TITLE:
Hydrogeochemical Assessment and Regional Suitability Mapping of Groundwater for Irrigation Use in the Permian Basin, West Texas
AUTHORS:
Chukwudi Onyeakusi, Chidubem Okwudiri Emedo, Chukwuebuka Benjamin Ezeh, Adaonu Onyeakusi, Ruth Ngusonun Anyor, Udeh Azuka, Prasad Pothana
KEYWORDS:
Texas, Irrigation Suitability, Sodium Hazard, Crop Productivity, Groundwater
JOURNAL NAME:
Journal of Geoscience and Environment Protection,
Vol.14 No.1,
January
19,
2026
ABSTRACT: Groundwater resources in West Texas, U.S.A., are the principal source of water for irrigation agriculture. However, its quality is under severe threat from both geogenic and anthropogenic sources. As a result, the quality of groundwater available to irrigators has had a significant impact on crop yield over the years, which makes it imperative to determine the variation in irrigation water suitability in the area. In this study, hydrogeochemical data from 127 groundwater samples obtained from the data base of Texas Water Development Board (TWDB) were analysed for irrigation suitability based on pH, percent sodium (%Na), Kelly ratio (KR), sodium adsorption ratio (SAR), magnesium adsorption ratio (MAR), soluble sodium percentage (SSP) and total dissolved solids (TDS). These samples were collected in five counties (Andrews, Gaines, Howard, Martin, and Midland) where agricultural activities are ongoing intensively. The pH, SAR, and SSP results, which ranged from 6.47 to 7.71, 0.49 to 13.34 meq/l, and 18.95 to 78.13 %, respectively, indicate that the groundwater samples are suitable for irrigated cropping. Although elevated levels of %Na were observed in a few samples in Andrews (max. value = 62%), Martin (max. value = 66%), and Howard (max. value = 70.44%) counties, irrigation suitability assessment based on %Na indicated that only 9% of the samples are “doubtful”. KR and MAR content analysis show that 4.72% and 25.98% of the samples, respectively, are in a critical state, thereby rendering the groundwater resources in parts of Andrews, Martin, and Howard counties unfit for irrigation utilization. Groundwater indices recorded in Gaines County also show unacceptable levels of MAR that could be inimical to crop growth and productivity. According to TDS analysis, all samples exhibit severe potential limitations for irrigation use due to elevated mineral content in groundwater. No sample fell within the preferred category, with the highest TDS values occurring in groundwater samples that were collected in Andrews, Martin, and Midland counties. This is probably caused by geogenic factors resulting from the dissolution of carbonate and dolomite minerals in the Ogallala regional aquifer system, and partly by anthropogenic influences from the discharge of industrial effluents and the use of fertilizer. To ameliorate this, a groundwater management policy that takes cognizance of these factors should be adopted to improve the quality of water in the study area.