KHOA H O C - C d N G N G H £
.So 10/2018
Nghien cuu sir dung CIS xay dimg ban do he so dong chay tinh Bac Kan
I TS. DOAN THj N 6 ! - TrUdng Dgi hoc Giao thdng v<
TOM TAT. H# s6 dong chay (C,p ho^c a) la dac trung quan trgng dung de tfnh lu thiet ke, phu thuoc vso dia hinh, hien tr^ng sd dyng dat va loai dat Bai bao ung dyng ky thuat GIS (Geographic Information System) de xay dung b i n do he so dong chay cho tinh Bac Kan dua vao d^c tinh cua loai dat, hi$n trang sd dyng dat va dg doc luu VUC V6i ban do h$ so dong chay c6 the chiet suat den tung luu vye thoat nuoc qua cau voi mdc dp chl tiet hon, vi the ma ket qua tinh lu thiet ke tien dyng va true quan so voi each xac dinh thgng thuong hten nay
TLT KHOA: He sg dong chay, GIS, tinh BSc K?n.
ABSTRACT: The run-off coefficient can be defined as an important feature to calculation of peak rate of run-off. The assignment of the run- off coefficient (C) is somewhat subjective At the time the rainfall producing run-off occurs, the coefficient vanes with tgpography, land use, vegetal cover, soil type, and moisture content of the soil (TxDOT, 2002).This research applies GIS technique to determination run- off coefficient map for Bac Kan prgvince depend on topography, land use, vegetal cover, soil type Results of run-off coefficients map to calculate design figod is more appropriate and detail than the current method
KEYV/ORDS: Run-off coefficient, GIS, Bac Kan Provine
l.DATVANOe
Den nay, tinh t o l n lu thiet ke true tiep t d lu thuc do cho elc cdng trinh thoat nude nhd ePn gap khP khan do thudng nam d nhdng vung thieu so lieu mUa va 10, chi ed the tinh bang phuong phap g i l n tiep. Phuong phap gian tiep bao gom: CUdng do giPi han [1,3] Xokolopski (Nga) [1], CIA (Rational method) [2]... De l p dung elc phuong phap nay, khP khan nhat la xac dinh he so ddng ehay (C,(p hoac a) bdi vi he sd dong chly phu thupe vao nhieu thpng sd khac nhau. Hien nay, viec dng dung eong nghe GIS trong viee tinh lu thiet ke eho eae ePng trinh t h o l t nude nhd da dupe nhieu tac g i l nghien cijru va ap dung eho nhieu nude (My, Nhat Ban...), tuy nhien PViet Nam van cPn han che. Bai b i o tien hanh tdng hop dd lieu mat
dem (hien trang sddijng dat - land use), dia hinh, loai dat, xay dung ban do he s6 C v l tinh thd nghiem cho cPng trinh cij the theo phuong phap CIA [2,4].
2. PHl/ONG PHAP NGHIEN CCfU 2.1. Gidi thieu veGIS
GIS {He thong thong tin dja ly) dau tien dupc hinh thanh vao nam 1964 trong cle chUong trinh phije hoi dat ndng nghiep tai Canada. Den cuoi nhdng nam 1970, Vien Nghien cdu cac he thong moi trUdng (ESRl) ra ddi d Canifornia va da phat hanh san pham Arc/Info, d l y la san pham thuong mai tron gdi cua GIS dau tien tren the gidi. GIS quan ly theo dang dCr lieu khong gian dUOc lUu giu dudi dang mpt cau true nhat dinh dugc gpi la cO sd dd lieu khong gian. Cau true dd lieu se quyet djnh clch thdc luu trU, truy cap va thao tac xd ly thpng tin eho phep ngudi dung xay dUng cac b i n do thuoc tinh phuc vu cho rat nhieu nganh, d i e biet la lien quan den t h i m phu va hien trang si> dyng dat. Bai b i o dng dung GIS (Arcgis 10) de xay dUng b i n do luu vUe, loat dat, hien trang sd dung dat va tdng hpp thanh ban do he so ddng ehay C. Doi vdi vtec phan tich, danh gia, dU b i o dong chly va tinh lu thiet ke, GIS la cdng eu die lUe trp gtijp eho viee xac djnh cac tham so nhU: Khoanh luu vUc va tinh cac thpng so luu vUe, xay dung eae b i n do d i e trUng nhu b i n do hien trang sd dyng dat, ban do dat, b i n do do ddc...
2.2. PhUtfng phdp nghien cihi
Bai bao xay dung ban do he sd ddng chly cho tinh Bac Kan va tinh lu thd nghiem cho eau Khuoi Tao, so sinh va danh gia vdi ket qua tinh theo phuong phap Cudng dpgtpi han.
