Optimal Development of Agricultural Sectors in the Basin Based on Economic Efficiency and Social Equality

The limitation of freshwater resources and the growing demand for water, make the issue of water resource development planning and water allocation among stakeholders even more important. Ideally, water allocation should be economically efficient and socially equitable. In this study, a water allocation model is presented in an integrated framework that considers the interaction of water supply and demand according to economic and social factors. To achieve this, a reliability-based multi-objective optimization - simulation approach has been employed. The objective functions of the problem are: 1) maximizing GDP from agricultural sectors and 2) maximizing social equality in different provinces of the basin (measured using the Williamson coefficient). The fair development and allocation among the shared provinces in the basin can reduce conflicts in the region. Karkheh basin has been considered as a case study and decision variables of the problem are area under cultivation of agricultural development sectors in different provinces. The results show that, without harming the income of the agricultural sector, the spatial distribution of development projects can be done in such a way that equality (according to income level and the number of people working in each province) is achieved. One of the solutions of Pareto front compared to previous studies shows that, in addition to an increase of about 12% of the objective function 1 (GDP), the value of the objective function 2 (Williamson coefficient) decreased from 1.19 to 0.98. This indicates a decrease in income inequality among the provinces of the basin.

     

A Novel Stochastic Approach for Optimization of Diversion System Dimension by Considering Hydrological and Hydraulic Uncertainties

Water Resources Management - This study proposes a new stochastic approach for optimizing diversion system design and its construction schedule by considering different hydrological and hydraulic...     

Sediment Flushing of Reservoirs under Environmental Considerations

Freshwater reservoirs are under threat because of huge amounts of sediments deposited annually. Sediment flushing seems to be effective to preserve reservoir storage, but it may have negative environmental impacts on downstream ecosystems such as fish mortality. Therefore, providing a suitable flushing strategy that could be compatible with the river ecosystem downstream is of great importance. Two numerical models were developed in this paper to predict the suspended sediment concentration (SSC) on the reservoir-river system and effects of different flushing scenarios on aquatic life. Developed models were applied to the Dez Resevoir system in the southwest of Iran which has suffered from the sediment problems in two last decades. The suitable values for flushing time, concentration limits, and flushing discharge have been recommended in this research by use of the existing information and previous flushing records, as well as field measurement and modeling. Based on social, environmental and technical limitations, March is the appropriate time for flushing. After hydraulic simulation of different flushing scenarios and sediment routing along the river, flushing with 1275 and 800 cubic meter per second with 30 and 20 g per lit concentration in dry and wet season respectively are feasible and have minimum environmental impacts.     

Pressure Management Model for Urban Water Distribution Networks

A technique for leakage reduction is pressure management, which considers the direct relationship between leakage and pressure. To control the hydraulic pressure in a water distribution system, water levels in the storage tanks should be maintained as much as the variations in the water demand allows. The problem is bounded by minimum and maximum allowable pressure at the demand nodes. In this study, a Genetic Algorithm (GA) based optimization model is used to develop the optimal hourly water level variations in a storage tank in different seasons in order to minimize the leakage level. Resiliency and failure indices of the system have been considered as constraints in the optimization model to achieve the minimum required performance. In the proposed model, the results of a water distribution simulation model are used to train an Artificial Neural Network (ANN) model. Outputs of the ANN model as a hydraulic pressure function is then linked to a GA based optimization model to simulate hydraulic pressure and leakage at each node of the water distribution network based on the water level in the storage tank, water consumption and elevation of each node. The proposed model is applied for pressure management of a major pressure zone with an integrated storage facility in the northwest part of Tehran Metropolitan area. The results show that network leakage can be reduced more than 30% during a year when tank water level is optimized by the proposed model.     

