نوع مقاله : پژوهشی
نویسندگان
1 کارشناسی ارشد مدیریت و کنترل بیابان، گروه طبیعت ، دانشکده کشاورزی و منابع طبیعی، دانشگاه اردکان، اردکان، یزد، ایران
2 دانشیار گروه طبیعت ، دانشکده کشاورزی و منابع طبیعی، دانشگاه اردکان، اردکان، یزد، ایران
3 استادیار گروه طبیعت ، دانشکده کشاورزی و منابع طبیعی، دانشگاه اردکان، اردکان، یزد، ایران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction and Objective
This research comprehensively evaluates the environmental consequences arising from the construction and operation of the Nesa Dam in Bam on downstream natural ecosystems, particularly the valuable Iranian Acacia forests in the Fahraj and Rigan regions. In the context of climate change and increasing water resource demands, large-scale water projects like dams can have profound impacts on the natural, social, and economic environments of surrounding areas. A precise understanding of these impacts, especially in Iran’s sensitive desert and semi-arid ecosystems, is crucial for formulating sustainable water resource management strategies and conserving biodiversity. The primary objective of this study is to quantitatively and qualitatively assess the extent of degradation in vegetation cover and soil moisture in the downstream areas of the dam, analyze the correlation between this degradation and dam-induced hydrological changes, and propose practical solutions to mitigate negative effects and enhance ecosystem resilience.
Materials and Methods
To achieve the research objectives, a robust and innovative methodology based on remote sensing and spatial analysis has been employed. The main technique used is Change Vector Analysis (CVA), which offers a significant advantage over simple pre- and post-intervention comparison methods (such as previous studies by Golbaf et al. (1404) and Rahimi et al. (1392)) due to its ability to simultaneously detect the magnitude and direction of changes over time. This method is complemented by the use of key remote sensing indices, including the Enhanced Vegetation Index (EVI), which is sensitive to subtle changes in vegetation cover, and the Vegetation and Soil Water Index (VSDI), directly related to soil moisture status and plant health. The combination of these indices and the CVA method allows for a comprehensive and accurate depiction of complex ecosystem dynamics, including changes in different vegetation growth phases, decreases or increases in soil moisture, and even shifts in vegetation degradation or recovery patterns. The application of remote sensing has been an effective solution for continuous and regional monitoring of these changes, considering the vastness of the study areas and the difficult accessibility of some regions.
Results and Discussion
The findings of this research indicate that the construction of the Nesa Dam in Bam has resulted in extensive and significant environmental impacts on the natural ecosystems downstream of the river. Spatial analyses reveal that over 83% of the total study area has experienced a substantial decline in vegetation cover and a noticeable decrease in soil moisture. This degradation is unevenly distributed across the region, with approximately 44.6% of the total area affected by “high” and “very high” levels of degradation. This intensity of degradation is particularly evident near the dam, in the Iranian Acacia Forest regions, and in agricultural areas traditionally dependent on river water. This pattern of degradation is directly linked to the hydrological changes induced by the dam. Reduced river flow rates, declining groundwater levels due to lack of natural recharge, and altered flood flow regimes have all contributed to the deterioration of vegetation cover and soil desiccation. The consequences of this degradation extend beyond purely environmental issues, encompassing broad socio-economic and ecological dimensions. The Iranian Acacia forests, which have suffered the most extensive degradation, play a vital role in maintaining soil stability, preventing wind and water erosion, stabilizing sand dunes, and providing habitat for regional biodiversity. The decline of these forests exacerbates desertification risks and can lead to the loss of livelihood resources for local communities who traditionally rely on these resources for fuel, livestock fodder, and other necessities. Furthermore, critical ecosystem services such as carbon sequestration, local temperature moderation, and air quality improvement are also negatively impacted. The findings of this study serve as a serious warning regarding the potential consequences of large water projects in arid and fragile regions, underscoring the necessity for a profound reconsideration of water resource management policies.
Conclusion and Recommendations
In conclusion, this research clearly demonstrates that the construction of the Nesa Dam, despite its objectives of water and energy supply, has had devastating environmental effects on the downstream ecosystems, particularly the Iranian Acacia forests. The state of vegetation cover and soil moisture degradation, affecting over 83% of the region, signifies a critical situation requiring immediate action. The study’s findings further highlight the imperative of adopting sustainable and comprehensive management approaches. These approaches must transcend purely engineering and water supply goals to address the long-term health of the ecosystem and the needs of local communities. To counter these environmental challenges, a set of key management strategies is proposed. The first step involves establishing effective inter-sectoral coordination through cooperative mechanisms among relevant organizations such as the Ministry of Energy, the Department of Environment, and the Ministry of Agriculture-Jihad, ensuring integrated decision-making. Second, it is essential to determine and allocate a specific flow rate from the dam as a minimum environmental flow to preserve the downstream ecosystem’s vitality and prevent the complete drying of the river. Third, implementing extensive and targeted programs for vegetation restoration, especially focusing on native drought-resistant species like various types of Acacia, is of paramount importance as a key solution for soil stabilization and erosion control. The fourth focus is on adopting necessary measures to prevent further decline in groundwater levels and, where possible, to facilitate their artificial recharge. Finally, the active participation of local communities in decision-making processes and the implementation of management and restoration plans, taking into account their indigenous knowledge and interests, is proposed as the fifth strategy.
کلیدواژهها [English]
)