- Xay dung ban do he so dong chly C, tinh Ctb:
Bai bao da thu thap ele loai tham phu v l loai dat (dang b i n do so) thuoc tinh Bac Kan, Ung dung GIS xlc djnh dp doe trung binh eua khu vUc, xac dinh nhdm dat (A, B, C, D) ket hpp vdi b i n g d i e tinh (Bdng 2.1) xly dUng b i n do he sd ddng chly C (khi S < 2%; S ^ 2 - 6%; S > 6) cho ca tinh Bac Kan. So do cac bUdc thuc hien duoc trinh bay d Hinh 2.1.
- Xly dUng dUdng cong IDF, tfnh cUdng do mua I:
So lieu mua dugc lay P tram Bac Kan, xly dUng dudng cong \Df (Hinh 2.1). DUa vao ketquadactrung luu vUc tinh thdi gian tap trung dPng chlyTe {phut}:
T^ = Mgi 1,0.77 „)
Trong do: L(m) - Chieu dat luu vUc; S - Dd doe trung binh tren lUu vUc S{m/m). CP Te tra euPng dp mUa 1
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KHOA H O C - C d N G NGHE
(mm/h) t d bp dudng cong IDF xay dUng eho tram Bac Kan t d 1975 den 2013. He so ddng chay dUOc xay dUng d tren v l ket qua tinh cht tiet dupe trinh bay trong Bdng 3.2.
C , = : ^ i £ i ^ (2)
DUONG CONG IDF TRAM B A C CAN - NORMAL
10 15 20 25
Hinh 2.1: So do cie bude xiy dung bin dd he sdddng chay C va Dudng cong IDF tram Bae Kan Bing 2.1. Bang tra he sdddng ehiy C
Nguon, Knox County Tennessee Stormwater Management Manual
Hinh 2.2: Cae ban do die tinh diing de xay dung bin do he saC -Tinh dien tieh lUu vueva cac thong so luu vUc cau KhuotTao- Bae Kan;
Cau KhuoiTao nam tren ly trinh 121-1-913, thuoc QL3, doan qua dia phIn tinh Bae Kan. Cau eo chieu dai 16m,
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rpng 6.5m, be tPng cot thep, trpng t l i 17T. DUdi d l y II ket q u i tinh eae thong so luu vUc cau:
Bing 2.2. Thdng sdluu vuc cSu Khudi Tao - Bic Kan STT
1 2 3 4 5 6 7 8 9
Cac dac triAig Tan suat thiet ke Dien tich lifu vUc Chieu dai s6ng chinh Tong chieu dai dong nhanh Chieu dai lu'u vuc 0 6 rpng binh quan luu v u t Sd sudn fiAi vUc 0 6 doc luu vUc Ooc doc long song
Kihifu P A L IL,
K
B n J^
J,^
Dcmvl km^
%
km km km kmVkm
% 0
% 0 GMtr|,
2% S.16 2.14 2.79 0.16 32.25 2.00 280.7 7.18
3. K^T QUA NGHIEN CCfU
3.1. Ket qud xay diTng bdn do h^ so dong chdy C Ket qua x l y dUng b i n do he so ddng chly C I I bin d o s o v a b i n g dactinh,td ket q u i eho thay tren khu vue nghien edu (Hinh 3.1), gia trj C t d 0.14 den 1 phu thuoc vao loai dat va tham phu. Cac thang mau bieu thj g i l trj eua he so ddng ehay tCfng khu vUc.
