Calculating the volume of Tan Mieu lake in Thanh Noi area, Hue City, for the urban stormwater drainage system

Abstract

Detention lakes, which are effective means of flood control, are highly effective in sustainable drainage solutions. Numerous factors diminish the regulating reservoir's function for urban drainages, such as the lake's small volume, an inadequate drainage system, and restricted outflow from the lake. Therefore, this study applies the method of limited rainfall intensity to calculate the stormwater flow into the lake and determine the volume of the detention lakes according to TCVN 7957: 2008 [1] to the sub-basin of Tan Mieu. It is confirmed that the volume of the lake in the region and the level of outflow from the lake, which are essential factors in flood mitigation, is not suitable for the rainfall characteristics of the area. The results show that with the planned outflow of Q_x = 1/3 × Q_t, the lake's actual capacity is roughly a half of the required lake capacity. With the option Q_x = 1/2 × Q_t, the actual volume of the lake is 1.2 times smaller than the calculated capacity. Therefore, increasing the lake's volume and outflow volume from the lake minimizes local flooding.