Limitations of GIS-based groundwater potential mapping

In this discussion paper, we highlight misapplications of the spatial analysis of groundwater potential (GP) using geographical information systems, knowledge-driven, and data-driven models. Using this analysis, GP can be evaluated over a large area with simplified and easy-to-develop factors. The result is a map that can identify the most productive parts of an aquifer for better management. However, the GP analysis lacks realism due to the common reliance of analyses on surficial factors such as topography, exposed lithology, soil, and land use/land cover for mapping, which do not consider the nature of the aquifer. These factors only affect the renewable storage of the aquifer under study (i.e., the recharge rate), which generally is only a small part of the fixed or strategic aquifer storage, especially in arid and semiarid regions. Most of the recent studies reviewed do not present a unified, detailed description of the aquifer under study. Groundwater quality is not considered as well in GP mapping; if the aquifer has high strategic storage but the quality of water is poor, the GP analysis is not useful. The use of advanced statistical and machine learning algorithms is not required; rather, it is important to have a realistic understanding of the nature of the aquifer being analyzed and the factors affecting it.