Regionalization of hydrological cycle changes in 31 source catchments of Yellow River Basin considering multiple hydrological variables

The 31 source catchments in the Yellow River Basin (YRB). Hydrological cycle changes showed remarkable regional heterogeneities, but existing studies usually focused on individual hydrological variable, which were insufficient to reflect comprehensive changes of entire hydrological cycles. In our study, different frequency metrics of runoff (R), evapotranspiration (ET) and water storage (WS) are adopted, and data source combinations are evaluated by water balance restriction. The hydrological change types are identified by classifying Sen’s slopes with statistical significance using cluster analysis. The water balance errors of the optimal data source combinations were −9.75–9.78 %. All the hydrological variables showed significant changes (-0.16–4.28 mm/a) in 31 source catchments from 2000 to 2020. The average slope was the largest in WS (1.65 mm/a), followed by ET (0.004 mm/a) and R (0.004 mm/a). The comprehensive changes were divided into three hydrological change types, namely significant intensification of R, ET and WS, significant intensification of ET and WS, and significant intensification of ET and WS but decreased in R, respectively. These three change types mainly occurred in the Yellow River Source Region (42 %), the north tributaries of Weihe River (10 %), and most of the Weihe and Yiluo rivers (48 %), respectively. This study is expected to provide better insights into the study of hydrological cycle in the watersheds under environmental changes. • Water balance equation is used to restrict multi-source accuracies of hydrological variables. • The water balance error of the optimal data source combination is between ± 10 %. • The significant change of 11 hydrological variables ranges from −0.16–4.28 mm/a. • The hydrological cycle has significant intensified in three hydrological change types.