Phan Chia Luu Vuc_SWAT_7.8.2013

Copyright 2013 | [email protected] Chuyn SWAT

Phn chia lu vc trong SWAT

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Trnh by: Nguyn Duy Lim

Copyright 2013 | [email protected]

Ni dung

L thuyt Mt s thut ng v lu vc

Cu trc lu vc trong SWAT

Phng php phn chia lu vc trong SWAT

Thc hnh Phn chia lu vc bng cng c Hydrology (ArcGIS)

Phn chia lu vc bng cng c ArcSWAT (ArcGIS)

Nhn xt, so snh

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Mt s thut ng

Lu vc Lu vc l mt vng t (c gii hn bi ng phn thy)

n nhn nc ri v hi t dng chy v mt im chung no thuc mt thc th cha nc c th nh sng, sui, m ly, h.

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Lu vc(tiu lu vc)

Ranh gii lu vc(ng phn thy)

imu ra

Trong mi lu vc c th bao gm nhiu lu vc nh hn (gi l tiu lu vc).

Lu vc c xc nh da trn ng ranh gii ca n. Ranh gii lu vc l mt ng khp kn v theo ng phn thy mt tnh t im u ra ca lu vc.

Dng chy(sng, sui)


Mt s thut ng

im u ra ca lu vc L im thot nc ch yu ca lu vc tnh t im tr ln.

Chng hn nh:im x nc chnh ca mt p thy in,

im thu nc ca mt nh my cp nc sch hoc c s sn xut cng nghip c s dng nc trc tip t ngun nc.

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Mt s thut ng

M hnh s ho cao M hnh s ho cao (DEM) l s th hin di dng s s thay

i lin tc ca cao trong khng gian.

DEM l mt trong nhng d liu u vo ca cc qu trnh x l s liu lin quan n xc nh ranh gii lu vc.

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Trong SWAT, lu vc c chia thnh cc tiu lu vc, trong mi tiu lu vc c chia thnh cc n v thy vn (HRUs). Lu vc (Basin)

Tiu lu vc (Subbasin)

n v thy vn (Hydrological Response Unit)

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Lu vc, Tiu lu vc, Dng chy

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n v thy vn

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Lu vcTiu lu vc

n v thy vn

Th nhng

S dng t

dc

DEM



n v thy vn

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n v thy vn

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S phn chia ny gip ngi s dng c th p dng kt qu nghin cu ca mt vng ny vo mt vng khc khi chng c s tng ng nht nh.

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Phng php phn chia lu vc, tiu lu vc

Xy dng DEM M hnh DEM c th c

xy dng t bn a hnh.

Kch thc li (grid cell) ph thuc vo quy m lu vc v t l bn a hnh, tuy nhin, thng dao ng trong khong t 10 100m.

Trong trng hp nu m hnh s ha cao c sn th trc khi s dng cn kim tra tnh ph hp ca cc thng tin c bn, bao gm kch thc li v h quy chiu.

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Hiu chnh DEM M hnh DEM nu cha hiu chnh c th c mt s li v nhng

im li hoc lm khng mong mun.

V vy, cn hiu chnh d liu ny, c th bng vic s dng hm Fill trong cng c Hydrology ca ArcGIS.

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Phng php phn chia lu vc, tiu lu vc Xc nh hng dng chy

Hng dng chy cho mt imbt k trong lu vc c xcnh trn c s so snh chnh cao ca im vi 8 im xung quanh.

Hng dng chy c xcnh l hng ti im c chnh cao chia cho khongcch ln nht. Qu trnh tnhton c lp li xc nhhng dng chy cho ton bcc im trong lu vc.

Bn hng dng chy c thc xc nh t ng trongcc phn mm GIS t m hnhDEM c hiu chnh.

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Tnh ton s tch ly dng chy S tch ly dng chy cho mt

no trong khu vc trn nn mhnh DEM c xc nh bngcch tnh tng s li tp trungnc v theo hng dngchy.

S tch ly dng chy c th cxc nh t ng trong cc phnmm GIS t bn hng dngchy.

Bn tch ly dng chy cngchnh l bn sng sui ca luvc trong iu kin t nhin.

