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Abstract of the Article

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Presentation of a Mathematical Model .to Evaluate the Hydrological Drought in Arid Central Regions of Iran

Authors:
[ Vafakhah ] - Department of Watershed Management, Faculty of &Natural Resources Marine Sciences, University of Tarbiat Modarres
[ bl. Mahdavi ] - hculty of Natural Resources, University of Tehran Karaj,Fdculty of Natural Resources

Abstract:

Drought is one of the natural catastrophes that leads to harmful and widespread effects on ecological environments . Scientific investigation of such catastrophes is one of the most fundamental and urgent needs for agricultural and water resources programming in arid and semi - arid environment. Low flows analyses are the methods of estimating hydrological drought. and among such methods, regional analysis which depends on real data reliable in the areas with lack of applying this method seems to be more useful based on the results. Therefore it was applied in the estimating of low flow arid central regions of Iran. In this study, all stations which exist in the given basin were considered. Then 22 hydrometrical stations were selected in order to estimate the low flows of 1,7,15,30 days using daily statistics and annual cumulative duration curves. Three parameters distribution functions of log- normal was selected as a most suitable regional distribution among 8 distribution functions. Low flow of 1,7,15,30 days with two return periods was also estimated . Different parameters, including 8 parameters of physiography, 2 parameters of climatology and 1 parameter of geology were determined for selected basin. Then low flow of 1,7,15,30 days with two return periods containing 11 variables were correlated using stepwise regression method. The results showed that 3 variables consisting of area, mean annual rainfall and permeability formation percentages are more significant than other variables.

Keywords:

Hydrological drought , Low flow, Regional analysis, three parameters, log normal, Stepwise regression.