جستجوی مقالات مرتبط با کلیدواژه "surface water" در نشریات گروه "آبخیزداری، بیابان، محیط زیست، مرتع"

In recent years, due to the rapid growth of the population, the increasing development of urbanization and the industrialization of societies, as a result, the hydrology of urban watersheds has been accompanied by many changes. These changes over time have caused floods and inundation of roads in urban areas, and on the other hand, flooding in these areas due to the density of population and facilities can cause severe damages and reduce the quality of runoff. New approaches have been proposed to manage runoff and prevent flooding and water pollution, and in this case, the development of low-impact LID is one of these approaches. The purpose of using this technique is to simulate the hydrological conditions of the urban area before development. For this purpose, in this research, the evaluation of quality parameters (BOD, TP, TN) was investigated using the best low-impact development management practices (LID/BMPs) in Gorgan city.

In the first stage, information related to intensity-duration-rainfall curves, urban and land use maps, and urban development maps were collected for Gorgan urban watershed. EPA-SWMM model was used to create a hydrological model in Gorgan city and investigate the effect of LID on runoff. According to the urban development of the region, six options of green roof, biological system, garden waterway, rain, infiltration trench and permeable covers, with a 6-hour rainstorm were considered with a return period of 2, 5 and 10 years for qualitative analysis using parameters Nitrate, phosphate and BOD.

The results of the calibration and validation of the model based on the Nash-Sutcliffe criterion more than 0.5 showed that the SWMM model has the required accuracy for simulating the quality of urban runoff. The results showed that, respectively, the green roof system, rain barrel and permeable covers have the best performance in improving the quality of surface runoff in the region by reducing surface runoff pollutants compared to the existing situation. The use of low-impact development methods in the region depends on various factors, including environmental, economic and efficiency factors. The results indicate that all the LID scenarios selected in the research were effective in improving the quality of surface runoff, but each of the scenarios showed different capabilities.

Conclusion and Suggestions:  
Even though all the LID scenarios examined in this research were effective in controlling surface runoff and improving its quality, but with the implementation of the green roof, rain barrel and permeable covers, the amounts of phosphate, nitrate and BOD compared to the existing situation and other scenarios has decreased further. As a result, the impact of green roof management measures, rain barrel and permeable cover has been greater. Finally, it is suggested that in order to improve the quantity and quality of surface runoff, these methods should be considered in the implementation priorities.

Identification and monitoring of surface water using remote sensing have become very important in recent decades due to its importance in human needs and political decisions. Therefore, surface water has been studied using remote sensing systems and Sentinel-1 and Sentinel-2 sensors in this study. In this paper, two data fusion approaches and decision fusion improve the accuracy of surface water identification for the two study areas in Mazandaran province, Iran, due to dense forests, turbid rivers, and land Agricultural products have been proposed. Data fusion approach by increasing the spatial resolution of Sentinel-2 optical sensor from 20 meters to 10 meters and using radar dataset and water indices in one layer, monitoring surface water with much higher accuracy by classification using supervised classifiers such as Support Vector Machine (SVM), Neural Network (NN), and Random Forest (RF) were performed. Then, by combining the results using the Maximum Voting (MV) method, the accuracy of the results compared to the data fusion approach increased by 4 percent to 5 percent. Since narrow and confused rivers are not easily identifiable and extractable, the proposed approach was able to extract an accurate map of surface water.

In order to influence the possible leakage of Chahar Gonbad copper tailings dam on water resources in the dam area, surface and groundwater quality studies were performed in two seasons, dry and wet. Some 10 water samples from different parts of the tailings dam area were evaluated for water quality analysis including Wilcox and Schuler. The results showed that the drinking and agricultural water samples in the region is in line with global environmental standards. The amount of chloride in the drainage water of the tailings dam was 499 mg / l, which is 99 units higher than the defined standard of Iranian drinking (400 mg / l) and 149 units higher than the standard agricultural level (350 mg / l). Also, the results showed that the amount of magnesium in the dry season compared to the wet season has a relative increase. That high amounts of magnesium compared to calcium in water in the irrigation system have a negative effect on soil quality and lead the soil to alkalinity. Molybdenum in tailings dam samples in both wet and dry seasons is higher than the standard level of agricultural use (10 mg / l), which is more evident in the dry season. The high concentration of molybdenum in waste samples is due to the proper mobility of this element in oxidative-acidic conditions. The amount of bicarbonate in the dry season increased more significantly than in the wet season. This increase can be due to the increasing temperature, pH and increase in water alkalinity, the source of those river bed rocks that with increasing water volume in the dry season has increased the concentration of these salts. Based on the results, it is suggested that 23 observation wells with a maximum depth of 50 meters be dug as monitoring grade 1 around the tailings dam of Chahar Gonbad copper mine.

In recent years, due to the increasing frequency of droughts in arid and semi-arid regions of the country, the water level of the lakes has dramatically decreased, and in addition to environmental damage, it has also challenged the economic and social sectors of society. In this study, drought events were quantified by standardized precipitation index (SPI), chinese Z index (CZI), Modified chinese Z index (MCZI) and Z-Score index (ZSI) using monthly and annual rainfall data of five synoptic stations (Yasuj, Gachsaran, Dehdasht, Sisakht and Likak) and one pluviometry station (Margoon and Dishmuk) those which are related to Kogilueh and Boyerahmad Meterological organization. The results showed that ZSI, CZI and SPI have a similar trend in all stations and the curves of these stations were well coincident with each other and had a very good fitness that was not same for MCZI. Then, iso-duration and iso-intensity maps of drought (drought zoning) were prepared for determination of the drought susceptible areas as well as forecasting the future status based on the four studied indices by the ArcMap application for annual periods.