Impacts of Agricultural Production Practices on the Quantity and Quality ofGroundwater in the Central High Plains

摘要

The study develops and applies an analytical framework, which includes a regionalprogramming model linked with crop yield-chemical movement (EPIC-PST) and aquifer (MODFLOW) models, to evaluate the potential impacts of various water quality policy alternatives on crop production patterns, irrigation management and technology decisions, agricultural chemical use, and the quality and quantity of groundwater in the Central High Plains. The analysis includes a baseline representing the current production situation and expected future conditions, and three water quality protection policies: limitations on the total quantity of nitrogen applied, limitations on per acre nitrogen applications, and restrictions on the availability of selected pesticides which have been identified as likely to leach through the plant root zone. Results consist on an initial 1990 model solution for each of five regions in the study area: Oklahoma, Texas Western, Texas Eastern, Kansas Western and Kansas Eastern. Model solutions show the acres of wheat, sorghum, corn and alfalfa produced under dryland conditions, and under furrow, improved furrow, sprinkler and LEPA irrigation systems. Also determined are applications and movements in runoff and percolation of nutrients and pesticides, irrigation water pumped, production and net income associated with the baseline and alternative water quality policies. A multi-year analysis predicts changes in the pattern of dryland and irrigated crop production, irrigation system decisions, and nutrient and pesticide movements, production and net income over a 20-year horizon for the baseline and water quality policies.