Tuyen tap Cdng trinh Hoi nghi Khoa hoc
Co' hoc Thiiy khi Todn qudc, Phan Thiet, 2008 19
Danh gia anh huong ciia cac tham so trong phan mem thiiy van tham so phan bo Marine
Nguyen Tien Cuong, Ngo Iluy Can
Vien Co hoc. Vien KflCN Viet Nam
Tom tdt: Mardie Id phdn mem tinh todn thuy van dang tham sd phdn hd dd vd dang duoc phdt trIen vd irng clung cho nhieu lini vuc sdng </ Viet Nam. Tir nam 2005 den nay Marine dd duac trIen khai irng dung trong cdng tdc canh bdo, du bdo lit tren hai he thdng lini vuc phire tap dd Id sdng Dd a mien Bdc vd he thdng sdng f lirang d tinh Thira thien -Hue.
Bdl bdo nay trinh bdy cdc ket qud ddiih gid dnh hucrng cua cdc tham sd trong md hinh thuy van tham sd phdn bd Marine, tren ca sd dd dira ra cdc kliuyen cdo vc cdch hieu chinh mo hinh sao cho hieu qud nhdt trong qud trinh irng dung.
Ket qud cua bdl hdo sc; glu/> Ich cho qud trinh hieu chinh md hinh trong qud trinh tdc nghiep vd xdc dinh bd tham sd tdt cho md hinh kill dp dung tinh todn cho mot viing mdi.
1. Phan loai cac n h o m tham so trong Marine:
Marine la md hinh thuy van tham sd phan bo nen trong md hinh cd nhieu tham sd dupe dua vao bao gdm cac tham sd ve dp nham eiia be mat luu vuc, tham sd anh hudng den dp tham nude eiia luu vuc, tham sd anh hudng den dp bdc hoi, ...
Trong bai bao nay sc phan cac tham sd trong Marine thanh ba loai tham so chinh theo dac tinh anh hudng ciia cac tham so den md hinh tinh dd la:
- Nhdm cac tham sd anh huong den tdc dp dong chay trong luu vuc.
- Nhdm cac tham sd anh hudng den dp tdn that cua ddng chay trong luu vuc.
- Nhom tham sd anh huong den lugng mua dau vao cua luu vuc,
2. Danh gia anh h u o n g ciia do nham be mat luu vuc den ket qua tinh ciia mo hinh thiiy van Marine:
Dp nham ciia b^ mat luu vuc dugc quyet dinh boi cac yeu id cau thanh nen be mat luu vuc cu the la:
- Dp go ghc ciia dia hinh mat luu vuc,
- Hien trang su dung dat ircn be mat luu vuc,
- Cau tnic cua cac loai tham phu, cae loai dat tren be mat luu vuc,
Vdi moi loai hien trang sir diing d5t tren be mat luu vuc se cd nhung dac trung ricng, cac dac trung nay lai cd cac mire dp anh huong den dp nham ciia be mat luu vuc khac nhau.
Cd nhi5u loai hien trang sir dung dk, dudi day la mot sd hien trang thudng gap o Vict Nam:
20
Dcmh gid dnh hirang cua cdc tham sd trong phdn mem thuy vein tham sd nhdn bd MiilJli^
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Hinh 1: Ban dd hien trang sir dung ddt
Ddng cd.
Hoa mau.
Cay bui rai rac.
Cay than go trdng khdng thanh rirng.
Cay bui trdng khdng thanh riing.
Cay bui trdng thanh rirng.
Cay bui xcn lan cd.
Rirng cay bui.
Rirng thua xen lan rirng cay bui.
Rirng thua,
Rirng gia cay la rdng, la kim, tre nira
Rirng nguycn sinh gdm nhieu tang cay dan sen day due, Nui da.
Dat trdng ddi niii trge Khu dan cu.
Do nham ciia be mat luu vuc trirc tiep anh huong d6n tdc dp ddng chay (ty le nghich vdi van toe ciia ddng chay) do do do nham la mot trong nhirng yeu td cd tac ddn^ manh nliat den pha cua ddng chay. ncu van tdc nhanh hay cham d6u se dan d<jn hien tugna lech pha.
