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| dc.contributor.author | Tesfaye, Mekonnen Wendem | |
| dc.date.accessioned | 2023-06-16T07:05:21Z | |
| dc.date.available | 2023-06-16T07:05:21Z | |
| dc.date.issued | 2023-03 | |
| dc.identifier.uri | http://ir.bdu.edu.et/handle/123456789/15368 | |
| dc.description.abstract | In Ethiopia, available rainfall records are mainly limited to daily time steps. Though rainfall time series data at shorter time steps are important for various purposes like modeling of erosion processes and flood hydrographs, they are hardly available in Ethiopia. The development of a disaggregation approach allows for the production of hourly data that add up to certain daily totals. The objectives of this study were (i) to examine the various methods of disaggregation of rainfall using the higher-level and lower-level, (ii) to evaluate the performance of stochastic and HYETOS disaggregation models, and (iii) to develop a rainfall distribution curve and evaluate a design storm using the US Soil Conservation System (SCS) approach as a base through the Tana basin. The analysis was based on rainfall data of Dangla, Debre Tabor, Bahir Dar and Gondar Automatic Gauge Stations. The disaggregation model used was the Stochastic and Modified Bartlett–Lewis Rectangular Pulse Model (MBLRPM) called HYETOS. The stochastic disaggregation model result was stated in monthly Cumulative Density Function (CDF) and monthly convergence parameter (ε) from 1.05 to 8.95 mm. HYETOS rainfall disaggregation model results obtained in the optimum magnitudes by model parameters for each month. The wettest months of July and August, which had extremely low chances of being dry, corresponded to higher Poisson arrival rates and mean cell rain depths. Their model validity has been examined using statistical comparison of variance, skewness, probability of dry period, and Lag-1 Autocorrelation function (ACF). The findings result show that the methods can preserve statistical characteristics and daily total rainfall depth. The US SCS method's underlying assumption was used to construct 1-day rainfall distribution curves and as a consequence have a better effect on the study area for each station with 24-hour rainfall duration and for design storm computation the designers are better to use 24-hour rainfall distribution curves by increasing computations. Key words; Disaggregation, Distribution curve, Downscaling, Rainfall Profile, HYETOS, Stochastic | en_US |
| dc.language.iso | en_US | en_US |
| dc.subject | Civil and Water Resources Engineering | en_US |
| dc.title | EVALUATION OF RAINFALL DISAGGREGATION MODELS AND ASSESS THE CHARACTERISTICS OF DESIGN RAINFALL IN TANA BASIN, ETHIOPIA | en_US |
| dc.type | Thesis | en_US |
