Morphometric Analysis and Prioritisation of the Punarbhaba-Atrai-Jamuna River Basins in the Northwest Bangladesh for Soil Conservation

Abstract

Morphometric analysis plays a key role in understanding the geological and hydrological behaviour of watersheds and their prioritisation for soil conservation. The Punarbhaba-Atrai-Jamuna river system of northwest Bangladesh is agriculturally important, but the watersheds are frequently affected by droughts in summer and river erosion during the monsoon season. The morphological studies on this river systems are very limited, and hence, the aim of this study was to investigate the morphological characteristics of their largest basins and prioritise the studied watersheds based on erosion vulnerability using two approaches. The remote sensing tools were used to delineate and analyse the linear, areal and relief aspects of the morphometric indices of the six largest river basins of Dinajpur district as the conventional methods of determining the morphological characteristics of a basin are expensive and time-consuming. The studied basins included the following regions—Dinajpur Sadar-Birganj (DS-B), Dinajpur Sadar-Khansama (DS-K), Chirirbandar-Khansama (C-K), Nawabganj-Chirirbandar (N-C), Birampur-Parbatipur (B-P) and Hakimpur-Parbatipur (H-P). The results of the bifurcation ratio, length of overland flow, drainage density, drainage texture and constant channel maintenance indicated that the watersheds were well-dissected and had less flood and erosion risk. The values of form factor, elongation ratio, circularity ratio and compactness coefficient dictated an elongated shape of all the basins with a mature geological adjustment. The multi-criteria prioritisation, combining morphometric analysis with land use factors, offers a holistic understanding of watershed vulnerability signifying DS-B and N-C the most vulnerable watersheds, which require a sustainable development decision making framework for their management. This research also provides the brief morphological features of the three complex river system to design management practices for conservation and open a dimension for future research on the application of soil erosion models to estimate soil loss.