Mapping favorable groundwater potential recharge zones using a GIS-based
analytical hierarchical process and probability frequency ratio model: A case
study from an agro-urban region of Pakistan
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Abstract
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). In order to evaluate both indexes, different thematic layers
corresponding to each index were overlaid in ArcGIS. In the overlay analysis, the weights (for various thematic
layers) and rating values (for sub-classes) were allocated based on a review of published literature. Both were then
normalized and modified using the analytical hierarchical process (AHP) and a frequency ratio model respectively.
After evaluating PRI and FPRI, these maps were validated using the area under the curve (AUC) method.
The PRI map indicates that 53% of the area assessed exists in very low to low recharge zones, 22% in moderate,
and 25% in high to excellent potential recharge zones. The VI map indicates that 38% of the area assessed exists in
very low to low vulnerability, 33% in moderate, and 29% in high to very high vulnerability zones. The FPRI map
shows that the central region of Punjab is moderately-to-highly favorable for recharge due to its low vulnerability
and high recharge potential. During the validation process, it was found that the AUC estimated with modified
weights and rating values was 79% and 67%, for PRI and VI indexes, respectively. The AUC was less when
evaluated using original weights and rating values taken from published literature. Maps of favorable groundwater
potential recharge zones are helpful for planning and implementation of wells and hydraulic structures in
this region.
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