STUDY TO DETERMINE APPROPRIATE LOCATION AND IMPACT OF LOOPCUT IN A RIVER: CASE STUDY LOOPCUT AT KALIA IN THE NABAGANGA RIVER IN SOUTH WEST REGION OF BANGLADESH

摘要

In 1999-2000, a study was undertaken by the Government of Bangladesh to carry out Feasibility Study for Loop-cuts in Minor Rivers of Bangladesh in view of the need for implementing loop cut on a number of medium / minor rivers. For assessing the technical feasibility of such measure, Institute of Water Modelling, IWM, was assigned with the Mathematical Modelling Study on Loop-cuts in Minor Rivers of Bangladesh in August 2000. This paper concentrates on one such loop-cut in the South West Region of Bangladesh. The study has been undertaken to use mathematical modelling technique to analyze the complex problem and obtain a sustainable solution. 2-Dimensional modeling technique along with planform analysis was used to achieve at the set objectives. A sub-model for the area has been setup from the existing South West Regional Model [1] of Bangladesh. The calibrated submodel has been used to study various options of loop-cut alignment for achieving the best alignment in terms of channel flow and long term sustainability. Later GIS flood depth maps have been produced to show the amount of improvement obtained in the various options. Satellite images have been analyzed to determine the maturity of the loop for implementation of the loop-cut option. It has been observed that impacts on the bed and water level in the Nabaganga river due to loop-cut is not so significant in the short term as well as in the long term.