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M phng mng li dng chy Mng li dng chy ca lu vc trn nn m hnh DEM c

xc nh bng cch thit lp ngng gi tr cho dng chy tchly. Khi , nhng li no c s dng chy tch ly ln hngi tr ngng trn th s c m phng.

Hnh nh di y minh ha mng li dng chy ca lu vckhi thit lp gi tr ngng ln hn 3 li.

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Phn nh ranh gii lu vc Hin th ta im u ra ca lu vc ln bn tch ly dng

chy, sau s dng chc nng chuyn dng trong cc phnmm GIS v t ng ranh gii lu vc. Din tch, hnh dng vcc c trng c bn khc ca lu vc s c xc nh d dngt bn ranh gii ca lu vc.

Bn ranh gii ca lu vc cn hin th r to im u ra, c cu trc d liu vector di dng vng (Polygon), c Trngch din tch theo n v ha c lm trn n mt ch s saudu phy.

Bn ranh gii lu vc sau khi c to ra t cc qu trnh trnphi c kim tra nh gi trong thc t v ch c thc hinmt ln trong iu kin khng c nhng bin ng ln v a hnhtrong khu vc.

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Phng php phn chia n v thy vn

C ba ty chn xc nh s phn b HRU Dominant HRU mt HRU cho ton b lu vc,

Dominant Landuse, Soil, Slope" mt HRU cho mi tiu lu vc,

Multiple HRUs nhiu HRU cho mi tiu lu vc.

Ty chn (1), (2): xc nh gi tr ph bin nht (chimdin tch ln nht) cho s dng t, t v dc.

Ty chn (3): xc nh ngng gi tr cho s dng t, t v dc.

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Th nhng

S dng t

dc



V d 1: Cho tiu lu vc c cc c im nh bng sau:

Nu chn ty chn Dominant Landuse, Soil, Slope", HRU ca tiu lu vc s c gn loi hnh s dng t, th nhng, dc no?

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S dng t Th nhng dc

35% t trng bp30% ng c21% rng9% t trng cy n qu 5% t th c

50% t ph sa30% t feralit20% t mn

55% dc 0 0.6%40% dc 0.6 1.5%5% dc 1.5 99.99%



p n v d 1 HRUs: t trng bp/t ph sa/0 0.6%

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Phng php phn chia n v thy vn V d 2: Cho tiu lu vc (din tch l 100ha) c cc c

im nh bng sau:

Bit rng nu dng ty chn Multiple HRUs vi gi trngng l 0% i vi s dng t, th nhng, dc, tiu lu vc trn s c 4 HRUs vi din tch nh sau: t la/t ph sa/ dc 0-5%: 45ha (45%) ng c/t feralit/ dc 5-99.99%: 30ha (20%) rng/t ph sa/ dc 0-5%: 5ha (5%) rng/t mn/ dc 0-5%: 20ha (20%)

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S dng t Th nhng dc

45ha (45%) t la30ha (30%) ng c25ha (25%) rng

50ha (50%) t ph sa30ha (30%) t feralit20ha (20%) t mn

70ha (55%) dc 0-5%30ha (40%) dc 5-9.99%



Vi ty chn Multiple HRUs vi gi tr ngng l 27%i vi s dng t, th nhng, dc cho tiu luvc trn, Cho bit c bao nhiu HRUs c to ra v din tch ca tng

HRUs (theo ha, t l %)?

Tnh ton li din tch cc loi hnh s dng t, th nhng, dc trn tiu lu vc (theo ha, t l %)?

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Phng php phn chia n v thy vn p n v d 2: Xc nh s lng HRUs c to ra v

din tch ca tng HRUs Do rng v t mn chim t l di ngng 27% nn nhng

HRUs cha t nht mt trong hai loi ny s b loi b. Khi , slng HRUs ch cn l 2.t la/t ph sa/ dc 0-5%: 45ha (45%) ng c/t feralit/ dc 5-99.99%: 30ha (20%) rng/t ph sa/ dc 0-5%: 5ha (5%) rng/t mn/ dc 0-5%: 20ha (20%)

Din tch ca tng HRUs c tnh ton li nh sau:t la/t ph sa/ dc 0-5%: 45ha (45%) 45+(45/75)*25= 60ha

