mua bao Idn d ha du sdng Ma, do triiu cudng vd lu Idn tren sdng Chu gdy ra. Day Id tran lu Idn, lu Ijch SLP vdi muc nude
7,51m tai Gidng (17/9/1980), eao hon muc nude lu nam 1973 Id 0,25m.
Toe dp truyen lu tren sdng Ma rit Idn va phu thudc vao tung doan sdng: phin sdng Ma thudc Thanh Hod, tic dp truyin lu Idn nhit tai thugng luu va giam din: doan tU Mu-dng Lat tdi Hdi Xudn (81km) dat tdi lOkm/h, doan tU Hdi Xudn tdi Cim Thuy (73 km) dat 7,3 km/h, tU Cim Thuy din Ly Nhan (36 km) dat 5,54 km/h vd doan tu Ly Nhdn din Gidng (28 km) dat 4,67 km/h. So vdi sdng Ma, tic dd truyin lu tren sdng Chu nhd hon rit nhiiu:
doan tu Cua Oat tdi Bdi Thu'gng (16 km) tic dp truyin lu dat 5,33 km/h vd doan tu Bdi Thugng tdi Xudn Khdnh (31 km) tie dp truyin lu ehi dat 3,44 km/h.
Nude lu da tung gay vd de, ngdp ung d nhiiu viing rdng Idn, gdy thiet hai v i ngudi vd tdi san cua nhan dan, Trdn lu 2007 Id trdn lu kinh hodng tren sdng Chu vd sdng Budi, da phd vd mdt phin dap h i Cifa Dat (sdng Chu) vd gdy ngdp ung viing Kim Tan, Thach Thanh (sdng Budi) trong nhiiu ngay ton thit v i ngudi vd cua la rit Idn.
O i du bdo lu tren sdng, gdp phin phdng trdnh vd Idm giam nhe thien tai do lu gay ra, nhiiu phuong phdp du bdo da dugc dp dung, nhung cho din nay phuong phdp muc nude tuong ung Id phuong phdp dugc su" dung nhiiu nhit. Cdc phuong phdp khdc chua hieu qua hay kha ndng dp dung Id rit khd
Nam 2008, trong d i tdi Nghien eUu quan ly ting hgp tdi nguyen vd mdi trudng luu vue sdng Ma ed ndi dung du bdo lu tren sdng bdng md hinh NAM- MIKE cho kit qua rit kha quan. Bdi bdo ndy xin gidi thieu lai cdc kit qua da dugc nghien cUu eua de tdi tren.
2.Gidi thieu v§ mo hinh Nam- IVIIKE
De tinh todn cho cdc luu vuc sdng hien nay thi MIKE Id cdng cu kha manh trong dd cd md hlnh NAM. Md hinh NAM Id cum tu viit t i t cua Nedbor- Afstromnings Model. Md hinh ndy dugc Nielsen vd
Tap chi Khi ttfgfng Thuy van * Thang 1/2009 27
Nghien cufu & Trao doi
Hansen xdy dung tai khoa Tdi nguyen nude va NAM thue c h i t giong nhau chi khac 1 Thiiy ddng lue - Trudng Dai hpc Bach Khoa Dan MIKE NAM cd them mdduyn v i thdnh Mach ndm 1973. Md hlnh NAM va md hlnh MIKE thdc nude n g i m vd moduyn v i tudi.
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Hinh 1. Ciu true mo hinh NAM-MIKE.
: D!un3
NAM la cdng cu du bdo khd hu'U hieu dang du'gc Ung dung dang thip nghiem nghien cuu cho mdt s i luu vuc sdng. Day la mdt md hlnh thuy van nhan thue dang be chua, md hinh quan niem luu vuc Id cdc be chUa x i p chdng nhau, trong dd mdi be chua dac trung cho mdt mdi trudng cd chUa cac y i u to gay anh hudng d i n qua trinh hlnh thdnh ddng chay tren luu vue va cdc be chua dugc lien k i t vdi nhau bang cdc bieu thue todn hpc, Trong md hlnh NAM, m i l mdt lu'u vuc dugc xem nhu' mdt don vj xd ly vdi cdc thdng sd Id dai dien eho cdc gid trj dugc trung binh hda tren toan lu'u vue, Md hinh NAM tinh todn qua trinh mua ddng chay theo each tinh lien tuc ham lugng am trong eae be chUa rieng biet tuong tac Idn nhau, nhu' du'gc ve trong hlnh 1, Cau triic cua cdc be bao gom :
a. Be chua tuyit dugc kiem soat b i n g cdc dieu kien nhiet dp vd buc xa, tuy nhien se khdng dugc
xet den trong dieu kien d Viet Nam.
