Geologic controls on ground-water flow in the Mimbres Basin, southwestern New Mexico

A BSTRACT — A three-dimensional calibrated regional ground-water flow model of the Mimbres Basin developed by McCoy and Finch (unpubl. report for Chino Mines Company, 2006) shows that ground-water flow is controlled by the geology and structure of the mountain bedrock and basin fill, and that the basin can be divided into four major hydrogeologic regions. These regions show distinct ground-water flow patterns based on recharge, discharge, and hydraulic properties controlled by geology and structure. Local and regional geologic controls on ground-water flow include permeability contrasts resulting from deposi- tion, volcanism, and deformation associated with Basin and Range faulting, paleo-drainage, and topography. Bedrock plays an important role in each hydrogeologic region. About 24% of the ground water in storage in the ground-water flow model is within bedrock, and up to 30% of total modeled recharge to the Mimbres Basin occurs as areal recharge to bedrock hydrogeologic units. Recharge to bedrock hydrogeologic units becomes ground water in storage and ground-water flow to the basin fill.