Analysis of the Impacts of Spatial Input Data Quality on the Determination of Runoff and Suspended Sediments in the Imha Watershed Using Swat Model

Transcription

1 Analyss of the Impacts of Spatal Input Data ualty on the Determnaton of Runoff and Suspended Sedments n the Imha Watershed Usng Swat Model Jeongkon Km, Joonwoo Noh, Kyungho Son, Ikjae Km K-water Insttute

2 Background Landslde Bank Washout Frequent occurrence of turbd water due to extreme events Typhoon Rusa(2002), Meam(2003) Dscharge release lmtaton due to hgh turbdty Optmzed reservor operaton for hgh turbd water Flood season: Release through selectve wthdrawal faclty to prevent turbdty spread and overturnng Dry season: Jont dam operaton to mantan the downstream turbdty less than 30 NTU Turbd water management Watershed assessment Identfy hgh turbdty layer Adequate Dscharge release When / how much Impact on reservor downstream Turbd Water Intruson & Overturnng Impact on Downstream

3 Problems Stop reservor operaton Hnders water treatment plant operaton Negatve Impact on Downstream

4 Introducton Focused on watershed management for turbd water control Assessment on the mpact of dfferent spatal data qualty and the effcency of SWAT model for runoff and suspended sedment Frst, the mpacts of fve DEM grd szes (.e. 30m, 60m, 90m, 120m, and 150m) on model nputs (parameters) and outputs Combnaton of 30m and 120m DEMs wth two dfferent scales of land cover and sol type map

5 Imha & Andong Watershed Propertes Imha Andong Table 1. comparson of two catchments Area (km 2 ) 1,361 1,584 Major Landcover Forest (79.8%) Agrculture (15.0%) Forest (82.2%) Agrculture (11.9%) Major Sol type Ms (Lthosols, Mcaceous and Hard Slceous Materals,slty loam or sandy loam) Ma (Lthosols, Slceous Crystallne Materals, slty loam or sandy loam) Avg. Ann. Precptaton (mm, ) Total channel length (km) 1,158 1,348 5,741 5,381 Storage volume (m 3 ) 424M 1000M Elevaton (m, EL) 54~1, ~1,550

6 Ste descrpton

7 5 dfferent scaled DEM

8 DEM wth General Watershed Parameters Grd sze (m) AREA (Km 2 ) SLOPE (m/m) SLOPEL (m) CHSLOPE (m/m) CHWID (m) CHLEN (Km) D30 1, D60 1, D90 1, D120 1, D150 1, DEM scale Increases (low DEM Resoluton) Slope decrease Slope Length ncrease Channel slope ncrease Channel wdth decrease Channel length decrease

9 DEM wth Water and Sedment Grd sze (m) SUR (mm) LAT (mm) GW (mm) WY (mm) SYL (ton/ha) D D D D D When DEM scale Increases (Coarser DEM Resoluton) Surface runoff ncrease Lateral flow decrease Ground water ncrease Net water yeld ncrease Sedment yelds ncrease

10 CV wth DEM resoluton Slope length, Lateral flow, subsurface flow, and sedment yeld are more senstve to DEM resoluton Coeffcents of Varaton Area Slope Slope length Channel slope Channel wdth Channel length Surface flow Lateral flow Grounwater Water yeld Sedment yeld Input Output

11 Land Cover maps 1:50,000 and 1:25,000

12 1:50,000 Landcover map - total 8 classes of landuse Class Area (%) Class Area (%) Class Area (%) Class Area (%) Urban 0.88 Wetland 10.1 Forest 0.88 Farm feld 10.1 Follow 0.02 Pasture 0.03 Rce 0.02 Water :25,000 Landcover map 18 classes of land use Class Area (%) Class Area (%) Class Area (%) Resdence 0.88 Paddy 3.34 Decduous forest Industry 0.02 Farm feld 10.1 Evergreen forest Commercal 0.05 Vnyl house 0.03 Mxed forest Recreaton 0.00 Orchard 1.43 Pasture 0.40 Transportaton 0.34 Other crops 0.07 Wetland 0.45 Insttutonal 0.08 Fallow 0.61 Water 2.4

