Temporal and Spatial Variation of Rainfall Erosivity in Middle Reaches of Yellow River Based on Different Models

Abstract

[Objective] Based on different models, the spatiotemporal evolution characteristics of rainfall erosivity in the middle reaches of the Yellow River were explored, in order to providing a reference basis for the assessment of soil erosion hazards and planning of soil and water conservation measures in this area. [Methods] Daily rainfall data from 1981 to 2020 for the middle reaches of the Yellow River was used to explore the temporal and spatial variation characteristics of rainfall and rainfall erosivity based on two rainfall erosivity models. [Results] Average annual rainfall in the middle reaches of the Yellow River was between 349.90 mm and 699.90 mm. Spatial variation followed a fluctuating decreasing trend from southeast to northwest. Temporal variation exhibited a multi-peak insignificant upward fluctuation that had a 2-year main cycle change feature. There were some similarities between the two models of rainfall erosivity from the interannual trend characteristics and periodicity in the middle reaches of the Yellow River. However, areas with greater rainfall exhibited greater differences in rainfall erosivity estimated by the two models. The average annual rainfall erosivity in the middle reaches of the Yellow River was 767.00~3 003.40 MJ·mm/(hm2·h), exhibiting a high monthly concentration (concentrated in July-August) and showing a single peak shape. [Conclusion] There were significant vertical spatial differences from annual average rainfall erosivity in the middle reaches of the Yellow River, and there were spatial differences resulting from the influence of topography and landforms. The coefficient of variation in high-altitude areas was generally greater than in low-altitude areas. In the Qinling Mountains and the Guanzhong Plain in the southeast, the erosivity of rainfall decreased rapidly with increasing altitude. In in the northwest of the Loess Plateau region, the erosivity of rainfall increased gradually with increasing altitude. Therefore, in areas where erosivity of rainfall increases in the middle reaches of the Yellow River, appropriate measures should be taken to reduce the potential risk of soil erosion and to ensure the sustainable development of regional ecological security.

Keywords

• rainfall erosivity model
• interannual variation
• spatial feature
• middle reaches of the yellow river