introduction there are significant differences in the spatial distribution of the iran annual precipitation. this is resulted from spatial behavior of precipitation in the one hand and variation in the sources of precipitation on the other. the lack of adequate distribution of meteorological stations and the unavailability of long-term statistics of precipitation makes the analysis of precipita...

in this paper trends of precipitation and stream flow are analyzed in the atrak river basin in the north khorasan province. normal score linear regression, mann-kendall, and seasonal kendall trend tests were adopted. three precipitation variables and two stream flow variables including total precipitation, maximum daily precipitation, and number of rainy days, mean discharge and peak discharge ...

meteorological radars estimate the precipitation using a reflection-precipitation relation as z=arb with a, b coefficients. these coefficients will change from one precipitation to the other one. for the tehran radars they are considered as a=200 and b=1.6. these values are proper when we have moderate precipitations. this assumption causes an error in the estimation of different precipitation ...

In this paper we present a synthesis method for obtaining hydroxyapatite nanopowders by chemical precipitation. As the starting reagents, analytical grade Ca(OH)2, H3PO4 and NH4OH were used. . In order to study the factors that have an important influence on the chemical precipitation process a experimental platform has been designed for hydroxyapatite synthesis. The experimental platform was d...

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abstract variation of climatic elements could be estimated by standard deviation, coefficients of variation and so on. in iranian climatological literature, variations of climatic elements have main attention during last decades. meanwhile worldwide climatologist desired to study the characteristics of variations as well as the distribution of frequency average of these elements. in this paper,...

The function of precipitation intensity-duration-frequency is needed for the planning and design of water resource projects. Short duration precipitation data are hardly available. However the total hourly-recorded available precipitation data for different parts of NWFP from different departments have been collected and analyzed for the present study. The data from WAPDA is found to be more au...