13 Sol Maps 1:250,000 and 1:50,000

14 Sol types and descrpton 11 sol types for 1:250,000 sol map, whle 32 sol types for and 1:50,000 Sol types Af An Ap Ma Mm Ms Mu Mv Ra Rocky Rs Descrptons alluval sols and rver wash, flood plans complex of sols, narrow valleys low-humc gley and alluval sols, alluval plans ltho sols, slceous crstallne materals ltho sols, mcaceous and hard slceous materals ltho sols, sedmentary materals brown forest sols and lthosols, undfferentated materals ltho sols, slceomafc materals red-yellow podzolc sols slceous crystallne materals rocky lands ltho sols and red-yellow podzolc sols, sedmentary materals

15 DEM wth Water and Sedment Grd sze (m) SUR (mm) LAT (mm) GW (mm) WY (mm) SYL (ton/ha) D D D D D When DEM scale Increases (Coarser DEM Resoluton) Surface runoff ncrease Lateral flow decrease Ground water ncrease Net water yeld ncrease Sedment yelds ncrease

16 Parameter varaton wth sol map scale Scale SOL_Z mm SOL_BD g/cm 3 SOL_AWC mm/mm SOL_K mm/hr USLE_K HRU SB(1:250,000) SM(1:50,000) ,567 Name SOL_Z Defnton Depth from sol surface to bottom of layer SOL_BD Most bulk densty (cm -3 ) SOL_AWC SOL_K USLE_K HRU Avalable water capacty of the sol layer (mm/mm sol) Saturated hydraulc conductvty (mm/h) USLE equaton sol erodblty (K) factor Multple hydrologc response unt number

17 Predcton of daly flow usng SWAT Cheongsong Precptaton Observed 100 (m 3 /s) Smulated P (mm/day) /4/1 2003/6/1 2003/8/1 2003/10/1 2003/12/1 Tme (date) 400 Youngyang Precptaton Observed 100 (m 3 /s) Smulated P (mm/day) /4/1 2004/6/1 2004/8/1 2004/10/1 2004/12/1 Tme (date) 400

18 Predcton of daly Suspended Sedment usng SWAT Cheongsong Youngyang

19 Statstcal ndexes for runoff computaton 2,, 2,, ) ( ) ( 1 = n obs obs n pred obs eff R = n obs n pred obs E V ) ( ) (,,, = n pred obs N RMSE 2,, ) ( 1 ) )( ( ) ( ,, 2 = n pred pred n obs obs n pred obs pred obs n n n R

20 Model effcency for runoff Scenaro DEMs Land cover Sol Scenaro DEMs Land cover Sol Case 1 30 m 1:50,000 1:250,000 Case m 1:50,000 1:250,000 Case 2 30 m 1:50,000 1:50,000 Case m 1:50,000 1:50,000 Case 3 30 m 1:25,000 1:250,000 Case m 1:25,000 1:250,000 Case 4 30 m 1:25,000 1:50,000 Case m 1:25,000 1:50, Effcency Value Reff R2 VE RMSE case-1 case-2 case-3 case-4 case-5 case-6 case-7 case Effcency Value (RMSE) Effcency Value Reff R2 VE RMSE case-1 case-2 case-3 case-4 case-5 case-6 case-7 case Effcency Value (RMSE)

21 Model effcency for suspended sedment Only R2 was used for model assessment Effcency value (R 2 ) case-1 case-2 case-3 case-4 case-5 case-6 case-7 case-8

22 Dscusson Wth fner DEM, model effcency mproved for runoff smulaton Wth coarser scaled Land use, model effcency decreases at Yongyang but ncreases at Chongsong staton Coarser scaled sol map mproves model effcency only for Ve, whle other statstcal ndexes showed no sgnfcant varaton For sedment, model effcency decreases wth coarser DEM Land use and sol maps dd not show any effects on the mprovement of suspended sedment Should fnd more consstent gudelnes n selecton of nput data resoluton

23 Thank You!!