Morphometric analysis using fuzzy analytical hierarchy process (FAHP) and geographic information systems (GIS) for the prioritization of watersheds

Abstract

River basins are prone to degradation due to soil erosion induced by anthropogenic activities and natural calamities. In this study, an integrated approach using morphometric analysis, geo-informatics, and fuzzy analytical hierarchy process was employed to prioritize the watersheds. Hydrological parameter “erosion” is a major deciding factor to assess and prioritize the watersheds using the fuzzy analytical hierarchy process (FAHP) method in the Peddavagu watershed of the Krishna river basin. The major characteristics of watershed parameters such as basin length (Lb), drainage density (Dd), form factor, stream frequency (Fs), elongation ratio (Re), circularity ratio (Rc), drainage texture (T), bifurcation ratio (Rb), and compactness constant (Cc) are arranged in matrix form for FAHP analysis. The FAHP analysis was carried out using Triangular Fuzzy Network; for further analysis, the values were classified as follows: 1.25 as moderate susceptibility, 1.5 as high susceptibility, and 1.75 as very high susceptibility. The results of FAHP analysis showed that five watersheds have a very high susceptibility to erosion (30.32%), 16 watersheds as high susceptibility (53.28%), and the remaining 10 watersheds were categorized as moderate susceptibility (16.4%). It implies that soil and water conservation measures have to be implemented on priority in “very high susceptibility category watersheds,” followed by the “high susceptibility” and “moderate susceptibility” categories. Furthermore, the universal soil loss equation (USLE) equation was used to compare the outcomes of the FAHP method. The results have been complacent with FAHP analysis, and the very high susceptibility, high susceptibility, and moderate susceptibility categories were having sediment yields of 54.96 t/ha/year (4D2D1-26), 30.00 t/ha/year (4D2D3-31), and 15.07 t/ha/year (4D2D2-17). The Spearman rank correlation coefficient has been used to validate the USLE and Fuzzy simulations. The results have shown a strong positive correlation for the study area. As the integrated morphometric analysis using FAHP for prioritizing watersheds has shown reliable outcomes, this method has the potential for adoption in other case studies elsewhere.