Large‐scale river flow archives: importance, current status and future needs

Abstract

Time-series for river gauging stations are core blue-skies and applied
\nresearch resources for understanding impacts of climate and anthropogenic
\nchange on basin hydrology. River flow archives hold vital information
\nfor evidence-based assessment of past hydrological variability,
\nand support hydrological modelling of future changes. River discharge
\nis an integration of basin input, storage and transfer processes to the
\ngauging point. It is important to set basin outlet data in regional to
\nglobal and long-term contexts: to better understand nested scales of
\nvariability; to pinpoint locations and time periods most sensitive to climate
\nand human impacts; to make predictions for ungauged basins;
\nand to inform decision makers on water security issues, and where and
\nwhen to take measures to mitigate water hazards and stress, including
\nfloods and droughts (Dai et al., 2009; Bonnell et al., 2006; Feyen &
\nDankers, 2009; Haddeland et al., 2006; Hannah et al., 2005). Thus, there
\nis clear rationale for supporting large-scale (i.e. regional to continental to
\nglobal) river flow archives. Notable examples of such databases include
\nthat held by the WMO Global Runoff Data Centre (GRDC) and the
\nUNESCO Flow Regimes from International Experimental and Network
\nData (FRIEND) European Water Archive (EWA). For large-scale river
\nflow archives to be valuable research resources, they must be fit for
\npurpose. However, these databases are at risk due to a possible decline
\nin network coverage, associated time-series truncation, growing human
\nimpact on (near-) natural flows, and increasingly restricted access to
\nnational-scale data. This commentary aims: (1) to demonstrate largescale
\nriver flow datasets are crucial to advance hydrological science and
\nsolve operational issues; (2) to assess the current status of large-scale
\nriver flow datasets; and (3) to propose ways forward to consolidate historical
\ndata and secure future river flow data.