مجله محیط زیست و مهندسی آب
سال هفتم شماره 1 (بهار 1400)

Investigating and understanding the impact of dust storms on wetland vegetation changes can lead to useful information for their optimal management. In this study, the wind rose and hurricane rose diagrams of the research area were prepared using wind statistics of Ahvaz meteorological stations. Changes in vegetation cover of Shadegan wetland were determined using classified soil-adjusted vegetation index (SAVI) maps of MODIS satellite images from 2002 to 2011 and correlations of vegetation changes were analyzed using dust storms data of Ahvaz meteorological station. The results showed that the major winds in the region flow from northwest to west and have the ability to create dust. The trend of changes of the number of stormy days, the concentration of dust and vegetation, were proportional to each other. The correlation between the number of dust days per year and the percentage of area with good vegetation cover showed relatively good relationship (the coefficient of determination was 0.47). The correlation between total dust concentration and vegetation cover, with a coefficient of determination of 0.58, indicated the high effect of dust on vegetation cover in the study area. The trend of changes in dust concentration with vegetation index was decreasing in one, two, three, four, and five months before image date. The relationship between dust concentration one month ago and vegetation percentage (SAVI index) with a coefficient of 0.99 showed the highest correlation. The negative and significant effect of dust storms on vegetation doubles the importance of the issue in Shadegan International Wetland, and on the other hand, the use of satellite images can provide accurate information with less cost and time to manage vegetation water and soil resources for managers.

The effluent from the backwashing of the filters used in water treatment can be considered as one of the potential functions for reuse for various applications, provided that it has the required quality. The purpose of this study was to determine the quality of effluent from backwashing of rapid sand filters in Sanandaj water treatment plant for reuse. For this purpose, in two high and low water seasons, the effluent of phases 1 and 2 of the water treatment plant was sampled and the physical, chemical and microbial properties of the samples were studied using standard methods for drinking water, agriculture and green space uses. The data were analyzed using SPSS software and one-sample t-test and independent t-test. The results showed that the mean value of all the studied parameters in the effluent from the backwashing of the filters of the phases No. 1 and 2 of the treatment plant was less than the standard of agricultural and green space use. Compared with the drinking water standard, only the mean values of turbidity (48 NTU in phase 1 and 45 NTU in phase 2), total coliform (4 MPN for phase 1 and 6 MPN for phase 2) and fecal coliforms (1 MPN for both phases) parameters in the effluent were significantly higher than the standard (p <0.05). The results also showed that there was no significant difference between the mean of the studied parameters in the treatment plant effluent in the two phases and the autumn and winter seasons (p <0.05). Finally, it was found that it is possible to use the effluent for agricultural and green space use, but it could be reused for drinking purpose only after treatment.

Heavy metals are one of the most important environmental contaminants, particularly in soil and water sources. Among heavy metals, lead is one of the most challenging toxic contaminants. Using lead-contaminated soils requires their decontamination and improvement. The objective of this study was to investigate the possibility of lead decontamination from soil and to estimate the optimal clean up time using Portulaca oleracea L. and Amaranthus retroflexus. For this purpose, a completely randomized design with five treatments of 30 (standard), 150, 300, 600 and 1200 mg/kg each with three replicates was performed. The results indicated that for both plants a non-linear positive relation exists between the lead concentrations in soil and that accumulated in plant roots and shoots. The highest extracted lead which was accumulated in roots of Portulaca oleracea L. and Amaranthus retroflexus were 173.39 and 149.76 mg/kg, and in their shoots were 20.01 and 5.82 mg/kg, respectively. Translocation factor was obtained from 0.62 to 0.12 for Portulaca oleracea L. and from 0.14 to 0.04 for Amaranthus retroflexus. The translocation factor in both plants was obtained to be less than one, indicating poor lead transfer from root to the shoot. Due to the ability of the above plants to absorb large amounts of lead from the root zone, high plant yield and the ability to accumulate lead in harvestable organs, both plants were highly effective for remediation of lead from soil surface up to concentrations several times of the allowable lead concentration. However, due to the clean-up time and the amount of biomass produced, the Amaranthus retroflexus had a better ability to remediate contaminated soils.

