This research tracks the abnormal system operating conditions of the city of Asyut water supply network over an extended period. EPANET software was used to perform hydraulic and water quality analysis. Firstly, the effect of roughness variation with time on pressure head distribution and water quality through the network is simulated. Secondly, leakage due to failure of some pipes on the flow, pressure heads and water quality are investigated. Also the effect of closing some pipes in the network on pressure head and chlorine distributions is taken into consideration. Finally, the effect of changing the source of chlorine disinfection on water quality in the network is studied. The results indicate the following: (1) The increasing roughness of pipes can significantly increase the head losses through the network and consequently decrease the head at the end of network below the minimum limit. The variability in nodal pressures also has a significant effect on chlorine decay if the bulk wall reaction coefficient is taken to be dependent on the roughness of the pipe.(2) The failure of some pipes in the networks not only increases the consumed discharge in the network and decreases the pressure head but also changes the flow directions in some pipes through the network. (3) Closing a pipeline increases pressure in a region and decreases it at another and also changes the direction of flow in the network. This may affect the chlorine distribution through the network. (4) Chlorine disinfection from one source can significantly decrease the residual concentrations under the minimum limit in part of the network, while it can increase variability in nodal concentrations.

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Flash flood is one of the most important natural hazards all over the world. It is very dangerous because of its effect on people's lives and can lead to death. So we must be aware of the flash flood by studying the factors that affect it and predict it. In this paper, hydrological parameters that affect flash floods in arid or semi-arid areas are studied. The study area is Wadi Al-Baroud El-Abiad which is located to the northwest of Safaga city on the red sea coast that is frequently subjected to a severe flash flood. Parameters affecting floods are considered i.e. meteorological (climatic), morphological, and geological factors. Climatic data are analyzed to reach the design storm values for different return periods by knowing the annual rainfall values of the study area by using rainfall data from a rain gauge station near the area. In this research, the mean monthly rainfall values of Safaga meteorological station from 1994 to 2018 are used and the annual maximum values of rainfall rates are extracted from it. Digital elevation model (DEM) and digital terrain data of the catchment are obtained from the USGS EathExplorer website and inserted into WMS and ArcGIS software. To obtain the hydrological characteristics such as unit hydrograph, concentration-time, delay time, and storage coefficient, the land use and soil type in the study area must first be determined by the geomorphological and geological study. SCS and curve number methods are used in estimating the soil type and land use of the basin. Many software and tools are used in data analysis and watershed delineation among them, GIS, WMS, SURFER, HYFRAN, GOOGLE EARTH. From this study, watershed morphological characteristics, flood quantity, and flow hydrograph at Wadi Al-Baroud El-Abiad dam are estimated for different rainfall intensity, duration, and return periods. Moreover, the storage capacity of the dam reservoir at different rainfall intensity, duration and return periods is estimated and the time required for storage water to evaporate and infiltrate into the subsurface soil is identified. The results of this research can help the developer, planners, and decisionmakers for flood management in arid areas.

This research studies the effect of abnormal operation conditions on water hammer phenomenon in water supply pipe network in order to provide an acceptable level of protection against system failure due to pipes collapse or bursting. Water Hammer and Mass Oscillation WHAMO software is used in the analysis which uses the implicit finite difference scheme for solving the momentum and continuity equations at unsteady state case. Assiut city water supply network is used in the analysis. Flow of pipe network is studied due to; firstly, the sudden change in water demand at one or more junctions, secondly, the closing of some pipes of the network on the transient pressure and flow rates, and finally the failure in some network pipelines on intrusion or leakage due to transient pressure head fluctuations. The previous cases are studied in steady normal case, without any protection, and under different protection device(s) such as non-return valve and open surge tank. The results showed that rapidly change in demand increases the pressure head and flow rate fluctuations. Closing some pipelines increases pressure in a region and decreases it at another and also changes the direction of flow in the network. Also, failure of some pipelines can cause intrusion and leakage from outside the network to inside and inversely, which affects the values of minimum pressure heads more than the maximum ones. Finally, using of open surge tank with nonreturn valve protects the pipe network effectively from the harm water hammer.

The effect of using different protection devices on water hammer phenomenon to provide an acceptable level of protection against system failure due to pipe collapse or bursting is presented. Water Hammer and Mass Oscillation (WHAMO) software is used in the analysis which uses the implicit finite difference scheme for solving the momentum and continuity equations at unsteady state case. Assiut city water supply network is used. The network is supplied from two points at pump No. 36 and pump No. 37. Flow of pipe network is studied under steady normal case, without any protection case against water hammer phenomenon, and the model under different operation cases; with a transient protection device(s) such as non-return valve, open surge tank, air chamber and pressure relief valve (PRV). The results are performed for three scenarios; the first is the normal operation of pump 36 and failure of pump 37, the second is the normal operation of pump 37 and failure of pump 36, and finally failure of pumps 36 and 37 together. The results showed that using of open surge tank or air chamber with non-return valve protects the pipe network effectively from the harm of water hammer. Also, using PRV with non-return valve protects the pipe network from extreme pressures. Although using non-return valve only doesn't have a great effect on the maximum pressure head than the normal case, it protects the network from the more low pressures than without protection one. All protection cases safeguard the pipe network from the extremes of water hammer, but increase the water hammer wave period. Finally, the sudden shut down of the pumps 36 and 37 together has the large effect on the pressure heads than the shut down of any of them only.