b. B i chua mat bao gdm lugng am bj chan do Idp phij thuc vat, lugng dien trung va lugng i m trong t i n g mat. Umax bieu thj gidi han tren cua lugng nude trong be nay.
c. B i chua t i n g dudi la vung r i cay ma tu dd tham thue vat cd t h i l i y nude phue vu eho su thodt hoi nude cua cay Do vay be chua nay cdn gpi la b i chua am. Lmax bieu thj gidi han tren cua b i chua nay
d. Sau Cling id b i ehUa n g i m cd xet d i n kha nang khai thac nu'dc n g i m .
Md hlnh NAM cd tong cdng 19 thdng s i nhu cdc thdng s i v i ddng chay mat, thdng s i bdc hoi, thdng so lu'di....Trong dieu kien eua Viet Nam ed the bd qua cac thdng sd v i t u y i t vdi 4 thdng so. Va theo thue t i tinh todn eho t h i y chi cd 5 thdng s i anh
Nghien cu'u & Trao doi
hudng manh din qua trinh hlnh thanh ddng chay dd Id Umax, Lmax, CK12, QOF, GIF.
3. Ap dung md hinh cho lifu vuc song Ma a. So lieu dau vao
Oe xdc djnh thdng so md hlnh, ta ein xdc djnh s i lieu diu vdo gom: tdi lieu mua, bie hoi Id bien diu vdo cua md hlnh:
- Chpn s i lieu bdc hoi cua tram Hdi Xudn, dai dien eho ca luu vuc,
- So lieu mua dugc su dung tu s i lieu cua cdc tram, tuong ung vdi 4 viing:
+ Chpn cdc tram mua Xa Ld vd Tuin Gido Idm dai dien eho viing thugng luu luu vuc den Xa Ld,
+ Chpn cdc tram mua Mudng Lat va Hdi Xuan va c i m Thiiy dai dien cho vung tu Xd La din Cam Thuy,
+ Chpn cdc tram mua Cu'a Dat, Chdm Gidng, Bit Mpt dai dien eho viing thugng luu luu vuc sdng Chu din CCpa Oat.
+ Chpn cae tram mua Lac Son, Thach Quang, Vu Ban vd Kim Tan dai dien cho luu vuc sdng Budi.
Day cung la 4 luu vue thanh phin trong luu vuc sdng Ma vdi so lieu mua ngdy tu 1999 din 2005 de hieu chinh md hinh vd sd lieu mua ngay tu 15/9/2007-20/10/2007 dugc sd dung de kiem tra md hinh, Lugng mua binh qudn luu vuc dugc tinh bing phuong phdp Thiesen - phuong phdp trung binh trpng s i ,
Sd lieu ddng chay d i kiim nghiem md hinh la so lieu cua cac tram: Xa La (6.436km2), Cim Thuy (12.151 km2)vdCLi'a Oat (6.081 km2). Diu ra eua md hlnh la qua trinh ddng chay luu lugng gid tu nam 1999-2005.
Bang 2. Gia tri thong so md hinh NAM-MIKE Thong so"(long chay sat mat
Tram X a L i Cam Thuy
Cua Dat Kim Tan
^ m a A .
19,5 12 12 14,6
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160 101 105 102
CQ.F 0,22
0,2 0,28
0,9
CKip 481,2 8 60^
493
CKi2 19 12 27,1
46
ToF 0,147
0,6 0,03
0,9
TIP :
0,78 0,6 0,337
0,07 Thong so' gia nhap nUdc ngiitn
T6n tram X a L i C^m Thuy
Ciia Dat Kim Tan
To 0,98
0,2 0,86
CKBP
3253 1200 1001
Dieu Iden ban dau
Ten tram X a L i C^m Thuy
Cua Dat Kim Tan
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0,5
L
0,5
QoF
20
QlF
30
Bp
0
Tap chi Khi tiifgfng Thuy van * Thang 1/2009 29
Nghi§n cufu & Trao d^i
b. Ap dung mo hinh vao Iwu vwe song Ma De dp dung md hinh, ta ein chuan bj cdc budc:
+ Xde djnh vj tri mat cit vd dien tich luu vue cin tinh todn tren ban do,
+ Xdc djnh vj tri, so lugng cdc tram do mua vd bdc hoi cd anh hudng tdi luu vuc cin tinh todn d i du-a len ban d i .
