GEOGRAPHY

The soil erosion modulus in the Holocene of China showed a significant increase trend


Due to the lack of continuous geological evidence that directly indicates soil erosion, soil erosion research in geological history is still in the qualitative stage, which limits the understanding of the evolution process and driving mechanism of soil erosion in the past.

Lake basin is a relatively independent geographical unit, lake as the “sink” of the basin, surface debris is deposited in the lake through the process of denudation-transport-sedimentation, lake sediment faithfully records sedimentation process and environmental evolution information, becomes an ideal carrier for reconstruction and study of soil erosion in geological history.

Due to the special topography of the Qinghai-Tibet Plateau, China is jointly affected by the Asian summer wind and the Central Asian westerly wind, and there are obvious differences in the environment in different regions, which provides natural materials for the comparative study of soil erosion evolution and the response relationship of environmental factors.

The team of Professor He Hongming of the Institute of Soil and Water Conservation, Ministry of Water Resources of the Chinese Academy of Sciences and the School of Geographic Sciences of East China Normal University selected 35 natural lakes in different regions of China, quantitatively estimated the soil erosion modulus of the corresponding watershed according to the lake sedimentation rate, and used statistical methods to analyze their response to climate, vegetation and human activity factors.

They found that during the Holocene period, 60% of the soil erosion modulus in all lakes studied showed a significant increase in soil erosion modulus. In the northwest and Qinghai-Tibet Plateau, the Holocene soil erosion modulus showed an overall increasing trend. Except for the south in 9.5-7.0 cal. The soil erosion modulus was high during ka B.P (calibrated age, i.e. 9.5-7.0 millennia before 1950 AD), and the soil erosion modulus in the northern, southern and southwestern regions was 12.0-2.0 cal. ka B.P. is relatively low, 2.0 cal. ka B.P. was followed by a rapid increase.

Changes of soil erosion modulus in Holocene lake basins in different subdivisions of China. Image courtesy of the paper author

Their study also shows regional differences in the response of changes in soil erosion to environmental factors under the influence of different climate systems. For example, increased rainfall has led to increased soil erosion on the Tibetan Plateau and the north, but has a weak impact on the south and southwest. Except for the northwest, the soil erosion modulus decreased with the increase of the proportion of pollen trees, indicating that the increase of the proportion of trees slowed down soil erosion.

“Human activities are the most important explanatory factors for soil erosion change in all regions, and it shows that the increase in soil erosion in the Holocene of China is mainly influenced by human activities.” Dr. Zhao Hongfei added interpretation.

The results of these related studies were recently published in Quaternary Science Reviews, a journal in the field of Quaternary geology.

The collaborators of the project include Kunming Branch of the Chinese Academy of Sciences, Guangzhou Metro Design and Research Institute Co., Ltd., East China Normal University and Shaanxi Normal University. The research was jointly funded by the Second Qinghai-Tibet Plateau Comprehensive Scientific Expedition and the National Natural Science Foundation of China. (Source: China Science News, Zhang Xingyong, Zhao Hongfei)

Related paper information:https://doi.org/10.1016/j.quascirev.2023.107993



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