Assessing the accuracy of GIS-based Multi-Criteria Decision Analysis approaches for mapping groundwater potential

Groundwater is the most important natural resource for reliable and sustainable water supplies throughout the world. However, the over-exploitation of groundwater has led to groundwater depletion over the world. Sustainable development and management of this vital resource under changing environmental conditions is the one of the major challenges of the 21st century. To this end, this study focuses on the evaluation of groundwater prospect following an integrated multi-criteria analysis and geospatial approach. GIS-based Multi-Criteria Decision Analysis (MCDA) techniques viz., Analytic Hierarchy Process (AHP) and Catastrophe theory were used for delineating groundwater potential zones in a Canal Command of Eastern India. Thematic layers (maps depicting features of the factors influencing groundwater) such as 'runoff coefficient', 'drainage density', 'geology', 'slope' and 'proximity to surface water bodies' were considered in this study. Weights were assigned to the themes and their features according to AHP and Catastrophe theories. Thereafter, the themes were integrated in GIS to yield groundwater potential maps based on AHP and Catastrophe techniques. The AHP-based groundwater potential map revealed four zones with varying areal coverage: (a) 'very good' (19% of the study area), (b) 'good' (49%), (c) 'moderate' (28%), and (d) 'poor' (4%). On the other hand, the Catastrophe-based map indicated spatial variation of groundwater potential as: (a) 'very good' (14% of the area), (b) 'good' (63%), (c) 'moderate' (19%), and (d) 'poor' (5%). Thus, both the techniques indicated good groundwater potential in the study area. The validation of the results of these GIS-based MCDA techniques indicated that although both the techniques are suitable for mapping groundwater potential with a reasonably high accuracy (82% for the AHP technique and 74% for the Catastrophe technique), the performance of the AHP technique is somewhat superior to the Catastrophe technique. The findings of this study are very useful to the water managers for cost-effective and efficient planning and development of scarce groundwater resources so as to ensure sustainable water supply in the future.