The Role of the Turkish Water Project in Altering Water Availability in the Aras River Basin

Upstream and regional regulation of the natural flow in the transboundary river basins can place certain parties at a disadvantage, resulting in socioeconomic and environmental challenges. These challenges can lead to asymmetric relationships and even geopolitical issues. The Aras River Basin, a transboundary river shared by Turkiye, Armenia, Iran, and Azerbaijan, has been affected by the regional water development under the DAP mega-project in Turkiye in recent years. To evaluate the impact of the implementation of this project on the Aras River Basin, the inflow to the Aras Dam, a dam located between Iran and Azerbaijan, and drought conditions in the basin were analyzed using the Pettitt test alongside drought indices like SPI, SPEI, and MSDI. Furthermore, to assess spatial/temporal changes in hydrometeorological variables, two non-parametric methods, including the modified Mann-Kendall method (MK3) and Innovative Trend Analysis (ITA), were applied. The results revealed a concerning trend in the Aras River Basin, characterized by decreasing inflow to the dam, no observable trend in precipitation, and rising temperatures. The Pettitt test identified a significant change point in 1995, after which the mean annual inflow to the dam dropped by approximately 800 million cubic meters (MCM), stabilizing around 3,700 MCM. A comparison of monthly mean values before and after this change point indicated that the greatest reduction occurred in May, the period of peak inflow to the dam. The analysis of drought indices further revealed that while precipitation deficits in the late 1990s significantly impacted inflows to the dam, the river has experienced drought conditions in recent years despite adequate precipitation. While climate change and global warming have influenced river flow in the Aras River Basin, the decline in annual mean inflow to the dam closely corresponds to the combined capacity of reservoirs operated by Turkiye after 1995. With the completion and operation of additional dams currently under construction or planned, the inflow to the Aras Dam is projected to decrease further, potentially falling below 1,500 MCM. The declining inflow to the Aras Dam could significantly impact the livelihoods of people in Iran and Azerbaijan living near the river, as well as for local communities. These impacts may lead to socio-economic and geopolitical challenges, like those observed in Syria and Iraq. Moreover, the reduced flow in the Aras River decreases inflow to the Caspian Sea, contributing to falling water levels, ecological degradation, and adverse impacts on regional economies and livelihoods.