A coupled SWAT-MODFLOW model to evaluate the effects of agricultural management practices on surface and groundwater

Author(s): Ni, X.

Water quality pollutants, which may be generated due to various agricultural activities, can affect both surface water and groundwater resources. The objective of this study is to assess the effects of agricultural management practices and climate variability on surface water and groundwater using Soil and Water Assessment Tool (SWAT) model in the Big Sunflower River Watershed (BSRW), which is major concerned by its agricultural purpose in Mississippi. In addition, the MODFLOW model, a finite-difference groundwater model, was used to simulate groundwater flow with boundary, recharge and HRUs calculated from the corresponding SWAT model. A coupled SWAT-MODFLOW model was applied to evaluate the water quality and quantity effects due to different agricultural management practices. The SWAT model was calibrated and validated by comparing monthly stream flow to observations from USGS gaging stations with both R2 and Nash–Sutcliffe model efficiency coefficient up to 0.67. Statistics increased first and then decreased with increasing hydraulic curve numbers. The model results are expected to be better after the groundwater model is coupled and calibrated with groundwater level data. Different agricultural management practices will be applied to the coupled SWAT-MODFLOW model to evaluate the effects on water quality and quantity of surface water and groundwater.

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