Evaluation of two physical and statistical approaches in probable maximum precipitation estimation in Bushehr province

Probable maximum precipitation (PMP) is one of the most important components for water resources management. In this study, 24-hour probable maximum precipitation (PMP24) was estimated and compared with Hershfield standard and modified and physical approaches in Bushehr province. Among the weather stations of Bushehr province, seven synoptic stations were selected. The data used to include 24-hour precipitation, dew point temperature, wind speed, station pressure, and sea-level pressure during 1968-2018 years. The results showed that in the Hershfield standard, the frequency factor and the PMP24 values in the studied stations were estimated in the range of 16.2-17.9 and 433.5-880.6 mm, respectively. Similarly, in the Hershfield modified, these values were estimated in the studied stations in the range of 2.39-44.64 and 103.61-23.4 mm, respectively. The regional PMP24 values for both the Hershfield standard and modified methods and physical approaches were estimated 660.5, 181.4, and 139.9 mm, respectively. In general, considering the physical characteristics of the air mass in the physical approach, the use of this approach is proposed to reduce uncertainty. If the Hershfield standard method is used, the design and construction costs increase unnecessarily.