Search

Gorgan Bay is the largest bay of Iran in the waters of the southeastern shores of the Caspian Sea. In this research, the effect of rivers on the salinity of Gorgan Bay in a period of one year has been investigated using the Mike 21 model on unstructured meshes and under two scenarios of the presence of rivers and the absence of rivers. The results of the research showed that the salinity level in the bay has an increasing trend from east to west in most seasons of the year and the average salinity was 16.4 psu in 2011. The salinity values in Gorgan Bay are closely related to the annual rise and fall of the water level in the Caspian Sea. Based on this, during the hot season of the year and the increase in the water level, the amount of salinity in Gorgan Bay decreases, and vice versa, the amount of salinity increases in the winter season along with the decrease in the water level. The salinity level in the western part of the bay with the maximum salinity of 25.6 psu was modeled more than the other areas due to the increase in water exchange time. From the beginning of autumn to the end of winter, due to the decrease of the water level and the movement of the water masses of the bay from the west to the east, the salinity values in the deep areas of the bay during this period compared to other seasons with a maximum of 16.5 psu increases. The entry of water from the sea into the bay and the evaporation process has the greatest effect on the salinity changes of the bay. The effect of rivers on the salinity changes of the southern coast of the bay has been low. Among the 13 rivers entering the bay, only the Qarasu River has had a larger area of influence (up to a distance of 500 meters from the estuary) compared to other rivers due to its higher water flow. In general, the input of rivers had the least effect on the salinity changes of Gorgan Bay, and the contribution of rivers to the salinity changes of Gorgan Bay was less than two hundred percent in 2011. [ABSTRACT FROM AUTHOR]

Materials and Methods: This descriptive study was conducted in the spring of 2019 from the water sample of Abbasabad River in 17 stations. In this study, the optimized and modified method of methylene blue was used to measure the amount of LAS. After preparing the samples using the methylene blue method, the organic phase of the sample was separated and the LAS absorption was read using a spectrophotometer at a wavelength of 650 nm, and the LAS concentration was calculated using the obtained absorption and calibration curve. LAS health risk assessment was performed by calculating the risk quotient (RQ) index. Results: The results showed LAS concentration ranged from 0.11 to 2.65 mg/L with a mean of 1.25 mg/L. Based on field observations, the entry of untreated wastewater into the Abbasabad River was the main cause of the high concentration of LAS. The results of the health risk assessment showed no risk in different age groups. Conclusion: The results show that at this level of LAS concentration in the Abbasabad River of Hamadan, there is no significant concern for human health. However, it is worthwhile to prevent the entry of untreated or inadequately treated wastewater into valuable water resources. [ABSTRACT FROM AUTHOR]

The aim of the present study was to estimate growth and mortality parameters and length-weight relationship of Barilius mesopotamicus populations in difrent Iran basins. For this purpose, 460 fish specimens from Diala, Jarrahi, Karun, Karkheh and Bushehr basins and subbasins, including Zardmashin, Aalaa, Jarrahi, Dez, Shur, Meymeh, Changooleh, Kangir, Doyrej, Ahram, Zohreh, Kheirabad, Karzin, Shahpur and Darolmizan rivers, were sampled. Total length, fork length and standard length were measured by a digital caliper (cm) and total weight by a digital scale (g). Also, some scales were prepared and studied for age determination. The length-weight relationships showed that population from Bushehr, Jarahi, Karun and Dila, had negative allomeric growth pattern while Karkheh population had an isometric growth pattern. The highest estimated total length and weight was 9.2 cm and 5.4 g. Age of the fish was between 0+ and 2+. The highest asumptetic total length was observed in Diala basin with Bertallanfy equation of Lt= 9.22[1-e-1.3(t+0.07)]. The condition factor was about 0.5. Considering body indices, Bushehr, Jarahi, Karun and Diala had a better condition, and Karkheh population had a lower index, probably indicating a poorer condition in this river. [ABSTRACT FROM AUTHOR]

