Assessing the Spatial Distribution of Rainfall and the Effect of Altitude in Iran (Hamadan Province)

Atmospheric phenomena have an enormous influence on natural resources and human life. Lack of sufficient information and knowledge in regard to the management of natural areas and ecosystems will bring about a huge cost. Hamadan province according to the topography, geomorphology, and soil condition is known as a particular area. In this region, intense rains have brought about hillsides, runoffs, and floods annually destroying a large amount of foundations and eroding fertile soils. This study was conducted using rainfall average data from 35 synoptic stations and rain measurements between the years 1982 and 2012 (30 years). Geostatistical techniques are applied for zoning, such as kriging, co-kriging, inverse distance weighting (IDW), radial basis function, global polynomial interpolation, and local polynomial interpolation. For comparing and evaluating geostatistical methods, cross-validation and statistical parameters such as correlation coefficient and mean absolute relative error (MARE) were used. According to the results, it can be realized that simple co-kriging (exponential) technique with the highest correlation coefficient (.75) and the lowest MARE (.124) is the most appropriate geostatistical method to predict rainfall distribution. Also, it is realized that there is a correct correlation between the accuracy of co-kriging technique and elevation changes. However, IDW with power 5 is the least accurate technique.