Abstract
Abstract. Understanding the hydrologic system surrounding crater lakes is of great importance for prevention of flooding damages, conservation of ecological environment, and assessment of socio-economic impact of dam failure on the civilians in the downstream regions. Lake Nyos is a crater lake formed by volcanic activities at the Oku volcanic field on the Cameroon Volcanic Line. It is a freshwater lake with a maximum depth of 200 meter. In 1986, a limnic eruption at the lake emitted 1.6 million tonnes of carbon dioxide from the bottom of saturated water into the air and suffocated up to 1,800 people and 3,500 livestock at nearby villages. The lake waters are held in place by a natural dam composed of loosely consolidated volcanic rock, which is now at the verge of collapse due to accelerated erosion. This study was carried out to determine the flood risks and vulnerability of population and infrastructure along Katsina-Ala drainage basins. The project integrated both satellite images and field datasets into a hydrologic model for Katsina-Ala River Basin and its vicinity including the Lake Nyos. ArcHydro was used to construct a hydrologic database as 'data models' and MIKE SHE was employed to conduct hydrologic simulations. Vulnerable infrastructures, population and socio-economic activities were identified to assist the Federal and State governments in disaster mitigation and management plans. The result of the project provides comprehensive knowledge of hydrologic system of Katsina-Ala drainage basin to mitigate potential future disasters from a potential dam failure and manage water resources against such disasters.
Highlights
Dam collapse is one of the most common disaster phenomena, causing considerable personal injury and property damage
The digital elevation model, flow direction and flow height models revealed that in the event of the dam failure, which could be caused by disturbances within the Earth crust, about 3 billion m3 of water will flow down the Katsina-Ala and Benue drainage valleys; to be aided by distinctly marked fracture zones controlling the stream flow direction and may serve as conduits/channels to the gas and water transport
Poor disaster management policies and practices are partly responsible for the poverty and poor living conditions of the survivors, and this appears to be a key determinant for the social vulnerability of the local population to the effects of the past disaster and subsequent hazards
Summary
Dam collapse is one of the most common disaster phenomena, causing considerable personal injury and property damage. This paper provides background information on the hazards and potential danger posed by the lake and the collapse of its dam on the population, infrastructures, agricultural/cultural resources, socio-economic activities and other environmental consequences in the area.
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