Effective Factors on Urban Run-off Water Qquality Considering Daily Spatiotemporal Crowd and Urban Land-use

Urban run-off water quality investigation was carried out to find effective factors based on urban land use and crowd dynamics. Run-off water samples were taken after a rainfall from urban drainage in three different urban land uses in the Tehran metropolitan. Tehran, the capital of Iran, faced with increasing freshwater demand and water resources limitation due to the rapid growth of population. In this paper, urban runoff water quality and local recycling potential are considered as a sustainable solution for water supply of Tehran. Three districts in different land uses were selected as main case study in region 6 at Tehran. Urban land use situation and in-site population has been recorded simultaneously. Crowd daily dynamics investigated base on land uses and public transport statistics. All urban patterns and circumstances were quantified by indices for comparative analysis with water quality variables. Multivariable regression analysis based on least square errors applied on all data finding out the relation between effective factors and independant variables. Prato graphs also illustrated the influenced levels of every individual factors. Field survey, administrative study district includes university campus, some national offices and commercial complexes. Green space study district includes a big park and some public urban spaces and urban squares. Residential urban land use study district includes some residential blocks and local apartments. Some water quality variations were measured in-situ via portable spectrophotometry instruments. Results declared crowd dynamics is not the main factor but the public transport which is designed by daily immigration and temporal population has significant impacts on urban run-off water quality in rush hours. Some water quality variables are defecating due to discharge of drains in high velocity reaches. Overall urban land use of each region had effects of water quality variables’ fate. Reaeration process that has major influence on pollutants’ fate affected by dimensions of drains and flow kinematic parameters. Chemical water quality variables such as hydrocarbons originated by public transport emissions. Physical water quality variables like water total solids are significant in region where dominated by green space land use.

Results showed that urban land use could be main factor in urban run-off water quality as stationary source but daily immigration and population dynamics considered as spatiotemporal source of pollution. The portion of each source in total pollution is depend on rainfall intensity, time of event and days in week. It seems stationary source is more controllable than stationary source.