Ve ca ban dp nham cd gia tri trong mot pham vi hep ddi vdi mot loai hien trang sir dyng dk. Nhung trong qua trinh xir ly sd lieu cung nhu sd lieu ban dd hien trang sir dung dat khdng the phan iinh dugc chinh xac loai hien trang sir dung d:it vi nhu vay sc qua chi tiet va yeu cau phai cap nhat sd lieu lien tue. Chinh vi vay de khiic phuc nhung thigu sdt klidng the kliac phuc dd can phai cd qua trinh hieu chinh de lam sao cd duge bd thdng sd
Nsuyen Tien Cirdng, Nsd Hiiy Cdn
nham phii hcrp luong irng vdi mdi loai hien trang su dung dat cua luu vuc. Ban chat ciia viec hieu chinh dp nham chinh la tim ra he sd nhiim trung binh cho mdi Idp tham phii ciia luu vuc.
luo no 1.'. 1 . I'j i'-.'j n-,0 1 .,- I h o t i i i . i i i (ut>,> I
Hinh 2: .inh hiivng cua dd nhdm den ket qua tinh
De danh gia miic dp anh hudng va dp nhay cua he so nham den ket qua tinh ciia md hinh thiiy van Marine, xet ba kich ban tinh loan:
- Kich ban he sd nham thuc ciia luu vuc.
- He sd nham cua luu vuc dugc cho rat nhd tren loan luu \-ue, - He so nham cua luu vuc dugc cho rat Idn tren toan luu vuc.
Tir cae ket qua tinh loan cua ba phuong an eho thay: He sd nham cd anh hudng Ion dt>n k(3t qua tinh loan cua md hinh, nhung anh huong cua he so nham den md hinh ehii yeu la Ac t6c do ddng chay tire la \c pha eiia ddng chay, eon vc gia tri cua luu lugng tinh toan CO chiu anh huong cua su bien doi dp nham nhung khdng Idn lam. Nhu vay de hieu chinh md hinh trong tru'dng hgp ket qua tinh bj lech pha eo the sir dung tham sd hieu chinh la he so nham.
Cac kit qua tinh cung cho thay pha cua qua trinh tinh loan cd the sai khac rat nhieu, pham vi di£u chinh pha cho luu vuc hd Tuycn Quang cd the Icn den 10 ticng, trong khi dd qua trinh dxcu chinh pha lam thay d6i gia tri luu luong tinh loan nho, chua den 600 m3/s so vdi gia tri luu luang lai dinh la 8000 mVs.
3. Danh gia anh h u o n g ciia cac tham so trong md hinh tham den ket qua tinh ciia M a r i n e :
Trong Marine md dun tinh tdn thdi ddng chay su dung ly thuyet tham Green Ampt, Phuang phap nay dugc xay dung tren co sd phuang trinh lien tue va dinh luat Darcy,
Theo phuang phap nay do sau tham tich IQy ti6m nang F(t) duge tinh thco cong thirc:
F ( / ) - \ | y A 0 1n
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22
Ddnh gid dnh hucrng cua cdc tham sd ti'0>^S phdn mem thuy van tham sd i>hdn bd MdjjM^
Sau khi xac dinh duge do sau tham tich lily se xiic dinh duge tdc do tham d i m nang f theo cdng thirc:
r
Trong hai cdng thirc tren ed:
- F(t): do siiu tham tich luy - f : tdc dd lliam licm nang
— k : do dan thuy luc cua cua dat - ^' : dp sau cot nude mao dan cua dat
— t : thdi gian
— ^ " : do rdng hieu dung cua dat.
Md dun tham dugc tinh loan dua tren Idp thdng tin nen la ban dd phan loai thanh phan cau true ciia dat. Chinh vi vay \ice xu ly dir lieu cung nhu chat lugng cua ban dd la rat quan trgng. Mdi nhdm cua ban dd cau triic dat dua \ao tinh loan trong md hinh thiiy van gdm bdn thdng tin chinh khdng ke cac thong tin xac dinh vi tri dd la:
— Do rdng
— Dp rdng hieu dung
- Cot nude mao dan cua mat udt - Do dan thiiy luc
Trong thuc le vdi moi loai dat cac ihong sd nhu dp dan thiiy luc, dp sau cot nude mao dan, dp rdng ciia dat deu da biet (cac thdng so nay dugc xiic dinh bang phuong phap thuc nghiem chi ra vice tra bang ket qua thuc nghicm da cd). Nhung do ban dd phan loai dat khdng du chi tiet \ i ty le ban dd nhd, cae du lieu khdng day dii chinh vi vay cSn phai hieu chinh cac tham sd dc tim ra bd tham sd tuong irng vdi cac Idp dat sao cho bd tham sd dd la gia tri trung binh ciia Idp ddt.
