Global Institute for Water Security
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Browsing Global Institute for Water Security by Author "Kummu, Matti"
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Item Hotspots for social and ecological impacts from freshwater stress and storage loss(Nature Portfolio, 2022) Huggins, Xander; Gleeson, Tom; Kummu, Matti; Zipper, Sam; Wada, Yoshihide; Troy, Tara; Famiglietti, James S.Humans and ecosystems are deeply connected to, and through, the hydrological cycle. However, impacts of hydrological change on social and ecological systems are infrequently evaluated together at the global scale. Here, we focus on the potential for social and ecological impacts from freshwater stress and storage loss. We find basins with existing freshwater stress are drying (losing storage) disproportionately, exacerbating the challenges facing the water stressed versus non-stressed basins of the world. We map the global gradient in social-ecological vulnerability to freshwater stress and storage loss and identify hotspot basins for prioritization (n = 168). These most-vulnerable basins encompass over 1.5 billion people, 17% of global food crop production, 13% of global gross domestic product, and hundreds of significant wetlands. There are thus substantial social and ecological benefits to reducing vulnerability in hotspot basins, which can be achieved through hydro-diplomacy, social adaptive capacity building, and integrated water resources management practices.Item Poor correlation between large-scale environmental flow violations and freshwater biodiversity: implications for water resource management and the freshwater planetary boundary(2022) Mohan, Chinchu; Gleeson, Tom; Famiglietti, James S.; Virkki, Vili; Kummu, Matti; Porkka, Miina; Wang-Erlandsson, Lan; Huggins, Xander; Gerten, Dieter; Jähnig, Sonja C.The freshwater ecosystems around the world are degrading, such that maintaining environmental flow1 (EF) in river networks is critical to their preservation. The relationship between streamflow alterations (subsequent EF violations2) and the freshwater biodiversity response is well established at the scale of stream reaches or small basins (~<100 km2). However, it is unclear if this relationship is robust at larger scales, even though there are large-scale initiatives to legalize the EF requirement. Moreover, EFs have been used in assessing a planetary boundary3 for freshwater. Therefore, this study intends to conduct an exploratory evaluation of the relationship between EF violation and freshwater biodiversity at globally aggregated scales and for freshwater ecoregions. Four EF violation indices (severity, frequency, probability of shifting to a violated state, and probability of staying violated) and seven independent freshwater biodiversity indicators (calculated from observed biota data) were used for correlation analysis. No statistically significant negative relationship between EF violation and freshwater biodiversity was found at global or ecoregion scales. These findings imply the need for a holistic bio-geo-hydro-physical approach in determining the environmental flows. While our results thus suggest that streamflow and EF may not be the only determinant of freshwater biodiversity at large scales, they do not preclude the existence of relationships at smaller scales or with more holistic EF methods (e.g., including water temperature, water quality, intermittency, connectivity, etc.) or with other biodiversity data or metrics.