Drainage Characteristics and Evolution of the Barind Tract, Bangladesh

The Barind Tract is highly dissected and elevated Pleistocene terrace (about 11-48 m amsl), which forms inlier within the Recent floodplains of the Bengal Basin. The tract is criss-crossed by a number of rivers and underlained by distinct oxidized red soils and sediments of Plio-Pleistocene and Holocene ages. The geomorphic evolution of this tract is a matter of unresolved debate since long. Some parts of the Barind Tract bear the characteristics of morphological origin but some other areas having the evidences of tectonic upliftment. This unresolved problem posed different issues like land use and urban development with variable dimensions and especially in the groundwater development for irrigation in the area. To accommodate heavy population and to meet up the increasing demand of food and water, the area has undergone tremendous environmental degradation. The present study attempts to unveil the processes which are responsible for the evolution of the tract with reflection of drainage characteristics and provide information for sustainable development. Historical maps with different satellite imagery interpretation, and field checking has been carried out to unveil the characteristics of drainage as well as evolution of the tract. The study indicates that the morphology of the tract is being structurally controlled. The rivers and valleys on the tract are comparatively more straight, incised and entrenched, and rivers are tightly meandered, more localized, form paired and unpaired terraces, and antecedent in nature. Few valleys and streams are disconnected and beheaded at places. The rivers flowing from the Himalayas change their morphology, trend, nature etc. near and within the tract. Some of the N-S flowing rivers turned towards southeast and southwest directions to maintain slope of the uplifted tract. All these are the indications of active upliftment and neotectonic of the tract. In the recent past few earthquakes as well as remarkable migration of rivers like the Ganges (Padma), Brahmaputra, Tista, Atrai, Kosi etc. and changes of geomorphology of the areas during last few hundred years also suggest an active upliftment of the Barind Tract during Late Pleistocene to Early Holocene time, which is still going on.