Assessment of Water Table and Water Quality Variations with Respect to the River Flow Along the Rio Grande Between Garfield NM and the New Mexico – Texas Border
B Stringam, M Shukla, and B Nana O Kuffour
The interaction between the Rio Grande and the groundwater in the Lower Rio Grande Basin in New Mexico was studied for a limited time from May of 2014 to June of 2015. During this period of time, river flow was observed and shallow groundwater levels were measured at various times from 58 monitoring wells owned and operated by the Elephant Butte Irrigation District. The monitoring wells are located between Hatch, New Mexico down to the New Mexico-Texas border and situated within the shallow alluvium of the Rio Grande floodplain in the area. In addition, select water quality attributes to include electrical conductivity (EC), salts (sodium, calcium, potassium and magnesium), and sodium adsorption ratio (SAR) were measured and recorded for water samples collected from monitoring wells both during times of flow in the river and times of no-flow. The measurements further validate that there is an interaction between the Rio Grande and the shallow groundwater aquifer. However, the relationship between the low EC water flows that percolated into the aquifer from the river did not seem to have much of an impact on the shallow alluvium groundwater EC. It is believed that possible sources for the salts are excessive irrigation and other groundwater sources. Further testing is required to determine the source of the salts. Empirical equations were developed for
modelling the initial flow from the Rio Grande into the groundwater aquifers in the Hatch-Rincon Valley and the Las Cruces areas. Despite the high correlation values that were determined for the equations, further study is required to validate these equations.
water table, water quality, Rio Grande, New Mexico-Texas border, surface groundwater interactions, river flow, Elephant Butte Irrigation District, monitoring wells, flow modeling