Comparison of multiple point and single point calibration performance for the Saginaw River Watershed

Transcription

1 Comparison of multiple point and single point calibration performance for the Saginaw River Watershed Fariborz Daneshvar, A 1. Pouyan Nejadhashemi 1, Matthew R. Herman 1 1 Department of Biosystems and Agricultural Engineering, Michigan State University 2015 SWAT Conference at Purdue October th

2 SWAT Model Calibration-Validation SWAT uses a large number of default input parameters for model development Subbasin level parameters (e.g. ground water, soil, routing ) Basin level parameters (e.g. surface runoff lag coefficient) Calibration-Validation process is required to verify the accuracy of the model for the simulated condition Single point calibration is the common approach for water quantity and water quality calibration 2

3 Challenges Single point calibration will not account for spatial variation of hydrological processes. Multiple point calibration was introduced to tackle this issue Multiple point calibration software (e.g. SWAT-CUP) still uses unique basin level parameters for the whole watershed. Time consuming process! 3

4 Solution Introduce a new multiple point calibration process which is: Faster Can use multiple values for basin level parameters. 4

5 Study Area Saginaw River Watershed Largest HUC-6 (040802) in Michigan Total drainage area 16,120 km 2 Drains to the Lake Huron Defined as an area of concern by EPA Mostly agricultural and forest lands (74%) Figure 1- Study area 5

6 SWAT Project SWAT 2012 (rev-622) Watershed Delineation Predefined reaches and Subbasins by Michigan Institute of Fisheries Research (IFR), based on National Hydrology Dataset Plus (NHDPlus) Land-use Cropland Data Layer 2013 Soil SSURGO soil Slope 5 slopes (1-2,2-4,4-7,7-10,>10) Climate Data NCDC data for period Figure 2- SWAT overlapping layers 6

7 Calibration Criteria Nash-Sutcliffe Efficiency (NSE) Percent Bias (PBIAS) RMSE-observations Standard-Deviation Ratio (RSR) Table 1- Flow calibration criteria 1 Criteria Very Good Good Satisfactory Unsatisfactory NSE < 0.5 PBIAS (%) < ±10 ±10 - ±15 ±15 - ±25 > ±25 RSR > Moriasi D.N., Arnold J.G., Van Liew M.W., Bingner R.L., Harmel R.D., Veith T. L., 2007, Model evaluation guidelines for systematic quantification of accuracy in watershed simulations. Trans. ASABE. vol. 50(3), pp

8 Single Point Calibration Saginaw River (USGS ) station is used for flow calibration out of reaches (~96% of watershed) drain to this river All reaches/subbasins parameters (e.g. ground water, soil, management, etc.) are assumed to be the same. Monthly flow calibration: Calibration: Validation: Calibration Validation NSE PBIAS (%) RSR NSE PBIAS(%) RSR Figure 3- Single point Calibration 8

9 Single Point Calibration Cons.: No spatial variation is considered Each year of SWAT run ~ 5 min. Figure 3- Single point Calibration 9

10 Multiple Points Calibration Using 9 USGS stations for calibration USGS (1053 reaches) USGS (1311 reaches) USGS (773 reaches) USGS (1048 reaches) USGS (3055 reaches) USGS (2140 reaches) USGS (627 reaches) USGS (2682 reaches) USGS (553 reaches) Figure 4- Multiple point Calibration 10

11 Multiple Points Calibration Daily Flow Calibration Calibration: Validation: Calibration Validation USGS Station NSE PBIAS (%) RSR NSE PBIAS(%) RSR Figure 4- Multiple point Calibration 11

12 Multiple Points Calibration /1/2001 1/1/2002 1/1/2003 1/1/2004 1/1/2005 1/1/2006 1/1/2007 1/1/2008 1/1/2009 1/1/2010 Obs. Series1 Sim. Series2 Figure 5- observed flow vs. simulated flow for USGS station 12

13 Conclusion Longer calibration period can be achieved. Multiple point calibration will speed up the process. SWAT parameters can be changed locally, which is more realistic compared to previous approaches. 13

14 Acknowledgement We would like to thank the Environmental Science and Policy Program (ESPP) at Michigan State University for funding this project 14

15 Thank You 15