River GeoDSS for Agroenvironmental Enhancement of Colorado’s Lower Arkansas River Basin. I: Model Development and Calibration

Abstract

The Lower Arkansas River (LAR) Basin in Colorado, like many intensively irrigated river basins in the Western United States, faces a variety of problems associated with inefficient irrigation, seepage from earthen canals, and inadequate drainage facilities. Upward flows from high water tables have salinized and waterlogged agricultural soils of the Valley, contributing to reduced crop yields and nonbeneficial water consumption on adjacent uncultivated lands. River water quality has also suffered since intensive irrigation of alluvial soils results in evaporative concentration and the accelerated dissolution of inherent salts and other mineral pollutants into the underlying aquifer, appearing as return flows that threaten the ecological health of the river. A geographic information system-based river basin decision-support system (River GeoDSS) has been developed and applied to the LAR Basin for assessing basinwide strategies for improving agricultural productivity, salvaging water from nonbeneficial consumptive use, and reducing solute concentrations while maintaining compliance with decreed water rights and the Arkansas River Compact between Colorado and Kansas. Development and calibration of River GeoDSS, based on extensive field data collection programs in the LAR Basin, is described herein, with a companion paper detailing its application to evaluation of a wide range of agroenvironmentally focused water management strategies.