Channel Water Storage Anomaly: A New Remotely Sensed Quantity for Global River Analysis

Abstract

River channels store large volumes of water globally, critically impacting ecological and biogeochemical processes. Despite the importance of river channel storage, there is not yet an observational constraint on this quantity. We introduce a 26‐year record of entirely remotely sensed volumetric channel water storage (CWS) change on 26 major world rivers. We find mainstem volumetric CWS climatology amplitude (CA) represents an appreciable amount of basin‐wide terrestrial water storage variability (median 2.78%, range 0.04%–12.54% across world rivers), despite mainstem rivers themselves represent an average of just 0.2% of basin area. We find that two global river routing schemes coupled with land surface models reasonably approximate CA (within ±50%) in only 11.5% (CaMa‐Flood) and 30.7% (HyMap) of rivers considered. These findings demonstrate volumetric CWS is a useful quantity for assessing global hydrological model performance, and for advancing understanding of spatial patterns in global hydrology.

Tracking River's Pulse From Space: A Global Analysis of River Stage Fluctuations

“…We anticipate the stage fluctuation data set will facilitate related work in a broad range of geosciences. For instance, river stage fluctuations can be used to estimate river channel storage changes (Coss et al., 2023). In analogy to the estimation of lake or reservoir storage change, channel storage change can be estimated by combining the stage fluctuation and corresponding river area derived from imagery for a given reach.…”

“…It serves various crucial purposes such as characterizing the patterns and processes of a river system, estimating river storage dynamics, managing hydrological disasters, validating hydraulic/hydrodynamic models, and enhancing our understanding of many interconnected hydro‐biogeochemical processes (Humphries et al., 2014). Recent studies (e.g., Coss et al., 2023; Trautmann et al., 2023) have highlighted the importance of river storage to the total water storage dynamics. However, the knowledge of stage fluctuations on a global scale is still very poor.…”