Groundwater vulnerability and risk mapping in a geologically complex area by using stable isotopes, remote sensing and GIS techniques

(GIS) The Paluxy aquifer in north-central Texas is composed primarily of Lower Cretaceous clastics. This aquifer provides water for both domestic and agricultural purposes in the region. The study area for this investigation incorporates the outcrop and recharge areas, as well as the confined and unconfined portions of the aquifer. The purpose of this investigation is to perform a groundwater vulnerability assessment on the Paluxy aquifer using the GRASS 4.1 geographic information system (GIS) combined with a modified DRASTIC approach.

DRASTIC is an acronym for the variables that control the groundwater pollution potential (Depth to water, net Recharge, Aquifer media, Soil media, Topography, Impact of the vadose zone, and Conductivity of the aquifer). Using such an approach allows one to investigate the potential for groundwater contamination on a regional, rather than site-specific, scale.

Based upon data from variables such as soil permeability, depth to water, aquifer hydraulic conductivity, and topography, subjective numerical weightings have been assigned according to the variable's relative importance in regional groundwater quality. The weights for each variable comprise a GIS map layer. These map layers are combined to formulate the final groundwater pollution potential map.

Using this method of investigation, the pollution potential map for the study area classifies 47% of the area as having low pollution potential, 26% as having moderate pollution potential, 22% as having high pollution potential, and 5% as having very high pollution potential (Fig. 1).

Figure 1. Generalized pollution potential map of the Paluxy aquifer, north-central Texas.

Original article:
An Aquifer Vulnerability Assessment of the Paluxy Aquifer, Central Texas, USA, Using GIS and a Modified DRASTIC Approach
Todd G. Fritch, Cleavy L. McKnight, Joe C. Yelderman Jr. and Jeff G. Arnold
Environmental Management, Volume 25, Number 3 / March, 2000