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Strengthening the resilience of integrated urban water systems (UWS) comprised of water supply and sewer systems against floods and water shortages can be a challenging task. In this paper, a new set of resilience performance indicators is introduced for concurrent assessment of both failure conditions of water shortage and floods in the UWS. A number of potential intervention strategies such as rainwater harvesting (RWH) and greywater recycling (GWR) schemes for enhancement of UWS resilience are evaluated through a conceptual model of urban water metabolism assessment. Modelling of main UWS components is conducted using the WaterMet2 to simulate the performance of intervention strategies in UWS through urban water metabolism. WaterMet2 calculates key performance indicators of urban water metabolisms over a long-term planning horizon that can be used to calculate various resilience performance indicators. The demonstration of the suggested approach on a real-world case study reveals how different elements of resilience performance can be improved in the UWS by specific strategies against failure events such as flood and water shortage conditions.

Sequential streamflow routing (SSR) with control on reliability of meeting energy demand is a common method for assessing energy potential in practical hydropower projects' design and operation in Iran. This approach results in developing a reliability-based simulation (RBS) model which is used for design of single- reservoir hydropower projects. On the other hand, in most cascade hydropower systems in the country, a single-reservoir RBS model is usually used for design and operation of each reservoir, independently. Considering the fact that the integrated analysis of the system may lead to design variables and system energy potential which could be different from those obtained by subsequent single-reservoir analysis, a multi-reservoir simulation-optimization model is proposed considering the integrated system operations. The core of the model developed is the same as what is used in a single-reservoir RBS model as a simple and well-known model in professional applied hydropower practices. However in multi-reservoir RBS model, the energy equation in each time period becomes indeterministic with more than one unknown variable, i.e. turbine releases. Therefore, an iterative single-period linear programming (LP) model is used in each time step of the simulation model. The LP model minimizes the sum of reservoir releases and/or maximizes the sum of reservoir storages subject to continuity equations, minimum energy demand requirement and bounds on state and decision variables as model constraints. Another multi-reservoir model was also tested in which a heuristic operating policy is used. The application of the above-mentioned models is analyzed in the Khersan hydropower reservoir system located in Iran as the case study. For reliability of meeting energy demand equal to 90%, results indicate that the multi-reservoir RBS model proposed increases the system firm energy by 7.9% compared to the model which sequentially uses single-reservoir RBS models.

Recently, conjunctive use of surface water and ground water has been one of the efficient ways in optimal management of water resources. Using conjunctive optimal use and management of conjunctive, we can compensate the nonuniform spatial and temporal distribution of precipitation. Without recent advances in computer hardware and software technology such as geographic information system (GIS) and data base management system technology (DBMS), it is not possible to develop a computer base conjunctive management of groundwater and surface water model. Developed Network flow models for analyzing optimal management of conjunctive use of surface water and groundwater have been used. The real physical system is represented in this system as a network system including nodes and links. Nodes are used for representing storage and non-storage points and links represent the natural channels or canals as connecting elements. Dynamically designing of this model allows the user to interactively develop the given water resource system. A mixed integer linear programming is used for optimum conjunctive operation of groundwater and surface water systems. In this study, conjunctive surface and ground water resources model has been applied in Tehran metropolitan. Tehran field water resources, which meet the potable, agricultural, industrial, environmental and urban water demands, include five reservoirs and several aquifers. Results obtained show the ability of the tools and the methods in integrated management of large scale water resources systems.