Optimal operation of reservoir systems is the most important issue in water resources management. It presents a large variety of multi-objective problems that require powerful optimization tools in order to fully characterize the existing trade-offs. Many optimization methods have been applied based on mathematical programming and evolutionary computation (especially heuristic methods) with various degrees of success more recently. This paper presents an implementation and comparison of multi-objective particle swarm optimization (MOPSO) and non-dominated sorting genetic algorithm II (NSGA-II) for the optimal operation of two reservoirs constructed on Ozan River catchment in order to maximize income from power generation and flood control capacity using MATLAB software. The alternative solutions were based on Pareto dominance. The results demonstrated superior capacity of the NSGA-II to optimize the operation of the reservoir system, and it provides better coverage of the true Pareto front than MOPSO.

Self-cleansing is a design criterion for drainage systems that mitigates the continuous deposition of sediments at the channel bottom. In recent decades, in order to improve the knowledge for determination of self-cleansing conditions applicable for drainage system design, laboratory experimental studies on sediment transport in rigid-boundary channels have been conducted. In this study, according to the definition of self-cleansing, the main studies in the literature are classified and projections for future studies are drawn. This review is limited to laboratory experimental studies that used noncohesive sediments. A brief comparison of existing equations are presented and discussed. It is found that a major discrepancy exists among performances and applicability of existing self-cleansing models from a variety of data sources. This fact can be attributed to the subjective definition of different sediment-transport conditions, channel cross-sectional shape, range of experimental data, and parameters used for the model development. It is expected that this review will be helpful for researchers looking for an integrated and classified literature review on sediment-transport studies in rigid-boundary channels and drainage systems.

The pressure-discharge relation used in continuity equations is one of the most important components of hydraulic models based on head-driven simulation method, as it has a great impact on the accuracy of the results of these models. Several pressure-discharge relations have been proposed and used in head-driven simulation method, but there are no laboratory and field studies available regarding the accuracy and correctness of these relations. In this research a laboratory set up and a field investigation in some parts of a real water distribution network are used to collect the required data. Flow discharge data from different faucets, based on laboratory and field measurements, are used to compare the proposed pressure-discharge relationships. Furthermore, in this paper, a new pressure-discharge relation is proposed for volumetric and human-based demands that is more reasonable than some previous relations and can be used in pressure-dependent models.