Assessment the Impact of Maroon dam on Jarahi river Regime

Dams, as massive hydraulic structures, widely affect the flow of rivers downstream. Assessment of the extent of this impact is one of the most important issues in flood control research. In the present study, the annual and flooding trends of the Jarahi River and the relationship of these changes with the establishment of Maroon Dam was investigated. For this purpose, the diagrams of annual average discharges and flood peak discharges in two hydrometric stations of Idnak (upstream of the dam) and Behbahan (downstream of the dam) were plotted and a pairwise t-test (in SPSS software) was used to analyze the difference. The maximum flow discharge of Jarahi River was used in a period of 17 years before and after the operation of Maroon Dam. The results show the effect of Maroon Dam on peak flood discharges; In the 17-year period after the date of the opening of the Maroon Dam, the peak flood discharges in the downstream station of the dam compared to the 33-year period before that, have decreased significantly (88.9% decrease after Since the opening of the dam). The average maximum flow rate in the two mentioned periods before and after the construction of the dam is 1757.9 and 194 cubic meters per second, respectively, which indicates that the Maroon Dam has restrained the flood peaks. The statistical test also shows that no significant difference between the maximum flood discharge before and after the opening of Maroon Dam is observed in the hydrometric station upstream of the dam; however, at the downstream hydrometric station, a significant difference of 1% is observed between the maximum flood discharges before and after the opening of the Maroon Dam. Also the average annual discharges were coincided in a decreasing trend, given the trends in the two upstream and downstream of the dam, which can be attributed to drought occurrence and climate change.