Modelling transformation and its impact on water quality of the wetlands of lower Gangetic plain: a geospatial approach for sustainable resource management

Abstract

ABSTRACT Over the past few decades, water quality in aquatic ecosystems has been deteriorating steadily due to population growth, urbanization and industry expansion, discharge of municipal wastewater, and agricultural runoff into surface water sources. Wetlands of the Indo-Gangetic plain are disappearing continuously by several geo-genic and anthropogenic factors. The study focuses on the most important wetland ecosystems in the Malda district of the lower Gangetic plain in terms of area and socioeconomic value. The study aims to emphasize the land transformation around the selected wetlands, and to determine the current status of the water quality of the wetlands. From 2003 to 2018, the land use land cover (LULC) and land transformation of wetland areas were computed using geospatial data. The water quality of the wetlands has been measured at different sampling sites in pre- and post-monsoon seasons. The focus of the study is to identify the causal factors of the degradation and disappearance of wetlands. For the water quality index (WQI), on-site and laboratory analyses of the chosen parameters were conducted. Over the past 15 years, the built-up area increased by+98.08%, +90.32%, and +67.17%, while waterbody experienced a considerable negative change, with percentages of −21.30%, −26.83%, and −29.63% for the Chakla Beel, Chatra wetland, and Nayabandh wetland complex, respectively. The WQI revealed poor and very poor water categories at various wetland sites, under the WQI scores with 100–200 indicating “poor water” and 200–300 “very poor water.” The study analyzed the causes of the change in land use and alteration in water quality of selected wetland ecosystems.