The aim of this study was to determine the accuracy of Landsat 8 and Sentinel 2 satellite data sets based on Maximum Likelihood, Support Vector Machine, Neural Network algorithms for mapping the LU/LC of Kobgian watershed in Kohgiluyeh and Boyer-Ahmad Province. For this purpose, corrections, data preparation, data set creation, classification and analysis, mapping and verification were done using ENVI® 5.3, ArcGIS® 10.5, Google Earth Pro and Excel 2016 software. The results showed that the highest total accuracy and kappa coefficient for Landsat 8 and Sentinel 2 satellites belongs to the maximum likelihood algorithm with a value of 74.18% and 0.69 and neural network algorithm with a value of 72.84% and 0.67, respectively. The overall accuracy order of the algorithms for mapping LU/LC the watershed using Landsat 8 and sentinel 2 data was as maximum likelihood > support vector machine > neural network and using data was as neural network> maximum likelihood > support vector machine, respectively. The accuracy of the algorithms indicated that if a specific LU/LC is the main goal such as basin rangelands, the support vector machine algorithm should be used. The area of eight classes of Kabgian watershed is: agriculture 1342, residential 1356, rock 3579, forest 23289, water body 407, abandoned lands 9571, garden 3139 and pasture 54125 ha. Therefore, depending on the type of LU/LC, the type of satellite data available, and the purpose of study, the priority of using algorithms will be different and based on the desired factor, suitable algorithm should be selected.

With the entry of various effluents into aquatic ecosystems such as wetlands, pollutants containing heavy metals are deposited in the sediments. The aim of this study was to determine the level of heavy metal contamination of surface sediments in Salehieh Wetland, Karaj, Alborz Province. For this purpose, samples were taken from the sediments of six stations along with the wetland in May 2020. After preparation and chemical digestion of the samples, the concentration of heavy metals was determined by the flame atomic absorption instrument. Mean concentrations with standard deviation of lead, cadmium, nickel and chromium in wetland bed sediments were 14.11 ± 1.52, 1.14± 0.17, 19.87± 2.67 and 64.1± 7.03 µg/g, respectively and the accumulation pattern of heavy metals obtained was Cr> Ni> Pb> Cd. The highest concentration of metals was observed in station number 1. Comparison of metal concentrations with the values ​​of international standards showed that the mean concentrations of lead 14.11, cadmium 1.14 and chromium 64.1 µg/g were higher than LAL standards for lead (2), cadmium (0.04) and chromium (26 µg/g), respectively. The mean concentration of nickel was 19.87 µg/g, which is more than the HAL standard (15.9 µg/g). The amount of cadmium and chromium was higher than the ISQGS standards (0.7 and 43 µg/g for cadmium and chromium respectively). Therefore, increasing the concentration of these metals, especially cadmium and chromium, if not monitoring and controlling the discharge of effluent from the industrial town adjacent to the wetland, can lead to a threat to the health of ecosystems and the region.

The importance of the corn plant has led to the widespread cultivation of different cultivars of this crop in many parts of Iran. Since the study of environmental and managerial factors such as planting density, irrigation amount and plant cultivar on grain yield, biomass and water use efficiency of crops requires costly and time-consuming field experiments, it seems that the effect of various factors on the crop yield can be stimulated using plant models. The present study was performed to evaluate the AquaCrop plant model for two maize cultivars,  mid cultivar SC500 and early cultivar SC302, under 75000, 85000 and 95000 and 80000, 90000 and 100000 plant/ha densities, respectively, with different irrigation values of 75, 100 and 125%. The results showed that the AquaCrop model had good accuracy (RSME = 0.89 ton/ha and NRSME = 0.10) in simulating grain yield and maize water use efficiency (EF and d = 0.99). In simulation of corn biomass, this plant model had acceptable accuracy (RSME = 2.47 ton/haand NRSME: = 0.14) and good performance (EF = 0.98 and d = 0.99). AquaCrop model also had good accuracy (RSME = 0.07 kg/m3 and NRSME = 0.07) and efficiency (EF and d = 0.99) in simulating corn water use efficiency. Based on these results, the AquaCrop model is proposed to simulate corn cultivars under the mentioned conditions..

Springs as one of the groundwater sources and suppliers of high volume of river basin discharge have been less analyzed and studied.  The origin of these resources, due to the passage of natural heights and filtration, has a good quality and only some formations or human activities cause a change in the quality of these resources. This study evaluated the quality of springs in Ajabshir study area in the east of Urmia Lake in 2018. According to the type of geological formations, discharge and location of springs in the region, 13 springs were analyzed for qualitative analysis and evaluation of qualitative changes. Studies have shown that 100% these springs are very good quality in terms of drinking, and the GQI quality index is 33.23-95.32, indicating good to excellent condition for these resources. In terms of exploitation in the agricultural sector, the only issue was the high level of electrical conductivity (157-6490 µs/Cm) in some springs, and the alkalinity of all springs was in class S1 in Wilcox diagram. The quality situation from the industry point of view also indicated a low range of changes, and 77% of the springs in the region were corrosive. Evaluation of water source in this area showed a high ratio of sodium to chlorine and differences in calcium and sodium origin, so that the initial sections of the study area and the east of the area had magnesium source and the rest had calcium source. Finally, the study of geological formations showed their low impact on quality and the high concentration of nitrate in the part leading to the plain and aquifer due to human activities and sewage leakage was evident and reached 27 mg/l.