Modelling Equitable and Reasonable Water Sharing in Transboundary Rivers: the Case of Sirwan-Diyala River

There are over 260 transboundary river and lake basins in the world that many of them are facing great challenges of water sharing between riparian countries concerned. The 1997 UN Watercourses Convention, entered into force in 2014, includes articles and factors on water sharing which have not been completely used for modelling of the basins yet. In this paper, legal aspects (i.e. Articles 5, 6, 7 and 10 of the Convention) are integrated with a technical approach for water allocation in transboundary rivers. For this purpose, a new conceptual model is developed for quantification of the Convention provisions concerning equitable and reasonable water sharing. The method is applied to the Sirwan-Diyala transboundary river shared by Iran and Iraq. Some indicators are developed and quantified for determination of water shares of the riparian countries and different scenarios considering extreme and equal weights of the factors are defined. The basin is simulated by WEAP model to evaluate effects of the scenarios on up- and downstream of the basin. Five demand management alternatives comprising increasing of irrigation efficiency and eliminating second cultivation are proposed as appropriate measures for elimination or mitigation of possible significant harm. The proposed technical-legal approach paves the way for enhancing bargaining potentials of the riparian countries and increasing their cooperation to achieve a win-win solution in using waters of transboundary rivers.     

Optimal Design and Operation of a Hydropower Reservoir Plant Using a WEAP-Based Simulation–Optimization Approach

Water Resources Management - Optimal design and operation of a hydropower reservoir is a complex optimization problem in terms of formulation and solution. In this study, a...     

Multi-Objective Optimization for Interactive Reservoir-Irrigation Planning Considering Environmental Issues by Using Parallel Processes Technique

Water Resources Management - Water allocation to different users implies a trade-off between the benefits perceived by different sectors and environmental demands. This conflict, considering the...     

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.     

Multi-Objective Differential Evolution for Design of Cascade Hydropower Reservoir Systems

After Paris Agreement and obligation made by various countries to decrease greenhouse gases, generation of clean energy with low carbon was taken into consideration. Hydropower plant is considered as a clean, cheap and renewable energy source for generating electrical energy. Through the construction of the multipurpose dams and their optimal planning and management, we may decrease the potential losses sustained by aquatic ecosystem in addition to supplying the energy and fulfilling the industrial, agricultural and drinking water demands. In the present study, a multi-objective optimization model was proposed for determination of design parameters in cascade hydropower multi-purpose reservoir systems. Considering the significant number of constraints and decision variables and non-convex form of the objective functions and constraints, particularly in multi-reservoir systems, a multi-objective evolutionary algorithm (MOEA) known as non-dominated sorting differential evolution (NSDE) was developed to solve the problem and reduce the computational costs. Karkheh River basin was selected as a case study in order to make an assessment on the capabilities and strength of the model. This basin is capable of generating hydropower energy and agricultural development with high environmental considerations due to Hurolazim International Wetland. Based on the results, we may supply various demands such as environmental demands of the aquatic ecosystem with high reliability as well as generating firm hydropower energy through optimal design of cascade hydropower reservoirs.     

Optimal Allocation of Flood Control Capacity for Multi-Reservoir Systems Using Multi-Objective Optimization Approach

Operation of multi-reservoir systems during flood periods is of great importance in the field of water resources management. This paper proposes a multi-objective optimization model with new formulation for optimal operation of multi-reservoir systems. In this model, the release rate and the flood control capacity of each reservoir is considered as decision variable and the resulting nonlinear non-convex multi-objective optimization problem is solved with ε-constraint method through the mixed integer linear programming (MILP). Objective functions of the model are minimizing the flood damage at downstream sites and the loss of hydropower generation. The developed model is used to determine optimal operating strategies for Karkheh multi-reservoir system in southwestern Iran. For this purpose, the model is executed in two scenarios based on “two-reservoir” and “six-reservoir” systems and for floods with return periods of 25 and 50 years. The results show that in two-reservoir system, flood damage is at least about 114 million dollars and cannot be mitigated any further no matter how hydropower generation is managed. But, in the case of developing all six reservoirs, optimal strategies of coordinated operation can mitigate and even fully prevent flood damage.