Estimating Maximum Daily Precipitation by Multi-Station Method: A Case Study of North Khorasan

Document Type : Original Article

Authors

1 Department of Civil Engineering, University of Azad, Mashhad, Iran

2 Associate Professor, College of Agriculture, Ferdowsi University of Mashhad, Mashhad. Iran

Abstract

In 1961 Hershfield introduced  a statistical method to estimate probable maximum precipitation (PMP). His method was based on the data of maximum daily precipitation of 2645 stations. Occurrences of rainfalls greater than PMP in the upcomming years, questioned Hershfield’s method. Eliason (1997) presented a multi-station method. Since PMP can occur at every point within a homogen region, this method was based on a combination of data from all stations in such a region. Gumble type 1 and its derived distributions were used as a mathematical tool. For parameter estimation however, Eliason used method of moment. In this paper, three other methods are used, namely maximum likelihood, maximum entropy, and probability weighted moments. Data of 41 homogen stations from North of Khorasan Province in Iran was utilized  for comparison purposes. The performance of maximum likelihood was proved via statistical analysis. In addition, PMP is compared for all stations using modified Hershfield method. Results were compared with multi-station methodand showed the performances of the former .

Keywords


رشتچی، ژاله (1374) ، بارندگی حداکثر محتمل، انتشارات وزارت نیرو.
رضایی پژند، حجت (1380)، کاربرد آمار و احتمال در منابع آب ،  انتشارات دانشگاه آزاد مشهد.
Asquith, G. (2000), "Precipitation areal-reduction factor estimating  using an annual–maxima,centered approach", J. Hyrol. , 230,  pp. 55-69.
Eliason, J. (1991),"Probable maximum precipitation in Iceland: Station value", Nord. Hydrol. 23(1), pp. 49-56.
Eliason, J. (1994),"Satistical estimation of PMP values", Nord. Hydrol., 25(4), pp. 301-312.
Eliason, J. (1997), "A Statistical model for extreme precipitation", Water Resour. Res., 33(3), pp. 449-455.
Hershfield, D. M. (1965), "Method for estimating maximum probable precipitation", J. Am. Water Works Assoc., 57, pp. 965-972.
Koutsoyainnis, D. (1999), "A probabilistic view of Hershfield`s method for estimating probable maximum precipitation" ,Water Resour. Res., 35(4), pp. 1313-1322.
Natural Environment Resource Council (NERC)(1975), "Flood Studies Report (FSR)", Vol. II. Oxon, U.K., 1975.
Schaefer, M. G. (1990), "Regional analysis of Precipitation annual maxima in Washington state", Water Resour. Res., 26(1), pp. 13-19.
World Meteorological Organization (WMO) (1986), "Manual for Estimation of Probable Maximum Precipitation: Summary", 2nd ed., WMO 332, Oper. Hydrol. Rep.1.