Role of tie channel on wetland hydrological security and sustenance

Abstract

How far the de-linking and morphological and hydrological degradation of tie channels connecting river to the wetland are caused for the areal and hydrological transformation of a wetland was not received enough attention in previous literature. This paper tried to explain this about the confluence reach of the Dwarka and Brahmni rivers in Moribund deltaic India. In order to explain the linkages 16 tie channels’ change depicting variables and seven wetland area and hydrological transformation (consistency, hydro-period, water depth, water richness etc.) related variables were taken. Ordinary least square (OLS) regression was applied for explain the linkage. Machine learning approaches were applied for water richness mapping. Tie channel evolution was digitized from the Survey of India (SOI) toposheet (1974) and historical Google Earth images.The result revealed that, the tie channel witnessed morphological and hydrological degradations like channel constriction, channel clogging, flow lowering etc. and these were further identified as some vectors of areal shrinkage and growing hydrological insecurity in the linked wetlands. The total wetland area declined from 44.89 km2 to 16.86 km2 from 1991 to 2021. The rate of areal loss, shallowing WD, growing inconsistency of water presence, narrowing HP, and weakening WR was found high in recent times due to de-linking and degradations of tie channels. This approach of explanation of hydrological insecurity of wetland in relation to tie channel degradations, de-linking and findings are quite unique. So, re-linking and morphological correction of the tie channels would be a good policy for wetland restoration.