Selecting Place and Time Patterns in Golestan Province Rainfall by Clustering Analysis

Recognition of precipitation areas can define the potential of regional development in Golestan Province. For this aim, we used the precipitation data of 52 stations including synoptic, climatology, rain gauge and transpiration stations. The missing values were reconstructed by interpolation methods. The precipitation local variation was surveyed by isorain maps and variation coefficient. Province stations were grouped using cluster analysis and the significance of this groping was tested by One-Way ANOVA. Then the province was divided by Arc_GIS based on the obtained grouping. The results showed that the most rainy and driest season belonged to winter and summer, respectively. The results of cluster analysis on rainfall also showed that the Golestan province could be divided in to three precipitation regions: maximum in the mountainous region, average in the mountainside region and minimum in the plain region as adapted with Golestan topography map. The significance of this classification was certified by One-Way ANOVA with the confidence level of 95%. Spatial distribution of rainfall in Golestan Province showed that the highest rainfall in the area was devoted to the Foothills area in three seasons of spring, autumn and winter. Most precipitation in the plain region was in the summer, indicating that Golestan, summer rainfall had local sources. In three rainy seasons of winter, autumn and spring, the highest amount of rainfall was in the mountainous region. This stressed that the nature of the rainfall in the north of the country has not changed in Golestan Province. The highest rainfall in winter (47.7 mm) was related to Foothills Precipitation type that included 17 percent of the province's total area.