Role of Lithology and Rock Structure in Drainage Development in the Kaliani River Basin, Assam, India
Lithology and Rock structure play a vital role in the development of Drainage Network in any drainage basin. The drainage patterns upon land surface develop as directed by the underlying lithology and rock structure. In fact, lithology and rock structure together shape the basin and are decisive parameters of nature and direction of channel flow. The Kaliani River Basin situated in Karbi Anglong district (Diphu subdivision), Assam State of India is strongly influenced by underlying lithology and rock structure. Tectonics play an important role, as the region has numerous minor lineaments and two major faults , and has undergone three phases of upliftment since late Cretaceous to late Miocene. The region is also influenced by neo-tectonics. The western and eastern parts of the basin are less influenced by structural lines of lithology while the northern and southern parts of the basin have fault-lines scarps and ridges. Trellised pattern of drainage is witnessed in most part of the basin which is made up of mostly Archaean gneiss and has developed along the lines of weakness with only some areas that have developed a dendritic pattern due to flowing over softer rocks. The presence of a profusion of streams within the basin has given it a rugged surface and an intensely dissected terrain due vertical erosion of these young channels. An attempt has been made to analyse the role of lithology and rock structure in influencing the development of drainage network in the Kaliani River Basin. Basin morphometric techniques have also been applied for assessing the nature of the drainage lines in the study area. An attempt has also been made to find out the stages of geomorphic development of the Kaliani River and its major tributaries basins.
Keywords: Upliftment, neotectonics, lithology, antecedent drainage, dissected terrain, trellis