Development and Application of Spatially Parameterized Depth Duration Frequency Model for Estimation of Design Rainfall for Oromia State, Ethiopia
Journal Title: STAR Journal - Year 2014, Vol 3, Issue 4
Abstract
The magnitude and frequency of extreme rainfall events are required for planning, design and operation of many hydrological and water resources projects. Design rainfall depth is often used to estimate the severity and rarity of floods in areas where flow records are not sufficient enough to warrant direct flood estimation. The design of hydraulic structures on un-gauged streams and creeks, such as bridges, culverts, spillways, water harvesting and flood defense mechanisms depends upon proper estimation of extreme rainfall events. Quantification of design rainfall is generally done by using information contained in Depth-Duration-Frequency (DDF) relationships. Depth Duration Frequency relationships are currently constructed based on at site frequency analysis of rainfall data separately for different durations. These relationships are not accurate and reliable since they depend on assumptions such as distribution selection for each duration; they require a large number of parameters, experience intensive equations and regionalization is also very poor and coarse. In this study a DDF model with gridded set of parameters is developed for estimation of point rainfall frequencies for a range of duration for any location in Oromia regional state. A DDF model was fitted to series of annual maxima and its parameters were determined by a least squares method and these parameters were interpolated and mapped on a 1km grid. The model allows for a parsimonious and efficient parameterization of DDF relationships, and its performance is shown to improve the reliability and robustness of design storm predictions as compared with those achievable by interpolating the quantile predictions of extreme rainfall data for specific durations. Moreover, design rainfall estimates found from the scaling DDF model are comparable to estimates obtained from traditional techniques; however, the scaled approach was more efficient and gives more reliable estimate compared with the observed rainfall depth at all stations.
Authors and Affiliations
Megersa Tesfaye| Department of Hydraulic and Water Resources Engineering, College of Engineering and Technology, Post Box No: 395, Wollega University, Nekemte, Ethiopia, Solomon Seyoum Demissie| Ethiopian Institute of Water Resources, Akaki Campus, Post Box No: 150461, Addis Ababa, Ethiopia
Keywords
Related Articles
- EP ID EP9727
- DOI http://dx.doi.org/10.4314/star.v3i4.21
- Views 359
- Downloads 13
Anticaries Activity of Usnea pictoides G. Awasthi -A macrolichen from Western Ghats of Karnataka, India
The present study was conducted to determine anticaries activity of solvent extracts of a macrolichen Usnea pictoides G. Awasthi (Parmeliaceae) collected at Mullayanagiri, Western Ghats of Chikmagalur district, Karnata...
Ameliorating Effect of Piperine on NO-cGMP Pathway in Stress Induced Depression
Depression has become a common illness among individuals of every age group. Among numerous factors held responsible for depression stress is most vital. Behind the specified disorder various hypothesis has been laid out...
Irrigation Water Management Practices in Smallholder Vegetable Crops Production: The Case of the Central Rift Valley of Ethiopia
Smallholder irrigated vegetable production in the Central Rift Valley region of Ethiopia is instrumental in ensuring the year-round availability of fresh vegetables in the local market in the country. However, a number...
A Socio-Economic Linkage of Urban Informal Sector to Formal and Other Informal Sectors in Hawassa Town: Intensifying Growth from the Street
A comprehensive survey pertaining to vendors and the role vendors’ play in economic links between urban informal and formal sectors in Hawasa town is not studied so far. Hence, the main purpose of this study has been t...
Assessment of Challenges and Opportunities of Wetlands Management in Bule Hora Woreda, Borena Zone, Southern Ethiopia
No Abstract