Extended Abstract
Introduction
   Water, as the most vital element for human survival and socio-economic development, plays a pivotal role in ensuring national, regional, and human security. In recent decades, the continuous decline in freshwater resources—driven by population growth, industrialization, urban expansion, and climate change—has made water scarcity one of the most critical global challenges. Metropolises such as Mashhad, which are heavily dependent on shared transboundary water resources, have become increasingly vulnerable to water shortages and water insecurity, particularly due to their significant reliance on the Harirud river basin and water infrastructure projects like the Doosti Dam. Changes in neighboring countries’ water policies (notably Afghanistan) and intensified global warming have further complicated the crisis, making comprehensive evaluation of water sustainability and security for Mashhad—with emphasis on hydro-political and climatic factors—an essential prerequisite for sustainable management and planning
 Materials / Methods
   This study adopts an applied and mixed-methods approach (quantitative and qualitative) to provide a comprehensive assessment of Mashhad’s water resources and the effects of upstream hydro-political policies. In the quantitative section, trends in climatic variables (temperature, precipitation, and drought) were analyzed using satellite imagery and calculation of the Standardized Precipitation Evapotranspiration Index (SPEI) to evaluate the impacts of climate change and drought on regional water resources. The qualitative analysis involved document review, examination of treaties and policies, and geopolitical analysis of relationships between Afghanistan (upstream country) and downstream countries (Iran and Turkmenistan), in order to elucidate dimensions of water competition and cooperation. Water level data for the dams were also assessed using remote sensing and statistical tests to clarify the correlation between the operations of Salma and Doosti Dams.
 Discussion and Findings
   Analysis of climatic trends over the past three decades (1991–2020) in the Harirud Basin reveals considerable annual precipitation variability and a persistent decline in rainfall, especially in downstream and urban areas such as Mashhad. Concurrently, annual temperature trends have shown an upward trajectory, with mean temperatures rising by over 2°C compared to the 1990s—a phenomenon that has increased evapotranspiration, reduced precipitation efficiency, intensified soil aridity, and put water resource sustainability at risk.
SPEI analysis indicates that drought episodes have become more frequent and severe in recent decades. During critical years such as 2000–2002, this has led to a noticeable reduction in inflow to the Salma and Doosti Dams. The consequences include decreased soil moisture, reduced river flow, and constrained dam storage and supply capacity. Field observations and satellite-based data confirm a continued declining trend in the water levels of these dams.
In the realm of transboundary and hydro-political relations, the findings show that Afghanistan, as the upstream country, has increasingly pursued the development of dam infrastructure (including Salma, Pashdan, and Kabdan) and maximum utilization of shared water resources. The absence of binding treaties, weak political will for cooperation, and Afghanistan’s emphasis on national sovereignty have resulted in diminished water shares for Iran and Turkmenistan and heightened downstream vulnerability. Statistical analysis of Doosti Dam water levels confirms that the operation of Salma Dam exerts a significant and direct influence on Mashhad’s water supply status.
Moreover, the lack of effective and multilateral cooperation frameworks has intensified a climate of competition, distrust, and even regional tension over water management. Iran’s high dependence on shared water resources—compounded by climatic pressures—places it in a highly vulnerable position, highlighting the necessity for enhanced flexibility, improved risk management, investment in resource management technologies, and stronger efforts to achieve more effective agreements.
 Conclusions
   Research on the Harirud Basin demonstrates that the combined impacts of climate change—particularly reduced rainfall and increased temperatures—have intensified drought trends and reduced available water in the region. Diminished average annual precipitation and higher evapotranspiration have weakened surface and groundwater resources, while drought indices underscore the growing severity and frequency of dry periods in recent decades. Both statistical analysis and field observations indicate that reservoir volumes behind key dams (Salma and Doosti) are influenced not only by annual precipitation but are highly dependent on upstream water management policies. The construction of Salma Dam and other water infrastructure projects have significantly reduced water deliveries to Iran and Turkmenistan, posing a serious threat to Mashhad’s water security. In recent years, Iran’s share of Harirud water has declined sharply, and in some years, only a negligible portion of the legally recognized allocation has been delivered.
Modeling results suggest that, if current trends and Afghanistan’s increased water withdrawals continue, the Doosti Dam will, under optimistic scenarios, be able to meet Mashhad’s potable water needs only until 2036 (1415 in the Iranian calendar); under severe drought scenarios, even less. Afghanistan, invoking national sovereignty and water securitization, and benefiting from foreign support, continues to expand its water infrastructure and restrict downstream flows, showing little inclination towards effective negotiation and binding agreements with Iran.
Despite these challenges, opportunities still exist to strengthen bilateral cooperation—with a focus on shared benefits and services (such as electricity exports, transfer of irrigation technologies, expanded trade, and leveraging historical and cultural ties like the Silk Road)—to build trust and achieve sustainable resource management. Global experiences in water governance demonstrate that multifaceted strategies—including enhanced water diplomacy, binding agreements, diversification of urban water supplies, increased efficiency, and scientific monitoring and modeling—can boost the resilience of cities such as Mashhad to climatic and hydro-political shocks. In summary, the long-term sustainability and security of Mashhad’s water resources requires a comprehensive, interdisciplinary, and participatory governance approach that simultaneously addresses regional climatic, political, and social conditions, and recognizes the necessity of regional cooperation with upstream countries.