Water supply at a desired rate at any time to meet the water requirements regardless of river discharge must be considered in the general design of intakes provided that the needs do not exceed the river flow. Due to the lack of necessary information in this field and the importance of sediment transport to the lateral intakes at river bends, this study aimed at understanding the mechanism of this phenomenon. To this end, the combined effect of convergence and divergence in lateral intakes on the sediment transport was investigated. According to the results, the diversion discharge to the intake was increased by converging the laboratory flume. By narrowing and converging the end of the flume, the diversion discharge was increased further, so that as the flume was converged to the size (b/B) of 0.75 and 0.5, the diversion discharge to the intake was increased by 13.6% and 75%, respectively. This could be connected to narrowing, flow obstruction and backflow to the intake. In contrast, different results were found by diverging the flume. In other words, the inflow to the intake was decreased by diverging the flume. As the flume end was diverged, the diversion discharge was decreased further. By diverging the flume to the size (b/B) of 0.75 and 0.5, the diversion discharge to the intake was decreased by 21.9 and 31.8%, respectively. The average diversion discharge to the intake at 30, 60 and 90º was 13.2, 15.2 and 11.5%, respectively. By converting the flume to the size (b/B) of 0.75 and 0.5, the diversion sediment to the intake was increased by 18.5 and 71.4%. In contrast, by diverging the flume to the size (b/B) of 0.75 and 0.5, the diversion sediment to the intake was decreased by 35.4 and 49.9%, respectively. [ABSTRACT FROM AUTHOR]

Rivers have different patterns along their path, and understanding these patterns could help researchers understand and predict the responses of human activities and natural factors of the river. In addition, in the morphological analysis, the flow power is one of the most important parameters. Therefore, the purpose of this study was to analyze the channel form and to evaluate the river power in different return periods as well as to estimate the shear stress in the Givi Chay River using Landsat 8 images, topographic maps, geology, hydrological, and field data. Morphological and hydrological indices, as well as methods for analyzing the total river power, river specific power, and shear stress, were used to achieve the purpose of the study. The calculation of the bending coefficient showed that the river pattern was sinusoidal in the first and third intervals and was meandering in the second interval. According to the central angle characteristics, the first and the second intervals were in the highlydeveloped meandering form and the third interval was in the developed meandering form. Also, according to the results of the study, the highest amount of the total river power was in the first interval at the 4th, 5th, and 6th sections. The specific strength of the river was high in the third intervals and the 2nd, 1st, 5th, and 6th sections. At present, due to the low strength of the lithological formations in these sections, the erosion of the riverbed is observed in these sections. The lowest specific power was due to the high river width and low bed slope at sections 12 and 13. The highest amount of shear stress was in the first interval in sections 5, 6, 2, and the lowest shear stress was in sections 12 and 13. In general, channel formation and channel dynamics in the Givi Chay River were influenced by discharge, lithological resistance of the riverbed, and human interference (encroachment on the riverbed, construction of bridges, and dumping of construction waste and debris). [ABSTRACT FROM AUTHOR]

In terms of geographical location, Mashhad metropolis has spread all over a wide alluvial plain. Locating between the Kopeh Dagh and the Hezar Masjed sedimentary heights and the Binalood igneous heights has led to the creation of specific morphology for the Mashhad alluvial plain. In the northern part of the city, the Kashafrood River drains all the rivers of Mashhad plain. And the Binalood heights drainage rivers run through the city of Mashhad and drain into the Kashafrood River. The city's physical development over the years has led to a change in the morphology of the city's rivers and in some ways, high-rise buildings are built on the abandoned river-beds and the probability of occurrence of geomorphological hazards has increased. In this research, the location of Mashhad and its physical growth, which led to the destruction and change of river's morphology, has been studied by using 1353, 1359, and 1390 satellite images and the old maps of Mashhad and geological and topographic maps in different periods. The purpose of this research is to investigate the comparative situation of rivers with urban built canals and the resulting risks. In this regard, it has been found that many urban canals are designed without regard to the natural morphology of the rivers and also regardless of the flow capacity of the water. The natural type of the river-beds has been sedimentary deposits including shale, clay and sand and rock along with the forms between the rifting of the rivers, but the canals have thick concrete walls and direct paths. [ABSTRACT FROM AUTHOR]