Hinh 3: Ban do ,ij^) dnh phdn cdiii true cua ddt
Nsiivd'n Tien Ciivns, Nsd Iluy Cdn 23
Trong ihue te vdi mdi loai dat cac thong so nhu dp dan ihuy lire, dp sau cot nude mao dan, dp rdng cua dat deu da biet (cac thdng sd nay da duge xiie dinh bang phuong phap thuc nghicm chi vice tra bang ket qua thirc nghicm da co), Nlurng do ban dd phan loai dat khdng dii chi tiet vi ty le ban dd nho, cac dii' lieu khong day dii chinh vi vay can phai hieu chinh cac tham sd de tim ra bd tham so tuong irng vdi cac Idp dat sao eho bd tham so do la gia trj trung binh eiia Idp dat.
Mire dp tdn that ciia ddng chay chinh la ket qua tinh loan cua md dun thdm. Qua trinh tham true tiep anh huirng den gia tri ciia luu luong dau ra cua mo hinh Ngoai ra dien bien cua qua trinh tham cdn lam anh huong den thdi gian dat dinh cua cac Iran Iii tinh loan. Do do can phai dieu chinh md dun tham sao eho lugng nude tdn thin hgp ly \'di thuc le,
De xet anh hiixVng eiia md hinh tham ed nhieu tham so co the hieu chinh. Nhung tir cong thirc tinh cua phuong phap tham Green Ampt cho thay dieu chinh tham sd dp rong hieu dung cua dat hay hieu chinh thanh phan ^^ sc hieu qua nhat. Dc dicu chinh ^^ la dua vao tham sd dp am ciia dat. vi ^ ^ la hieu cua dp rong cua dat (co dugc tii' thuc nghiem) va do am ciia dat. Do dp am ciia dat la tham so do dac (bien ddi theo thdi gian) nen de dieu chinh ^ ^ sir dung tham sd nay la hoiin toan hgp ly,
De nghien ciru anh hudng cua md dun tham hay chinh la cua dp am cua dat den ket qua tinh loan ciia md hinh thiiy van Marine nhom nghicn ciru xem xet ba phuong an sau:
- Dp iim eiia dat lay trung binh hoac theo sd lieu thuc do, - Dp am ciia dat cho rat nho,
- Dd am ciia dat cho Idn,
Hinh 4: Anh hm'mg cua tham den ket qua tinh cua Marine
Ba phuong an tinh tren da bao ham cac trudng hgp lir trudng hgp khoang khdng gian gianh cho tham Idn nhdl den trudng hgp khoang khong gian gianh cho tham nhd nhat.
Cae kit qua tinh loan theo ba phuong an trong hinh Ircn eho thay khi dieu chinh mire dp thiim cua md dun thim sc true tiep anh hudng dcm giii tri luu lugng tinh loan cua mo hinh, cdn vi} pha cd chiu anh hudng nhung la nhd. Nhu vay dicu chinh md dun tham hay
Ddnh gid dnh hudng cua cdc tham sd trong 24 phdn mem thiiy van tham sd phdn bd MajAll^
chinh la dicu chinh do am cua dat la each nhanh va hieu qua nhat de dieu chinh gia tri cua luu lugng dau ra cua md hinh tinh loan,
3 . D a n h gia anh h u d n g cua phan bo m u a trong luu vuc den ket q u a tinh cua M a r i n e :
Md hinh thiiy van Marine cho phcp dua so lieu mua vao md hinh tinh d hai dang phii hgp vdi tinh hinh sd lieu cua mdi khu vuc tinh khac nhau.
