Long-term assessment of changes in environmental flow regime for sustainable water resources management in a permanent river, Northwest Iran

Identification and analysis of changes in hydrological indices of river flow play a key role in assessing the impacts of climate change and human interventions on river regimes. This study investigates the long-term trends of hydrological indices in the Samian watershed, located in Ardabil province. Daily river discharge data from 1973 to 2019 were analyzed using the Indicators of Hydrologic Alteration (IHA) approach. The results revealed that river flow values in the fall and winter months, particularly from October to February, exhibited a significant decreasing trend (P-value < 0.01). Additionally, minimum flows (1 to 90-day periods), base flow indices, and the timing of minimum flows showed significant decreasing trends, indicating reduced flow stability during dry periods and heightened water stress. The highest dispersion coefficients (over 4) were associated with low-flow events in May, June, and July, indicating high variability. In contrast, indices related to short-term and intense floods showed lower dispersion. The median of maximum flows (1 to 7 days) was estimated between 27 and 40 cms, while minimum flows were much lower (below 0.1) and exhibited considerable variability. EFC Low Flow indices in most months showed low medians and high dispersion, indicating the vulnerability of riverine ecosystems. Long-term flow trend analysis enables the identification of critical dry periods and hydrological regime changes, aiding decision-making in water resource allocation, and the protection of aquatic ecosystems. Furthermore, these results provide a scientific basis for developing climate adaptation strategies at the watershed scale and optimizing surface water resource management.

Identification and analysis of changes in hydrological indices of river flow play a key role in assessing the impacts of climate change and human interventions on river regimes. This study investigates the long-term trends of hydrological indices in the Samian watershed, located in Ardabil province. Daily river discharge data from 1973 to 2019 were analyzed using the Indicators of Hydrologic Alteration (IHA) approach. The results revealed that river flow values in the fall and winter months, particularly from October to February, exhibited a significant decreasing trend (P-value < 0.01). Additionally, minimum flows (1 to 90-day periods), base flow indices, and the timing of minimum flows showed significant decreasing trends, indicating reduced flow stability during dry periods and heightened water stress. The highest dispersion coefficients (over 4) were associated with low-flow events in May, June, and July, indicating high variability. In contrast, indices related to short-term and intense floods showed lower dispersion. The median of maximum flows (1 to 7 days) was estimated between 27 and 40 cms, while minimum flows were much lower (below 0.1) and exhibited considerable variability. EFC Low Flow indices in most months showed low medians and high dispersion, indicating the vulnerability of riverine ecosystems. Long-term flow trend analysis enables the identification of critical dry periods and hydrological regime changes, aiding decision-making in water resource allocation, and the protection of aquatic ecosystems. Furthermore, these results provide a scientific basis for developing climate adaptation strategies at the watershed scale and optimizing surface water resource management.

Identification and analysis of changes in hydrological indices of river flow play a key role in assessing the impacts of climate change and human interventions on river regimes. This study investigates the long-term trends of hydrological indices in the Samian watershed, located in Ardabil province. Daily river discharge data from 1973 to 2019 were analyzed using the Indicators of Hydrologic Alteration (IHA) approach. The results revealed that river flow values in the fall and winter months, particularly from October to February, exhibited a significant decreasing trend (P-value < 0.01). Additionally, minimum flows (1 to 90-day periods), base flow indices, and the timing of minimum flows showed significant decreasing trends, indicating reduced flow stability during dry periods and heightened water stress. The highest dispersion coefficients (over 4) were associated with low-flow events in May, June, and July, indicating high variability. In contrast, indices related to short-term and intense floods showed lower dispersion. The median of maximum flows (1 to 7 days) was estimated between 27 and 40 cms, while minimum flows were much lower (below 0.1) and exhibited considerable variability. EFC Low Flow indices in most months showed low medians and high dispersion, indicating the vulnerability of riverine ecosystems. Long-term flow trend analysis enables the identification of critical dry periods and hydrological regime changes, aiding decision-making in water resource allocation, and the protection of aquatic ecosystems. Furthermore, these results provide a scientific basis for developing climate adaptation strategies at the watershed scale and optimizing surface water resource management.

Identification and analysis of changes in hydrological indices of river flow play a key role in assessing the impacts of climate change and human interventions on river regimes. This study investigates the long-term trends of hydrological indices in the Samian watershed, located in Ardabil province. Daily river discharge data from 1973 to 2019 were analyzed using the Indicators of Hydrologic Alteration (IHA) approach. The results revealed that river flow values in the fall and winter months, particularly from October to February, exhibited a significant decreasing trend (P-value < 0.01). Additionally, minimum flows (1 to 90-day periods), base flow indices, and the timing of minimum flows showed significant decreasing trends, indicating reduced flow stability during dry periods and heightened water stress. The highest dispersion coefficients (over 4) were associated with low-flow events in May, June, and July, indicating high variability. In contrast, indices related to short-term and intense floods showed lower dispersion. The median of maximum flows (1 to 7 days) was estimated between 27 and 40 cms, while minimum flows were much lower (below 0.1) and exhibited considerable variability. EFC Low Flow indices in most months showed low medians and high dispersion, indicating the vulnerability of riverine ecosystems. Long-term flow trend analysis enables the identification of critical dry periods and hydrological regime changes, aiding decision-making in water resource allocation, and the protection of aquatic ecosystems. Furthermore, these results provide a scientific basis for developing climate adaptation strategies at the watershed scale and optimizing surface water resource management.