An Empirical Investigation on Hydro-Morphological Process of Surma River: Substantiation from North-East Zone of Bangladesh

摘要

Objectiveof the study is to know the inherent morphological process of the river systemin the Haor areas of sylhet basin. The specific objective is to “validate theexisting conceptual Model of the CEGIS”. This research for the validation ofthe CEGIS Model. Primary data was collected through routine measurements ofdischarge, sediment concentration, measurements of cross-sections, sedimentconcentration measurements. Secondary data was collected on water level,discharge, velocity and cross-section from the BWDB. Satellite images have beencollected from USGS. A thorough review of the manuals of different numericalmodels were carried out. After evaluation of the models HEC-RAS 5.0.3 has beenselected. Validation of the CEGIS conceptual Model was tried using bothconventional way of data analysis as well as from model output. Both the modelshave been fine-tuned and simulated to predict the future scenarios with 20%increase of discharge as well as 20% decrease of discharge at the upstream.Findings of the study confirms the acceptability of Hypothesis 1, Hypothesis 2could not be (conclusively) validated. Concluded that, the bankfull waterlevels at the downstream decrease, changes in channel dimension, the change ofboth the area and the top width shows a scattered pattern and change of averagedepth shows a decreasing trend towards downstream direction. (i) Conventionalanalysis, Hypotheses 3 may be considered validated (ii) From Model output, itmay be stated that the Hypothesis 3 may be considered as not validated.Hypotheses 4 and 5 relate to the hypothetical ‘Regime Condition’ of the river.Its clear that the Surma River is not in ‘Regime Condition’. So the hypothesiscould not be validated through the model output. But ‘Regime Condition’ is atheoretical condition of a river, the validity of these two hypotheses (4 and5) can be accepted on Theoretical explanation basis.