A Study on Seasonal Variation of Hydro-Morphodynamic Parameters of Jamuna River

Owing to heavy sediment deposition, Jamuna River, the largest braided river in Bangladesh changes its hydromophodynamic characteristics rapidly. Due to the changes, we lost thousand hectares of mainland floodplain causing thousands of people landless. Therefore study on the variation of the hydro-morphodynamic parameters is immensely important. In this study, the hydro-morphodynamic changes of Jamuna River has been investigated by using HEC-RAS 1D and historical data analysis. Data has been sorted, analyzed and plotted for the investigation of variation of various parameters during pre-monsoon, monsoon and post-monsoon seasons for a 80 Km reach of Jamuna River. The model is calibrated (in 2004) and validated (in 2008) at Kazipur station by using manning's n 0.025 for which the correlation factor (r), NSE and RSR are respectively 0.9889, 0.9144 and 0.2926 that indicates the performance of this model “very good”. Results reveal that between 1980 to 2014 during monsoon period discharge, water level, sediment transport rate and velocity significantly increase than pre-monsoon and postmonsoon period. From analyses, maximum discharge, water level, velocity and sediment transport rate found as 103129 m3/s, 15.11 m, 2.84 m/s and 32662117 tons/day respectively in 8th September 1998, 30th August 1988, 29th August 2005 and 9th October 2013 in monsoon. During this time, discharge, water level and sediment transport rate decreases in pre-monsoon and post-monsoon period respectively 66%, 70%; 38%, 40% and 87%, 72% with comparative to monsoon. The analysis also shows that velocity in monsoon increases about 45% to 75% than pre-monsoon and post-monsoon period. Velocity, flow area, top width and water surface elevation have been found to be decreased about 35%, 50%; 61%,70%; 55%, 66% and 29%, 36% during pre-monsoon and post-monsoon period with respect to monsoon period. It is hoped that this study will help in understanding the seasonal change of hydro-dynamic characteristics of Jamuna River and will help to predict future situation and undertake appropriate future development activities.