Soheila Pouyan; Mohammad Zare; Mohammad Reza Ekhtesasi
Abstract
Dust event is one of the common and destructive phenomenon in arid and desert regions. This phenomenon has negative impacts on human life and environment. Dust storms, in addition to soil loss, can cause and aggravate health problems, food production reduction, economical damages into the industrial, ...
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Dust event is one of the common and destructive phenomenon in arid and desert regions. This phenomenon has negative impacts on human life and environment. Dust storms, in addition to soil loss, can cause and aggravate health problems, food production reduction, economical damages into the industrial, agricultural and communication sections. Therefore, accurate investigative of this phenomenon is necessary. The aim of this research was regional analysis of dust storm index (DSI) in 44 meteorological stations of Iran. At first stage, the dust storm index for each station was calculated using hourly dust data. Next, monthly averages of dust storm index (DSI) were used for regional analysis using linear moments approach. Based on regional analysis, the study area is divided to six homogeneous dust storm index regions. Pearson Type III (PE3) and Generalized Logistic (GLO) distribution models were the best regional distribution models for 1, 4, 5, 6 homogeneous regions, and 2, 3 homogeneous regions, respectively. Estimation of the dust storm index and its regional analysis can be used in many environmental studies, decision making and management processes in relation to combating desertification and dust storms.
kazem Nosrati; sepide imeni; arash talari
Abstract
Sediment yield caused by soil erosion process as the most important land degradation index is considered a main challenge in sustainable development and threats the ecosystems. It is therefore very important to estimate the reliable sediment discharge at watersheds outlets. The large river drainage basins ...
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Sediment yield caused by soil erosion process as the most important land degradation index is considered a main challenge in sustainable development and threats the ecosystems. It is therefore very important to estimate the reliable sediment discharge at watersheds outlets. The large river drainage basins and the lack of sediment gauges have led to apply regional analysis methods, to estimate suspended sediment load in the basins without gauges or the gauges with lack of data. The objective of this study was to estimate regional suspended sediment load using principal components regression in homogeneous regions of Sefidrood drainage basin with an area of 59273 km2as dependent variable and 18 physiographic and hydrologic factors in sediment load were recognized in each homogenous region based on principal components analysis (PCA). Finally, the relationship between suspended sediment load with different return periods and controlling factors were determined. The results showed that the stations located in the study area were clustered in two homogeneous groups. In the homogeneous region one, based on the PCA, 18 variables reduced into 5 factors accounting more than 87% of total variance and in the second homogenous region reduced into 3 factors accounting more than 92%. Using the principal component regression in the first homogeneous region, the first factor with the coefficient of determination of sediment discharge with 25- year return period, 0.67, and in the second homogeneous region, the first and second factors with coefficient of determination 0.32 were entered in model.
