Mohammad Bashirgonbad; Alireza Moghaddam Nia; Shahram Khalighi Sigaroodi; Mohammad Mahdavi; Emmanuel Paquet; Michel Lang
Abstract
There are many methods for estimating the maximum flood discharge including frequency analysis methods and risk study of hydraulic structures based on flood frequency analysis is often sensitive to the observations and selected statistical distribution that cause errors in design. Since heavy rainfalls ...
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There are many methods for estimating the maximum flood discharge including frequency analysis methods and risk study of hydraulic structures based on flood frequency analysis is often sensitive to the observations and selected statistical distribution that cause errors in design. Since heavy rainfalls are the main cause of floods and the rainfall records are longer than flow records, hence long-term records of rainfall at rain gauge stations of Bakhtiary basin in a 66-year period and the 58-year records of daily maximum discharge were used in this study. In this research, peak and maximum daily flows were estimated by using hydro-climatic methods of Agregee and Gradex. Then, the results obtained from the simulation based on hydro-climatic approach for the different return periods were compared with those of classical statistical techniques of Gumbel and Generalized Extreme Values (GEV). The results showed that using additional information like rainfall data plus hydrometric data in hydro-climatic methods gives better estimates rather than frequency analysis methods. Because each three evaluation criteria of Root Mean Squared Error (RMSE), Nash–Sutcliffe efficiency (NSE) coefficient, Kling-Gupta efficiency (KGE) coefficient confirm performance of hydro-climatic methods in comparison with Gumbel and Generalized Extreme Values (GEV) distributions. Finally, a peak to volume ratio extracted from the 26 major flood events detected at Tang-e panj hydrometric station within the hourly discharge records was used to transform the cumulative distribution function of daily discharge into peak discharge.
S. H. Hosseini; M. Abbasizadeh; M.R. Khaleghi
Abstract
In regions with deficient or no data, it is necessary to apply indirect methods to estimate the peak flow. Regional flood analysis is the most accurate and reliable technique in such cases. One of the regional flood methods for flood analysis in arid and semi arid regions is Hybrid technique, which was ...
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In regions with deficient or no data, it is necessary to apply indirect methods to estimate the peak flow. Regional flood analysis is the most accurate and reliable technique in such cases. One of the regional flood methods for flood analysis in arid and semi arid regions is Hybrid technique, which was applied on data of Khorasan Razavi province watersheds to estimate the peak flow. Hybrid method based on station - year method which considers available statistics from all stations to overcome statistics shortage problem. Hybrid method consists of two sections. At first, the most important parameters including area, annual rainfall and height are determined using factor analysis. Annual peak flow was standardized based on an approximate factor and then approximate standard factor was improved based on combined regression and analysis frequency. The results showed that the lowest relative error for the models was related to 50-year return period while relative error increased in other return period. As the relative errors were 1.03 and 0.79, respectively in the return periods of 2 and 100 years. Therefore, according to results, Hybrid method is suitable for return periods 20 to 50 years in the study area.
