Rivers are usually exposed to floods that cause significant human and financial loss, for which structures are considered in the rivers for preventing floods and reducing damage. In this way, it is necessary to acquire design discharge for building these structures. The case study was conducted on the Tar River of Ghazi Station in Tehran Province, which originates from 1 km west of Tar Lake in 13 km east of Damavand. The Tar River is one of the tributaries of Damavand River. In this study, the cross section of the river was first measured through surveying and existing maps. The design discharge of flood control structures was designed using the methods described in this study. Moreover, the stage-discharge table was used to obtain the Manning roughness coefficient. The effective discharge was calculated using the sediment rating curve and sediment frequency histogram, while the bankfull discharge was derived from the return period of 17 years discharge record and fitting of Gumbel distribution to the data. The results indicated that the average of dominant, effective, and bankfull discharges could be the appropriate design discharge for the river, as their values are significantly close to each other. However, there is no need to use flood control structures in this river, due to the occurrence of medium frequent flood events in the river.

河流通常会遭受洪灾，造成重大的人力和财力损失，为此，人们在河流中考虑使用各种结构来防止洪灾和减少损失。这样，必须获取用于建造这些结构的设计排放量。案例研究是在德黑兰省加兹站的塔尔河上进行的，该河发源于达拉万德以东13公里的塔尔湖以西1公里。焦油河是达马万德河的支流之一。在这项研究中，首先通过测量和现有地图来测量河流的横截面。防洪结构的设计排水量是采用本研究中描述的方法进行设计的。此外，使用级放电表来获得曼宁粗糙度系数。使用沉积物等级曲线和沉积物频率直方图来计算有效排放量，而满溢排放量则是根据17年排放记录的回收期以及Gumbel分布与数据的拟合得出的。结果表明，主要，有效和河岸流量的平均值可能是该河流的适当设计流量，因为它们的值彼此非常接近。但是，由于该河中发生频繁的洪水事件，因此无需在该河中使用防洪结构。满溢流量可能是河流的合适设计流量，因为它们的值彼此非常接近。但是，由于该河中发生频繁的洪水事件，因此无需在该河中使用防洪结构。满溢流量可能是河流的合适设计流量，因为它们的值彼此非常接近。但是，由于在该河中发生频繁的洪水事件，因此无需在该河中使用防洪结构。