Modeling nitrates in projecting the future ground-water quality of the Cortaro area, Arizona

Abstract

The Discrete State Compartment (DSC) Model was used to model ground-water quality in the Cortaro Area, Arizona. The objective was to project ground-water quality to the year 2005 in the area in response to changing land use and increasing population. In modeling various scenarios, the constituent nitrate was used as the indicator of water quality. The 31 compartment (cell) design was based upon knowledge of the ground-water flow system, current and historic land use, ground-water elevation changes through time, and estimates for ground-water recharge and aquifer parameters. A modification of the computer code was done in order to more directly address excessive pumping in certain cells which can cause dewatering. Trends in nitrate concentrations among selected cells were compared graphically. Every scenario showed improvement in water quality of the ground-water system through time, based on the land uses defined for the scenarios.