Flood Plain Evaluation in the Ganga-Brahmaputra Delta: A Tectonic Review

Abstract

The world’s largest Ganga-Brahmaputra Delta has been characterized by an interesting and complicated tectonic background and geomorphic history. Actually the delta is situated in the southern part of Bengal Basin in Eastern India. The Bengal Basin as well as Ganga-Brahmaputra Delta, is a significant low flat terrain which has elevation of 10-30m above the m.s.l. Delta building processes are active over southern part, while the Northern part shows the characteristics of a mature landscape. The Delta is named as ‘khadar’. The eastern part of Indo-gangetic plain is joined with the lower Brahmaputra plain and helps to form the delta. The delta has passed through a long evolutionary history and phases i.e. early Triassic, Jurrassic, Cretaceous, Oligocene, Miocene and Holocene. The Basin contains silt, clay, several minerals, metals etc. The delta is mainly created by the deposition after the sea-transgression in the upper cretaceous period. The mineralogy is dominated by detrital quartz, some feldspar and minor amounts of carbonates illite and kaolinite. Therefore its geological setup and the tectonic events and their influence on the geomorphic features particularly the flood-plain have been thoroughly investigated and presented in this paper. Keywords: Flood Plain, Ganha-Brahamputra Delta, Geological Formations, Tectonic History, Sea-transgression.