Research Article
A Methodological Comparison of Rainfall Frequency Distribution Derived from Disaggregated Rainfall Records
Mezen Desse Agza*
Issue:
Volume 14, Issue 1, March 2026
Pages:
1-14
Received:
10 March 2026
Accepted:
25 March 2026
Published:
7 April 2026
Abstract: Rainfall is essential in hydrologic and hydraulic analyses, serving as critical parameter in water resource studies. Hydraulic structures are designed to manage flooding triggered by extreme rainfall events. One common approach to analyze these extreme occurrences is through probability distribution or frequency analysis. This study evaluates various methods of rainfall frequency analysis. Rainfall data was sourced from the Ethiopian Meteorological Agency (EMA), specifically the Addis Ababa Observatory. Before conducting frequency analyses, data quality was assessed for outliers, with findings within acceptable limits. The frequency analysis utilizes four different distribution methods: Gumbel Extreme Value I, Lognormal, Pearson II and Log-Pearson III. Moreover, these distribution methods were fitted using RMC BestFit software to select a method that fits best for the dataset. The fitted distribution methods were also calibrated with non-probability Intensity-Duration-Frequency (IDF) models. Results indicated that while all methods performed satisfactorily, the Gumbel EVI displayed the best balance between model fit and error reduction in this IDF analysis. The study underscores the importance of selecting appropriate statistical methods for accurate rainfall modeling, which is vital for the design and operation of hydraulic structures. Future research could investigate the applicability of these findings in other regions or integrate climate change variables into rainfall frequency analysis for enhanced flood risk management. Additionally, employing advanced techniques, like machine learning algorithms, may improve prediction accuracy and provide deeper understanding of rainfall variability and trends.
Abstract: Rainfall is essential in hydrologic and hydraulic analyses, serving as critical parameter in water resource studies. Hydraulic structures are designed to manage flooding triggered by extreme rainfall events. One common approach to analyze these extreme occurrences is through probability distribution or frequency analysis. This study evaluates vario...
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Research Article
Determination of Optimal Irrigation Scheduling for Onion Under Furrow Irrigation Method in Eastern Hararghe Zone, Ethiopia
Ayela Tade*,
Lalisa Ofga,
Jemal Nur
Issue:
Volume 14, Issue 1, March 2026
Pages:
15-21
Received:
1 May 2026
Accepted:
29 May 2026
Published:
10 June 2026
DOI:
10.11648/j.hyd.20261401.12
Downloads:
Views:
Abstract: Efficient irrigation water management is critical for optimizing crop productivity and ensuring the sustainable use of limited water resources, particularly in semi-arid regions. This study was conducted during the 2022/23 and 2023/24 cropping seasons at Kombolcha District, East Hararghe Zone, Oromia regional state, Ethiopia. The purpose of the activity was to create optimal irrigation regimes (when and how much to irrigate) for onions and evaluate the effect of different irrigation timings on the water productivity and yield of the onion crop. The results showed that irrigation water, maximum irrigation frequency, and short irrigation intervals were achieved by scheduling irrigation at 60% of the ASMDL treatment. The next maximum irrigation frequency was obtained by scheduling irrigation at 80% of ASMDL treatment. Minimum irrigation frequency and minimum water consumed by scheduling irrigation at 140% ASMDL treatment. The results show that the maximum onion yield was obtained by scheduling irrigation at 60% of ASMDL treatment, followed by 80% ASMDL treatment. Statistically, there is no significant difference between 60% ASMDL and 80% ASMDL treatments in terms of onion yield. Maximum water productivity was obtained by scheduling irrigation at 80% ASMD treatment followed by 60% ASMDL treatment. Statistically, there is no significant difference between 60%, 100%, and 120% ASMDL treatments in terms of onion water productivity. The minimum water productivity was reached by scheduling irrigation at 140% ASMDL treatment. So, scheduling irrigation at 80% ASMDL is recommended for onion with 5-day, 6-day, 7-day, and 10-day irrigation intervals at initial, development, mid, and maturity stages of onion, respectively.
Abstract: Efficient irrigation water management is critical for optimizing crop productivity and ensuring the sustainable use of limited water resources, particularly in semi-arid regions. This study was conducted during the 2022/23 and 2023/24 cropping seasons at Kombolcha District, East Hararghe Zone, Oromia regional state, Ethiopia. The purpose of the act...
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