Temporal analysis of storms in East of Urmia Lake using the Huff curves method

In this study, the Huff curves were extracted using the 418 events in the four selected stations. Firstly, the total storms were classified into the four distinct classes according to their durations including i) 0-2, ii) 2-6, iii) 6-12 and more than 12 hours. Then, the Huff curves were plotted for the 10%, 20%, … and 90% non-exceedance probabilities. Analysis conducted for each of the classes, separately, for the stations. Another Huff curve plotted using the all events in a unit class. Some statistical distributions commonly used in hydrology were utilized. The three indices (S2/10, I2/10, and Q2/10) calculated. The design hyetographs for each of the selected stations using the information of all events in a unit class prepared for 2 and 10-years return periods. The mathematical models of Huff curves derived as the Logistic model. The parameters estimated for all models. Results indicated that except Sarab, having the first quartile precipitation type, the three other stations had the second quartile types. The same results obtained for the class of storms with duration less than two hours. But for the classes of 2-6 and 6-12 hours, in some stations the type of precipitation shifted to the further quartile. The vertical distance of 50% and 90% Huff curves in the first, second and third quartiles shortened as the quartiles increases (S>I>Q). It was found that the Logistic model is capable in fitting the curves. The correlation coefficients between the observed and modeled values were found to be from 0.978 to 0.998.