Using Analytical Hierarchy Process and Multi-Influencing Factors to Map Groundwater Recharge Zones in a Semi-Arid Mediterranean Coastal Aquifer

Abstract

Mapping groundwater recharge zones (GWRZs) is essential for planning artificial recharge programs to mitigate groundwater decline and saltwater intrusion into coastal aquifers. We applied two multi-criteria decision-making approaches, namely the analytical hierarchy process (AHP) and the multi-influencing factors (MIF), to map GWRZs in the Korba aquifer in northeastern Tunisia. GWRZ results from the AHP indicate that the majority (69%) of the area can be classified as very good and good for groundwater recharge. The MIF results suggest larger (80.7%) very good and good GWRZs. The GWRZ maps improve groundwater balance calculations by providing estimates of recharge-precipitation ratios to quantify percolation. Lithology, land use/cover and slope were the most sensitive parameters followed by geomorphology, lineament density, rainfall, drainage density and soil type. The AHP approach produced relatively more accurate results than the MIF technique based on correlation of the obtained GWRZs with groundwater well discharge data from 20 wells across the study area. The accuracy of the approaches ultimately depends on the classification criteria, mean rating score and weights assigned to the thematic layers. Nonetheless, the GWRZ maps suggest that there is ample opportunity to implement aquifer recharge programs to reduce groundwater stress in the Korba aquifer.

Identification of Groundwater Potential Zones Using GIS and Multi-Criteria Decision-Making Techniques: A Case Study Upper Coruh River Basin (NE Turkey)

“…Therefore, these factors' importance on groundwater recharge and storage is very low [19,35,68]. Agricultural and floodplain lands have more porosity, increasing water percolation into the subsurface; hence, these factors have moderately high to high potential for groundwater storage [69,70]. The arable land and agricultural land largely overlap with the high and very high potential classes of the GWPZs map of the UCRB.…”

“…The valleys formed due to the rivers' incising action contain rocks and sediments with high permeability, where the water quickly infiltrates to the ground [88]. The pediplain is a spacious flat area formed by the unification of pediments [89] and represents a highly permeable unit promoting water recharge and percolation, thus the high potential of groundwater [69]. Escarpment and high ridges are typically associated with poor infiltration capacities or being unsuitable for groundwater occurrence [24,90].…”

“…Rainfall is the primary water source on the earth, and it controls the surface and groundwater amount [65][66][67]. For this reason, it is widely used in groundwater potential determination studies [11,[68][69][70]. The total annual rainfall amount (between the periods of 1981 and 2019 [41]) obtained from six meteorology stations (Bayburt, Trabzon, Rize, Erzurum, Erzincan and Gümüşhane) around the study area were used to create the rainfall layer.…”

AHP as a Useful Tool in the Assessment of the Technical Condition of Hydrotechnical Constructions

“…Based on the hierarchical tree, matrices were created, which were complemented by the obtained results of comparisons of the importance pairs of individual factors and particular elements of the hydrotechnical construction according to the Saaty scale (Figure 4) [64,65]. The scale values equal to 1 indicate equal importance, 3 a slight advantage of one factor over another, 5 a clear advantage between factors, 7 a very clear advantage, and 9 an absolute advantage [66,67]. Comparison by pairs of all assessment criteria, and sub-criteria, made it possible to create an A = [ai,j] matrix, with n.n dimensions, in which n(n -1)/2 comparisons were made (Equation ( 1)) [68].…”

“…The hierarchical tree of factors that influence the assessment of the technical condition of the most important elements of a water structure.Based on the hierarchical tree, matrices were created, which were complemented by the obtained results of comparisons of the importance pairs of individual factors and particular elements of the hydrotechnical construction according to the Saaty scale (Figure4)[64,65]. The scale values equal to 1 indicate equal importance, 3 a slight advantage of one factor over another, 5 a clear advantage between factors, 7 a very clear advantage, and 9 an absolute advantage[66,67].…”