Spatial analysis of precipitation intensity and concentration in Iran

Abstract

Understanding rainfall variability in the arid, rugged landscapes of Iran requires studying the climatology and spatial patterns of daily precipitation. This paper applies geostatistical and other methods to daily precipitation data from 90 stations that are distributed across Iran to calculate daily rainfall concentration and intensity and map their spatial distribution. The results show that daily precipitation tends to be irregular and intense across much of Iran and that a disproportionately large share of the annual rainfall comes from a small number of high intensity to extreme rainfall events. Analysis of daily rainfall concentration confirms that extreme events are widely distributed across the country, with more than 20% of the land area exposed to the risk of extreme rainfall. The areas experiencing the most frequent extreme events are the hot, dry southern coast and the western slopes of the main north–south range, the Zagros Mountains. Even the wettest parts of the country along the Caspian Sea coast derive a significant amount of their rain from high intensity and extreme events. A cross-validation analysis supports the reliability and accuracy of the geostatistical modeling.