基于元胞自动机的城市地表积水模拟研究

An Urban Surface Flooding Modeling Based on Cellular Automata

[目的]对城市地表水文产汇流时空过程进行模拟研究,以期为城市排水防涝应急决策提供依据。[方法]针对城市地表覆盖破碎性和地形复杂性的特征,构建基于元胞自动机(CA)的城市地表积水模型,结合水力水文学原理定义元胞及其规则。[结果]与传统统计经验模型、物理模型相比,该模型避免了汇水区划分、水流路径确定、参数提取等数据预处理问题,以广州市番禺区富华东路段区域作为试验区进行参数率定及模型验证,根据规则更新每个元胞的状态参数可获得任意时刻地表积水量、径流量和水流。[结论]该CA模型可以准确模拟地表水流时空分布及其变化,模拟结果可靠、表达直观;通过雨水口不同排放量模拟和常用数学模型对比分析表明,CA城市地表积水模型在城市内涝模拟中具有良好的实用性及易操作性。

[Objective]It is necessary to study on the spatial and temporal process of urban overland runoff that could provide support decisions for waterlogging prevention and drainage emergency.[Methods]Because of the fragmentation of underlying surface and complexity of micro topology in urban environment,urban hydrology process is too complicated to present exactly characteristics,such as changeability of flow routes,spatial and temporal variation of flooding.Based on cellular automata,an urban surface flooding model（USFM）is built to simulate surface hydrologic process by defining cellular＇s state and its evolution rules.In this model,several processes were considered,including rainfall,vegetation intercept,depression storage,runoff generation,infiltration and inlet discharging.The runoff process was handled by Manning＇s equations and rules,and runoff volume and flow path were calculated respectively.[Results]Because the hydrologic response units（HRU）are treated as grids,USFM can be defined as a distributed model,which can deal with the spatial variability of urban space very well based on DEM and land use data.Moreover,by combining the cell rules with mathematical formula for urban space flow uncertainty,USFM has the capacity of determining the flow routing and volume of runoff automatically.The basic input data of USFM are DEM data,land use data and gutter inlet data,which are raster data format.The USFM output data is a spatial and temporal dataset,which contains surface runoff information of any given time and space.A basin in Guangzhou Panyu District was chosen as the experimental area to test the model.[Conclusion]Through parameter calibration and model validation,the proposed approach well reflects the urban surface flooding hydrological details with a small amount of input data and simple modeling working.The USFM is useful to forecast the flooded areas in urban areas.