Integrated approach of AHP and TOPSIS (MCDM) techniques with GIS for dam site suitability mapping: a case study of Navsari City, Gujarat, India

In recent years, climate change, frequent rainfall, and an inefficient drainage pattern have had a grievous influence on the city of Navsari in Gujarat province, causing flooding. Construction of the dam in appropriate locations is a paramount water management approach for flood and water scarcity relief. Subjective and quantifiable criteria such as elevation, soil, and geology are essential parameters for the site selection of dam. The use of multiple criteria decision-making (MCDM) techniques coupled with GIS is now being used to solve real-world problems. The Analytic Hierarchy Process (AHP) and Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) are two of the upmost extensively used MCDM techniques for dealing with water-related issues. The aim of the present study was to compare AHP and TOPSIS approach with GIS for decision making of identifying the suitable site of the dam. SRTM DEM was utilized to generate a total of 10 spatial layers (i.e. elevation, slope, drainage density, rainfall, lulc, distance to river, road network density, geology, geomorphology, and soil) for a dam site suitability map. The weights of these criteria were determined using a ratio estimation approach. The results show that the maximum areal coverage of a very high suitability level (25.25%) was observed from the TOPSIS map and significantly less coverage (19.11%) from the AHP map. Consequently, three dam sites have been proposed in the study area. The storage capacities of dams A, B, and C were evaluated as 27,843, 146,732, and 46,786 m3 respectively. Dam B was ranked 1st followed by Dam C and B based on storage capacity, width, height, and cost. As per the government proposal plan we had validated the location near upstream and downstream of the city and interestingly the presented model was admirably matched. However, more accurate data are required to validate the model precisely. The comparative MCDM approach coupled with GIS presented in this study can be applied to any other region around the globe for a similar application.