1 | Page International Conference on Climate Change Impact and Adaptation (I3CIA-2013) Center for Climate Change and Sustainability Research (3CSR), Department of Civil Engineering DUET - Gazipur, Bangladesh ASSESSING THE CAUSES OF DETERIORATION OF THE MONGLA- GHASHIAKHALI NAVIGATION ROUTE FOR RESTORATION OF NAVIGABILITY Mohammed Mizanur Rahman 1 , Mahid Ahsan 1 , Sudipta Kumar Hore 1 , Maminul Haque Sarker 1 and A. T. M. Kamal Hossain 1 ABSTRACT: Human interventions occur frequently in deltas for exploiting natural resources. Such interventions may adversely affect the whole ecosystem. The southwest region of Bangladesh is a moribund delta. Transport of commodities and passengers mainly depends on the large navigation network in this region. The Mongla-Ghasiakhali is a very important navigation route in the southwest region of Bangladesh. The route links the Mongla Sea Port and Khulna with other parts of the country. Navigability of the route, however, has been deteriorating rapidly during the last few years and vessels are able to sail only in high tide. This article describes the causes of deterioration and monitoring results of the dredged channel of the route in order to enhace knowledge on the prevailing process and restore the navigability. Time series satellite images, old maps, cross sectional data, water level and monitoring data on dredging have been analyzed to find out the causes of deterioration. Empoldering and intensive shrimp cultivation from the early 1980s to the 1990’s in the tidal plain caused reduction of the tidal prism and resulted in large scale riverbed sedimentation. Restoration of tidal volume through creating a tidal basin as well as restoration of the tidal creek within shrimp ghers may increase tidal flux and would be helpful for restoring the navigability of this route. Keywords: delta, dredging, navigability, southwest region of Bangladesh, tidal basin, tidal flux. 1. Introduction The Bengal delta is one of the largest deltas of the world. Every year major rivers such as the Jamuna, the Ganges and the Meghna carry about one billion tons of sediment to the Bay of Bengal. As this is a tide dominated delta, tide redistributes the sediment over the delta which is carried by numerous tidal rivers. This redistribution of sediments makes the river systems of this country very dynamic especially in the south-west region of Bangladesh. The rivers of the south- west region of Bangladesh are very important for navigation facilities not only within the country but also with the neighboring countries. Navigability of some of these routes is declining due to human interventions and abundant sediment which is supplied through the so called tidal pumping process. The Mongla-Ghasiakhali navigation route, which consists of the Mongla and Kumarkhali rivers and the Mongla-Ghasiakhali canal, is a very important route in the southwest region of Bangladesh (Figure: 1). _________________________________ 1 Center for Enivironmental and Geographic Information Services, Dhaka-1212, Bangladesh, e-mail: mmrahman@cegisbd.com