Evaluating Hydrological Effect Of Sponge Basin Based On Multi-Layer Cellular Automata

In recent years,climate change,rapid urbanization and inappropriate urban planning policies have brought about urban waterlogging,floods,water shortage and other problems.China has implemented a strategy known as "sponge city" to deal with these problems.Quantitative assessment of the hydrological effect of Sponge Basin can guide the construction of sponge city projects more effectively.At present,the relevant researches are mainly focused on the urban block scale.They evaluate the sponge effect of sponge engineering facilities by the methods of rainwater experiment and hydrological simulation.On the basin scale,people usually use conventional hydrological simulation software to study the hydrological effects in changing environments by simulating hydrological processes in future land use scenarios,but the sponge effect of their sponges is rarely discussed.However,for the development and design of small watershed with urban-rural integration,the above two situations need to be considered.This paper proposes a multi-level cellular automata model to simulate the hydrological process of the basin in the horizontal and vertical directions.This model divides the hierarchical structure of multi-layer cellular automata into vegetation layer,surface layer and soil layer.We integrate hydrological models and empirical formulas as cell conversion rules,set basic attributes for cells based on DEM,soil type,land use type,leaf area index,etc.,locate and quantify the size of sponge engineering facilities,and parameterize cell attributes.This model can be used to simulate and calculate the water transport in each layer corresponding to the hydrological process,and output the spatiotemporal distribution of runoff in the watershed,the spatiotemporal distribution of canopy interception,the spatiotemporal distribution of watershed evapotranspiration,and the spatiotemporal distribution of soil water content.Then,we can evaluate the basin sponge effect based on the output,which can make the construction of the basin sponge system more measurable.Based on the above methods,we developed a hydrological effect simulation and visualization tool,and used GPU parallel computing to improve the model's operating efficiency.Finally,we took Xiyuan river basin,where Fuzhou university town is located,as an example.Based on the simulation of precipitation events of Megi typhoon in 2016,we evaluated the impact of urbanization and construction of Qishan Lake on the sponge hydrological effect of the basin.The system can be used as an auxiliary tool for sponge basin planning verification,and it can provide decision support for sponge basin planning design and project acceptance assessment.