Water supply systems (WSS) are commonly collected of water sources (WS), transmission pipes, treatment plants, and distribution networks from source to tap and generally are subjected to variation of risks. However, the present study provides an adaptive risk management framework for water supply systems that provides drinkable water to various Cairo regions. However, three risk assessment and management case studies were conducted at different Cairo drinkable water supply systems during 2015-2018, including the location served by North Helwan, Fostat and ElMarg water treatment plants (WTP). The work scope was involved in two main parts. In the first part, the common risk challenges in water distribution systems (WDS) are assessed to adopt the methodology for risk management in the Cairo water system. Moreover, these types of risks are sectored according to their potential impact and probability of occurrence is developed. While, the second part involved on developing a Grey Relational Analysis (GRA) approach to integrate risk alternatives mitigation based on supply reliability, environmental, social and economic key criteria and consequently supply decision support on the choosing of risk response strategies according to the correlation between their reference and comparability sequences. Then, in order to monitor the tolerability of acceptable residual risk levels after applying the proposed alternative strategies, the principal of As Low As Reasonably Practicable (ALARP) is applied. The outcomes of this paper displayed that several risks constitute the main parameter within which to characterize water supply systems and its operation, thus, it is a key factor in supply and distribution system operation and planning decision making. Moreover, this study put forward the basis for water services providers to mitigate the risk of non-compliance and realize the target supply standards within the short, medium and long term.

Rivers are the main source of water and life to humans so all of their activities are located on its banks. River navigation is one of the most important activities in current ages. Navigation bottlenecks are appeared and conventional solution is occurred to try to mitigate this problem. Dredging is currently used as a temporary work but some of bottlenecks are repeated again at most regions and needed to periodic maintenance. This research shows that each zone of bottleneck has special properties. The relationship between morphological changes (such as bends, island form, changes of bed level and river width) and appearance of bottlenecks in Nile Rivers. The human interventions in the study reach are determined and studied its impacts on navigational path. Data are collected and delft 3d model is used to simulate study reach from kilometer 462 to 498 U.S. Roda gauge. Nine zones of navigational bottlenecks were appeared in 1982 in minimum discharge case but eight zones were appeared in 2010 in normal case and after prediction of model for seven year. Four zones are appeared after using dredging process and prediction by delft 3d model, where three of them are determined in last report of observed navigation bottlenecks at 2017-2018 therefore this model can be applied to large area in Nile river and predication of navigation problems in the future. In average discharge case, minimum value of longitudinal velocity is revealed at location of bottlenecks so it caused of sedimentation in these zones.

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Reservoirs are an important source of water supply, provide hydropower, reduce the deficiency influences, and provide flood protection. Due to the dam structure and reservoir founding, the releases from the dam has become more restrained and the hanging sediment concentricity summits have been decreased considerably and accumulated upstream the dam. Sediment siltation has increasingly reduced the efficiency of reservoir functionality throughout the years by declining the storage capability. Determining the reservoir sedimentation influence on the dam operation is important to holding current operation and preparing for future polices. The existing paper deals with the review and assessment of the reservoir sedimentation effect on operation of Aswan High Dam (AHD) in Egypt. A new simulation model was developed and calibrated for Aswan High Dam Reservoir (AHDR) to evaluate the reservoir sedimentation effects on the factors affecting the operation of the dam. These factors are Toshka spillway outflows, upstream water levels of AHD, dam safety, withdraw from the reservoir, the losses due to the evaporation and the hydropower generation from AHD. The results of the study displayed that the factors affecting the operation of AHD were affected due to presence of these deposits in AHDR. Therefore, the reservoir sedimentation effect should be considered to implement or develop of simulation models for AHDR.

Sufficient dissolved oxygen is required for helpful water quality. Natural stream cleansing procedures need enough oxygen levels for the purpose of supply for aerobic life systems. The happening of oxygen and water mixing together is titled aeration. There are several techniques to add air or oxygen to water, for instance open air reservoirs, submergible pumps, domestic aeration systems, compressor systems and air pump systems. However, the Venturi system, relied on the easiness of Ejectors, gives a easy, preservation free aeration solution. venturi system permits air to be injected inside running water from air inlet orifices and so rises oxygen levels in the water. The main objective of this research is to evaluate effect of geometric characteristics on the aeration efficiency in the venturi system. To achieve this goal, the venturi is designed and carried out, from transparent polycarbonate. Experiments were conducted under clear-water conditions at different discharges (Qwater): 44.16, 58.88, 73.59 and 88.31 lit/min which correspond to four inlet velocities (v): 1.5, 2.0, 2.5 and 3.0 m/s. The study involved selecting three different throat lengths (Lt): 12, 24 and 36 mm, and three different air inlets orifices diameters (ds): 3, 5 and 8 mm. Five different outlets angles have been used (β): 7 o , 10 o , 15 o , 21 o , and 25 o with inlet angle (α) stabilization at 7 o . The inlet and the outlet diameter (D) and throat diameter (dt) in all the experiments were constants and equals to 25 and 10 mm, respectively. The results of the study demonstrated that the geometric characteristics of the venturi system affects the aeration efficiency. Additionally, empirical equations were gotten for venturi tubes linking air flow and water flow to throat lengths and diameters, venturi outlets angles, air inlets orifices diameters and Reynolds numbers.