Sd lieu mua dugc xu ly tir anh may ve tinh hoac anh ra da: Vdi loai sd lieu nay anh chup tir ve tinh hoac ra da dugc dua qua phan mem xu ly \i\ hieu chinh thdng qua mot sd tram hieu chinh mua thuc do tren mat dat. Sd lieu sau khi xu ly sc bao gdm ca gia tri mua dinh lugng va phan bd mua tren luu vuc. Ludi phan bd mua liiy thudc vao loai anh. Vdi anh ra da dp phan giai eiia ludi mua thudng la 1000m (1km) cdn vdi anh ve tinh _thi dp phan giai cua ludi mua la 11km hoac 14km, hoac 5km tiiy thudc vao he anh. Tren mdi mot ludi mua cd ga tri mua khac nhau, chinh vi vay sd lieu mua nay rat gan vdi sd lieu mua da rai thuc te tren luu \ uc.
Sd lieu mua do dac tai cac tram khi tuang thiiy \an: Vdi cac nude hoac khu vuc dicu kien kinh le khd khan nhu Viel Nam chi cd so lieu mua qua Irae lai cae tram khi lugng thiiy van, tham tri mang ludi cac tram quan Irac eilng rat thua ihdt \ a khdng ddng hd. Vdi loai sd lieu mua do dac tai ciie tram ta chi ed gia tri vc mat dinh lugng eiia mua tai diem do, cdn cac diem khac khdng phai lai vi tri do, phai sir dung ciie phuong phap phan bd mua dc tim gia tn mua. Vdi sd lieu mua loai nay, cac tram do phai dugc chon vi tri dat sao cho lugng mua tai dd la gia tri dai dien ciia lugng mua trong viing, mang ludi cac tram cung can phai dugc bd tri sao cho hpp ly de phan anh lot nhat thuc trang mua.
Cac sd lieu mua cd dugc o Vict Nam la cac sd lieu mua ciic bd do dac tai cac tram quan trac. Chinh vi the can phai chpn mot phuong phap phan bd mua dc xac dinh mua tren toan luu vuc.
6 day khdng danh gia anh hudng cua cac phuong phap phan bo mua di5n ket qua tinh cua md hinh, ma chi danh gia trong sd cua phan bd mua. Vi vdi bat cu phuang phap phan bd mua nao cung dcu cd trpng sd phan bo, day chinh la tham sd dicu chinh ciia phuong phap, nen dc di sau vao chi tiet nhdm nghicn ciru chpn phuang phap phan bd la phuang phap da giac Thiesscn, Vi phan bd mua dugc tao ra chir khdng phai la thuc Id nen neu sd lieu mua tai tram do khdng phai la gia tri dai dien ma chi la gia tri mua cue bd thi phan bd mua khong cdn hgp ly. Do dd can phai dicu chinh lai phan bd mua sao cho tdng gia tri luang mua tren luu vuc gan nhat vdi tdng gia trj lugng mua da roi tren luu vuc. Dg danh gia anh hudng ciia tham sd dicu chinh trong phuong phap plian bo mua xet ba phuang an tinh sau:
- Tham sd phan bd mua chuan.
- Tham sd phan bd mua nhd.
- Tham sd phan bd mua Idn.
bd. Nhung do mua ciia tr^m khdng phai la mua dai dien nen he so nay cd \hk dikn chinh Idn hon hoac nhd hon 1 de cho phii hgp hon ve tdng l u g n c
Trgng sd phan bd mua chu5n cd gia trj la 1. Day la gia trj mua thuc cua phuang phap phan Cac ket qua tinh ciia ba phuong an dieu chinh tham so phan bd mua tren luu vuc
Nguvd'n Tien Cirdns, Ngd Iluy Cdn 25
vdi phan bd mua theo phuong phap da guie Thiesscn o hinh 5 tren day cho thay, trpng sd ciia phan bd mua true tiep anh hudng den gia tri ciia luu lugng tinh loan IrcMi luu vuc. Day chinh la tham sd dieu chinh tdng lugng nude vao md hinh tinh chinh vi vay tham so nay rat nhay vdi ket qua tinh eiia md hinh. Tham sd hieu chinh nay vc nguyen tac khdng nen dieu chinh qua thap hoac qua cao so vdi gia tri thuc la 1. Vi khi dicu chinh qua nhi6u tham sd nay sc dan den sai ve ban chat ciia md hinh tinh
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Hinh 5: Anh birdrng cua trong sd phdn hd inira den ket qud tinh cua Marine
4. Mot so ket luan
Sau khi nghien ciru miie dp anh huong ciia cac tham sd den ket qua tinh cua md hinh thuy van Marine d ba loai tham sd la:
- Tham sd dd nham be mat luu vuc.
