Systematic Assessment on Waterlogging Control Facilities in Hefei City of Anhui Province in East China

Both the renovation of rainwater pipes and the addition of sponge city facilities in the low-terrain residences of urban fringes were rarely systematically simulated using the Storm Water Management Model (SWMM). With the waterlogging prevention project in an old residential quarter at a fringe of Hefei city being an example, this study used the SWMM to simulate the effect of the renovation of rainwater pipes and sponge city facilities under different return periods. The results showed the key nodes on the main pipes met the drainage requirements based on water depth analysis after renovation below the 20-year return period, and the reduction rate of the maximum water depth at the key node J5 was the greatest, with 87.7%. The four flow parameters (the average flow rate, the peak flow rate, the total discharge, and the percentage of water flow frequency) for the two outlets (PFK1 and PFK2) all improved after renovation under five return periods (2, 5, 10, 20, and 50 years [a]). The addition of sponge city facilities effectively reduced the amount of rainwater runoff from 28.68% to 14.78% during 2 a to 50 a, and the maximum reduction rate of water depth, being 61.15%, appeared in J5 under 20 a. The curve integral area of the depth over the elapsed time was innovatively used to indirectly express the accumulated rainwater volume through the rainwater well. This study verified that the SWMM model can be well applied to old low-terrain residential quarters in urban fringes and broadened the application scenario of the model.