Managing complex social-hydrological systems for water security: the case of the mountain cryosphere

In many mountain regions, the cryosphere is a crucial component of water provision to downstream societies, as it contributes to dry-season flows and sustains diverse ecosystems. However, many of the world’s glacierized watersheds experience far-reaching changes at accelerated pace due to declining glaciers and snowpack, climate change impacts and socioeconomic development in the non-cryospheric parts of the catchment. The implications for downstream water supply are therefore manifold and complex. Coupled effects of reduced and less reliable water availability, changes in water quality, and growing water demand exert increasing pressure on water resources and threaten future water security and management.

We argue that the limited understanding of interactions between the cryosphere, glacial and non-glacial water stores, river runoff and people hamper climate change adaptation and long-term water security. Meaningful assessments of mountain water security require therefore a holistic social-ecological perspective that interlinks the wider catchment hydrology considering both, surface and subsurface stores, and people including human water demand with improved data and process understanding. Water security assessments can then be guided by a fully coupled hydrological risk framework. This approach needs to integrate multiple social-ecological vulnerabilities as well as the degree of exposure to water shortage under a variety of possible future scenarios of glacier shrinkage, catchment alteration and socioeconomic development. Essentially, this requires a thorough understanding of interrelated upstream-downstream systems and the spatiotemporal propagation of meltwater through the terrestrial water cycle.

Improved data and more diverse knowledge collection that point to the missing links in the terrestrial water cycle are a priority. Multiple sources of knowledge should be co-produced and integrated into a collaborative science-policy-community framework, ideally from the early stages of research planning with attention to local practices and governance. This approach can support a wide set of incremental and transformational strategies that guide robust, locally tailored and effective adaptation pathways. These may include, among other, exploring catchment-specific benefits of nature-based solutions to increase the buffer function of wider catchment hydrology against water loss from glacier shrinkage to enhance long-term water security.