Terrestrial water storage is the primary source of river flow. We introduce storage sensitivity of streamflow (ϵS), which for a given flow rate indicates the relative change in streamflow per change in catchment water storage. ϵS can be directly derived from streamflow observations. Analysis of 725 catchments in Europe reveals that ϵS is high in e.g. parts of Spain, England, Germany and Denmark, whereas flow regimes in parts of the Alps are more resilient (that is, less sensitive) to storage changes. A regional comparison of ϵS with observations indicates that ϵS is significantly correlated with variability of low (R2 = 0.41), median (R2 = 0.27), and high flow conditions (R2 = 0.35). Streamflow sensitivity provides new guidance for a changing hydrosphere where groundwater abstraction and climatic changes are altering water storage and flow regimes.
- Flow regime