چکیده:
Statistical frequency analysis is the most common procedure for the analysis of flood data at a gauged location that
in first step it is needed to select a model to represent the population. Among them, the central moment has been the
most common and widely used, and with the using of computers, the application of the maximum likelihood has
increased. This research was carried out in order to recognition of suitable probability distributions with pervious
common methods. In order to investigate of suitable probability distribution for flood flow, using L-moment method
through the existing hydrometric stations in the region, 17 hydrometric stations were selected for peak discharges
data studies. According to results of this research for peak discharge, LP3 distribution and ordinary moment method,
P3 distribution and L-moment method, LN2 and LN3 distributions and ordinary method have been suitable
distinguished for 53%, 35%, 6% and 6% of stations, respectively. We concluded that L-moment method is suitable to
determine peak series probability distributions in the Iran central plateau and P3 is the best probability distribution for
modeling peak series in this region.
خلاصه ماشینی:
Flood Flow Frequency Model Selection Using L-moment Method in Arid and Semi Arid Regions of Iran A.
In order to investigate of suitable probability distribution for flood flow, using L-moment method through the existing hydrometric stations in the region, 17 hydrometric stations were selected for peak discharges data studies.
In recent years there have been many applications of L-moments diagrams for selecting various distributional alternatives in a region and the skewness and kurtosis L- moment-ratio diagram (LMRD) was suggested as a useful tool for discrimination between candidate distributions (Hosking and Wallis, 1987; Hosking, 1990; Hosking and Wallis, 1993; Vogel and Fennesset, 1993; Hosking and Wallis, 1997 and Peel et al.
L-moments are defined as linear combinations of probability weighted moments (PWM): (4a) b2 = (4b) Where mr = (4c) S= (4d) Sample estimates of ) and (β2) do not always coincide with the theoretical points or curves of their parent distributions, and method of GOF test using b2) have thus been developed for normal distribution (D,Agostino and Pearson, 1973 and Bowman and Shenton, 1975).
, 1993b; Vogel and Wilson, 1996; Adamowski, 2000 and Kjeldson et al; 2002 that were used L-moment diagrams for choosing various distributional alternatives for annual maximum data in a region.
To study of the appropriate probability distributions for annual maximum series using L-moment method in arid and semi-arid regions of Iran.