A Thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering

Thesis (M.Eng.) - Asian Institute of Technology, 2004

The water allocation has become severe problem for many parts of the world as the demand of water has increased due to population growth, rapid urbanization, improved standard of living and industrialization. This has resulted in scarcity of water resources particularly in dry season. As a result conflicts within and among user-sectors have aroused and increased in frequency. Thus, there is a need for water allocation system that considers socio-economic, environmental and technical aspects of distributing water to different user-sectors considering water as social and economic good. The study is intended to apply a water allocation model developed by Nayak (2003) in Karnafuli River basin for efficient use of water among the downstream user sectors (Industry, Agriculture, Domestic and Environment). The model has been modified with the incorporation of benefit sharing concept. In Karnafuli River basin, salinity intrusion has adverse effects on the users in terms of quality and quantity. Therefore, consideration of downstream flow requirement for salinity control is crucial in allocation. The minimum flow requirement to control the salinity level in tolerable limit has been established based on results of salinity intrusion study, done in the past using mathematical model analysis. The water allocation has been done for three different situations: 1) when available water is greater than total normal demand, then full supply given to all sector; 2) when water is in between total minimum and normal demand, then water is allocated by two criteria, single objective function using linear programming, and multiobjective criteria by weighting and SICCON techniques; and 3) when available water is less than the total minimum demand, the allocation is based on priority or stress supply. The model considers three single objective functions: maximization of satisfaction of demand, maximization of net economic return, benefit sharing among the water use sectors. The water allocation scenarios have been devised considering 300 m3/s and 325 m3/s flows for downstream requirement and various minimum demands by the sectors. The net economic return from the environment sector has been calculated based on user benefit directly coming from the domestic and agriculture sectors for salinity control. The non-users benefit for environmental use of water has been ignored. The economic returns of the others sectors are calculated for their water use. From this study, water allocation has been formulated for Karnafuli River basin for scarce situation in dry season. With the incorporation of benefit sharing concept, the model is capable to allocate water, for which equal benefits could be achieved among the sectors.