Analysis of Regional Flow Duration Curve for the Rainwater Harvesting Systems in Different Climate of Iran

Water harvesting has been widely applied in different climate zones, proving to be a valuable approach to sustainable water resource management. Regional estimates of the potential of water harvesting are generally based on purely hydrological assessments and mostly neglect the flow duration dimension of river. The purpose of this study was to analyze the indices to be extracted from flow duration curve (FDC) in the different climate areas. In this research, the basins in each climatic region were first separated by intersecting of climatic map and the border map of the basins. Then, 30 hydrometric stations with the common period (1976-2017) in two climate areas were selected. FDC using daily stream flow data were extracted by Hydro Office - software (2015) and then indices of Q2, Q5, Q10, Q15, Q20, Q50, Q75, and Q90 were computed. The slope of FDC were computed and finally the results were analyzed and interpreted. The results showed that variation of FDC slope in the basins of humid area was in the interval of (0 to 39%) and in the semi-humid climate in the interval (0 to 48%). In humid basins, the minimum difference between the indices were related to the beginning and end of FDC (Q2 and Q90) and the maximum changes were in the middle part of FDC (Q15 and Q20).