With its 15-year mission duration, the satellite mission GRACE provided a time series of time-variable global mass redistribution that allows to identify regions experiencing long-term changes in their water resources. The common indicator for water stress is the linear trend in ground-water storage. In this contribution, the authors around Bramha Dutt Vishwakarma argue that trends in storage behaviour should be assessed against the non-seasonal natural variability in river catchments. Small trends may be highly relevant for river systems with low natural variability, e.g. in semi-arid areas, whereas, on the opposite, large trends may "drown" in the natural variability, e.g. in case of large tropical river systems. As such this publication provides a more differentiated view on the long-term storage characteristics of river catchments.