Because of the complex terrain and frequent typhoon, Zhujiajian Island, located in the southeast of Zhoushan Archipelogo is prone to flooding disasters. MIKE FLOOD is applied to study the flood disaster of Zhujiajian Island by analyzing water level, inundated water depth, inundated area and inundated duration of the flood. The results show that the reasonable measures of widening the river width or reducing the elevation of the riverbed can effectively reduce the river water level, decrease the inundated area and the inundated water depth of the study area, and cut down the flood duration of the key areas.
As a key component of the hydrological cycle in nature, urban river not only offers sufficient water for urban development, but also plays an important role in transportation, climate regulation, ecological landscape as well as flood control and water storage. Because of the development of urbanization in China, the increasing demand for land resources and the influence of natural conditions, the environment of urban river is getting worse with the decreasing number of urban rivers (Yin et al., 2015), the change of river structure, and the weakening flood control capacity of urban river networks (Du et al. 2019; Lyu et al., 2018). The resulting urban floods and the corresponding disasters also threat the safety of people's life and the stability of society development (Jiang et al., 2018; Kundzewicz et al., 2019). In view of this, study on the protection of urban rivers and the relationship between river network conditions and functions attracts more and more attention.
In order to improve the city's ability to deal with flood disasters and reduce its harm to society and people, researchers both at home and abroad have successively carried out simulations on urban flood disasters through a variety of models and have achieved good social and economic effects. The modeling approaches for urban flood can be divided into three categories according to their calculation method, i.e., the hydrodynamic method, hydrologic method, and simplified method (Meng et al., 2019), among which the hydrodynamic method is commonly applied due to the clear physical laws (Rubinato et al., 2013). Some typical hydrodynamic models are MIKE-Urban (DHI, Denmark) (Lowe et al., 2017; Wang et al., 2017) or InfoWorks CS (Wallingford Software, UK) (Archetti et al., 2011; Hurford et al., 2010). Storm water management model (SWMM) (Zhou et al., 2018; Zhu et al., 2018; Babaei et al., 2018) is a popular urban hydrological model and suitable to generate floodwater in large catchment (Zhao et al., 2019). The well-known Soil Conservation Service-Curve Number (SCS-CN) method (Li et al., 2019) is also rapidly applied to calculate the surface runoff. Beside these models, GIS (Ozkan et al., 2016) is particularly useful in flood hazard mapping as it can incorporate both the spatial and physical dimension of the floods (Kourgialas et al., 2017), from which models such as UFIM (Urban Flood Inundation Model) (Chen et al., 2009), TSR (Tokyo Storm Runoff) model (Amaguchi, et al., 2011) are derived. For the areas lack of hydrological data, artificial neural network (ANN) technique (Panda, et al., 2009; Han et al., 2011) is always applied in order to get more accurate simulation results.
