فهرست مطالب مهدی صهبا

Green roof is one of the new approaches of the architecture and urban planning and derived from the concepts of sustainable development which can be used to increase the green space per capita, environmental quality and urban sustainable development. Applied usage of roofs could be considered as an optimized utilization of urban lands. The main objective of this paper is to study the role of green roofs as a strategy to improve urban environmental quality from the sustainable architecture perspective.
Initially, a questionnaire was designed on the base of experts’ opinions, including 22 questions. Then 30 experts in the field of urban planning and architecture were selected as the study sample. Considering architectural issues and urban sustainable development, questions were categorized according to three main scopes: 1. The effects of green roofs on the ecological, continental, environmental, and economic-cultural aspects, 2. The differences between intensive and extensive green roofs, and 3. The differences between the green roofs and common roofs. The Alpha method was used for the evaluation of the reliability, and 3 hypotheses were presented for analyzing the questionnaire.
The alpha factor was gained to be 0.727, showing that the questionnaire had a proper reliability. After analyzing the hypotheses, they were confirmed. This implied the great effect of green roofs on improvement of urban environmental quality from the sustainable architecture perspective. The results showed that totally 70-80% of experts declared that the green roofs had high importance in the improving the environmental quality and sustainable urban development. Indeed, green roofs are our connector with nature in designing and planning and can reduce the negative effects of buildings in local ecosystem and consequently reduce the energy consumption. Moreover, green roofs can have a determinative role in fluctuation of energy circulation in buildings and may play an aesthetical role for the residents of cities.

The objective of this research is to assess the contamination of Eshtehard aquifer using the concepts of carrying capacity and threshold. For this purpose, on the basis of continuous measurement of groundwater level of 16 wells in the study area, the isolevel map of groundwater was prepared, then 14 resources including 9 wells and 5 aqueducts were selected and two sampling were carried out in 2010- 2011. After chemical analysis of samples, the maps of EC and NO3 were drawn in GIS. The average annual drawdown of water table was calculated to be 0.69 meter using the annual hydrograph, which was indicative of the over exploitation of the aquifer. Moreover, the results showed that the EC and Nitrate concentration was high, for they passed the thresholds in most parts. Thus, it would be a serious threat to the aquifer. According to the concepts of threshold and carrying capacity, groundwater has been exploited over the carrying capacity of aquifer in most parts and since the exploitation and use of water in agriculture is the major consumption in the study area, the residual of chemical fertilizers has been kept in the soil and permeated to the aquifer by the agricultural water which leads to the increase in Nitrate.

Eshtehard plain has been subjected to over exploitation of ground water in recent years and disregarding to the quality of ground water was led to pollution and salinity of aquifer. In this research the spatial distribution of some of the qualitative properties of ground water such as Electrical Conductivity, the concentration of sulfate and chloride and finally the drawdown of water table are studied. For this purpose, initially on the base of existing data in the field of water table during 1376-90 years, the graph of long-term changes in water levels in the aquifer is plotted and the average annual drawdown is calculated 0.69 meter. Also on the base of continuous measurement of groundwater level of the 16 wells in the study area, the map of iso-level groundwater is produced for the year of 1389-90. Then, 14 resources including 9 wells and 5 aqueducts are selected and two sampling is done in the 1389-90. After chemical analysis of samples, the concentrations of cations and anions suchas sulfate and chloride are determined and the maps of EC, SO4 and Cl are drawn. Also annual comograph of aquifer is produced using arithmetic average for 8 years period between 1382-90. Results showed that owing to limited recharges of the study area, unbalanced exploitation is led to drawdown of water table and changing the flow path in the aquifer. On the base of annual hydrograph, the average annual recharge is 29.7 m cubic meter and average annual drawdown of water table is 0.69 meter which shows the over exploitation of aquifer. The maps of EC, SO4 and Cl indicated that brackish waters has been spread from the north of plain to the southern parts of plain so the EC is increased from 4258.1 micromoss in the 1382-83 to the 6733.9 between 1389-90. Given that in the northern part of plain, the concentration of chloride is high, the infiltration of brackish waters with high chloride has had greater increase than sulfate. So the gradual salitinization of groundwater and the spreading of saltwater front into the fresh water front can be seen in this area as one of the consequences of continuous drawdown of water table or over exploitation. Therefore continuation of the current trend does not draw a clear vision for the plain.