Morphologic study of rivers is very important in stabilization and determination of river boundaries. Dams are structures which have the highest effects on river morphology. Studies of river changes are usually time-consuming and possible only in the long-term timescales. To detect these changes, using satellite images over specific time periods and cartographic methods are useful. In the present study, morphological changes of Zayandehrud River, at downstream of Zayandehrud dam, between hydrometric stations of Sad-e-Tanzimi and Pol-e-Zamankhan, were investigated through 7 series of Landsat satellite photos from 1980 to 2015 by applying ENVI 4.8 and Arc GIS10.2 software. Based on the results, the method of enhancing the contrast as saturated linear expansion, along with the edge enhancement filter, was found an appropriate method for determining the boundary between land and water. In the next step, the river path was entered into Arc GIS 10.2, and geometric parameters of the river such as wavelength, sinuosity ratio, central angle and radius of circle tangent to the curve were determined. Also, statistical analysis of geometric parameters was performed by applying SPSS software. Results showed that from 1986 up to now the sinuosity ratio has risen from 2.14 to 2.38, while the radius of river curvatures and wavelength of meanders have decreased by 5% and 11.4%, respectively. Overall, the river has decreased its arcs' curvature and bends have been moved to downstream. The main cause of this phenomenon is constructions in the river borders (e.g. in Markadeh and Cham-Kaka), which have disturbed the natural situation of the river. In Cham-Jangal, Cham-Khalifeh and Cham-Ali regions, due to the increase in slope and improper vegetation cover, bank erosion has reached to its highest degree. In general, although flood events have been contained by Zayandehrud dam, yet the river has great potential for erosion in the meandering sections. [ABSTRACT FROM AUTHOR]

Accurate estimation of ET0 in any region is very important. The aim of this study is to compare and calibrate the 20 empirical methods of estimating evapotranspiration (ET0) based on three categories in monthly timescale at the Urmia Lake watershed. These categories are: 1) temperature-based models (Hargreaves (HG), Thornthwaite (TW), Blaney-Criddle (BC), Linacre (Lin)), 2) radiation-based model (the Doorenbos-Pruitt (DP), Priestly-Taylor (PT), Makkink (Mak), Jensen-Haise (JH), Turc (T), Abtew (A), McGuinness-Bordne (MB)) and 3) mass transfer-based model (Meyer (M), Dalton (D), Rohwer (R), Penman (P), Brockamp-Wenner (BW), Mahringer (Ma), Trabert (Tr), WMO and Albrecht (AL)). For this purpose, the information of 10 synoptic meteorological stations during the period of 1986-2010 was used. Results from the above mentioned methods were compared with the output of the FAO Penman-Monteith (PMF-56) method. Performance of the methods evaluated using the R2, RMSE, MBE and MAE statistics. The best and worst methods of each category were determined for the study area. The best methods of each category were calibrated for the area under study. Results indicated that there is a significant difference between the results of selected methods of each category and the PMF-56 method. Performance of the selected methods remarkably increased after calibration. Among the temperature-based group, the HG method having the median R2 value of 0.9597 was recognized as the best method. After calibration the medians of RMSE, MBE, and MAE were 72.09, 3.14 and 10.70 mm/ month, respectively. After HG, the Lin and BC found to be the best second and third methods in the study area. The TW showed Large error, therefore, it was not a suitable method for ET0 estimation in study area. Among the radiation-based group, the DP model was selected as the best method in the study area. Furthermore, the median of R2 values was 0.982. In this method, the medians of RMSE, MBE and MAE after calibration were 7.89. -0.62 and 6.03 mm/month, respectively. Following DP, the PT method was recognized as the 2nd best one. The methods namely M, JH, T, A and MB were put in the 3rd to seventh rank of the radiation category. Finally, among the mass transfer-based group, having R2=0.8945, the Meyer method was selected as the best method of this group for the study area. In the mentioned method (after calibration) the medians of RMSE, MBE, and MAE were 21.8, -8.7 and 17.3 mm per month, respectively. From mass transfer based group, the D method was found as the second best method in the study area. The methods namely R, P, BW, Ma, Tr, WMO and A were ranked 3rd to 7th, respectively. In general, the performance of radiation based methods was superior than others in Urmia Lake basin. Temperature based methods and mass transfer based methods were ranked second and third, respectively. Further examination of the performance resulted in the following rank of accuracy as compared with the PMF-56: DP (Radiation based), HG (Temperature based) and Meyer (Mass transfer). In general, it can be concluded that after calibration the DP method is suitable to estimate reference crop evapotranspiration among 20 selected methods in the Urmia Lake basin. [ABSTRACT FROM AUTHOR]

