Global Runoff Signatures Changes and Their Response to Atmospheric Environment, GRACE Water Storage, and Dams

Abstract

Runoff signatures (RS), a special set of runoff indexes reflecting the hydrological process, have an important influence on many fields of both human and natural systems by flooding, drought, and available water resources. However, the global RS changes and their causes remain largely unknown. Here, we make a comprehensive investigation of RS changes and their response to total water storage anomalies (TWSA) from GRACE satellites, atmospheric circulation, and reservoir construction by using daily runoff data from 21,955 hydrological stations during 1975–2017. The global assessment shows that (1) in recent years, the global extreme flow signatures tend to decrease, while the low and average flow signatures are likely to increase in more regions; (2) the spatial patterns of trends are similar for different RS, suggesting that the runoff distribution tends to entirely upward in some regions, while downward in other regions; (3) the trends in RS are largely consistent with that in TWSA over most regions in North America and eastern South America during 1979–2017, indicating that the GRACE-based TWSA have great potential in hydrological monitoring and attribution; (4) atmospheric circulation change could partly explain the global spatiotemporal variation patterns of RS; (5) dams have important influences on reducing the high flow signature in the catchments including dams built during 1975–2017. This study provides a full picture of RS changes and their possible causes, which has important implications for water resources management and flood and drought disaster assessment.

Keywords

• runoff signatures
• GRACE satellites
• atmospheric circulation
• floods