+ Khai bdo ede thdng s i luu vuc: ten luu vue, dien tich luu vuc, vj tri vd ten cdc tram mua, bie hoi vd vj tri mat cit cu-a ra luu vue, khai bdo dudng din tdi ede tap tin luu tru' s i lieu mua, bde hoi vd so lieu ddng chay d i kiim nghiem md hlnh.
+ Thiit lap cae thdng s i , diiu kien ban diu eua md hinh eho tUng luu vue.
O i hieu chinh md hinh ta dp dung kit hgp ea hai phuong phdp thu' sai vd phuong phdp dd tim t i i uu nhim giam bdt thdi gian dd tim tren mdy. Sai s i giUa luu lu'gng tinh todn va thuc do trong budc hieu ehinh vd kiim nghiem md hlnh dugc ddnh gid theo
ehl so Nash-Sutcliffe:
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Qsim,i Id luu lugng tinh todn vd Id luu lugng trung binh cdc thdi doan. K i t qua hieu chmh thdng s i dugc thing ke trong bang 2.
Sau khi ed cdc thdng s i da hieu ehinh tiin hanh tinh todn lai qua trinh ddng chay nam 1999 tai cdc tram thuy vdn Xa Ld, Cam Thuy, Cu'a Dat nhu cdc hinh ve : 2,3, 4 vd cho thiy dudng qud trinh thue do va qud trinh tinh todn ding pha nhau, chenh lech nhau khdng nhiiu. Sai s i tinh theo ehl s i Nash dat 90,3-91,7% Id rit tit, cho phep su- dung bd tham s i da tinh de du bdo kiim tra vd du bdo tdc nghiep.
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Hinh 2. Dw&ng qua trinh Iwu Iwang nam 1999 tai tram Xa La
Hinh 3. Dw&ng qua trinh Iwu Iwang nam 1999 tai tram Cam Thuy
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Hinh 4. Dw&ng qua trinh Iwu Iwang nam 1999 tai tram Cam Thuy
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Nghien cufu & Trao dO'i
Bang 3. Sal so tinh theo ehf tieu Nash
Lifu viic bo phan
Thudng song Ma TfirXaLadenCamThuy
Sdng Chu
Vi tri hi^u chinh qua trinh dong chay
Tram Thuy van Xa La Tram Thuy van Cam Thuy
Tram Thuy vSn CuTa Dat
Chi so'Nash (%)
82,2 75,04 76,38
- Du bdo kiim tra MIKE11 ta dugc qud trinh ddng chay kiem tra cua Su' dung s i lieu mua gid tu 15/9/2007 din tram Cua Dat vd Cam Thuy tuong ung (vdi sai s i 20/10/2007, s i lieu bie hoi trung binh eua tram Hoi theo ehi s i Nsish Id 75,03-82,2 eho trong bang 3) Xudn vd so lieu luu lugng gid cua cdc tram da chpn nhu ede hinh 5 vd 6.
tren tiin hanh du bdo kiem tra bang md hinh NAM- -
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Hinh 5. Dw&ng qua trinh Iwu Iwang 15/9 20/10/2007 tai tram Cam Thuy
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Hinh 6. Dw&ng qua trinh Iwu Iwang 15/9 • 20/10/2007 tai tram Cu'a Dat
c. Nhan xet kit qua tinh toan Kit qua tinh todn tren da cho thiy:
1) Dudng qud trinh du bdo vd qua trinh thue do dao ddng dong pha nhau, kit qua du bdo id kha quan.
2) Sai s i ehi s i Nash Id khd tit, dap Ung yeu ciu du bao.
3) Cd t h i SLK dung md hinh NAM-MIKE eho viee du bdo lu tren sdng tai Cu'a Oat vd Cim Thuy.
Tuy nhien, ddy cung mdi Id nghien cUu budc diu, d i hodn thien ein ed su kiem nghiem them cho cdc qud trinh ddng chay tai mdt s i vj tri khac tren luu vue.
£ , ; ; . , ; ; . Tai lieu tham khao
1. Hodng Ngoc Quang, Trudng Cao dang TNMT Hd Ndi: Nghien cuu qudn ly tdng hopu tdi nguyen vd mdi trudng luu vuc sdng Ma, di tdi cip Bp-2008.
2. Nguyin Vdn Nau, Vien QH Thuy lol: Tdng quan luu vue sdng Ma, 2006
3. Sd Tdi nguyen Mdi trudng Thanh Hod: Hien trang moi trudng Thanh Hod, 2006,2007.