Introduction & Objective: Rivers are one of the main water supply resources for various uses such as agricultural, industrial and drinking purposes. As population and consumption increase, monitoring of rivers water quality becomes an important function of environmental management field. Because Darreh-Morad Beyg river of Hamadan is a water supply for different purposes and many pollutants are discharged in it, its water quality assessment seems necessary. Zoning of pollution and depicting a detailed image of surface water resources quality using geographic information system (GIS) are the key factors for the better management of these resources. Materials & Methods: This research is a cross sectional- descriptive study and river water samples were taken for 7 months from 6 sampling stations on the length of the river. Biochemical oxygen demand (BOD), electrical conductivity, dissolved oxygen (D.O.), pH, fecal coli form, nitrate, temperature, phosphate and total solids were determined in the samples. Obtained data were analyzed by national sanitation foundation water quality index (NSFWQI) and the river was zoned using GIS software. Results: Results of the analyses by NSFWQI showed the best water quality for station 1 and the worst water quality for station 6 with scores of 62.78 and 27.49, respectively. Conclusion: The NSFWQI is a suitable index for zoning of Darreh-Morad Beyg river. Monitoring of physical, chemical, bacteriological quality parameters and using water quality index in various sampling stations are used in the assessment of water pollution. It also helps the officials to correctly decide about the water uses for different purposes.

Rivers are dynamic features of landscapes, whose characteristics vary over time and space related to changes in environmental controls and human impacts. The longitudinal extent of changes, their variability with time, how response the tributary to occasions, the kind of changes in mainstream cross-section, disturbance on slope in semi-arid area, are important from hydrological and geomorphological aspects. Dams, as man made structures, have major impacts on river hydrology, primarly through in the timing, magnitude, and frequency of low and high flows, ultimately producing a hydrologic artificial regime differing significantly from the pre-impoundment natural flow regime. Despite the profiles of dams on river regulation for water resources management, they create artificial flow regimes downstream and interrupt the transfer of sediments from headwater source area. These changes are started on acts of the fluvial processes at below of dams and caused adjustments of channel form. For study of effects of dams on upstream and downstream of semi-arid catchments, Gharanghou's catchment is selected. This catchment is located on the eastern slopes of Sahand Mt. This paper emphasizes the downstream effects of Sahand's dam on Gharanghou river, on the sedimentation rate of dam and also the effects of dam on downstream geomorphology. For assessing of rate of erosion, amount of sediment, evaluated method and GIS have been used then produced map of suitable area for erosion, sedimentation and landslides. The mapping is often performed through the identification and analysis instability factors. For mapping, firstly distribution map of factor produce and digitized factors then analyzed by bivariated methods and the next stage, weighted to factors and final produced hazard donation map by using Arc/View. This map shows upper part of Gharanghou's catchment erosion is critical and about of all products of erosion processes and materials of resulted by the landslides occurrence, remove into streams and the final stage, deposit in the lake of dam .The predictions show that the construction of dam will changed the longitudinal and cross of Gharanghou river's bed, rate of degradation and aggradations in Gharanghou catchment.

We analyzed the physico-chemical properties of estuarine water in Mazandaran Province Rivers (Shirood, Tonekabon, Larim, Tajan, and Goharbaran) during release of fish fingerlings in spring and summer 2000-2001. Water temperature, pH, DO, BOD5, TSS, T DS, Cl-, P043-, NH4+, NO2- and hardness were determined for 52 samples. The results showed the present condition of rivers Shirood and Tonekabon to be suitable for release of fish fingerlings and classified them as AA to A. Ranking as class C, rivers Larim, Goharbaran and Tajan were found unsuitable according to EPA standards, due to agricultural water extraction and improper land use development.

