The sponge city concept is a new strategy for China designed to solve its urban water problems. The tasks involved in sponge city construction (SCC) have brought new challenges regarding the urban construction process for local Chinese governments. However, there is still no comprehensive and systematic study of the government mechanisms for guiding the construction of sponge cities. This paper aims to develop an evaluation index system of government mechanisms at the whole-of-nation scale. This system covers five elements of government mechanisms. This evaluation index system covers the specific content of the government mechanism anticipated before the process of SCC. Since work systems, functions, and capacities differ with each given local government, the work mechanism of local governments can be adapted to local conditions according to the research results of this paper. By doing so it is possible to make full use of the constraint and management function of each indicator, so that all departments can constantly optimize the allocation of resources and clarify responsibilities, so as to effectively promote the construction of a sponge city.

Green roofs are a sustainable, low-impact development technique. They can reduce peak stormwater runoff and runoff volume and improve the quality of runoff from individual buildings and developments, which can lower the risk of frequent urban flooding and improve the quality of receiving waters. Few studies have compared different types of green roof models under the same rainfall intensities; thus, in this study, the predictions of a non-linear storage reservoirs model, Storm Water Management Model (SWMM), and a physical process model (HYDRUS-1D) were discussed. Both models were compared against measured data obtained from a series of laboratory experiments, designed to represent different storm categories and rainfall events. It was concluded that the total runoff of the SWMM model is always less than that of HYDRUS-1D. The maximum flowrate of the SWMM model is more than that of HYDRUS-1D during all events.