Simulation of Groundwater Flow in the Soutehrn Jornada Del Muerto Basin, Dona Ana County, New Mexico

摘要

The Lower Rio Grande Water Users Organization (LRGWUO) is working to develop a unified groundwater flow model for the Lower Rio Grande Project deliverables. To meet their goal, a three-layer conceptual model of the southern Jornada del Muerto Basin is developed in the current work. The flow model is developed with grid properties and parameter distributions consistent with the groundwater flow model for administration and management in the Lower Rio Grande Basin (OSE-2007 flow model) prepared by S.S. Papadopulos and Associates for the Rincon-Mesilla Basins. Field data that includes layer elevations, aquifer properties, boundary stresses, and initial piezometric heads were delineated in ArcGIS. MODFLOW numerical code is used for solving the governing differential equations with Groundwater Vistas (Version 5) used as the graphical user interface for performing model simulation and calibration. The model has 180 rows, 105 columns, and three layers with a uniform grid resolution of 402.336 m (one quarter of a mile). The model is rotated 24 degrees in counter clock direction to maintain consistency with the OSE-2007 flow model. The model is simulated under transient conditions from 1968 to 2007 with two seasons per irrigation year. Pumping from domestic and municipal wells, interbasin flows through specified boundaries, and recharge from the mountain upfronts forms the major stress components of the study area. Recharge to the basin from the upland areas behind the model boundary was estimated based on the calibration statistics and basin specific characteristics. Aquifer properties of model layer 1 were identified as the most sensitive parameters. Water table elevations in the 72 analytical wells were considered during calibration. The simulation results were interpreted in terms of volumetric budget and water table elevation contours for selected stress periods. A significant decrease in the water table during simulation was observed in southern and southeastern parts of the basin. However, the water table in the northeastern and central parts of the basin is increasing with time. The kriged surface of water table elevations predicted that the groundwater gradient slopes predominantly east to west and is flattening at a decreasing rate during the simulation period.