The Mechanism And Modeling Of Urban Water Dissipation

Water dissipation is an accompanying process of various urban water use activities.Besides,it is also a significant basis for the planning management of urban water resources,including water supply and drainage system.This study adopted experiment,investigation,statistics,model simulation,and data mining methods to explore the mechanism and calculation of water dissipation in urban area(UWD).Firstly,the concept,process,and mechanism of UWD were introduced,based on which,the analysis framework and balance model of UWD were created.The underlying surface of the city was divided into five categories: building interior,building roof and hardened ground,bare soil,vegetation,and water surface according to the UWD characteristics.The water dissipation inside the building was regarded as the UWD on the social side while the other four kinds happened outdoor were regarded as the UWD on the natural side,representing the surface evapotranspiration in urban area.Based on the experimental monitoring of water use,displacement,population,indoor temperature and humidity of the typical buildings,a calculation model of building water dissipation using quota method was established.Then the water dissipation quota and the interval of water dissipation ratio of the buildings were calculated.In the experiment,the characteristics of interception rain water of the hardened impermeable ground,as well as the characteristics of the impermeable ground and the soil moisture variation of the hardened permeable ground were monitored.The calculation model of the hardened ground evaporation was established.Combined with the existing simulation methods of evapotranspiration of bare soil,vegetation and water surface,a calculation model of UWD based on the type of urban land use was set up.Considering the diversity and complexity of impact factors,the factors of water dissipation inside buildings and UWD were analyzed by applying the method of data mining,and probed into the characteristics of inherent relationship.The characteristics of UWD were analyzed at three levels: micro scale,unit scale and urban scale.The results showed that the internal water dissipation of the building was closely related to the function of the building.The water dissipation of the same function buildings had a good linear relationship with the populations,aera of the building,and the volume of water consumed water.Evaporation on the hardened ground depended on the number of rainy days and the volume of artificial sprinkling.The water dissipation intensity of residential and commercial land increased with urbanization,and the contribution rate of UWD on the social side increased at the same time.Water dissipation inside the buildings and evaporation of hardened ground are the important compoents of UWD,reflecting the urban dualistic water cycle significantly.At the urban scale,the regional comprehensive UWD intensity will decrease first and then increase from the natural state to the middle urbanization and then to the process of high urbanization.