عنوان مقاله [English]
Rainwater harvesting is an effective method for the utilization of surface water resources in different regions. Since the impervious surfaces have noticeable potential of rainwater harvesting, designing and planning in order to collecting of rainwater is a suitable solution for adapting of water shortage in many places. In this research, the possibility of rainwater harvesting for supplementary irrigation of wheat and barley in their cultivation periods from third decade of November to second decade of June in the Rigcheshmeh village, south of Sari city, Mazandaran Province has been investigated. The average of required annual water for wheat and barley has been calculated 271 and 230 mm, respectively, by NETWAT software. For calculating of the precipitation average, 35-year precipitation of the Rigcheshmeh rain gauge station has been used. The cumulative amount average of 10-days precipitation with cumulative evapotranspiration of wheat and barley were compared in the same period during the 35-year period calculated and sprinkle irrigation system gross irrigation requirement was obtained. The amount of runoff from a 250 m2 roof covered with tar paper has been estimated and a reservoir with dimension of 2.5*5*8 m has been considered. The results showed in this place for supplementary irrigation of wheat and barley due to the average 35-year precipitation and with 80% confidence level, could be at least 15 percent of the farm area to be considered as impervious surface for collect rainwater.