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CHU GlAl H e _ s o d c C , 1 0.44 t ^ ^ 0.34 ^ ^ M "-^
Ej^^i^.&ji 0.42 ^ ^ ^ ^ 1 ^ ^ ^ ^ CAUKHUblTAO
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Hinh 3.1: Bin do he sdddng chiy C cda tinh Bac K$n va cOa luu vuc eSu Khudi Tao
KHOA H O C - C O N G NGHE
So 10/2018
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2
11
13
14
15 16
Bing 3.1. Thdng sddSc tfnh luu vuc va luu vuc Khudi Tao
H i e n t r a n g s i f d u n g d<t Loai 4j(t
N i i d c m a t D a l « a m
he sdddng ehiy
H^sd d t _ C
Ktiu vUc ttii/c ptiCi n o n g ngtiiep ^ '^"' j 0 34 D o n g c f i D a t x a m
1 feralit 1 " ' * ' RCmg
Khu v u c dan c u T6ng T f u n g b i n h
Dat nam f^raht
feralit . 6
0 4 2 Dien tich
0.02
0 J 1
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0.017
0.107
0 0 1 8
4.79 2 872
0 00 5.16
0.000 3 0 1 4
; 0.5B4
3.2. Ket qua t i n h lu theo phuong phdp CIA Cle bUPe tinh lu t d b i n do he so dong ehay C,
Hinh 3.2: So do cac bude tinh lu thiet ketuhe sdddng chiy C - Ket q u i tinh lu theo CIA:
Bing 3.2. Ket qui tfnh lu thiet kStheo phuong phap CIA TT
1 2 3 4
Thdng so 1 C A Q
Dac tri/ng Cudng do mUa He so dong chay Dien tich luu vUe LUu luong thiet ke
Gid tri 28.5 0.584 5.16 85.9
Dcmvi mm/h km^
mVs - Ket q u i tinh lu theo phuong phap euPng dp giPi han(TCVN9845:2013)[l]
Bing 3.3. Ket qui tinh 10 thea phuong phip cudng dp gidi han TT 1 DictrUng
1 ! Lu'ffng m u a n g a y \6r\ n h a l H „ ( T t a m B3c Kan) 2
3 4 5
C a p d a i 111, V i i n g m u a tV H e so d b n g chSy IC (Cap flat: H p ; F):
He so n h S m s u d n lUu v u c H e so n h a m d o n g c h m h 6 ; H e so t t i e l g i ^ m d o a o ho- 7
8 8 10
B E r o n g t r u n g b i n h s U o n d o c E>ac t r u n g dta m a o sucJn d o c T „ [ V u n g m u a ; f s d l O a c t r U n g d i a m a o l o n g s d n g M 6 - d u n d o n g c h a y d i n h iCi ( V u n g m u a , t s d ; f t s ) 12 1 L u l l l u o n g Q , ^
G i d t r i 2 4 3 . 1 I V 0 . 6 7 0 . 1 5 7 1 0 . 5 8 1 7 . 3 0 3 0 2 9 . 4 3 2 0 . 0 9 5 8 0
D o n VI m m
l(m
p h u t
mVs
- 6 phuong phap 1: £)e xae dinh he so C {a hoac (p) phai lua chpn vung mUa, lUpng mUa, cap dat, dien tich luu vuc ((p = 0.67), tuy nhien vung mUa la ca vijng rpng Idn, cl'p d^t phu thupe vao loai dat tren luu vUc, khong p h l i lUu vuc nao cung cijng mpt loai dat,
- d phuong phIp 2: (1) Xay dung b i n do he so ddng chay (dng dung GIS) dUa vao ban do dat dupe cap nhat theo Cue QuIn ly Dat dai cua BpTai nguyen va MPi trudng.
CIc loai hien trang (dat rdng, dat d, dat ndng nghiep...) va dp doe trung binh tren khu vUc se eho rat nhieu trj so C phu thupe vao viec to hpp cac dat luong (ke ca luu viJe rat nhd nhu eau Khuoi Tao); (2) Bin dd so xay diing dUpe co the xuat ra d dang bang excel tien cho tfnh t o l n ; (3) Bin do dugc xay dung cho ca vung rpng Idn (tinh, vijng) sau dp ehie't suat ra gia trj C cho tdng lUu vUc nho, dng vdi ele loai tham phu va dat, tren co sd do tinh C,^ each tinh tien dung hon, ehi tiet hon (do tinh trung binh trpng so (C - 0.584)). Nhupe diem cua phuong phap 2 la can cd dupe b i n do so ve loai dat va hien trang sd dung dat cap nhat, ket hpp vdi dieu tra thuc dja.
Ket q u i tinh C^^^ dUOc i^ng dung trong tinh lu theo phuong phap mP hinh quan he (phuong phap CIA) eho cac lUu vUc cau nam tren khu viic nghien edu giup viee tinh lu trp nen don gian, hieu q u i trong dieu kien hien nay.
Tdi lieu tham khdo
[1]. Bp ThCiy Ipi (1977), Quy pham tinh todn cdc ddc trung thOy van thiet ke.
[2]. Engineers Australia (2006), Australian Rainfall
& Runoff, Loss Modes for catchment Simulation-Rural Catchments...
[3]. TCVN (2013), Tieu chudn tinh todn cdc dac trUng ddngehdylCJCVN 9845:2013.
[4]. Richard H. McCuen at al. Highway Hydrology, National Highw/ay Institute.
[5]. Z,P Kirpich (1940), 7/me of concentration of small agricultural watersheds, Civil Engineering 10(6), vol.60, no.. The original source for the Kirpich equation, p.362.
Ngdy nhdn bdi: 29/9/2018 Ngay chdp nhdn tfdng: 10/10/2018 Ngi/di phdn biSn: PGS.TS. N g u y i n Hoang Son
TS. Mai Quang Huy
4. K^T LUAN
Xae dinh he sd ddng chly bang phuong phIp tra b i n g truyen thong (phUOng phap 1) va phuong p h I p x l y dung b i n dd he sd dong chly C (phUOng phap 2) eho thay nhQng uu, nhupe diem sau: