A fuzzy based MCDM–GIS framework to evaluate groundwater potential index for sustainable groundwater management - A case study in an urban-periurban ensemble, southern India

Abstract

The study encompasses the application of fuzzy based multi-criteria decision making (MCDM)- geospatial framework (GIS-Fuzzy-AHP) for evaluating index based groundwater potential assessment in two differently urbanized clusters of Northern Kerala, Southern India. The framework presents a very powerful way of managing groundwater at a regional and global level due to its succinct performance. The study area is characterized by a coastal zone with a high rate of urban development and relying on groundwater supply to meet their basic needs. In the Fuzzy-analytic hierarchy process (Fuzzy-AHP), a three-level hierarchical model is built using 8 criteria and 34 subcriteria of groundwater controlling factors. Weights and ratios of these factors have been generated by pairwise comparisons of fuzzified values in Saaty's 9-point fundamental scale, taking relative importance into account. Finally, the integration of spatial and non-spatial data into the GIS platform created a groundwater potential zone map with a unique integer value known as the groundwater potential index (GWPI). The resulting groundwater potential map classified the study area into four zones using quantile method and has shown that the very good potential zone occupies 34% and 10% of the urban and peri-urban zones of the study area, respectively. Gentle slope gradient with coastal alluvium formation, sandy loam to sandy clay textured soil type with moderate to rapid permeability favours aquifer recharge in these zones, resulting in a very high potential zone. The consistency analysis using the Eigenvector method showed that the consistency was well within the tolerance limit and validation analysis using the average depth of water level data checked the statistical efficiency and reliability of results in the overall decision-making phase. A well-balanced fuzzy framework has allowed the rapid and reliable assessment of hydrological behaviour of two differently urbanized environments.