Investigating the effect of urban elements and urban land use changes on runoff quality A case study of Tehran metropolis

The present study is an interdisciplinary study and has investigated the type and extent of the impact of different urban land use on the quality of surface runoff. The purpose of this study was to create a practical relationship to estimate the quality of urban runoff through different types of urban land uses. The data collection tools in this study were documents, documents, field observation and sampling and their laboratory measurement. After field study and initial sampling in area six and concluding that there is a direct relationship between land use and runoff quality, three metropolitan sub-basins were selected and then each of these sub-basins was divided into more detailed cumulative sub-basins. So that the exit points of each sub-basin was the entry point of the next sub-basin downstream. For the main sampling, which was performed in three simultaneous shifts with three rainfalls, the impact and changes in urban land use were emphasized. The results show a close correlation between urban land use and runoff quality categories and changes in the amount of runoff quality parameters in specific land uses indicate that demographic characteristics and land use are the main sources of urban runoff pollution. According to the results of this study, the risk of lead in Tehran urban runoff with its cumulative trend is one of the most difficult and important pollutants that should be considered in the quantitative and qualitative management of urban runoff and its reuse. Also, the layout and use of urban lands is the most important indicator affecting the quality of urban runoff and there is a need to implement proper programs to control changes in urban land use in maintaining the balance of the aquatic ecosystem.