Effects of Multi-time Scale Meteorological Drought on Vegetation in the Yellow River Basin from 1982 to 2020

Abstract

[Objective] Intensive research on the spatial and temporal response characteristics of meteorological drought to vegetation at different time scales in the Yellow River Basin provides valuable information for ecological conservation, water resource management, and climate change adaptation, and can mitigate the environmental and economic problems caused by drought. [Methods] Based on the standardized precipitation evapotranspiration index (SPEI) and normalized vegetation index (NDVI) for the Yellow River Basin during the period of 1982—2020, image-by-image metric linear regression models, Sen’s trend analysis and Mann-Kendall test were used to study the spatial and temporal distribution characteristics of meteorological droughts at different time scales in the Yellow River Basin, as well as their impacts on vegetation. [Results] (1) From 1982 to 2020, the Yellow River Basin showed an insignificant increasing trend in aridity, with regions exhibiting negative trends in SPEI mainly concentrated in the western region from Longyangxia to Lanzhou, the southern part of the Yellow River Basin, and the surrounding areas of the Hetao Plain. (2) The spatial distribution pattern of average vegetation coverage in the Yellow River Basin demonstrated a decreasing trend from south to north and from southeast to northwest. The proportion of regions with a significant increase in vegetation coverage (61.94%) was greater than that of those with a significant decrease (5.43%). (3) In most areas of the Yellow River Basin, drought conditions were positively correlated with vegetation status. Regions exhibiting significant positive correlations were mainly concentrated in the northwest and northernmost areas of the Yellow River Basin, indicating that vegetation in these areas was severely affected by drought. (4) Grassland and cultivated land showed the strongest response to drought at a six-month time scale, while forests and unused land were more vulnerable to long-term drought compared to other land types. All four landform types were susceptible to medium- to long-term water shortages, with vegetation in hilly areas being the most affected by drought. [Conclusion] The results of the study provide an effective scientific basis for disaster prevention and mitigation as well as ecological environment construction in the Yellow River Basin, and provide important information for ecological protection, water resource management and climate change adaptation in the Yellow River Basin, which will help to formulate more precise policies and measures to mitigate the potential impacts of drought on the environment and the economy, and to promote sustainable development.

Keywords

• spei
• meteorological drought
• vegetation change
• ndvi
• yellow river basin