| چکیده انگلیسی مقاله |
Introduction: Estuaries provide important habitats and maintain the health of marine ecosystems. They provide unique ecological services. On the other hand, estuaries can be considered as one of the most threatened ecosystems that are threatened by environmental hazards caused by human activities, climate change, and invasive and non-native species. They are under pressure. In most of the researches conducted in the country on the subject of evaluating the ecological situation, they either focus only on the types of pollution, or the pressures have been investigated in a scattered manner and in inappropriate scales. The main goal of this research is to evaluate various human pressures on Tajan River estuary in different scales and dimensions. Based on this, while investigating the status of water quality parameters, all kinds of human pressures in the aquatic ecosystems of Tajan River and its estuary have also been taken into consideration.
Material and Methods: In this study, after reviewing the information related to other studies conducted so far, field visits with the aim of identifying environmental hazards, spatial mapping and analyzes related to the type of hazards, in the environment of geographic information system (GIS) and processing. Necessary things have been done. Also, various physical and chemical samplings including measurement of parameters of temperature, total hardness, phosphate, nitrate, biologically oxygen demand, chemically oxygen demand, acidity, fecal coliform and turbidity, in order to use the water quality index. Iranian surface surveys (IRWQIsc) were carried out. Then, different environmental hazards were placed on top of each other in the geographic information system (GIS) environment for integrated evaluation. The results obtained in this study were compared with other studies conducted in the studied area and fundamental analyzes were presented for its management.
Results and Discussion: The results of this research showed that the estuary of the Tajan River has been affected by various human interventions such as agricultural use, urban use, livestock grazing, creating obstacles and footings of bridges, creating non-principal water management uses such as dam construction, creating morphological changes from Including canalization, unprincipled activities such as sand harvesting, sand washing, existence of fish breeding farms, industrial pollutants and lack of waste management are threatened. These threats were shown in different layers by Geographical Information System (GIS) in different scales, and finally their cumulative effects were drawn by combining the layers. The results of overlaying the pressure layers also showed that the diversity and intensity of the pressure increases from the upstream to the downstream (especially in the middle to the downstream parts) of the river or estuary. On the other hand, the results of the use of the index (IRWQIsc) in this research confirmed the poor quality of Tajan river water. And based on this, using the Water Framework Directive (WFD), it was determined the need to carry out restoration activities for the middle to downstream parts of this water body.
Conclusion: Most of the main Tajan river leading to the estuary are affected by high pressure and various human interventions. The results obtained from the measurement of physical and chemical parameters in this research also showed that the quality and health of water in the middle to downstream parts of the river and Tajan estuary is unfavorable. Therefore, there is an urgent need to carry out strategic and management measures in order to reduce the aforementioned pressures for the revival of estuarine ecosystems. Based on this; in order to achieve the integrated management and revival of this water body, it is necessary to focus on different aspects of risks and at different scales, and this study model can be used for other river water bodies and Mosabi is also used in the country. In the end, it should be mentioned that the irregular establishment of cities and their development on the edge of estuaries, without conducting EIA studies, has caused these valuable ecosystems to come under severe pressure in many parts of the world, and this pressure In most of the estuary ecosystems, they show themselves in the form of industrial and urban pollution, habitat destruction, reduction of biodiversity, evenness and fragmentation of the habitat, loss of aesthetic values and ultimately the loss of ecological services. This study can be used as significant basic information to prevent the managers of the country's environmental sector from facing bigger environmental challenges. |