Using unsuitable quality water for agricultural purposes has  negative consequences on plant growth and the soil physical properties. The aim of this study was to investigate the spatial changes in ground water quality with agricultural applicability in central Chabahar and Kenark Distircts. For this purpose, we first performed interpolation for EC and SAR parameters from 40 wells in the study area in 2019. Then we employed  inverse distance weighting , global polynomial, local polynomial, radial basis function and kriging with circular, spherical, exponential, gaussian, as well as quadratic equation semivariograms; the most suitable method for interpolation was selected baed on the Root Mean Square Error (RMSE) and coefficient of determination (R2) criteria. The research found that kriging interpolation method with a Gaussian variogram having RSME=13.85 and R2=0.77 was the most suitable methods for interolating with the SAR paramete and the kriging interpolation method with as spherical variogram having RSME=797.89 and R2=0.68 was considered as the most suitable methods for interpolating EC. Then, based on Wilcox method, the groundwater quality map for agricultural and irrigation uses was prepared using the spatial variation map of two parameters, EC and SAR. The results showed that the quality classification of the groundwater in the study area was: about 10% as good, 51% as fair, 16% as poor, and about 23% as unusable water.

In order to investigate the effect of low irrigation on yield and yield components of Marigold in different soil textures, a factorial experiment was conducted in a completely randomized design in the research greenhouse of the Faculty of Agriculture, Ferdowsi University of Mashhad in 2018-2019 based on pot cultivation with 3 replications. The treatments studied in this research included four irrigation levels of 100, 85, 70 and 55% of field capacity and three soil textures including silty clay S1, clay loam S2 and sandy loam S3. The results showed a downward trend in changes in the number of flowers as one of the important components of flower yield due to deficit irrigation with a field capacity of 0.85, 0.70 and 0.55 and 7.7, 17.9 and 38.5%, respectively. The use of different soil textures led to a reduction in the number of flowers, lateral branches and leaves compared to the treatment with silty clay soil. From clay loam and silty clay texture compared to sandy loam led to a significant reduction in the number of flowers (26.2 and 38.1%), in the number of lateral branches (24.5 and 32.7%) and in number of leaves (14.8 and 19.1%). According to the results of this study, irrigation treatment of 85% FC and sandy loam soil texture can be considered for Marigold (Calendula officinalis L.) under greenhouse conditions.

Today, the use of underground dam technology is considered as one of the efficient methods of rainwater harvesting systems and flood management in order to eliminate the shortage of water resources in arid and semi-arid regions. Underground dams block the subsurface flow of water across the river and stores it in the riverbed. The construction of an underground dam, while helping the environment, will compensate for surface water and expand cultivated lands. The content of water extracted from these dams depends on the hydraulic and hydrodynamic of alluvial sediments. The aim of the present study was to determine the hydrodynamics of the riverbed deposits of the Meshnaqeh underground dam in the north of Lake Urmia. Feasibility study and location of the dam axis was done using ArcGIS system. Three options were determined and finalized after a geophysical evaluation of the location of the main alluvium with a thickness of 14 m. Engineering studies showed that the sedimentation of bed was in gravel and sandy soils in UNIFIDE division with more than 78% of sand, and according ASTM method, were in the GC and GM. Lefranc experiment showed that alluvial sediments had a permeability of 0.0012 cm/s and a porosity above 35%. According to the special discharge, 163,800 m3 of water can be harvested in each flooding period. Drinking water and sanitation of the region is provided hundreds of kilometers away through Zarrinehroud water transmission line. The construction of this dam with a realistic view of the real value of water and its role in human societies, will have constructive environmental effects requiring independent study.