The streams and river valleys of southern hillside of Alborz Mountains have created a special geographical and topographical situation for Tehran city. The rigid and confined approach in confronting river valleys of Tehran in development plans of 1968 has ignored their structural role in providing a city life. It has changed these rivers into a disposal channel for surface water, sewage and a dangerous spot in Tehran city. In master Plan of Tehran (2006), potential river valleys in shaping and defining the spatial organizing of tourism zones Tehran was on the agenda of urban management. Kan River Valley was assigned a tourism element of the city and and an organizing plan for the river was legislated. Javanmardan Park along Kan River valley, located between Hemmat and Hakim highways, within the 5th and 22nd district, was projected and implemented as a product of these policies. Today, after more than 3 years of implementation, the questions on transformation of this significant project into one of the worst parks is still queried. Why a project on this scale with a special emphasis of upstream documents and urban management happen to fail in the end? Why with regeneration aims of river valley, this project is not only successful in attracting audiences, but also changing to a factor in the destruction of the natural and cultural identity of the river valley? This article explains the reasons why Javanmardan Park ignored the primary purposes of organizing and generation based on existing documents and the process of definition, planning, design and implementation. The gap between the objectives and strategies outlined in the organizing plan for Kan River valleys in local and thematic master plan of 2006 and organizing plan of Kan River valley and its surrounding by Armanshahr consulting engineers and major and minor policies of Atak consulting engineers as the major plan of this project are mainly discussed in this paper. Having compared the policies and purposes of upstream plans in organizing of Kan River valley and transforming it into a tourism zone of Tehran city and its obtained results in "Javanmardan Iran", two main factors are recognized for failure of project definition (Maintaining the natural quality of the valley as one of the most important elements of the city and creating personality, identity and visibility alongside the river). The first factor counts for lack of understanding of consultant designers in recognizing landscape values of the site and landscaping elements of Kan river valley while the second one roots from lack of sufficient technical experience in the design and implementation of landscape architecture in the river bed. While utilizing the river valley potential and generating a tourism zone was primarily planned in the early stages of development and project definition and management. In fact, the designers' impose landscape and non-landscape identity while changing the valuable natural landscape; a landscape which was aimed for regeneration and conservation. [ABSTRACT FROM AUTHOR]

Background and purpose: Using water quality indices is one of the methods for checking river's water quality. NSFWQI, is the most widely used among water quality indices. This study aimed to evaluate the water quality in Dohezar river, Tonekabon, using NSFWQI. Materials and methods: In this study, sampling was performed during 6 months (3 month with low level of water and 3 months with high level of water) in 6 selected stations along the river. Quality parameters included temperature, dissolved oxygen, biological oxygen demand, PH, nitrate, phosphate, total dissolved solids, turbidity, opacity, and excremental coliform. Data was analysed applying NSFWQI and finally river route was zoned in different sections using GIS. Results: Compared to drinking water and surface water quality standards, apart from opacity parameter, which was not in permitted range in up-stream and mid-stream, the other measured parameters in both low and high-level of water periods in all stations, were in acceptable range. Conclusion: According to the results obtained from NFSWQI in Dohezar river, on low-level of water periods, water quality in up-stream, mid-stream, and down-stream were in acceptable range (71-90). In high-level of water periods, water quality was in good range just in up-stream but mid-stream and down-stream water qualities were in average range (51-70). Due to the river's high flow and limited influx of contaminants, most contaminators were associated with aquaculture farms. [ABSTRACT FROM AUTHOR]

Zayanderoud Basin is one of the important agricultural areas in country level because of climatic variety and resuscitative water of Zayanderoud River. Since frost phenomenon especially late spring frost incurs great damages on fruit trees and agricultural products of this region, it is necessary to study frost in this basin.In this research, the intensity of frost during cold period and spring season in Zayanderoud Basin in five thresholds: mild (0 to -5 °C), moderate (-1.5 to -10 °C), strong (-1.10 to -15°C), very strong (-1.15 to -20 °C) and extraordinarily strong (lower than -20°C) was studied using daily minimum temperature statistics of 13 meteorological stations during 16-years statistical period (1992-1993 to 2007-2008). Frequency zoning map of different frost intensities was also drawn in ARC MAP environment. The results of research show that all studied stations of Zayanderoud Basin experience mild to very strong frost during cold period, but the extraordinarily strong frost only is occurred within elevated regions (above 2000 m). In spring season, mild frost is occurred in until late Farvardin month and within elevated stations until third decade of Ordibehesht and moderate frost is only occurred within 2000 m stations and above in Farvardin month. Strong frost is only occurred in the studied north-western region. According to zoning maps, north-western Zayanderoud Basin is hazardous in terms of the frequency of occurrence of different frost intensities. [ABSTRACT FROM AUTHOR]

The basin area of the Furk and Darmian river is located in northern-east of the Southern Khorasan province. The whole area was 11137 hectares. The area is mountainous with mild weather and dry climate and the average precipitation is about 250 mm per year. In this study, 268 species belonging to 47 families were investigated and 194 genus were identified. The Asteraceae family with 44 species and 34 genera was the largest family in the area. The largest genera were Cousinia with 6 species and Astragalus and Ephorbia with 5 species.The largest life forms in the Darmian area belong to Therophytes with 43% and Hemicryptophytes 37%, Phanaerophytes 9%, Chamaephytes 6%, Bulbous Geophytes and Rhizomatous Geophytes each with 2% and Tuberous Geophytes 1%. [ABSTRACT FROM AUTHOR]

