Author(s): Elsie Akwei; Lu Boahong; Amos Tiereyangnkabo-Bah; Raphael Akesseh
Linked Author(s):
Keywords: Multi-spectral SPOT-5HRVR imagery; Spatio-spectral assessment; Normalized Difference Water Index; False color composite; ILWIS
Abstract: Floods and droughts are normal phenomena, but with great influence from anthropological activities and climate change, they are causing great havoc worldwide. The White Volta river basin has been experiencing frequent and abnormal floods that have caused hazards to lives and property and has made the area an area a global concern. The White Volta River Basin is one of the main sub-basin systems of the Volta River system of Ghana and spans Burkina Faso, Ghana and Togo. In Ghana and Southern Burkina Faso, the White Volta plays a significant role in providing substantial economic power to the vulnerable communities living in this region. The use of satellite imagery for hazard monitoring is used ubiquitously as it informs decision making in the prevention of droughts and flood hazards, but it lacks adequate research and application in West Africa. In this paper, multi-spectral SPOT (Satellite Pour l'Observation de la Terre) – 5 HRVR, imagery was used to analyze the flood and drought problem in the White Volta River Basin in 2010. In order to do this, free and open source GIS software – Integrated Land and Water Information System (ILWIS) was used to perform the analysis. False color composite and Normalized Difference Water Index (NDWI) were computed in ILWIS to exhibit flood and drought susceptible areas in the White Volta basin. The study revealed the water-logged areas and water-scarce areas in the satellite imageries used. Standardized Precipitation Index (SPI) was generated from Rainfall data of the area form 1975-2008 from the Kintampo station to verify the results from the satellite imagery. The analysis showed that satellite imagery use is vital for monitoring crucial environmental hazards such as flooding and perennial droughts. It was concluded that Simple False color imagery and indices such as Normalized Difference Water Index can be used to monitor flood and drought. An integrated solution of harvesting the excess rain water in the wet season and using it in the dry season is recommended. This study anticipates a part contribution to the knowledge-base of Spatio-spectral assessment of droughts and flooding in the White Volta River Basin and is applicable in other parts of Africa.
Year: 2013