Land-Use Impact and Nitrate Analysis to Validate DRASTIC Vulnerability Maps Using a GIS Platform of Pablillo River Basin, Linares, N.L., Mexico

Abstract

Preventive management of groundwater resources and their protection against pollution is one of the major challenges of our society. Groundwater systems are related with the surficial processes like territorial administration that is one of the most important tasks into the human development, because it involves serious problems to define the spatial medium, the industrial site-selection and the land-use allocation. Land-use and anthropogenic distribution could be the origin of the emission of pollutants that constitutes a serious health risk in urban areas. Nitrate was used as a pollution indicator in the Pablillo River Basin (PRB), to know the evolution of groundwater quality between 1981 and 2009 using GIS platform linked to vulnerability maps of DRASTIC ( D epth to the water table; net groundwater R echarge; A quifer type; S oil type; T opography; I mpact of the vadose zone and hydraulic C onductivity of the saturated zone). The study area is centered on the Linares city; changes in aquifer vulnerability were assessed over time on two stages (2007 and 2001). In both cases, depth from surface to groundwater plays an important role by being the most dynamic variable over time. This study shows that the depth of water table is the key factor in the evaluation of groundwater vulnerability. The significance of land-use impact in contamination process called Index of Pollution Risk ( IPR ) and nitrate distribution process in the aquifer system was used as anthropogenic indicator together with the IPR in order to associate the land-use, the aquifer-vulnerability and human-activities. The final map of IPR allows determining possible polluted zones verified by high nitrate contents over the aquifer system. Land-use proved to be an important parameter necessary to correct the vulnerability maps using the DRASTIC method. This assessment is valid for situations where a specific time is defined because six of seven parameters change their properties in a very long term. The IPR-map could be an important key tool to prevent complex scenarios of groundwater contamination and to improve the aquifer management for decision makers, governments and private companies.