Morphometric analysis of Moridhal watershed in Dhemaji District of Assam, India using remote sensing and Geographic Information System techniques

The present investigation was carried out to study the morphometric properties of the Moridhal watershed in the Dhemaji district of Assam, India to understand its nature for proper utilization of natural resources of the watershed. The Moridhal watershed, encompassing a 30,730 ha geographical area, is situated between 94 degrees 52 E to 94 degrees 69 E longitude and 27 degrees 38 N to 27 degrees 64 N latitude. Based on total variation in satellite data (Resourcesat-2, LISS-4), four distinct physiographic units of the watershed were delineated which included: upper piedmont plain (1,844 ha), lower piedmont plain (2,391 ha), alluvial plain (9,888 ha), and flood plain (16,607 ha). The stream order map of the Moridhal River Basin was prepared by on-screen digitization using QGIS 3.12.0 software. Twenty-nine numbers of morphometric parameters were evaluated through the measurement of linear, areal, and relief aspects of the river basin. The drainage streams were delineated up to fourth order with stream numbers of 36, 14, 5, and 1, for I, II, III, and IV order, respectively. The computed value of aerial aspects like elongation ratio, circulatory ratio, and form factor revealed the elongated shape of the watershed area. The studied relief aspects included parameters like basin relief, relief ratio, ruggedness number, and relative relief. The morphometric properties of the Moridhal watershed depicted the permeable nature of the soil which indicated that the precipitation would mostly penetrate the soil and, thereby, a lesser amount would contribute to the runoff. The present study also revealed that Geographic Information System software has immense utility in the analysis of the linear and aerial morphometric aspects of the drainage basins.