Vegetation dynamics alter the hydrological interconnections between upper and mid-lower reaches of the Yellow River Basin, China

Abstract

Vegetation coverage has changed substantially in the Yellow River Basin in recent decades, which may have influenced the interaction between midstream and upstream hydrological processes. On the basis of trend analysis and grey correlation analysis, we used structural equation modeling to explore relationships between hydrology and vegetation, and to clarify how these relationships affect the hydrological interconnections between the upper and mid-lower reaches of the Yellow River Basin. During the observation period, the normalized difference vegetation index showed an increasing trend. The area of grassland and cropland decreased, while the area of shrubland and forest increased. Precipitation, evapotranspiration and total water consumption increased. Precipitation, total water consumption, and vegetation dynamics exerted stronger influence than temperature on upstream export runoff. Upstream export runoff influenced midstream runoff to an even greater extent than the local vegetation and meteorological conditions. Our results suggest that upstream vegetation dynamics should be carefully considered when exploring the ecohydrology of the middle and lower reaches of the Yellow River Basin. These findings may provide a theoretical basis for implementation of ecological restoration projects in the upper parts of the Yellow River Basin.

Keywords

• Eco-hydrology
• Normalized Difference Vegetation Index
• Evapotranspiration
• Runoff
• Grey Relation Analysis
• Structural Equation Model