Tehran's River Valley has had positive effects on the environment and it has played an important role in strengthening a sense of place and identity as a natural ecosystem of the city and as a place for social events. Expanding Tehran development along the valley has led to creation of the most important natural organs in the physical structure of the city. The invasion of construction and the built fabric of the city to the River Valley have resulted in disruption of the balance between the natural environment and the built urban landscape of the city and it has undermined the quality of role of River Valley in Tehran's urban landscape. There are still large and tall buildings which define formation, identity and legibility of the city. For this reason, in recent years the authorities have been planning, organizing and restoring them to a full potential detrimental effect of the artificial body, the original plan was comprehensive plan of Tehran. Since 2007 Tehran's River Valley was considered natural part of the city and its recreational function in the master plan have been underscored. However, the planning and implementation of few projects on Tehran's River Valley suggests that the potential of natural and important component of identity in Tehran in three dimensions of sustainable urban management and urban planning and design in the space scale have been neglected in a serious way. The taken actions changed the major natural -structural elements of the city into urban gardens. This paper attempts to critically review two projects within the organizing Kann River Valley (Park Javanmardan) and organizing Farahzad River Valley (Park Nahjolbalaghe). Approaches to the management, urban planning and design of these projects in Tehran will be criticized and their success in achieving the goals of sustainable urban development in these two measures will be studied as well. [ABSTRACT FROM AUTHOR]

Background and purpose: Using Water Quality Indices are necessary for monitoring the quality of water in various applications, including agriculture. This study aimed to assess the quality of Takab Sarugh river right branch by WILCOX index. Materials and methods: In this cross sectional study some quality parameters including water temperature, sodium, calcium, magnesium, total hardness, pH, electrical conductivity, sodium adsorption rate, total dissolved solids were measured monthly in five stations located along the river during spring and summer 2011. EC and SAR levels changes toward river discharge were determined for each station. Also, quality of water in each station was determined using WILCOX diagram and geographical information system. Results: The maximum SAR and EC values (1.3 and 1368 s/cmµ, respectively) were found in station C in September, while the lowest values were seen in station A in May. Results showed that the concentration of parameters decreased when the river flow increased. Based on SAR index the quality of water was in class S1 (low alkaline risk) and the EC was fluctuating between C1, C2, C3 classes (salinity risk: low, medium, and high, respectively). Conclusion: The results showed that quality class of river water in low water season decreased into moderate class from good and excellent classes. Probably sedimentary rocks, limestone springs and effluent of a gold extraction factory located in the studied area resulted in declining quality of water. [ABSTRACT FROM AUTHOR]

Water presence has always been one of the significant fac-tors in creating merriness and exhilaration in landscape design. In the past, due to the fundamental role of water in the structure and identity of the city, the presence of water has had a special effect in shaping the urban landscape and would participate at a variety of scales in city. Aque-ducts are technological achievements in history and culture of this land in the arid cities of the plateau of Iran that had supplied the city>s water with the discovery, guidance and extraction of groundwater and has had a ma-jor role in shaping the landscape of the city. Tehran is one of cities that use this method in shaping water networks since it benefits from groundwater surface and a topographic location. Therefore the elements of this water network and streams that were subterranean crossing place of the aque-ducts are always the key elements in shaping the landscape of Tehran. Tehran was provided with s structure based on its designers> thoughts which supplied people's requirements in the city. Following the master and development plans of western approaches, people's requirements and presence of natural elements in the city were eventually ignored. Having destroyed the streams which were responsible for supplying water storages and reservoirs and turned them into dumping places, they were no longer considered as essential elements in city landscape. Aside from losing their functional role and people's conceptual rupture from natural processes, they have lost their reminiscent and mental role. Paying attention to Tehran streams as one of the landscape elements of the city and using this element in urban design and landscape archi-tecture at neighborhood scale can help making proper landscape in the context of neighborhood and provide freshness and vitality. In between at-tention to subterranean aqueducts as one of the main pillars in water sup-plies for non-potable usages, landscape and various facilities in Tehran needs to be studied, identified and organized which can be an effective in strengthening Tehran urban identity. Tehran streams as vital capillaries of city can strengthen the city's identity with changing quality of urban spaces and can have an effective role in citizens' perception of the City rather than offering a destructive role. Natural infrastructures can be an effective matter way in promoting citizens' perception of the city and create a sense and identity of place. Sustainable way of developing nature presence in the city is investing on the potential and internal capabilities of the system. Tehran subterranean aqueducts as available natural vital vessels in the city were one of impor-tant and effective element in shaping the landscape of Tehran. The way of nature presence and influence recovery at least in Tehran city spaces is rehabilitation of the capillary of this natural flow or streams. [ABSTRACT FROM AUTHOR]

