Effect of low impact development measures on inundation reduction—Taking Jinan pilot area as example

Flood Simulation Numerical Model and Flood Risk Analysis Software (FRAS) developed independently by IWHR are used in this study to evaluate the effect of individual and combined low impact development (LID) measures on inundation reduction. In addition, the SCS method is added to the original rain- fall-runoff model, which is coupled with the 2D surface hydraulic model in real-time. Therefore, the soft- ware can reflect the runoff and confluence process more accurately. The simulation results indicate:(1) Combined LID measures can decrease the flooding area at pilot area, small watershed and block scale under all the 24h design storm with 5-year, 10-year and 20-year return period. Besides, the total runoff volume and peak discharge are also reduced at watershed scale after implementing these measures. The effects are most significant under the 5-year return period storm, where the total runoff and peak discharge are cut respectively by 6.5% and 9.7% and the inundation area is cut by 48.96% in the measure-intensive block. (2) Individual LID measures have different effects under the 24h design storm with 10-year return period at basin scale. All measures can reduce inundation volume but it tends to increase at first and then decrease during the rainfall procedure. The effects of different individual LID measures on inundation area reduction are ranked as: sunken lawn, permeable pavement, green roof. (3) Inundation reduction effect of LID measure is also closely related to the measure type and scale, terrain, underlying surface condition and setting location. It is necessary to have multi-scheme simulation as well as analysis through hydrological-hydraulic model when design the LID measures. © 2018, China Water Power Press. All right reserved.