(60%)ng c/t feralit/ dc 5-99.99%: 30ha (20%) 30+(30/75)*25= 40ha

(40%)

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p n v d 2: Tnh ton din tch cc loi hnh s dng t, th nhng, dc ca tiu lu vc Da trn din tch HRUs c gi li, din tch cc loi hnh s

dng t, th nhng, dc ca tiu lu vc c thng k linh bng sau:

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S dng t Th nhng dc

60ha (60%) t la40ha (40%) ng c

60ha (60%) t ph sa40ha (40%) t feralit

60ha (60%) dc 0-5%40ha (40%) dc 5-9.99%


Thc hnh

Phn chia lu vc bng cng c Hydrology (ArcGIS)


Nhn xt, so snh

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Phn chia lu vc bng cng c Hydrology (ArcGIS)

Tin trnh thc hin trong ArcGIS bao gm cc bc sau: DEM

Fill DEM

Flow Direction

Flow Accumulation

Stream Line

Stream Link/ Snap Pour Point

Watershed

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Tin trnh thc hin trong ArcGIS

To DEM t bn a hnh

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TIN

DEM

Bn a hnh(ng ng mc)



Hiu chnh DEM

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DEM Fill DEM



Flow Direction

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Flow DirectionFill DEM



Flow Accumulation

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Flow AccumulationFlow Direction



Stream Line Con("flowacc" >= 100,1)

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Stream LineFlow Accumulation



Stream Link/ Snap Pour Point

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Stream Link

Stream Line

Flow Direction



Watershed

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Watershed

Flow Direction

Stream Link


Kt qu

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Kt qu

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Kt qu

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Phn chia lu vc trong ArcSWAT

Tin trnh thc hin trong ArcSWAT bao gm cc bcsau:

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DEM Setup

Stream Definition

Outlet and Inlet Definition

Watershed Outlet(s)

Selection and Definition

Calculation of Subbasin

Parameters


Tin trnh thc hin trong ArcSWAT

DEM Setup Load the DEM:

Ti DEM t a hoc t bn trongArcMap

DEM projection setupKhai bo n v cao thnh mt

Define Mask (optional)nh ngha khu vc cn m phng

Burn in a stream network (optional)S dng mng li dng chy c sn

m phng lu vc

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Tin trnh thc hin trong ArcSWAT Stream Definition

DEM-based S dng DEM m phng lu vc

Flow direction and accumulation Tnh ton hng dng chy v dng

chy tch ly

Area Thit lp ngng din tch tiu lu

vc (ha)

Stream network To mng li dng chy, ca x

Pre-defined streams and watersheds S dng mng li dng chy, tiu

lu vc c sn

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Outlet and Inlet Definition Subbasin outlet

Add by Table (optional): Thmca x s dng bng

Add/Delete/Redefine (optional): Thm/xa/di chuyn ca x thcng

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Watershed Outlet(s) Selection and Definition Whole watershed outlet(s)

La chn 1 hay nhiu ca x lu vc

Cancel selectionHy b vic la chn ca x

Delineate watershedTin hnh phn nh lu vc

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Tin trnh thc hin trong ArcSWAT Calculation of Subbasin Parameters

Reduced Report Output (Optional) B qua thng k a hnh cp tiu lu

vc

Skip Stream Geometry Check (Optional) B qua vic kim tra hnh hc ca dng

chy

Skip Longest Flow Path Calculation (Optional) B qua tnh ton ng dng chy di

nht

Calculate Subbasin Parameters Tnh ton cc thng s ca tiu lu vc

Adding or Delete Reservoir (Optional) Thm/xa h cha

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Hon tt tin trnh phn nh lu vc Click nt Exit hon tt ton b qu trnh phn nh lu vc

Kt qu

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Nhn xt, so snh

Phn chia lu vc bng cng c Hydrology (ArcGIS) D liu u vo

Thut ton s dng

Tin trnh thao tc

Kt qu u ra


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Cu hi n tp

Tm hiu cc ni dung trong bn a hnh

Tm hiu l thuyt v m hnh TIN, DEM

Tm hiu mi lin h gia t l bn v phn giiraster

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Phan Chia Luu Vuc_SWAT_7.8.2013