Urban Flood Hazards: issues, Monitoring, Process and Guidelines
Floods are natural occurrences resulting from either excessive precipitation, unusual and rapid accumulation or runoff of surface waters, mudflows, tidal waters or results of earthquakes occurring in sub-oceanic plate margins. Floods which can be categorized into Urban, River channel and Coastal types have hazards which can be mitigated in several ways. Guidelines and Standards on Flood Monitoring, Forecasting and Mitigation as applicable to Rivers State of Nigeria are discussed in this paper. In recent times the incident of the coastal flooding resulting from the earthquake-induced tsunamis in the Indian Ocean has brought to the fore the need for all coastal countries to take appropriate measures to acquire the expertise to monitor, forecast and fore-warn of impending flood episodes. The Low-Earth-Orbit (LEO) NigeriaSat-1 satellite currently orbiting the earth at about 800krn altitude can be employed, if appropriately and adequately equipped, through telemetry to monitor crustal geodynamics and attendant floods. This paper also discusses in details the processes of installation of a proposed ocean- floor Tsunamis BPR station to transmit signals from crustal plate motions through acoustic telemetry to hydrophones placed beneath a well-positioned bouy with transmitters to and from orbiting Disaster-Monitoring-Constellation (DMC) satellites (including the NigeriaSat-I). The positions of geodynamic spots on the ocean floors can be precisely located in time and space by land-based GPS Stations. These data can thereafter be centrally collated at the proposed Bori Station (mobile platform) for Coastal Crustal Geodynamics and referenced to the immobile Toro Geodesy and Geodynamic Center for dissemination to relevant Meteorological Stations and Space Centers within Nigeria for necessary actions. These processes will serve as monitoring and forecasting systems of flooding along all coastal towns and communities such as Lagos, Epe, Warri, Escravos, Port Harcourt, Eket, Calabar and other West African coastal cities such as Accra, Takoradi and Tema. The processes described in this paper are presently emplaced off the western coast of North America with successful attempts to monitor the motions of the Pacific plates and destructive giant waves from earthquake sources to coastal lands several kilometers away.