GIS-AHP based site selection to identify the optimum number of meteorological stations: Karasu Watershed case study

The density of meteorological stations in most watersheds across the globe is far lower than recommended by the World Meteorological Organization (WMO). However, for some basins, including those used as pilot, an adequate quantity of weather stations is crucial for collecting high-accuracy data. This study aimed to 1) estimate the optimum number of meteorological stations and 2) demarcate the most appropriate sites for their installation considering physical and environmental factors directly and indirectly influencing both objectives, i.e. to develop a well-optimized weather station network. The Weighted Overlay method and six (6) environmental factors –- precipitation variance, slope, elevation, proximity of existing stations, land cover and land use, as well as distance from roads –- were applied to delineate the potential locations. All parameters were mapped out separately and then reclassified for scoring (0 to 100 scale) based on their significance. The Analytic Hierarchy Process (AHP) method was applied to determine the impact of each factor. Based on the analysis, the precipitation variance received 38% weight, while the distance from road was computed to reach only 3% weight. The Weighted Overlay map of the Karasu Watershed was delineated into corresponding highly suitable, moderately suitable, suitable, marginally suitable, and not suitable zones. Finally, the recommended station locations were validated using a hypsometric curve to ensure proper coverage of different elevations. The research will improve the climate change and water resource management applications by informing them with sufficient climatic data about the entire target area including all variations, as well as will help addressing the challenge of data shortage and thus increase the quality of future thematic research.