Development of optimization schemes for floodplain management; A case study

In this paper, two optimization models are presented. The first model is developed to determine economical combination of permanent and emergency flood control options and the second one is used to determine the optimal crop pattern along a river based on the assigned flood control options by the first optimization model. The optimal combination of flood protection options is determined to minimize flood damages and construction cost of flood control options along the river using the genetic algorithm (GA) optimization model. In order to consider the effects of flood control options on hydraulic characteristics of flow, two hydrological routing models for the reservoir and the river are coupled with the optimization model. Discharge–elevation and elevation–damage curves obtained based on separate hydraulic simulations of the river are used for flood damage calculations in the optimization model. The parameters of a hydrologic river routing model are also calibrated using the developed hydraulic model results. The proposed model is applied to the Kajoo river in the south-eastern part of Iran. The results demonstrate an economical integration of permanent and emergency flood control options along the river which include minimum expected value of damages related to floods with different return periods and construction cost of flood control options. Finally the resulting protection scheme is used for land use planning through identifying the optimal crop mix along the river. In this approach, the objective function of the optimization model is an economic function with a probabilistic framework to maximize the net benefit of agricultural activities. The study exhibits the importance of floodplain management and land use planning to achieve the development goals in the river basins.