جستجوی مقالات مرتبط با کلیدواژه « بام سبز » در نشریات گروه « محیط زیست »

Due to the rapid growth of cities and increasing urbanization in recent decades, urban runoff and flood damage is one of the most important and fundamental issues in the field of urban management. The purpose of this study is in the first part; Quantitative simulation of floods caused by rainfall for region 4 of Tehran for the years 1349-1396 using the SWMM model.

The simulation was performed for six-hour showers with 2, 5 and 10 year return periods for 12 hours. In this research, two projects of the best management strategies (BMP) under the garden and green roof climate scenario and a combination of both scenarios to control the maximum runoff in terms of quantity and finally their efficiency in reducing the total volume of runoff out of the basin, is studied. In the second part; Evaluation and analysis of resilience caused by urban floods in the 9 districts of Tehran's 4th district in four dimensions: socio-cultural, economic, managerial-institutional and physical. This section is applied in terms of purpose and in terms of survey and descriptive-analytical methods. The statistical population of the study is the total citizens of Region 4, of which the sample size was calculated using the Cochran's formula of 384 people. According to the obtained results, the third scenario (combining the first and second scenarios) will have the greatest impact on reducing the flow depth and flow rate in the entire surface water collection network.     

Findings of the research in the field of resilience assessment and analysis showed that District 5, District 4 of Tehran is the most desirable district and District 1 and District 8, 4 are the most undesirable in terms of resilience against urban floods.

Districts 4 and 9 are ranked last in terms of resilience-cultural, economic, managerial-institutional), which indicates that this area is weak in some cases, which is to reduce the level of vulnerability. to be noticed.

Urbanization in the world is increasing and the world's urban population is becoming denser in cities. One of the effects of urbanization is to increase the percentage of impermeable surfaces in these areas. Today, many important cities in the world, to reduce the effects of their city development on the quality and quantity of runoff, pay attention to the concept of sustainable development and use modern green management technologies, including the Best Management Practices (BMP) and Low Impact Development (LID) methods. Green roof is a multi-layer system that covers the roof and balcony of a building with vegetation and absorbs and retains part of the rain, and affects the processes of evapotranspiration, treatment, volume and intensity of runoff peak runoff. Reduces the dimensions of the downstream drainage system and improves the quality of the climate, preserves the beauty of the city and prevents wastage of building energy.

This study was conducted as a field experiment in the Faculty of Agriculture, University of Zanjan. The test period was from April to August 2018. In this study, the effect of using superabsorbent (zeolite) on water uptake and retention, maximum and minimum runoff volume, drainage volume, sedimentation and runoff time of rainfall at rainfall intensities of 35, 45, 55, 65 and 75 mm/hr on a green roof with a slope of 5% has been studied in cold dry climates.

Accordingly, with increasing rainfall intensity, runoff volume also increases and runoff volume in barren soil is more than other treatments and its downward trend is soil containing 1% zeolite, soil containing 3% zeolite and cultivated soil, respectively. Also, the volume of drainage increased with increasing rainfall intensity and the highest amount of drainage volume belongs to barren soil. Sediment measured in runoff also increases with increasing rainfall intensity in treatments other than grass treatment.

Barren soil has a very high runoff volume due to the closure of its surface layers and clogged pores. Addition of zeolite to the soil significantly reduced runoff volume and retained more water than barren soil. The rate of soil erosion was high in 1% zeolite and the lowest rate of erosion was in grass. In barren soils, infiltration is low, and runoff flows rapidly, but with the addition of zeolite to the soil, runoff start time is 3 % longer.

