An integrated approach for aquifer vulnerability mapping using GIS and rough sets: study from an alluvial aquifer in North IndiaUne approche intégrée pour cartographier la vulnérabilité d’un aquifère, basée sur un SIG et les ensembles approximatifs: étude d’un aquifère alluvial dans le Nord de l’IndeUn enfoque integrado para el mapeo de la vulnerabilidad de un acuífero usando GIS y los conjuntos aproximados: estudio de un acuífero aluvial en el norte de la India采用地理信息系统和粗集进行含水层脆弱性填图的一个综合方法:印度北部一个冲积含水层的研究实例Uma aproximação integrada para o mapeamento da vulnerabilidade aquífera utilizando SIG e conjuntos irregulares: estudo de um aquífero aluvial no norte da Índia

A modified DRASTIC model in a geographic information system (GIS) environment coupled with an information-analytic technique called ‘rough sets’ is used to understand the aquifer vulnerability characteristics of a segment of the lower Kali watershed in western Uttar Pradesh, India. Since the region is a flat plain, topography (T) is removed as a potential control. Other parameters are the same as in DRASTIC, hence the new model is termed as DRASIC. The rough set technique is employed to provide insight into the relative vulnerabilities of different administrative units (blocks) within the study area. Using rough sets, three important factors are computed: strength, certainty and coverage. Strength indicates how the vulnerability characteristics vary in the entire area, certainty gives the relative fractions of low, medium and high vulnerability regions within a particular block, and coverage computes the percentage of a particular vulnerability state in each block. The purpose of the work is to demonstrate the utility of this integrated approach in classifying different administrative blocks in the study area according to their aquifer vulnerability characteristics. This approach is particularly useful for block-level planning and decision making for sustainable management of groundwater resources.