Undoubtedly, the seven river val-leys of Tehran city have been the most sig-nificant natural factors in the city structure throughout history; the factors which no longer play a part in city estimation. Although the river valleys, as the most important factors of urban ecological structure, play a role in creating a balanced relationship between city and nature space, they have not been considered as sig-nificant factors of Tehran master plan. Despite the fact that the last master plan largely refers to the potentials of the river valleys, the proper way of fulfillment has not been clarified in the organization program. This paper focuses on the facilities, opportunities, limitations, threats and strategies for planning and restoration of the natural environment as initial proposals aimed at improving the quality of life by re-viewing the position of Tehran river valleys in municipal documents and actions taken in the case of Farahzad river valley in Tehran. This article will also focus on these two basic points: 1) natural potentials of river valleys including green space and water flow 2) human scale and construction of pedestrian path connected to river valleys. Considering these two facts and combining the natural potentials of river valleys with human needs can lead to favor-able results in organization of the valleys. [ABSTRACT FROM AUTHOR]

Background and Aim: Agricultural and industrial activities, as well as population growth, have resulted in increases in the amounts of pollutants in the environment, the human body, and other organisms. Cadmium is one of the common heavy metals entering the biological cycles through different paths causing disease in humans, animals and plants. This study aimed at determining cadmium levels and physicochemical and biological factors in water and sediment samples, as well as determining relationships between culturable bacterial counts and cadmium toxicity and assessing bacterial resistance/tolerance spectrum through MIC and MBC. Materials and Methods: Surface water and sediment samples were taken from five stations in areas believed to be polluted along the Kor River. The stations included 1. Dorudzan Dam outflow, 2. Petrochemistry Bridge, 3. Khan Bridge, 4. Doshakh Bridge, and 5. the mouth of the Kor River to the Bakhtegan Lake. Two sets of samples were taken. Set 1was used for measuring cadmium level, physicochemical and biological factors, while Set 2 was used for the isolation and identification of cadmium resistant/tolerant bacteria and determination of their resistance spectrum. Pure cultures of each bacterial species were prepared and the more resistant bacteria were identified by exposure to media with different cadmium concentrations. Results: Stations 2 and 3 were found to be significantly more polluted with cadmium than the other 3 stations (p<0.001). The cadmium level in sediments of all the stations was higher than in water (p<0.001) and quite high as compared with the existing standards. The data also showed a lower BOD/COD ratio in the last 2 stations and higher phosphate levels in the last 4 stations. As compared to control, the bacterial count decreased in the presence of 1 mM cadmium chloride solution (p<0.001). Cadmium-resistant bacterial counts were higher in stations 3 and 5 than in the others (p<0.001). The most cadmiumresistant/ tolerant bacteria were P. aeruginosa ETs and Bacillus ABs with MIC 6 and 4 and MBC 7 and 5 mM, respectively. The most resistant bacteria were gram-negative, isolated from the sediments. Conclusion: Cadmium pollution, especially in stations 2 and 3, are due to man's activities. Although many bacterial types were found to be sensitive to cadmium in this study, some of them showed resistance/tolerance to it to different extents. Our findings also show that unlike water, which is an unstable environment, sediments are stable and provide a suitable environment for bacteria to form biofilms as a way to reduce cadmium accumulation. The most resistant bacteria were found in the stations with the highest cadmium concentrations. This may be a result of cadmium-resistant gene expression in the presence of this heavy metal. The use of these resistant strains in biofilters and wastewater bioremediation can potentially help to reduce cadmium pollution, a problem in some rivers. [ABSTRACT FROM AUTHOR]