Comparing the Sensitivity of Pixel-Based and Sub-Watershed-Based Analytic Hierarchy Process to Weighting Criteria for Flood Hazard Estimation

In flood hazard estimation via the analytic hierarchy process (AHP), using the pixel as the basic unit might lead to accuracy relying on the optimal weighting criteria. To this end, considering the sub-watershed as the basic unit is new. In this study, taking the Chaohu Basin in Anhui Province, China, as a study case, the accuracy of the sensitivity of the pixel-based and sub-watershed-based AHP models influenced by weighting criteria was compared. There were 48 judgment ma-trixes defined, following the same order of importance of the involved indicators. Validation ground truthing is constructed by the extracted flooded regions from GF-3 images. As weighting criteria changed, the results indicated that the pixel-based AHP fluctuated significantly, while the correct ratio and fit ratio derived by the sub-watershed-based AHP could improve by >35% and >5%, respectively, over the pixel-based-AHP. It indicated that the sub-watershed-based AHP has an advantage in relying less on in situ weighting criteria than the pixel-based AHP.