JOURNAL OF ENVIRONMENT AND WATER ENGINEERING
Year:2021 | Volume:6 | Issue:4|Papers Count:9

By analyzing the historical records of the drought phenomenon and relying on the available statistics and information, it is possible to estimate the period of drought returns for different regions. By creating drought preparedness plans, the problems caused by drought can be greatly reduced. Frequency along with severity, duration and range are the most important features studied in drought studies. The purpose of this study was to calculate the relative drought frequencies of the Persian Gulf basin with the help of the standardized precipitation evapotranspiration drought index (SPETI) and to prepare a map of their frequencies. For this purpose, SPETI index was used as a selected index to study droughts in 10 stations located inside and outside the basin with a common statistical period of 30 years (1988-2017) in four scales of 12, 9, 6 and 3 months. After reviewing the output results, the relative frequencies of drought were extracted and mapped at each scale. Trend graphs of precipitation and temperature showed that the annual data of precipitation and temperature had a decreasing and increasing trend, respectively, with a temperature increase of 28%; hence, the results showed that SPETI index in presenting drought phenomena was faced with an increase in temperature and a decrease in precipitation. Therefore, these stations are introduced as stations with the potential for drought sensitivity.

Cement manufacturing can be an entrance source for heavy metals to the environment. Hence, the purpose of this study was to determine the amount of pollution of heavy metals, cadmium and nickel, in the lands around the Yasouj Cement Company. For this purpose, 61 soil samples from zero to 30 cm depth around the plant were randomly sampled. Some of soil properties and total concentration of Cd and Ni were measured. Kolmogorov-Smirnov test was used to examine the normality of the data. In the normal and abnormal data series, kriging and IDW methods were used to prepare zoning maps. The highest concentration of cadmium was observed in the northern part of the plant (11. 12 mg/kg). The results of nickel concentration zoning showed that the amount of nickel was highest in the sampled areas. The levels of cadmium in 10% of the samples and nickel in 100% of the samples were higher than the standard values reported by the Department of Environmental of Iran, and this indicates the risk of accumulation of these metals in the soil and pollution of the cement plant. Generally, high concentrations of these metals in soils around the cement factory showed that the pollutants are as a result of the different activities such as material processing in the process of cement production and the movement of vehicles around the cement company. According to these results, it is recommended that environmental preventive measures be taken to reduce the emission of pollutants in the cement production line.

One of the most important steps to prevent and deal with the destructive effects of floods is to identify areas with the highest flood potential in the watershed and its sub-basins. In this research, an attempt was made to determine the regions with the highest capacity of runoff and flood production in Mazandaran Province basin using the hierarchical analysis process (AHP) model. On this basis, six factors including heights, slope, land use, geology, flow accumulation, and rainfall were used. After calculating the final weight of each input factor using the hierarchical process model in ArcGIS (V. 10. 5) software, a combination of input layers was used to construct a flooding map of the study area in five different categories including very high, high, Medium, low, and very little. Results showed that 38. 79% of the Mazandaran Province, equivalent to the area of 9244. 82 km2, has a high and very high flooding hazard. Moreover, almost half of this province, equivalent to the area of 12028. 51 km2 has a moderate flooding hazard. The results reveal that flooding hazard at each hydrometric stations was in good agreement with the historical observations of floods, that most of them have the return periods of 50-and 100-year. It implies the high accuracy of the method and the weights assigned to each of the effective factors. This clarifies the usability of this research results for future preventive implementation.

Groundwater vulnerability assessment is important in order to prioritize these resources from the perspective of exploitation, management and control of pollution in different areas. The purpose of this study was to evaluate the qualitative vulnerability of Birjand plain aquifer using DRASTIC-LU model. In this research, the DRASTIC base model with the land use parameter of the developed lands was used. In this method, the basic model parameters including groundwater depth, net nutrition, aquifer environment, soil type, topography, unsaturated area constituents, and hydraulic guidance were analyzed in GIS environment along with land use variable as a model development based on standard weights and the vulnerability zoning map was prepared. Vulnerability zoning map of DRASTIC-LU model showed that 62. 27, 25. 07, 17. 17, and 2. 38% of the area have low to medium, medium to high, low and high vulnerability, respectively. In addition, the sensitivity analysis of the model used to evaluate the assigned weights was performed. To validate the model, the correlation of the model with the nitrate concentration was performed; the obtained correlation of 86% indicated the appropriate correlation of this model with the nitrate concentration as an indicator of groundwater pollution.

Accurate estimation of reference evapotranspiration has great importance in irrigation scheduling. Moreover, the lack of availability of lysimetric data has led researchers to use indirect methods, including data-driven approaches. In the present study, the ability of Gaussian process regression (GPR), support vector regression (SVR) and random forest (RF) data-driven methods was investigated to estimate the evapotranspiration of the reference plant. For this purpose, meteorological data on average temperature, wind speed, relative humidity and sunny hours in the period 2013-18 were collected in nine northern stations of Iran including Astara, Bandar Anzali, Rasht, Ramsar, Nowshahr, Sari, Turkmen port, Gorgan, and Gonbad Kavous. Evapotranspiration calculated using FAO-Penman-Montith method was considered as the target output and four combined scenarios of meteorological parameters were considered to calibrate and validate the studied methods. The accuracy of the mentioned methods was compared using the statistical parameters of correlation coefficient, scatter index, and Wilmott’ s coefficient. The results showed that GPR4 model with scatter index in the range of 0. 132 to 0. 179 in Astara, Bandar Anzali, Rasht, Ramsar, Nowshahr and Sari stations, SVR4 model with dispersion index of 0. 116 to 0. 120 in Turkmen and Gonbad Kavous stations and the Hargreaves-Samani method with a scatter index of 0. 509 at Gorgan station had much more accurate estimates of the evapotranspiration of the reference plant.

