Developing Equivalent Weight Coefficients for Ecosystem Service Valuation in Dhaka City, Bangladesh

Abstract

Understanding and quantifying ecosystem services in urban landscapes is vital for achieving sustainable environmental management. Dhaka, one of the fastest growing megacities in South Asia, has undergone drastic transformations in its land use and land cover, which has severely altered ecosystem structure and function. This study introduces a modified framework for developing and applying Equivalent Weight Coefficients (EWCs) to estimate ecosystem service values (ESVs) at a regional scale. Using multi-temporal remote sensing data and spatial modeling, regional EWC adjustments were made based on biophysical variables such as Normalized Difference Vegetation Index (NDVI), Fractional vegetation cover (FVC), Net primary productivity (NPP), Rainfall, and Crop yield. After incorporating biophysical parameters, the total ecosystem service values (ESVs) increased across all land cover types. The most significant percentage increases occurred in bare land (38%) and built-up areas (38%), followed by forest and vegetation (35.56%), agricultural land (25.46%), and waterbodies (19.28%). Although the proportional rise in bare land and built-up categories appears large, these categories contribute minimally to total ESV, while the major ecological gain in absolute value was from waterbodies (+7,001.64 × 10⁶ US$), confirming their dominant contribution to Dhaka’s ecosystem functions. The methodological framework developed in this study is scalable and can be applied to other tropical megacities facing similar urbanization pressures, improving global efforts to harmonize development with ecosystem conservation.