- Tham sd ciia md hinh tham.
- Tham sd ciia md hinh phan bd mua
Co the nhan thiiy la trong ba loai tham sd hieu chinh da bao g(3m ca hai yeu to de hieu chinh md hinh dd la yeu td ve pha va yen td ve dinh lugng. Vc pha cua ddng chay thi dp nham be mat luu vuc ed anh hudng Idn nhat sau dd den dp tham cua diit, euoi eiing mdi la so lieu mua. Cdn vc gia trj tinh thi tham so hieu chinh dp tham va tham sd hicu chinh phan bo mua dhu cd tac dong manh din gia tri tinh loan cdn dp nham be mat cd anh huong nhung d miic dp it hon. Tren co sd dd eo the dua ra khuyen cao cho qua trinh hieu chinh mo hinh nhu sau.
Ddu lien chay md hinh vdi cac thdng sd trung binh hoac cac thdng sd chuan da dugc
<ac dinh qua cac thuc nghiem. Sau dd so sanh ket qua tinh vdi sd lieu thuc do, Neu ket qua :inh va sd lieu thuc do lech nhau ve pha co the sir dung dp nhimi be mat de hieu chinh, neu
<ct qua tinh nhanh pha thi can tang dp nham he. mat luu vuc, ncu ket qua tinh bi cham pha hi phai giam dp nham ciia be mat luu vuc. Tuong tu nhu vay neu gia tri luu lugng tinh oan lech vdi gia tri thue do, cd thi su dung trgng sd phan bd mua hoac tham sd ciia md linh tham de hieu chinh. Neu sai sd v6 gia tri nhd nen cd dinh trpng sd phan bd mua la 1 va
;hi hieu chinh md dun tham. Trong trudng hgp kit qua tinh cd gia tri sai khac nhieu so vdi
tiJann gia anh hirang cua cac tham sd "'^'^''i 26 phdn mem thiiy vein tham sd nhdn hdJJSJA^
gia tri thuc do phai su dung din trpng so phan bd mua de hieu chinh Irutrc sau do mdi hicU chinh bang md hinh tham,
Cac kit qua nghien ciru cua bai bao khdng chi cd y nghia trong qua trinh hicu chinl^
md hinh, ma nd cd \ai trd vd cimg to Idn ddi vdi ngudi su khai thiic md hinh trong cdng ta:
du bao, Trong qua trinh dir bao, sd lieu mua do dac khdng phai luc nao cung la dac trung cho luu vuc, vi thi cin phai hieu chinh mo hinh, cac kit qua cua bai bao giiip cho qua trinh hicu chinh md hinh dc dat ket qua mong mudn nhanh nhat
Bai bao dugc ho:'n thanh bai sir ho Irg mdi phan kmh phi ciia dc lai nghien ciru co baa nganh Co hge,
Tai lieu tham khao
[1] Bahrain Saghaflan. Pierre Y, Julicn. H, Rajaic. "Runoff hvdrograph simulation based on turn, variable isochrone technique". .lournal of I lydrology 26 1 (2002) 193-203
[2] Roger J. M Dc W'lcst. "Gecdndrology". John Wiley & Son, Inc., New York, London. Sydney.
[3] Ven Tc Chow, David R, Maidmcnt. Lairy W. Ma\s, "Applied Hvdrulogy".. Mc Graw-HiK Book Company,
[4] Nguyen Tien Cuong. .Mane NLidcleinc .Maubourgiict. "Thu nghiem md hinh thuy van cho lim virc song Dd, phdn thudc Idiih ihd Viet Nam". Tuyen tiip bao cao hoi nghi eo hot loan quoe 2004. T2.
[5] Nguyen Ticn Cudng. Tran Thu Ha, ".\Id hinh canh bdo. du bdo lu he thdng sdng Hirc/ng' Tuycn tap bao cao hoi nghi cir hoc toiin quoc 2007. T3,
