In the heart of the Tibetan Plateau, a complex interplay of snow, reservoirs, and precipitation is reshaping the region’s water dynamics, with significant implications for the energy sector. A recent study published in ‘Hydrology and Earth System Sciences’ (or in English, ‘Water and Earth System Sciences’) has shed light on these intricate processes, offering valuable insights for long-term water resource management and hydropower development.
The research, led by N. Wu from the State Key Laboratory of Water Disaster Prevention at Hohai University in Nanjing, China, focused on the Yalong River basin, a hydrologically complex region with elevations ranging from 1000 to 5900 meters above sea level. The team developed an extended Budyko framework to analyze monthly water balances over 15 years (2002-2016), explicitly separating snow storage dynamics from other terrestrial water storage changes, including those related to hydropower reservoir construction.
The findings revealed a pronounced altitudinal heterogeneity in the drivers of monthly runoff. “Snow accumulation and snowmelt are the main drivers of runoff seasonality in the upper sub-catchments,” explained Wu. “Their effects propagate to the lower-elevation snow-free sub-catchments, which are also subject to additional influence from hydropower reservoirs.”
This altitudinal variation in runoff drivers is a phenomenon rarely quantified at such high spatio-temporal resolution in other global regions. The study also observed a decrease in runoff seasonality in the Yalong River at its Yangtze River outlet, a change likely driven by trends in unfrozen precipitation seasonality and/or flow-modulating impacts of reservoirs, natural lakes, and groundwater.
The implications for the energy sector are substantial. As Wu noted, “Future snow thinning may exacerbate these trends, potentially impacting hydropower generation and water resource management.” The study’s findings could guide the development of more resilient and adaptive hydropower infrastructure, as well as inform water resource management strategies in the face of climate change.
Moreover, the research demonstrated the applicability of the extended monthly Budyko framework for identifying dominant processes in runoff generation. By implementing a variance decomposition method, the team captured intra-annual runoff variability with high accuracy, achieving R² values above 0.9 in most sub-basins. This method could be a valuable tool for other regions experiencing rapid environmental changes.
The study’s findings are particularly relevant for the Tibetan Plateau and other high-elevation, seasonally cold regions. As the world grapples with the impacts of climate change, understanding these complex hydrological processes will be crucial for sustainable water resource management and energy production.
In the words of Wu, “Our findings support the applicability of the extended monthly Budyko framework for identifying dominant processes in the context of runoff generation and the rapid environmental changes that the Yalong River basin and other cold regions are currently experiencing.” This research not only advances our scientific understanding but also paves the way for more informed decision-making in the energy sector.