Investigating the effect of hydro-climatic homogeneous regions on priority of the best- fit probability distributions for daily raifall analysis in Iran

Subject Areas : Article frome a thesis

Somayeh Mohammadi Jouzdani ¹ , Hossein Malekinezhad ² , Ali Dolati ³

1 - Ph.D. Student of Watershed Management Sciences and Engineering, Department of Natural Resources eng. Faculty of Agriculture and Natural Resources, Hormozgan university, Bandar-e-Abbas, Iran
2 - Associate Professor, Department of Watershed & Range Management, Faculty of Natural Resources and Desertification, Yazd University, Iran
3 - Associate Professor, Department Of Statistics, Faculty of Science, Yazd University , Iran.

Received: 2013-12-04 Accepted : 2019-06-09 Published : 2019-05-22

Keywords: Watershed, Maximum daily rainfall Probability distribution, Hydrologic homogeneous regions,

Abstract :

Choosing the methods and techniques of statistic and probability science for predicting the variable with certain return period is very important in hydrologic analyses. Maximum daily rainfall is one of the important hydrologic variables that have a basic role in flood magnitude and peak. More accurately prediction of maximum daily rainfall can help us for better planning and management of water resources and flood control. The purpose of this study is determination the suitable probability distribution for maximum daily rainfall in throughout of Iran and also in identified hydro-climatic homogeneous regions. For this purpose, the data of 46 Sinoptics and four Climatologic stations were used. After data prossecing, EasyFit software was used to identify the best-fit distribution. Kolmogrov-Smirnov test was carried out in order to select the best fit probability distribution. The homogeneous regions were determined using the cluster Analysis technique with Ward method based on six parameters; Altitude, the mean annual rainfall, the mean of maximum daily rainfall, the mean of rainfall in winter, spring and autumn.Then five region were obtaned. Then, frequency of suitable probability distributions for maximum daily rainfall in every homogeniuse area were determinated and compared with its in throughout the country. The results showed the Wakeby distribution is most suitable distributions for estimating the maximum daily rainfall in both cases. But the next probability distributions in every homogenius region were different from each other.

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