Analysis of the evolution and attenuation attribution of runoff in the LRB based on ESMD and Budyko framework

Study Region：The Laoha River Basin (LRB) of northeast ChinaStudy Focus: To eliminate inconsistencies arising from multi-method disparities in scale and analytical focus, the ESMD (Extreme-point Symmetric Mode Decomposition) method was employed to comprehensively analyze the evolution characteristics of non-stationary runoff within a unified method framework. The EN (Elastic Net) method was proposed to analyze runoff sensitivity to CC (climate change) and HA (human activities), and further validate the interpretability and effectiveness of the Elasticity Coefficient method. The main drivers of runoff attenuation and their contribution rates in each sub-basin of LRB was quantitatively identified based on the Budyko framework. The main contributing areas of runoff attenuation were identified based on the "observed-simulated" comparison approach.New Hydrological Insights for the Region: (1) The annual runoff in the LRB showed a significantly fluctuating downward trend, and two abrupt changes occurred in 1979 and 1998. (2) Runoff sensitivity to CC and HA increased during the HIPs (human impact phases) compared to the BP (baseline period), and it was higher in the middle and lower reaches than in the upper reaches. (3) HA have had the most significant impact on the runoff attenuation, of which the human water use and the expansion of cropland were the most direct factors. (4) The middle reaches were the key contributions area of runoff attenuation in the whole basin.