فصلنامه سنجش از دور و GIS ایران
سال چهارم شماره 3 (پیاپی 15، پاییز 1391)

It is important to achieve accurate monthly precipitation field for climatology and evaluation simulated result of regional models. Because of high temporal and spatial precipitation variability، as well as limited rain gauges، improvements in precipitation estimates using satellite images is critical. Some projects have initiated in this purpose and many products have been produced. Monthly 3B43 product of TRMM project is one of them that have been evaluated in this paper. Precision of monthly and annually 3B43 product have been evaluated during 2001-2003 using Weather Organization synoptic and climatology station data. Result showed that usually values less than average have been overestimated and values more than average have been underestimated. Also precision of values less than average is lower. Nevertheless there has seen no correlation between precision of this product with thermal and humidity characteristics of mounts. Besides، precision amount is various in different zones of Iran، so that in South of Alborz mountain range، central and somewhat Eastern regions of Iran it is incredible; while in Western and Southern regions it is credible. Because precision of 3B43 product is lower than precision of Kriging interpolation technique estimates، thus utilize of this product is not recommended.

Flood control and optimal use of it, and artificial recharge of aquifers are among the most important issues, and usage of water spreading in arid and semi-arid regions is considered. The aim of this study is selecting the most appropriate location for water spreading in Kashan, using multi-criteria decision making techniques and hierarchical analysis process. In this plain the parameters such as slope, land use, runoff volume, quaternary units, thickness of Vadose zone, permeability coefficient, storage coefficient and chemical quality of groundwater have been selected in order to determine suitable areas for flood spreading. Then Using GIS, a map prepared has been for each parameter. In next step, by AHP method, the importance of various factors in the location has been evaluated. Results of the weight of evaluation criteria indicated that the factor of runoff volume with a weight equal to 37% was the most important factor; and then in sequence: Quaternary units, slope, Thickness of Vadose of aquifer layer, permeability coefficient, storage coefficient, water quality and landuse, respectively with relative weights of 0.23, 0.16, 0.094, 0.061, 0.039, 0.025 and 0.018. Finally According to zoning map of flood spreading, three priorities for flood spreading area were determined in Kashan plain. The results of the sensitivity analysis showed that using performance and dynamic range between minus 10 to 10 percent of the variation in weight criteria Change significantly in the priorities of the criteria and sub-criteria has not happened and is not a lot of sensitivity. In other words, variability is not so important in this required. These findings indicated that the runoff criterion care now according to the mentioned ranges of others in selecting a suitable location. Furthermore, Quaternary units and slope suitable places are among decisive ones.