Given the importance of soil and water resources in the development of sustainable agriculture, increasing world population and the growing need for crop production, predicting crop yields using plant simulation models and remote sensing technology is very crucial. The aim of this study was to estimate the yield of rice components including straw, paddy and biomass of Hashemi cultivar during different growth stages with SWAP model and to provide regression equations by extracting NDVI and SAVI plant indices from Sentinel-2 and Landsat-7 and 8 satellite images. It was done in the National Rice Research Institute. Comparison of statistical variables indicated that the mean values of coefficient of determination (R2) and model efficiency factor (EF) in estimating the yield of rice components in different stages of growth with SWAP model were more than 0. 70 and 0. 90, respectively, and with an error of 1. 93 to 6. 54% was equivalent to 134. 21 to 470. 43 kg/ha. The slight difference between the measured and simulated values showed that the SWAP model estimates the rice yield in the study area with appropriate accuracy. The results also showed that the extracted NDVI and SAVI indices with very good accuracy estimate the yield of rice components at different stages of growth. However, the highest amount of correlation was related to the reproductive development stage. Finally, R2 for NDVI at different growth stages as well as the entire growth period for straw, paddy, and biomass were higher than the SAVI index, revealing more accuracy of NDVI than SAVI.

In this study, changes in flood characteristics due to the failure of Vahdat Dam (Gheshlagh) in areas where the cross section of the river has changed, because of human activities, were investigated. For this purpose, the HEC-RAS model was used to simulate the failure of the dam and the resulting flood flow. Data on the dam structures and flow of the Gheshlagh River in Kurdistan Province, on which the Vahdat Dam is located, were obtained from the Kurdistan Regional Water Company. Using the ArcMap software, after converting the digital elevation model (DEM) to a three-dimensional model (TIN), the required parameters and lines related to the cross sections on the river were drawn. This data was transferred to the HEC-RAS model. Through field studies, cross sections were corrected and Manning coefficient was measured in different zones. After preparing images of bridges and embankments along the flow path, the height of the bridge and the embankments in the flow path were measured using station GPS. The Grize Bridge and the location of the studied embankments in this study located 23 and 33 km downstream of the Vahdat Dam, respectively, were selected to investigate the changes in flood characteristics due to local narrowing. Changes in water height and width in the study areas were investigated. At the site of the Grize Bridge, the peak of flooding due to dam failure and water depth was 4773. 79 m3/s and 10 m, respectively. These values at the embankments were 4330. 04 m3/s and 10. 8 m, respectively. Comparing these numbers with the data calculated in the previous sections of these contracted sites indicates a significant reduction in the flow capacity.

Economic growth is the essence of all economic activities and actions of governments in a certain period, which if not desirable, has negative consequences, including environmental degradation. The environment is one of the main pillars of sustainable development; in recent decades, the importance of the environment has increased and the quality of the environment has become very important. With the growth of urbanization and the development of communities, more importance has been given to the quality of the environment. The aim of this study was to evaluate the effect of the selected economical indicators and urbanization on the emission of CO2 in Iran during the year's 1980 to 2018 using Bayesian causal map (BCM) analysis method in five scenarios. Testing the degree of impact of changes in economic variables on the growth rate of CO2 emissions using one-way sensitivity analysis showed that among these five indicators, first trade with 58. 78 and secondly private sector credit with 32. 48 and then tax with 4. 85, followed by urban growth with 4. 21 and finally private sector investment with a reduction of variance of 1. 04, respectively, had the greatest impact on CO2 emissions. The results of the five scenarios show that after changing the probability of high status of variables, high probability of CO2 emission is also more likely.

In the present study, the electrochemical coagulation process (electrocoagulation) in the mining industry was investigated in order to remove one of the heavy metals, cadmium, from the leaching solution of the copper processing plant. The response surface methodology (RSM) was used to optimize the factors affecting the removal of this metal in the electrocoagulation process. For this purpose, Behnken Box Designv(BBD) was used to optimize the experiments. The effects of three independent parameters such as pH (X1), electrolysis time (X2), current density (X3) were investigated in order to investigate the removal of cadmium from the leaching solution. The quadratic model was used to respond to the cadmium removal efficiency. The most important independent variables and the interaction between them were evaluated using ANOVA test. This study showed that the optimal operating conditions for cadmium removal are 96. 96% at initial pH: 6. 83, electrolysis time: 116 min and current density: 69. 262 A/m2. The results showed that the ability of electrocoagulation process can be considered as a reliable method to remove cadmium from industrial effluents, especially in mineral processing plants.