Rainfall Partitioning into Throughfall, Stemflow, and Interception of Pomegranate and its Importance in Ecohydrology

Computing of rainfall partitioning into throughfall, stemflow, and interception are new discussions in ecohydrology and water resources studies of horticulture. The aim of this research was to compute of throughfall, stemflow, and interception of Malas-e-Torsh-e-Saveh pomegranate 6-years old (plant spacing 2.5×3 m) during January 2015 to Dec 2015 in Saveh city with an arid climate. To measure gross rainfall and throughfall, 10 and 50 manual rain-gauges (in a plot with an area was 500 m2) were used, respectively, and stemflow was measured using average of 9 individual trees equaled to the stemflow amount of trees. A total of 46 rainfall events were measured (cumulative: 159.1 mm) over the study period and rainfall magnitude varied from 0.5 to 11.8 mm with average of 3.5 mm. Over the measurement period, the cumulative percentage of throughfall, stemflow, and interception were 65.4, 4.7, and 29.0%, respectively. During the leafed period (21 April to 21 November), the corresponding values were 62.1, 2.9, and 35.0% vs. 67.5, 5.8, and 26.7% during the leafless period. In the overall time scales, the most suitable relationship between gross rainfall and rational throughfall percentage, rational stemflow percentage, and rational interception percentage were observed as positive logarithmic, positive polynomial, and negative power, respectively. Since in the arid and semiarid climates, the most economical and main way to supply water of plants are gross rainfall, therefore, it is necessary to have the highest possible efficiency from rain water.