Paper/Poster/Presentation Title
Keywords
SWAT-MODFLOW-RT3D; solute transport; irrigated system
Start Date
25-6-2018 10:40 AM
End Date
25-6-2018 12:00 PM
Abstract
In irrigated semi-arid watersheds, nitrogen (N) and phosphorus (P) are essential for crop growth but their application often results in nonpoint-source pollution of both surface water and groundwater. The Soil Water Assessment Tool (SWAT) has been used extensively to identify changes in water and nutrient transport due to land use and water management practices in watersheds of varying scale and complexity. However, the performance of the model is limited in watershed systems wherein groundwater discharge is a significant component of streamflow due to the simplistic representation of subsurface processes. In this study, the recently developed SWAT-MODFLOW model is linked to the groundwater reactive solute transport model RT3D (Reactive Transport in 3 Dimensions) and applied to a 950 km2 watershed in the Lower Arkansas River Valley (southeastern Colorado). This study region has been intensively irrigated for over 100 years and is threatened by shallow water tables and high nutrient concentrations in the groundwater and river network. The newly developed model is calibrated and tested against stream discharge and nutrient instream loading from 5 stream gauges in the Arkansas River and its tributaries, groundwater elevations from 70 observation wells, and nutrient mass loading from/to the stream system during the 2001-2016 period. After model testing, the model is used to explore the fate and transport of chemical species in coupled surface-subsurface systems, and identify plausible best-management practices for controlling nutrient pollution in agricultural watersheds.
Estimating spatio-temporal patterns of groundwater-surface water interactions and solute transport in an irrigated stream-aquifer system
In irrigated semi-arid watersheds, nitrogen (N) and phosphorus (P) are essential for crop growth but their application often results in nonpoint-source pollution of both surface water and groundwater. The Soil Water Assessment Tool (SWAT) has been used extensively to identify changes in water and nutrient transport due to land use and water management practices in watersheds of varying scale and complexity. However, the performance of the model is limited in watershed systems wherein groundwater discharge is a significant component of streamflow due to the simplistic representation of subsurface processes. In this study, the recently developed SWAT-MODFLOW model is linked to the groundwater reactive solute transport model RT3D (Reactive Transport in 3 Dimensions) and applied to a 950 km2 watershed in the Lower Arkansas River Valley (southeastern Colorado). This study region has been intensively irrigated for over 100 years and is threatened by shallow water tables and high nutrient concentrations in the groundwater and river network. The newly developed model is calibrated and tested against stream discharge and nutrient instream loading from 5 stream gauges in the Arkansas River and its tributaries, groundwater elevations from 70 observation wells, and nutrient mass loading from/to the stream system during the 2001-2016 period. After model testing, the model is used to explore the fate and transport of chemical species in coupled surface-subsurface systems, and identify plausible best-management practices for controlling nutrient pollution in agricultural watersheds.
Stream and Session
E1: Coupled Surface-Subsurface Hydrologic Modelling