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Title: Satellite-Based Rainfall Estimation: Evaluation and Characterization (A Case Study Over Omo-Gibe River Basin)
???metadata.dc.contributor.*???: Dr. K. S. R. Murthy
Dereje, Mekonnen
Issue Date: 1-Oct-2007
Publisher: Addis Ababa University
Abstract: Rainfall is a key climatic element considered as the most important factor that influencing the Ethiopian agriculture and it is also principal cause of droughts and flood triggered by the fluctuation and excess of rainfall extreme events respectively. It is known that the pattern and distribution of rainfall in Ethiopia is highly variable. Therefore, the understanding of such situations and integration of this knowledge into planning and decision making process is not doubtful. At present, the great amount of available rainfall data does not allow to a direct access by human user to the whole content of information. As D.Grimes, professor of reading university in UK, cited in the proceeding of meteorological satellite data users conference in 1997, the past 30 years there has been concern about decreasing rainfall in Africa and weather this is linked to climate change. He stressed that the problem of accurately assessing the situation are exacerbated by the sparseness of the raingauge network, which has meant difficult to determine it with out satellite applications. The development of remote sensing technology and application which are now able to manage the Satellite –based rainfall estimates by giving answer for specific complain such as - stations do not adequately reflect the various climatic zones of the country, unevenly distribution of Gauge Networking system, establishing dense network is not economically viable, accuracy and missing of gauge readings and records, and so on. Therefore, this problem can be alleviated only through the application of satellite data. The fact that satellite derived data is continuous in space and could be obtained regularly has made it very useful for early warning purposes. Most operational rainfall monitoring system in Africa including our country uses thermal infrared (TIR) imagery from MetoSat satellite. This is because of high repetitions rate of MetoSat images and the link between the rainfall and its convective source of clouds which is sensitive to TIR data. Half-hourly digital data from European Meteorological Satellite METEOSAT has been receiving at the National Meteorological Service agency since 1990.The study presented in this paper took place to investigate and show methods and practical application of satellite based rainfall estimates of TAMSAT methodology developed at the University of Reading, UK for tropical Africa. The data used are two types, dekadal MetoSat-TIR CCD image and ground gauge measurements represented the study area of Omo-Gibe basin. The CCD images are converted into RFE image through automated image processing module and values are extracted at delineated homogeneous rainfall region (HRR). The extracted rainfall values obtained are further processed and characterized quantitatively using statistical and GIS Geostatistical tools, indicated that reasonable agreement and in small extent variability between the satellite estimate and gauge value.
Description: A Thesis Submitted To The School Of Graduate Studies Of Addis Ababa University In Partial Fulfillment Of The Requirements For The Degree Of Master Of Science In GIS And Remote Sensing.
Appears in Collections:Thesis - Earth Sciences

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