Document Type : Research Paper
university of tehran
Islamic Azad University
Population increase in Tehran metropolis led to Increase utilization of water resources and its following reduce the quantity and quality of water supplies around city and environs Watersheds. Hence, Surface water management should be considered efficient According to the needs of water supply quantitatively and qualitatively for Irrigation of green spaces, Street cleaning and other uses in the city along with other purposes such as Improving urban landscape and improve the quality of runoff production. Urban runoff control Save and reduce runoff volume by using of new approaches to control including LID and BMP On a local scale that it is very important In addition to cost-effectiveness as well as aesthetics. This mechanism is done by various Structural forms including Bioretention Systems that is led to guide Surface runoff for storage in a Small scale or in Underground which in these systems are distributed Throughout the region aimed at managing surface runoff so that cause to delay runoff Moving. The success of surface runoff caused the control by rainfall requiring the identification of sites has the potential to use this system. This research follows to find prone areas for using this system in Region 2 of Tehran that has been done by Using of fuzzy logic and expert opinions and in order to complete a the results of the study that is to study Zoning runoff according to different return periods in this area.
Materials and Methods
The sample in this research is Tehran 2nd District that is Located southwest of Tehran and its major use including Road, highway, Residential and green space. Given that a significant percentage of area covered by highway, the use of Bioretention Systems is an effective step in controlling urban runoff. A bioretention system receiving water from a light industrial catchment and a busy road was designed, built and monitored for changes in soil physics as well as hydrological and hydrochemical efficiency. Bioretention areas function as soil and plant-based filtration devices that remove pollutants through a variety of physical, biological, and chemical treatment processes.The soils in the bioretention system were designed to have high metal removal potential and high permeability to compensate for undersized bioretention volume. The inflow hydrograph was a series of sharp peaks with little baseflow, typical of runoff from impervious surfaces.
The steps of the research are showed in the following diagram
Fig1. Conceptual Diagram of Research
Discussion and Results
Positioningof Bioretention Systems were done by using of fuzzy logic and AHP in GIS and the final layer has been incorporated according to the classification of Priority areas and by movement directions and Units of the cumulative runoff. The final map shows that spatial priorities is related to Zones that have been Located in the eastern part of the region. According to The results of previous research, the greatest potential for runoff is related to Residential uses and Highway In the eastern part of the region (Highways) and the least potential is related to Steep parts of central and northern with green space use. This result is showing the importance of land use type the potential runoff Creation To the extent that makes ineffective the importance of important factors such as slope. When it rains in the Region 2 Tehran, Runoff do not drain toward the watercourse because Watercourse do not match on natural slopes and Compliance with the old thalweg. In fact, there is not a suitable synchrony between the natural drainage lines and Current network Watercourse and Watercourse will not be able to perform the task. This duty do urban symbols such as highways, streets, etc.
The results show that the conversion of highway network threats to Regional opportunities Free of any negligence and ordinary encounters that leading to increase natural hazards in urban centers is required. The final layer in the GIS software has been classified in accordance with local priorities and indicates the priority areas which are partially related to the eastern part of the region. According to previous results the highest potential for generation of runoff is related to residential and highway land use in eastern part of district, and lowest potential is in slope parts in central and north districts with green space land – use that should be management priority. Consequently, it is Indicating the importance of land-use in creating the potential of runoff to the extent that the important factor to affect the slope is ineffective. This would be possible by urban data integration and offer new approaches and Localize so-.called sustainable drainage systems that is strategy for management of surface runoff by using of Systems designed to collect runoff along with maintain ecological processes. The main purpose of this strategy in urban landscapes is to create a network in order to Imitation of the urban water cycle In order to artificially restore the natural cycle with low-impact development approach. Due to the impossibility to enter surface runoff to Network of urban wastewater Purification, It seems that accumulated runoff Management at best case in Bioretention Systems in Its scale is related to the system and Local access. So that final network has been determined from combining the appropriate places for building Bioretention Systems, Surface runoff Paths in each of sub-basins and Units of the cumulative runoff. As for to the point that every system offers Services offers on a local scale and it's around for irrigation of green areas, Street washing and other services. And considering this relation is gained on a regional scale and according to the Up-stream down-stream effects of sub-basins of final Network communication And it causes to revive natural cycle of urban water artificially by organized activities. Building structures and Equipment for Collect surface runoff in urban areas especially on Highways and urban roads will maintain water resources for green space in the long term and economic advantage. As for increasing growth of impervious surfaces city, the existence of clear guidance is necessary for local authorities and decision-makers in order to codify Necessary designs to more tendency towards urban data integration. And providing new approaches can be mu