Assessment of wetland health dynamics: Comparing fuzzy- AHP and composite indexing methods in an urban agglomeration in east India

Abstract

In Kolkata metropolitan area population growth, built-up land expansion, and infrastructure development shrinkages wetland area and degrades wetland health. Wetland health index was computed using composite-indexing (CI) and fuzzy-AHP (FA) models. Both CI and FA models performed well to assess wetland health where FA outperformed CI. The area under curve value ranges from 0.728 to 0.780 for CI and 0.745 to 0.855 for FA model. During the last two decades, the growth rate of built-up land was 1.86% per year and the shrinkage rate of wetland was 1.56% per year. The spatial coverage of excellent wetland area was decreased from 52.46% to 43.11% over last two decades, but the area under very poor wetlands have increased from 5.55% to 9.62%. Due to wetland health degradation, ecosystem service value was decreased by 23.50% over the last two decades. Wetland health has direct relationship with wetland size, which needs further research.