Study On The Method Of The Mathematical Model On Urban Rainstorm Water Logging In Representative Region Of Tianjin

The majority of cities in our country are in the monsoon climate zone,under the condition of global warming,the frequency of rainfall increases the time of it is relatively concentrated.Fast modernization of city makes more and more types of structure,imperfection of plan is easy to cause water logging.Rise of cementation index of underlying surface shortens the time of runoff and enhances the water,what's more,aging of network of drains lower the drainability.All the elements above make rainstorm water logging a non-ignorable which restricts benign development of cities,the settlement of water logging is extremely urgent.In the model the two-dimensional unsteady flow equations are adopted to simulate overland runoff and river flow.Continuity equation and momentum equation are deduced and dispersed allowing for the characteristics and catchment ways of land features.Based on the and data provided by Tianjin weather bureau,institute of surveying and mapping,drainage management office,limited volume method method is applied to mesh study area.Water collected areas are divided depends on pump stations,intensity and range of water collecting are determined by modeling the influence of the radius Considering the climatic hydrologic condition and complexity of buildings of Tianjin typical region,diverse generalizability methods are adopted.The region can be creatively meshed using the method of multigrid which are partitioned and stratified.Flow of river,ground,pipeline and steep slope can be calculated in different ways.The model analyzes catchment ways of different structures and adopts respective computing method between different modules.Ten times of rainstorm data provided by Tianjin weather bureau are used as rainfall boundary conditions.Data are compared between measured value and simulation value from three aspects,these aspects are water level of Jinhe river near Xiangjiang road,ponding depth and time of verification points,water balance.Results show that model precision is acceptable.In addition,water logging of modules in survey region is analyzed to evaluate the degree of risk.The result can not only provides criterion for flood control and disaster reduction but also contributes to reasonable planning and instant notification of areas liable to water logging,thus preventing the happenings of disasters.