Hydrological effect of typical low impact development approaches in a residential district

Understanding how low impact development approaches (LIDs) reduce urban stormwater runoff and increase baseflow is significant for urban water resources management. The SCS model and baseflow equation were employed to evaluate the performance of green roofs (GRs), permeable pavement (PP) and rain barrels (RBs) as retrofitting technologies in a high-density residential community in Nanjing, China. In addition, the factors relevant to the performance of LIDs were explored by estimating runoff variations at different rainfall frequencies. The findings are that the application of GR, PP and RB resulted in reduction in surface runoff by 0.6-36.8 % and increased in baseflow by 2.68-60.93 x 10(3) m(3). In addition, there is a negative linear correlation between runoff depth and effective storage, and the effectiveness of RB on runoff reduction is greater than that of PP. The baseflow generated by 100 % LID implementation is 1.94 times greater than that generated by 50 % LID implementation. For PP, generated baseflow increased with the increase in effective storage. The baseflow generated by GR is 1.16 times greater than that generated by RB in the same roof area.