Hydrological Risk Mitigation from Natural Hazards in Ojirami Dam Edo State Nigeria

Abstract

The objective of this paper works is to analyze the rainfall and runoff discharge of the Ojirami dam area, and effective modeling and simulation of hydraulic parameters in water distribution network and design of hydraulic structure (Reservoir water tank). The engineering tools used in this research work are EPANET PROGRAM, AUTOCAD, GOOGLE EARTH and GIS for portable pipe born-water supply, regarding to the relief of the inhabitants towards mitigation of risk from natural hazard, by protecting lives and properties against diseases: such as cholera and dysentery. During investigation and modeling the water network, the following climatic elements are defined: monthly and annual rainfall, maximum wind velocity for prevailing direction, free water surface evaporation, air temperature, relative humidity and sediment transportation. The capacity of the reservoir of the Ojirami dam is equal to 5 Mcm (5 X 106) the dam height of 7m and is located within Akuku community boundaries, Akoko-Edo Local Government Area, Edo-State. The area has a moderate slope around the dam too steep in higher parts of the dam. Due to proper researched on the internet and other information collected from Edo state water board and relevant statistics data from census of Nigeria. The dam was constructed across Onyami river the output capacity of the reservoir is about 473m3 per/hr. The construction dam is used as a source to supply water to the water distribution network. Google earth was used to generate toposheet of Akoko-Edo Local Government boundary, while Geographic information system was used to create Nigeria local government map and boundaries, due to local government shapefile data of Nigeria. Epanet program was used to digitalized the water network, which is based on census data and to estimate water demand. The Epanet tracks the flow of water in each pipe, the pressure at each node, the height of water in the tanks, and the concentration. The preliminary modeling of the (WDN) concluded that the water distribution network is sufficient to supplied water to communities. The water quality and the cost of modeling the water distribution network (pipe network) were estimated.