Characteristics of rainstorm temporal distributions in arid mountainous and coastal regions

Data from 2042 rainstorm events occurring from 1983 to 2003 in the Rustaq watershed and surrounding area in Oman were used to develop hyetographs, or temporal distribution curves characteristic of arid climates. Orographic effects on rainfall were also investigated by separating the data into two regions, mountainous and coastal, and hyetographs were developed for both regions. The curves for both regions are similar and display a very high intensity at the beginning of the storm, which is known to be a characteristic of storms in arid regions. The new distributions were compared to other standard established distributions derived for regions in Canada and the United States. In addition, curves were developed for an area of southern Alberta which has a similar climate. From all the comparisons, the greatest similarity was found between the Oman and Calgary curves but there was significantly higher intensity earlier in the storm in the Oman curves. Significant differences between the mountainous and coastal regions in terms of rainfall amount were found but there was only a minor difference in rainstorm temporal distribution.