IMPROVEMENT AND APPLICATION OF THE MODEL FOR PREDICTING PESTICIDE TRANSPORT: A CASE STUDY OF THE SAKURA RIVER WATERSHED

Transcription

1 SWAT 2018 / VUB-Brussels, Belgium IMPROVEMENT AND APPLICATION OF THE PCPF-1@SWAT2012 MODEL FOR PREDICTING PESTICIDE TRANSPORT: A CASE STUDY OF THE SAKURA RIVER WATERSHED GLOBAL SUSTAINABLE RICE PRODUCTION Le Hoang Tu (1) (2) (1) Tokyo University of Agriculture and Technology, Tokyo, Japan (2) Nong Lam University, HoChiMinh, Vietnam

2 A combination of the Pesticide Concentration in Paddy Field (PCPF-1) model and the Soil and Water Assessment Tool (SWAT) model version PCPF-1 Simulating hydrology and pesticide transport from the whole watershed. Using ArcSWAT program for generating input files. 2

3 The implementing of PCPF-1 into SWAT2009 models. SWAT2009 Upland Soil layer 1 Soil layer n PCPF-1@SWAT Soil layer n +1 Aquifer layer (Boulange et al., 2014) PCPF-1 Runoff Paddy water Paddy soil (1cm) Percolation Percolation Percolation Percolation Runoff Lateral flow Stream Water flow Processes in water body: Diffusion Volatilization Settling Resuspension Burial Note: Pesticide Concentration in Paddy Field (PCPF-1); Soil and Water Assessment Tool version 2009 (SWAT2009) 3

4 SWAT ver.2009 and 2012 Updating between SWAT 2009 and 2012 (Neitsch et al., 2011). Process Version 2009 Version 2012 Pothole - Based on sub-basin and HRU file. - Only based on HRU file. Percolation - No update soil profile water. - Update soil profile water. - No compute and update shallow - Modify calculations of shallow water table depth. water table depth and tile flow. - Add new variables such as tile flow, water table depth and, maximum depression storage. Evaporation - No minimum LAI value. - Corrected the biomass reporting zero error when harvest and kill operations. 4

5 SWAT ver.2009 and 2012 Pothole definition in SWAT2009 (a) and SWAT2012 (b). 5

6 Objective SWAT2009 Soil layer 1 Soil layer n PCPF-1@SWAT Soil layer n +1 Aquifer layer (Boulange et al., 2014) PCPF-1 Runoff Paddy soil (1cm) Percolation Percolation Percolation Percolation Lateral flow Stream Water flow Processes in water body: Diffusion Volatilization Settling Resuspension Burial To improve the PCPF-1@SWAT Runoff model for Upland Paddy water predicting the water quality risk of pollutant transport at watershed scale. Note: Pesticide Concentration in Paddy Field (PCPF-1); Soil and Water Assessment Tool version 2009 (SWAT2009) 6

7 The updating procedures. SWAT2012 (ver.637) Download from SWAT website: at-executables/ PCPF-1 Analyze, modify and debugging 7

8 The updating procedures. SWAT2012 (ver.637) PCPF-1 Analyze, modify and debugging 8

9 The updating procedures. SWAT2012 (ver.637) PCPF-1 Analyze, modify and debugging 9

10 Study area The Sakura River watershed. Located about 50 km North-East of Tokyo. Area about 335 km 2. An agricultural watershed. More than 39 kinds of herbicides, insecticides, and fungicides (Vu et al., 2006; Iwafune et al., 2010). 10

11 Input data GIS data of study area. Land use map (2008) Pesticide concentration ( ) + Topography + Soil + Land use + Pesticide + Hydrology + Weather + Observed Water Discharge Rate ( ) Source: Ministry of Land, Infrastructure and Transport, Japan 11

12 Pesticide input data Solubility 1 st order dissolution Pesticide properties 1 st order desorption rate constant, etc. Pesticide data Date of application Application information Application rate Application area Water holding period 12

13 Pesticide input data The herbicide data Pesticide name Chemical formula Solubility of the herbicide in water (mg/l) Herbicide application rate (g/m 2 ) Percentage rice treated area (%) Mefenacet C 16 H 14 N 2 O 2 S Pretilachlor C 17 H 26 ClNO Bensulfuronmethyl C 16 H 18 N 4 O 7 S Imazosulfuron C 14 H 13 ClN 6 O 5 S

14 Calibration and validation Calibration period (2007) and validation period ( ). Nash Sutcliffe Efficiency (NSE), Root Mean Square Error (RMSE) and Percentage BIAS (PBIAS). Calibration of parameters for water discharge Groundwater delay Groundwater "revap" coefficient Threshold depth of water in the shallow aquifer for "revap" to occur Manning's "n" value for overland flow Lateral flow travel time Initial SCS CN II value Calibration of parameters for pesticide concentration Pesticide percolation coefficient Pesticide reaction coefficient in reach 14

15 Comparison with previous version Comparison simulated water discharge between the original and new versions. Original version New version NSE RMSE

16 Comparison with previous version Comparison simulated mefenacet between the original and new versions. Original version New version NSE RMSE

17 Water discharge rate Statistical indies Units Validation NSE None 0.73 PBIAS % Note: Satisfactory streamflow simulation NSE > 0.5 and PBIAS <± 25% (Moriasi et al., 2007) 17

18 Pesticide concentrations Herbicide name Validation NSE RMSE (µg/l) PBIAS (%) Mefenacet Pretilachlor Bensulfuron-methyl Imazosulfuron Note: Satisfactory streamflow simulation NSE > 0.35 and PBIAS <± 70% (Moriasi et al., 2015) 18

19 Pesticide concentrations

20 Pesticide concentrations Rice season 2008 and 2009 Herbicides Average maximum (μg/l) Mean (μg/l) Obs Sim Obs Sim Pretilachlor Imazosulfuron Mefenacet Bensulfuron-methyl Note: Observed (Obs), Simulated (Sim) 20

21 Conclusion The model was updated and renamed to model. The new model version was applied to simulate the transport of four rice herbicides in the Sakura river watershed. The simulated results showed moderate accuracy and good tendency with monitored data. Further application of the model needs to be conducted. 21

22 Future study plan Develop an independent rice module. PCPF-1 Model capability RICE module Model input variables SWAT+ SWAT+RICE 22

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