Quantifying Eco-hydrological risks in the Yellow River Basin, China

The Yellow River Basin (YRB) is an important ecological corridor in northern China, which has undergone substantial changes in multiple eco-hydrological processes. Such changes may decouple carbon, water and energy within ecosystem and cause substantial eco-hydrological risks. In this study, changes in key eco-hydrological variables are investigated and general associtions of evolution trends are revealed by correlation-based networks. Causal networks are then used with physical constraints, to quantitatively portray the directions and magnitudes of eco-hydrological feedbacks. A new index called the Standardized Compound Drought-Vegetation Loss Index (SCDVI) is proposed and used to quantify EHS risk based on stability (derived from resistance and resilience). The results show that the upper reaches of the basin, particularly the source and nearby subregion, show synergistic evolutions between ecological and hydrological subsystems while in the middle and lower reaches eco- and hydro-subsystems show poor synergistic changes. EHS stability was relatively low in the southeastern YRB, where the risk of experiencing compound drought and vegetation loss event (CDVE) was high. The study also found that regions with high vegetation productivity were more prone to a high resistance–low resilience trade-off, while areas with low vegetation productivity exhibited the opposite trade-off.