Iran’s Dam Waterbodies: A 10-Year Trend Analysis (2013–2023)

Previous studies have shown instances where aquatic ecosystems in Iran have experienced water loss even in the absence of upstream dams, while other ecosystems with upstream dams did not show significant declines in water levels. Thus, attributing the drying of these ecosystems solely to climate change in the watershed is not definitive, especially when water levels behind dams have increased while wetlands’ water volumes decreased due to water diversion. This complexity underscores the challenge of linking the decline of aquatic ecosystems exclusively to climate change, as reduced rainfall would naturally lead to decreased water levels behind dams as well. This study addresses this complex issue by analyzing 60 water bodies behind dams across various regions of Iran from 2013 to 2023, using Landsat 8 satellite images and the AWEIsh water index. We employed linear regression to detect surface change trends during this period. Our findings revealed statistically significant (P-value < 0.05) trends in 13 out of the 60 water bodies, with four showing an increasing trend in water levels, indicating diverse precipitation patterns across Iran rather than a uniform decline. Among these, nine dams with significant trends experienced decreased water levels, reflecting reduced upstream rainfall in their watersheds over the past decade. This supports existing research highlighting climate change’s impact on Iran’s water resources. Despite highlighting the impact of declining precipitation and increasing temperatures in certain regions, our study also reveals that certain areas in Iran have not faced such severe conditions. In fact, some regions have seen a notable increase in dam water levels over the past decade. This study emphasizes the importance of an impartial assessment of Iran’s water reserves, free from preconceived notions from previous studies. Such an objective evaluation is crucial for effective management of Iran’s water resources.