Evaluating and detecting potential of groundwater resources using Fuzzy-AHP method (Fuzzy-AHP) and remote sensing data (Case study: Bam-Narmashir Plain)

Detecting the potential of groundwater resources is one of the most important methods of water exploitation management to deal with water shortage, which is inevitable due to the growing need for water in the country. The first step in managing groundwater resources is to recognize the potential of groundwater. Fuzzy-Analytic Hierarchy Process (AHP) is also recognized as an important tool in decision-making about natural resources management, especially water resources. Bam-Narmashir plain, in Kerman province, is one of the most important plains of the country. This plain plays a very important role in the region in terms of supplying the water resources needed by agriculture, industry and drinking parts.

In this study, AHP-fuzzy model and GIS were used to identify suitable areas for potential groundwater resources in Bam-Narmashir plain. Criteria such as rainfall, temperature, geographical direction, slope, land use, vegetation cover, distance from the road, distance from the river, distance from the fault, distance from the city and village, distance from wells and springs, soil texture and the permeability of the formation were selected for decision making and the weight of each of them was calculated and prioritized using AHP model. Then, the desired layers were fuzzy and indicator maps were prepared using Arc GIS software. Then, the groundwater potential map was prepared. Finally, the ROC curve was used to validate the groundwater potential map in the region.

The result of ROC curve indicated the high accuracy of Fuzzy-AHP method in preparing the groundwater potential map in the study area. The results were consistent with the results of researchers such as Rezaei Moghadam et al. (2017) and Faraji Sabokbar et al. (2011). Also, the results showed that the regions with geological sub-criteria have the highest weight of 0.614 and the climatic sub-criteria have the lowest weight of 0.117. The value of inconsistency ratio was 0.07, which is smaller than 0.1, and it indicates consistency in the opinions and judgments of research decision-makers. Finally, the results showed that about 7.77% of the total area of the plain, equivalent to 755.54 square kilometers, is suitable for the implementation of underground water resources potential detection systems. Also, 1.57, 31.71, 58.98 and 7% of plain lands have very weak, weak, medium, and high potential for finding the potential of underground water resources, respectively.The results showed a sparse distribution of suitable areas for groundwater potential in Bam-Narmashir plain, which is compatible with the results of Sekar and Randir (2007), who stated that the groundwater recharge potential at the scale of the watershed has non-uniform spatial distribution. The results showed that in the northern and western part of the plain, where the soil is mostly low capacity for groundwater potential and infiltration, which is in line with the results of Akbarpour et al. (2015), who stated in west and north-west of Birjand basin, the soil has a low capacity for groundwater penetration due to the low depth of the soil and high slope.

In recent years, the use of geographic information system (GIS) and its combination with multi-criteria and decision-making methods to obtain more accurate results have increased and played a key role in studies of the finding potential of groundwater resources. Even though it is very difficult and complicated to accurately identify suitable places for the potential of underground water resources, this study showed that the use of GIS makes it possible to identify these suitable places with minimal facilities, which is consistent with the findings of Khairkhah et al. (2013). Overall, according to the results of this study, about 7% of the region has high groundwater potential. Therefore, it is necessary to adopt scenarios to reduce the over-exploitation of groundwater and to apply the measures to improve the irrigation systems, the methods to reduce evaporation and improve the cultivation system.