Flood runoff modelling for the planning of civil engineering protective construction: the case of Turgen soum, Uvs aimag

The study is aimed at planning civil engineering constructions based on the estimation of maximum runoff volume during the flood and determination of susceptible parcels for flood risk in the dry riverbed which directs to the centre of Turgen soum, Uvs province. We have determined the channel width, flood level, bank height, flood-prone households and parcels by flood runoff modelling using HEC-RAS software. The hydraulic analysis of civil engineering construction to avoid risk was implemented by Flow pro software. The volume of water flowing through a channel was carried out by Pipe flow advisor software. The hydraulic parameters were estimated using a digital elevation model. The maximum discharge of flood with 1% rainfall feeding was Q1%=11.06 m3/s when daily precipitation was at maximum. Therefore, there is a need for the planning of civil engineering construction that can drain the amount of the estimated discharge. The application of flood runoff modelling with the help of HEC-RAS software showed that the inundation width, channel bottom width, the difference between the highest point and the lowest point, and slope angle for the civil engineering construction were 10.66 m, 2 m, 6.01, and 0.0028, respectively. The flood-prone areas in the soum centre were 32 parcels with an area of 4.8 hectares. The hydraulic estimation results revealed 11.06 m3/s for discharge and 2 m for channel bottom width, while 0.8 m for water depth. Based on this estimation, the ferroconcrete channel for the flood will be planned to be the width of 2 m and height of 1 m and it is also calculated to be 0.2 m from the surface water level to the edge of the channel. We have suggested that the total length and discharge of the channel would be 1673 m and 13.896 m3/s.