Dealing with Con ict over Water Quality and Quantity Allocation: A Case Study

Available water resources are often not sucient or too polluted to satisfy the needs of all
water users. Therefore, con
ict over water, as a result of limitations on quantity and quality,
is a major challenge in water allocation. In this paper, a methodology for con
ict resolution
over water allocation in river-reservoir systems is presented. The proposed model includes the
genetic algorithm (GA)-based optimization and a water quantity/quality simulation model. The
objective function of the optimization model is based on the Nash bargaining theory. Nash theory
can incorporate the utility functions of the decision makers and the stakeholders, as well as their
relative authorities over the water allocation process. The WQRRS (Water Quality for River-
Reservoir Systems) model of the U.S. Hydrologic Engineering Center (HEC) and Qual2e model of
the U.S. Environmental Protection Agency (EPA) are used for simulating the Karkheh reservoir
and river water quality. In these models, the reservoir thermal stratication cycle, the reservoir
discharge quality and the water quality downstream of the reservoir are simulated. The model is
applied to the Karkheh river-reservoir system in the southern part of Iran. The utility functions
are based on the reliability of the allocated water to dierent sectors, the environmental water
demands (quality of the allocated water and in-stream
ow), water storage in the reservoir and
the quantity and quality of the return
ows. The results show that this model can be eectively
used in optimal water allocation of river-reservoir systems with con
icting objectives. In this
paper, in order to generate the policies of the Karkheh reservoir operation and the river water
quality management, the results of the optimization model are used to train the ANN model.