An evaluation of precipitation gauge density in western Iran

Accurate evaluation of regional mean annual rainfall is important for the design of water recourses projects.The objective of this study is to evaluate the precipitation gauge density in western Iran covering provinces of Kermanshah, Ilam, Hamadan, Kurdistan and Lorestan.In this research, the average annual precipitation for thirteen raingauge stations was evaluated for a period of 15-years for the study area. Correlation Coefficient(r) and standard errors (SE) of estimate were computed for all station pairs within a 100 Kilometers distance and 360 meter elevation differences.A third-degree polynomial equation the best available relationship based on inter-station distance.Elevation and land slope were actually eliminated from the equation. Based on the results obtained a raingauge network of additional station is required, with a quantity errore and a quantity correlation coefficient.