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Regional Flood Frequency Analysis For Upper Awash Sub- Basin (Upstream of Koka)

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dc.contributor.advisor Michael, Yonas(PhD)
dc.contributor.author Demissie, Mengistu
dc.date.accessioned 2018-06-19T12:18:19Z
dc.date.available 2018-06-19T12:18:19Z
dc.date.issued 2008-05
dc.identifier.uri http://etd.aau.edu.et/handle/123456789/1720
dc.description.abstract The conventional and L-moment method of flood frequency analysis are applied in determining flood magnitude of defined return periods by selecting the best-fit theoretical probability distribution. The most important part of the distribution is the tail as far as extreme flooding phenomena. These phenomena of floods are of utmost concern in water resources development and management. In most cases the central part of the theoretical distribution fits satisfactorily with the empirical points. In FFA the objective is to estimate flood magnitude (Q) corresponding to any specified recurrence interval of (T) years. The estimation is complicated due to lack of a physical basis for determining the form of the underlying flood frequency distribution and the necessity of evaluating flood event for return periods that exceed the observation period (Leulseged, 2002). Regionalization is generally accepted term to explain the transfer of information about flood peak at one catchment derived from other catchments with similar characteristics. The advantage of such procedure is particularly great in the estimation of frequencies for higher flood magnitudes with limited at site data do exist and inference in the tail of probability distributions makes the stabilization of the estimators difficult. It is quite clear that regionalization is most viable way of improving flood quantile estimation. Although there remain researchable topics in development and application of regionalization method. The performance of regional Extreme value and LN distributions are found to be highly satisfactory and can be widely applied in this paper. More attention is given to at-site homogeneity test to group stations in the upper Awash sub-basin (u/s koka) in to two regions after checking them for the consistency and independency testes and estimation of standard error. The upper Awash sub-basin (u/s of koka) has 10-selected gauged stations consisting of stream flow record varying from 12 to 37 years, out of which 6 stations are found in the upper region and 4 of the stations are found in the lower region. An Extreme value EV1, GEV and Lognormal LN2, LN3 distributions are selected as the best fit distribution for the stations in the sub-basin. The sub-basin has been divided into two regions the upper and lower region, the upper region covers 18.46% of the sub-basin and the lower region covers 81.54% of the sub-basin. en_US
dc.language.iso en en_US
dc.publisher Addis Ababa University en_US
dc.subject Upstream ; koka en_US
dc.title Regional Flood Frequency Analysis For Upper Awash Sub- Basin (Upstream of Koka) en_US
dc.type Thesis en_US


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