Trend Analysis of Terrestrial Water Availability in the Amu River Basin Under Climate Change

Amu River basin is one of Central Asia's largest international transboundary river basins, gradually experiencing more water stress due to increased human interventions and climate change. The objective of this study was to find trends in water availability in the Amu river basin. For this purpose, the Jet Propulsion Laboratory (JPL) data as one of the Gravity Recovery and Climate Experiment (GRACE) solutions with a high spatial resolution of 0.5° for the period 2002–2019 was used. The results of variability in Terrestrial Water Storage (TWS) showed higher variability (≥30 cm) in the Tundra and warm-dry continental climate and gradually decreased towards the hot-summer Mediterranean climate zone. In contrast, the spatial variability is low towards the west and northwest of the basin, which means water resource reliability increases in the steppe and cold desert climate zone. The trend analysis results revealed a higher decrease in water availability in the Tundra and warm, dry continental climate zones and the delta region of the basin, with a negative value ranging from 0.04 to –0.08 cm/year. Therefore, the results indicate that GRACE could be applied successfully for a large-scale basin with a diverse climate condition.