Variation Of Urban Runoff Pollution Load Based On Land Use Change Simulation

Urban storm runoff has become one of the major sources of water pollution inChina in association with the rapid urbanization. The spatial evolution of urban land usereflects the urban development trajectory, as well as the profiles of urban resource useand environmental stress. Therefore, systematic quantification of the causal relationshipbetween urban land use and urban runoff pollution load is deemed of significance forurban runoff management as well as urban governance and planning.This study developed an Urban Runoff Load Model based on Urban Land UseChange Simulation (UNRUN), combing a Cellular Automata (CA) module and a StormWater Management Module (SWMM). A regional sensitive analysis method combininga HSY algorithm and a Latin sampling process was applied to the CA module, theSWMM module, respectively, and the UNRUN model as a whole. The key factorsaffecting urban runoff were thereafter identified. Multi-dimensional driving forces onurban land use change were quantified and coupled to develop transformation rules forconstructing the CA module. The SWMM module was operationalized via mapping theland use unit to urban watersheds.The UNRUN model was then applied to a case study on Sanya city in Hainanprovince in southern China. Local land use and runoff monitoring data were used forparameter identification and model validation. The results of regional sensitivityanalysis shows that various neighborhood and genetic control parameters are the mostsensitive ones in the UNRUN model, while the hydrology parameters in the SWMMmodule are moderately sensitive and all weighting parameters and interventionalparameters are less sensitive. It is remarkable that the sensitivity sorting sequence of theUNRUN model is significantly different from that of either CA or SWMM.The potential changes in urban land use and urban runoff load in Sanya werefurther projected using a scenario analysis method. The results suggest that theconstructed land areas, the urban runoff flux and the pollution loads would be mostintensified in the trend extrapolation scenario (BAU). Compared to the planningscenario (baseline), the ecological priority scenario proposes a less environmentally stressed city layout.