Identification of suitable areas for underground dams using remote sensing and GIS techniques

The sustainability of water resources is of vital importance in arid and semi-arid regions. Stress and risk on water resources negatively affect both the region and human development. In order to prevent and mitigate these adverse effects, underground dams have been defined as an effective method for the conservation of water resources from past to present. As the study area, the Yeşilırmak Basin-one of Turkiye's major river basins-was selected. This study aims to identify areas suitable for the construction of underground dams using geographic information systems and remote sensing techniques. Constructing underground dams solely in geologically and topographically suitable areas poses a risk in terms of efficiency and sustainability, since the accumulation and infiltration of water into the ground are not governed only by these two factors. Therefore, in this study, site selection analysis was carried out using the analytic hierarchy process (AHP) method, considering the main and sub-criteria of factors that effectively influence the suitability for underground dam construction. The factors evaluated separately for site selection include hydrogeology, topography, hydrology, land use classification, and major soil groups. The main and sub-criteria that influence site selection were determined based on expert evaluations. Using the AHP method, pairwise comparison matrices were constructed by considering the effect and priority of each criterion within its factor, and weight and consistency ratios were calculated. The weights of the main and sub-criteria were defined by reclassifying each layer in the QGIS software, and suitability analyses were performed through weighted overlay analyses. Finally, an overlay analysis was conducted based on the weight ratios of each factor. As a result of these analyses, areas suitable for the construction of underground dams within the boundaries of the Yeşilırmak Basin were identified at varying levels of suitability. Accordingly, it was determined that within the Yeşilırmak Basin, 2.786,27 km² of land is classified as highly suitable, 2.436,27 km² as suitable, 4.853,29 km² as moderately suitable, 14.692,54 km² as less suitable, and 14.797,62 km² as unsuitable. The results obtained were presented on final maps and supported with statistical data.