How far damming induced wetland fragmentation and water richness change affect wetland ecosystem services?

Abstract

In inland wetland, river and lakes, the ecosystem service values (ESV) vary from 4267 to 25682 US$/ha/year, but when the landscape gets fragmented and becomes hydrologically inconsistent, will they produce the same ESV? With this fundamental query, the present work evaluated the ESV in different fragmented wetland units and over different water richness zones in reference to hydrological alteration introduced by damming (1992) over Punarbhaba river (a transboundary of India and Bangladesh). The wetlands were mapped using the support vector machine (SVM) model for pre and post-dam conditions. Subsequently, satellite image-derived parameters, such as hydro-period, water depth, and water presence consistency, were prepared and used for spatial weighted and fuzzy logic-based water richness modelling and wetland fragmentation analysis for both pre (1989) and post-dam periods (2019). Results showed that wetland area was reduced from 205.24 km2 to 73.22 km2 in between pre-and post-dam periods, and consequently, the ESV was reduced from 10596 × 104 US$ to 3874 × 104 US$. Damming effect has decreased the high-water richness area from 71.83% to 7.65%, which caused a 62% of ESV reduction in the post-dam period. Due to increasing patch frequency and decreasing the core area in the post-dam period, the ESV value was reduced by 45%, which could be considered the fragmentation effect. As the study identified the areas with decreasing ESV values, this work has very good policy implications on a priority basis for wetland conservation.