Simulation of the effects of ground-water withdrawal from a well field adjacent to the Rio Grande, Santa Fe County, New Mexico

Abstract

A digital three-dimensional ground-water flow model developed for the Santa Fe area was used to demonstrate the use of a basinwide model to evaluate the effects of ground-water withdrawal from wells on flow in nearby rivers. Model simulations of ground-water withdrawal from the Buckman well field were made in order to estimate the magnitude of effects of the withdrawal on flow in the Rio Grande, Pojoaque River, and Rio Tesuque. A simulation of historical withdrawal from the well field from 1972 through 1986 resulted in an estimated streamflow capture for the same time period of 8,450 acre-feet (36 percent of withdrawal) from the Rio Grande and 112 acre-feet (0.5 percent of withdrawal) from the Pojoaque River. A series of simulations that used hypothetical withdrawals from specific wells in the Buckman well field is presented to illustrate the effects of withdrawals from these wells on the rivers. When some wells withdrew water at a rate of 1,000 acre-feet per year for 1 year, then stopped withdrawal, the simulated cumulative streamflow capture was 40 to 64 percent of withdrawal after 21 to 36 years from the Rio Grande and was 6.6 to 7.2 percent of withdrawal after 2.4 to 3 years from the Pojoaque River, depending upon which wells were pumped. When wells 1 and 2 together withdrew 2,500 acre-feet of water per year continuously, the simulated annual streamflow capture after 100 years, as a percentage of annual ground-water withdrawal, was 74 percent from the Rio Grande, 2.8 percent from the Pojoaque River, and 1.2 percent from the Rio Tesuque. Two simulations for the time period of 1987 to 2045 were made based on possible future withdrawal from the Buckman well field. Withdrawal from Buckman well field in the simulations for 2045 ranged from 3,860 to 6,660 acre-feet of water per year. Simulated capture of flow for 2045 ranged from 2,380 to 4,260 acre-feet per year from the Rio Grande, 49 to 99 acre-feet per year from the Pojoaque River, and 11 to 28 acre-feet per year from the Rio Tesuque. INTRODUCTION! Many alluvial-hasin aquifers in New Mexibo are hydraulically connected to perennial rivers. The relation of ground water and surface water is a major consideration in management of the water resources of these basins. Because the water of most rivers in New Mexico is fully appropriated it is important to evaluate the effects of ground-water withdrawal from wells adjacent to these rivers on the flow of the rivers. Basinwide ground-water flow models, which include simulation of the interaction between the aquifer and the major rivers, have been developed for some of the alluvial basins in New Mexico. These models may be a valuable tool for evaluating effects of ground-water Withdrawal from wells on flow in nearby rivers. Purpose and Scope This report demonstrates the use of a to provide estimates of the effect of groundflow in nearby rivers. The Buckman well basinwide ground-water flow model water withdrawal from wells on field was selected for this study because of its proximity to major rivers, thej existence of a basinwide model that can simulate the interaction between the aquifer and the major rivers, and the availability of detailed pumping records for the well field. The model used in this report was developed for the Santa Fe area of the Espanola Basin by McAda and Wasiolek (1988). i Description of the Squdy Area The Buckman well field was put into operation in July 1972 to increase the water supply for the city of Santa F^, New Mexico. The well field is about 15 miles northwest of Santa Fe, near the abandoned town of Buckman on the east side of the Rio Grande (fig. 1). shown in figure 2. The production wells are 1.5 miles (well 6) from the Rio Grande. the Rio Grande, is about 5 miles north of tho well field. The Rio Tesuque, tributary of the Pojoaque River, is about 9 miles east of the well field. A map of the well-field area is about 600 feet (well 1) to about The Pojoaque River, a tributary of a EXPLANATION WELL WITHIN BUCKMAN WELL FIELD Detailed locations and well names shown in figure 2