Predicting groundwater recharge potential zones using geospatial technique

Rapid urbanization increases impervious surfaces, thus interrupting natural groundwater recharge, and finally poses serious threat to the city water demands due to groundwater level depletion. In this context, artificial ground water recharge (GWR) using excess rainfall is getting interest among the urban areas. This study selected Chittagong, the second largest and commercial capital city of Bangladesh, is facing issues with groundwater level lowering. Potentialities of GWR were assessed using multi-criteria decision analysis (MCDA) in association with the geospatial techniques. After evaluating primary and secondary datasets, eight thematic layers, i.e., urban storm water logging depth, drainage density, slope, rainfall/runoff, soil texture, existing groundwater level, lineament and land use/land cover, were used to locate the potential areas for GWR. Using reclassification techniques, the thematic layers were individually classified into five categories and assigned a specific normalized weighted value using analytical hierarchy process (AHP) in ArcGIS environment. Then, weighted linear combination method was employed to predict the potential GWR areas. The whole study area was then divided into five categories, viz. low, medium, medium–high, high and very high potential zone. Analysis showed that 5.5% of the total area is highly potential for GWR. In this analysis, expertise knowledge and practical experiences were used to analyze the data and map preparation. Therefore, along with the high-resolution ground data, findings of this paper envisaged to provide useful information to the decision support system.