Assessing the role of hydrological modifications on land use/land cover dynamics in Punarbhaba river basin of Indo-Bangladesh

Abstract

Punarbhaba river basin (length 160 km. and area 5265.93 km2) of India and Bangladesh experienced a solemn hydrological paradigm alteration due to installation of Komardanga dam (1992) and other forms of water lifting and diversions from this river. Consequently, maximum and average water level in the downstream part of dam has been lessened by 32.34 and 36.74% correspondingly. Such flow reduction also causes shrinking of flood-prone area, shallowing of water bodies and lateral wetland disconnectivity from Main River. The main aim of the present paper is to focus on the land use/land cover change in reference to the changing hydrological regime. Supervised pixel- and object-based image classification has been carried out to show the nature of LULC dynamics for pre- and post-dam phases. The findings of the classified images stated that agricultural land and built-up area has been progressively amplified in the altered hydrological milieu and episodic decline of wetland areas is noticeable in this river basin. In pre-dam phase (up to 1989), agriculture land area was 59.19% to total basin area and it has become 84.2% in 2015 (post-dam period). Similarly, spatial extent of water body was 4.49% in former phase and it is reduced to 1.26% in later phase. Balance in LULC is obligatory for the sake ecologically healthy society.