The geographical location of Tehran, its position among the Alborz mountains and the large number of vehicles in circulation are among the factors that have endangered the comfort of residents and brought chaos to urban life. These issues have doubled the need for tranquility and access to nature. Due to the high value of land, the use of unused surfaces, including buildings’ roofs, is an appropriate way to expand green spaces. In this regard, the present study was conducted with the aim of investigating the economic and economic-environmental justification of the construction of a green roof in District 9 of Tehran Municipality. For this purpose, the Discrete Choice Experiment method is used for green roof evaluation. And also, three criteria of benefit to cost ratio (BCR), net present value (NPV), and internal rate of return (IRR) are used in order to accept or reject the investment plan in the framework of this analysis.
According to the results of calculating the willingness to pay, the highest amount that people are willing to pay is equal to 6.2 million rials per square meter and the lowest amount willing to pay equals to 4.69 million rials per square meter. It can also be said that people are willing to pay an average of 5.44 million rials per square meter for a green roof. Meanwhile, the highest willingness to pay with a figure equal to 6.2 million rials per square meter is related to the percentage of greenery more than 60% and the lowest willingness to pay is related to the percentage of greenery between 30% to 60%, which is equal to 4.69 million Rials per square meter. It is worth mentioning that due to the insignificance of the coefficients for the characteristics of the implementation method and the negation of the coefficients of the type of coating, these coefficients are not included in the analysis and as a result the willingness to pay is equal to the willingness of individuals to pay for green roof percentage. Finally, the results of economic evaluation indicators were calculated. These indicators are first calculated from an economic point of view, meaning that only the costs and economic benefits of a green roof are taken into account. Then, by introducing environmental benefits, the construction of a green roof has been examined from an economic-environmental point of view. From a purely economic point of view, the numbers related to financial indicators indicate that if we consider only the economic benefits and costs of building a green roof, this plan in this region is not justifiable. So that in the period under review, the net present value for this numerical region is less than zero and the internal rate of return is not defined for it. But these numbers improve with the introduction of environmental benefits. So that in the state of maximum willingness to pay, the net present value has reached 14.385 million rials. In this case, the internal rate of return reaches 61%. Taking into account the average willingness to pay the net present value reaches 11.349 million rials. In this case, the internal rate of return reaches 53%. Taking into account the minimum willingness to pay, the net present value reaches 8.353 million rials, in which case the internal rate of return will reach 46%.
The results showed that the construction of a green roof was unjustifiable only in terms of economic benefits and costs, so that the net present value was -10.385 million rials per square meter, which is less than zero, indicating unjustifiability, and therefore the internal rate of return is not defined for it. By adding environmental benefits and costs, taking into account the maximum willingness to pay, the net present value reaches 14.385 million rials. In this case, the internal rate of return is equal to 61%. Taking into account the average willingness to pay, the net present value reaches 11.349 million rials. In this case, the internal rate of return is 53%. Taking into account the minimum willingness to pay, the net present value reaches 8.353 million rials, in which case the internal rate of return will reach 46%. According to the theoretical foundations of the field of economic evaluation, the positive net present value, higher domestic rate of return than the current interest rate in the country (bank interest rate) and greater than one cost-benefit ratio, make a project economically justifiable, which Considering only two benefits (beauty, recreation, health and economic added value) among all the benefits of green roof, in District 9 of Tehran Municipality, this project is purely economically unjustifiable and is justified by the inclusion of environmental benefits. According to the results of collecting the questionnaire in the section of individual-economic attitude, the majority of people believe that in Tehran there is no culture of using green roofs collectively, so the need for culture in this area is felt and it is necessary to negotiate and consult with organizations such as The Environmental Protection Organization and the municipality should be trained and cultured in the field of using these common spaces. Also, the majority of people believe that using this technology is costly and its use requires the support of government organizations and the existence of incentives. Therefore, it is suggested that the district municipality take action through incentive policies in areas such as toll collection, completion of work, obtaining permits and density.

Today، thinkers and environment and urban designers are concerned about the inevitable growth of metropolises trying to propose some methods to moderate its effects. This has resulted in some patterns that reduce its disturbing effects along with improving the quality of life in these cities. Mankind is aware of the value of the sustained spaces and is trying to answer his needs، holding permanent horizons in view. These efforts resulted in patterns of sustained metropolises، a steady and dense city. But this human achievement is not، like his other achievements، without a consequence. Research shows that increase in the density of the city disturbs the balance in the illumination of the city spaces in addition to damaging the heat transfer between the earth، buildings and the atmosphere. It also affects the internal heat of the city، increases the temperature and influences the velocity of the wind. In another view. Higher density means a decreased opportunity for building green spaces resulting in a demolished desirability of the spaces. It also results in crowdedness and brings about air pollution. As flat planes that occupy a large share in such dense cities، roofs are of great importance to us. Good effects of green patterns on improving the climatic conditions like moderating undesirable consequences of dense cities decrease of heat and sun waves، the velocity of the wind and pollution posits a good potential in plans. Bruce''s non-hydrostatic model is used in this research to simulate a site in three conditions of its current state، increase in density and greening the roofs. Then effects of rooftop greening especially on air temperature and wind velocity are studied. Finally a comparison is made between the results of this research and other researches done in this field achieve a broader insight into how greening the roofs may affect low-scale environmental conditions specially in dense cities by using plants in higher scales. There is also a discussion about other benefits of this approach to show its value in architectural and urban projects.

Today، thinkers and environment and urban designers are concerned about the inevitable growth of metropolises trying to propose some methods to moderate its effects. This has resulted in some patterns that reduce its disturbing effects along with improving the quality of life in these cities. Mankind is aware of the value of the sustained spaces and is trying to answer his needs، holding permanent horizons in view. These efforts resulted in patterns of sustained metropolises، a steady and dense city. But this human achievement is not، like his other achievements، without a consequence. Research shows that increase in the density of the city disturbs the balance in the illumination of the city spaces in addition to damaging the heat transfer between the earth، buildings and the atmosphere. It also affects the internal heat of the city، increases the temperature and influences the velocity of the wind. In another view، higher density means a decreased opportunity for building green spaces resulting in a demolished desirability of the spaces. It also results in crowdedness and brings about air pollution. As flat planes that occupy a large share in such dense cities، roofs are of great importance to us. Good effects of green patterns on improving the climatic conditions like moderating undesirable consequences of dense cities decrease of heat and sun waves، the velocity of the wind and pollution posits a good potential in plans. Bruce’s non-hydrostatic model is used in this research to simulate a site in three conditions of its current state، increase in density and greening the roofs. Then effects of rooftop greening especially on air temperature and wind velocity are studied. Finally a comparison is made between the results of this research and other researches done in this field t achieve a broader insight into how greening the roofs may affect low-scale environmental conditions specially in dense cities by using plants in higher scales. There is also a discussion about other benefits of this approach to show its value in architectural and urban projects.