Keywords

agricultural watershed, surface-groundwater interactions, SWAT-MODFLOW, nitrate transport

Start Date

25-6-2018 10:40 AM

End Date

25-6-2018 12:00 PM

Abstract

Understanding the interaction between groundwater and surface water in watersheds is essential for assessment of long-term anthropogenic impacts on ecosystems due to agricultural farming practices. Nitrate leaching from intensified agricultural farming practices percolates through the surficial aquifer and degrading groundwater quality in many parts of North Carolina. To evaluate the process of nitrate accumulation and leaching in surface and groundwater, we developed an integrated model using SWAT-MODFLOW and simulated the nitrate transport in aquifer using MODFLOW’s reactive transport model, RT3D. This study is applied to the Northeast Cape Fear Watershed (4480 km2) within the Cape Fear River Basin in North Carolina, USA. The data required to build the individual SWAT and MODFLOW model includes groundwater surface elevations, hydrological information, aquifer properties, soil characteristics, water quality, boundary conditions, land use, crop and livestock farming etc. The coupled SWAT-MODFLOW model is set up for the time period of 1995-2014 and the groundwater level, groundwater discharge rates are calculated at monitoring points along the stream at daily time steps. Model simulated temporal trends of streamflow show how groundwater discharge and base-flow are affected by climate change. The nitrate transport within aquifer through the concentration distribution over years is analyzed using the breakthrough curves (i.e., concentration vs time) in the proposed study. A spatially varying groundwater discharge map is obtained to identify areas of nitrate mass loading from aquifer to the streams. These findings will have profound impacts on nutrient management for potential application in other watersheds.

Stream and Session

Stream E: Modeling for Planetary Health and Environmental Sustainibility

Session E1: Coupled Surface-Subsurface Hydrologic Modeling

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Jun 25th, 10:40 AM Jun 25th, 12:00 PM

An integrated SWAT-MODFLOW model for estimating nitrate transport from agricultural practices for a watershed in North Carolina

Understanding the interaction between groundwater and surface water in watersheds is essential for assessment of long-term anthropogenic impacts on ecosystems due to agricultural farming practices. Nitrate leaching from intensified agricultural farming practices percolates through the surficial aquifer and degrading groundwater quality in many parts of North Carolina. To evaluate the process of nitrate accumulation and leaching in surface and groundwater, we developed an integrated model using SWAT-MODFLOW and simulated the nitrate transport in aquifer using MODFLOW’s reactive transport model, RT3D. This study is applied to the Northeast Cape Fear Watershed (4480 km2) within the Cape Fear River Basin in North Carolina, USA. The data required to build the individual SWAT and MODFLOW model includes groundwater surface elevations, hydrological information, aquifer properties, soil characteristics, water quality, boundary conditions, land use, crop and livestock farming etc. The coupled SWAT-MODFLOW model is set up for the time period of 1995-2014 and the groundwater level, groundwater discharge rates are calculated at monitoring points along the stream at daily time steps. Model simulated temporal trends of streamflow show how groundwater discharge and base-flow are affected by climate change. The nitrate transport within aquifer through the concentration distribution over years is analyzed using the breakthrough curves (i.e., concentration vs time) in the proposed study. A spatially varying groundwater discharge map is obtained to identify areas of nitrate mass loading from aquifer to the streams. These findings will have profound impacts on nutrient management for potential application in other watersheds.