Ecological consequences of urban blue space transformation

This study presents the ecological consequences of the blue space conversion and its qualitative degradation in the English Bazar Municipality (EBM) and its surrounding area. The primary blue spaces of the area, the marshy wetland called Chatra and Mohananda river, are the most affected due to urban activities like built-up expansion and sewage and wastewater discharge. Built-up development encroached more than 300 m within wetland territory and caused a 0.57 km² conversion of wetland area. It is also evident within the bed of the Mohananda river. Agriculture also caused the conversion of the blue space. As a result, the wetland's ecosystem service value (ESV) was reduced by 12.7%, along with a reduction of cultural services by 27.86%. The massive pouring of sewage and wastewater caused hyper-eutrophication in almost the entire wetland area. The trophic state index (TSI) value increased significantly in the last 10 years, causing high growth and areal expansion of water hyacinth. The expanding settlements and agricultural land that captured the river channel face inundation vulnerability during peak discharge. Extreme danger level discharge causes floods in the extensive municipality area. The areal encroachment, water extraction, sewage and wastewater discharge, and water quality deterioration caused severe hydro-ecological degradation of the river. Since blue space is critically essential for urban environmental health, these ecological consequences can cause a crisis for urban wellbeing. Therefore, the anthropogenic adversities towards the urban blue space must be restricted, and the blue space's ecological sustenance must be paid enough attention.