Paper/Poster/Presentation Title

Simulating Coupled Salinity Transport Model in an Agricultural Groundwater System

Presenter/Author Information

Saman TavakoliFollow

Start Date

25-6-2018 2:00 PM

End Date

25-6-2018 2:20 PM

Abstract

The Lower Arkansas River Valley (LARV) in southeastern Colorado is a key resource for stakeholders in southeastern Colorado due to its valuable agriculture production. Because of a rising water table due to excessive irrigation and canal seepage, much of the soil-aquifer system in the valley has become salinized, thereby negatively impacting crop yield. High groundwater salinity loading to the Arkansas River stream network also impacts downstream areas, with saline river water diverted for application on irrigated fields. The overall aim of this project is to develop a numerical modeling framework capable of simulating the transport of salt ions within the stream-aquifer-soil system, so that current conditions of salinity can be assessed and possible remediation strategies in the region can be explored. Results of simulating the fate and transport of sulfur species (principally sulfate SO4) in a 500 km2 region of the LARV using the UZF-RT3D groundwater reactive transport model indicate that advection-dispersion processes, first-order kinetic reactions, and sources/sinks cannot account for the high groundwater SO4 concentrations and loadings to the Arkansas River. Hence, a comprehensive salinity module that can be coupled with the UZF-RT3D model and that accounts for salt ions equilibrium chemistry and precipitation-dissolution processes is being developed. Initial model testing with the nested equilibrium module will occur at the field scale, with model results compared with collected salinity data from a lysimeter site at the Arkansas Valley Research Center in Rocky Ford, CO.

Stream and Session

C6

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Jun 25th, 2:00 PM Jun 25th, 2:20 PM

Simulating Coupled Salinity Transport Model in an Agricultural Groundwater System

The Lower Arkansas River Valley (LARV) in southeastern Colorado is a key resource for stakeholders in southeastern Colorado due to its valuable agriculture production. Because of a rising water table due to excessive irrigation and canal seepage, much of the soil-aquifer system in the valley has become salinized, thereby negatively impacting crop yield. High groundwater salinity loading to the Arkansas River stream network also impacts downstream areas, with saline river water diverted for application on irrigated fields. The overall aim of this project is to develop a numerical modeling framework capable of simulating the transport of salt ions within the stream-aquifer-soil system, so that current conditions of salinity can be assessed and possible remediation strategies in the region can be explored. Results of simulating the fate and transport of sulfur species (principally sulfate SO4) in a 500 km2 region of the LARV using the UZF-RT3D groundwater reactive transport model indicate that advection-dispersion processes, first-order kinetic reactions, and sources/sinks cannot account for the high groundwater SO4 concentrations and loadings to the Arkansas River. Hence, a comprehensive salinity module that can be coupled with the UZF-RT3D model and that accounts for salt ions equilibrium chemistry and precipitation-dissolution processes is being developed. Initial model testing with the nested equilibrium module will occur at the field scale, with model results compared with collected salinity data from a lysimeter site at the Arkansas Valley Research Center in Rocky Ford, CO.