In Punjab (Pakistan), the increasing population and expansion of land use for agriculture have severely exploited the regional groundwater resources. Intensive pumping has resulted in a rapid decline in the level of the water table as well as its quality. Better management practices and artificial recharge are needed for the development of sustainable groundwater resources. This study proposes a methodology to delineate favorable groundwater potential recharge zones (FPRI) by integrating maps of groundwater potential recharge index (PRI) with the DRASTIC-based groundwater vulnerability index (VI).
Groundwater decline in recent decade in the study region.
What previous studies have not considered?
•Numerous studies delineate potential groundwater recharge zones considering only recharge as a factor [1-3], however pay less attention to the identification of recharge zones that are susceptible to pollution. [We have considered both factors, the vulnerability to pollution as well as potential for recharge towards aquifer to delineate favorable potential groundwater recharge zones]. Favorable potential groundwater recharge zones are zones which are corresponding to less vulnerability and high potential to recharge.
•The assignment of weight (for thematic layers) and rating scale (for sub-classes) is subjective, and depends on expert opinion and previously published values. However, optimizing scale validity for each thematic layers is an important step. [we have used PFR and AHP techniques to modify the weights and rating scales].
Conceptual framework to identify favorable potential groundwater recharge zones.
Maps of the potential groundwater recharge index (PRI) and vulnerability index (VI); (a) derived based on original rates and weights, and (b) derived based on FR-rates and AHP-weights.
Maps of the favorable potential recharge index (FPRI) with (a) original weights and rating value, and (b) modified AHP-weights and FR-rates.
Validation curves of the AUC derived for groundwater vulnerability and potential recharge index.
Conclusion, Discussion and Outlook
•The PRI results showed that the 24%–25% area exists in high to very high potential zones for recharge correspond to the central region of the study area.
•VI maps indicated that 30%–60% of the total area is occupied by high to very high vulnerability zones.
•AUC values for PRI and VI are higher when mapped with modified weights and rating scale which indicates successful nature of the techniques used in this study.
•FPRI maps may serve as a blueprint for recharge assessment and groundwater resources management.
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