Spatiotemporal shifts in key hydrological variables and dominant factors over China

• Published in: Hydrological processes Vol. 35; no. 8
• Main Authors: Sun, Shanlei, Bi, Zaoying, Zhou, Shujia, Wang, Hongzhou, Li, Qingqing, Liu, Yi, Wang, Guojie, Li, Shijie, Chen, Haishan, Zhou, Yang
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 01.08.2021; Wiley Subscription Services, Inc
• Subjects: Budyko hypothesis; Catchment area; China; dominant factor; Dynamics; Evapotranspiration; hydrological cycle; Hydrology; Meteorological research; Population density; Runoff; separation method; shift; Stream discharge; Stream flow; Water resources; China
• ISSN: 0885-6087; 1099-1085
• DOI: 10.1002/hyp.14319

Quantitatively and physically understanding changes in land surface hydrology is a hot topic in the hydro‐meteorological research, especially over China with high population density but uneven distribution of water resources. Therefore, the spatiotemporal dynamics (i.e., the 1980s [1981–1990] and 1990s [1991–2000] relative to the baseline of 1961–1980) in evapotranspiration (ET) and streamflow/runoff (Q) were examined across 426 hydrological divisions (HDs) of China. Both the 1980s and 1990s ET decreased over roughly 50% HDs mainly in the central and southeast parts of China, while the 1980s (1990s) Q decreased over slightly higher than 50% (63%) HDs generally in north and southwest China (the central and north parts of China). Relative to the 1980s, more HDs had strong changes in ET and Q in 1990s. Based on the separated contributions of precipitation (P), reference ET and Budyko‐type equation parameter n (an integrated variable of catchment property) to ET and Q changes, we found that in 1980s and 1990s, n dominated ET changes over about 60% HDs mainly in the south, with the dominant of P around 35% HDs generally in the north and northeast, while for Q changes, nearly 60% (slightly less than 40%) HDs were dominated by n (P). Moreover, the dominants for ET (Q) changes have shifted from 1980s to 1990s over 36% (45%) HDs, mainly changing from P to n. This study provides a framework for quantitatively understanding land surface hydrological dynamics from the perspectives of climatic and physiographic controls over regions. Changes in ET and Q during 1980s and 1990s (relative to 1961–1980) were analysed across 426 hydrological divisions (HDs) of China. In 1980s and 1990s, ET (Q) decreased over roughly (higher than) 50% HDs, but with different spatial patterns and magnitudes. Based on contributions of P, reference ET and catchment parameter (n) to ET and Q changes, dominants were examined and were detected to shift from 1980s to 1990s, primarily from P to n.