Variations in annual water-energy balance and their correlations with vegetation and soil moisture dynamics: A case study in the Wei River Basin, China

Abstract

It is of importance to investigate watershed water-energy balance variations and to explore their correlations with vegetation and soil moisture dynamics, which helps better understand the interplays between underlying surface dynamics and the terrestrial water cycle. The heuristic segmentation method was adopted to identify change points in the parameter ω series in Fu’s equation belonging to the Budyko framework in the Wei River Basin (WRB) and its sub-basins aiming to examine the validity of stationary assumptions. Additionally, the cross wavelet analysis was applied to explore the correlations between vegetation and soil moisture dynamics and ω variations. Results indicated that (1) the ω variations in the WRB are significant, with some change points identified except for the sub-basin above Zhangjiashan, implying that the stationarity of ω series in the WRB is invalid except for the sub-basin above Zhangjiashan; (2) the correlations between soil moisture series and ω series are weaker than those between Normalized Difference Vegetation Index (NDVI) series and ω series; (3) vegetation dynamics show significantly negative correlations with ω variations in 1983–2003 with a 4–8year signal in the whole WRB, and both vegetation and soil moisture dynamics exert strong impacts on the parameter ω changes. This study helps understanding the interactions between underlying land surface dynamics and watershed water-energy balance.