Studying the effects of different types of water and soil protection systems on soil properties is of great importance in soil planning and management and is considered as a move towards sustainable development. The purpose of this study was to investigate the effect of three systems of water and soil protection in Chaharmahal and Bakhtiari province on topsoil and subssoil of soil organic carbon content, bulk density, soil stability, nitrogen, potassium, phosphorus, soil texture, acidity, electrical conductivity and soil permeability at depth of 0-30 and 30-60 cm. By comparing each of the soil physical and chemical properties in exclosure, contour furrow and Pitt seeding and the control areas, it was concluded that in soil and water conservation systems, organic carbon, bulk density, stability, Phosphorus, soil texture, acidity, electrical conductivity of topsoil did not increase significantly and in some cases nitrogen and potassium increased significantly (at the level of 5%). The lowest amount of surface soil nitrogen (0.087%) was observed in excavation improvement operation which had a significant difference with surface soil nitrogen (0.072%) in contour operation. The lowest and highest amount of surface soil organic carbon with significant differences (1.02 and 1.43%) were related to pitt seeding and contour farrow, respectively. Comparison of permeability data in control and protected areas showed that the implementation of water and soil protection operations had a positive effect on soil permeability. In general, the effect of water and soil protection systems on improving soil quality is not absolute and depends entirely on different climatic conditions, geology of each region.

One of the main problems in flood predicting is often lack of hydrological and climatic data in most basins of Iran. Soil Conservation Service Curve Number (SCS-CN) method is used to estimate the maximum flood discharge in the ungauged basins. In this study, the runoff height and the maximum flood discharge were estimated by SCS-CN method in Balarood Basin on Khuzestan Province of Iran. Firstly, geometric correction, enhancement and nearest neighbor algorithm of object-oriented classification on Landsat 8 satellite’s OLI sensor images were used to prepare the land use maps. Then the soil hydrological groups and curve number (CN) were determined for each sub-basin using land use map. Finally, the runoff and maximum flood discharge of the basin were estimated by SCS-CN method. The results indicated that the Balarood basin had three soil hydrological groups A, B, and C, with 60.64, 11.62, and 27.74% respectively. The CN of the basin was 62.81. The maximum soil water retention (S) of Dokohe, Anarki and Mongareh sub-basins and the basin calculated were 7.5, 16.8, 17, and 15 cm respectively. The height of runoff and maximum flood discharge of them were estimated 0.05, 0.06, 0.73, 0.12 cm and 71, 67.2, 435, 282.1 m3/s respectively. The results also demonstrated the good efficiency of remote sensing and GIS techniques in study on SCS-CN method.

The GCM models are widely used to assess the effects of global climate change, but they are not accurate enough to assess climate change locally and regionally. In this study, using the statistical model of SDSM in the study area, the output of the CanESM2 model was downscaled and compared with data from Sanandaj synoptic station, which has long-term statistics. Then, considering the release scenarios of RCP2.6, RCP4.5 and RCP8.5 for the future periods of 2025-2050 and 2051-2075, the effect of climate change on the temperature of Sanandaj city was evaluated. The minimum and maximum daily temperatures for the base period of 1979-2005 were considered as the input of the model. The results of the SDSM model show that the average monthly minimum temperature drops below zero for the periods 2025-2050 and 2051-2075 and decreases under all three scenarios, and when the average air temperature is less than zero for both future periods, it increases under all three scenarios. The average maximum temperature for the next periods is 2025-2050 and 2051-2075 and under all three scenarios RCP2.6, RCP4.5, RCP8.5 increase and this increase is mostly related to the warm months of the year. According to the obtained results, Sanandaj city will have warmer days and colder nights in the future.

The water used in swimming pools, like drinking water, must comply with the required quality. Failure to comply with the physical, chemical and biological criteria of the pools will lead to health hurt to swimmers. In this cross-sectional paper carried out with a descriptive-analytical approach in the summer of 2019, 23 public and private pools located in the south of Tehran (districts 18 and 19) were selected. Pool water sampling was performed to determine microbial indices including thermophilic coliforms, heterotrophic plate count (HPC), and physicochemical parameters including turbidity, pH and residual chlorine. Then, each of the studied parameters was assigned a weight based on their importance and their status was analyzed by water quality index. Based on the findings, the microbial indices of thermophilic coliforms and HPC in the water of the sampled pools were at the desired level in 74 and 26.1% of samples, respectively. Regarding turbidity, pH and residual chlorine content in 13.1, 60.9 and 47.9% of the samples, were at the acceptable values, respectively. The results also showed that none of the sampled water was in excellent condition and 68% of the samples were in fair condition in terms of water quality. According to the obtained results, the necessity of continuous sampling of pool water to check their quality and effective interventions and finally the imposition of fines is suggested for those which their quality is not in accordance with the standards.