Research on holocene loess erosion associated to climate evolution in china

Abstract

Loess is the carrier for the Chinese nation’s survival, and we can accurately know its erosion changes since the Holocene, the current period of geologic time, which is very important to predict future trends. However, there is very limited quantitative research on Holocene climate change and loess erosion intensity. This research takes the Holocene loess depositional sequence of Shaolingyuan in Xi’an at southern loess plateau as the research object to analyze the magnetic susceptibility and stratigraphic age structure of sedimentary sequences, and describe the climate change in different periods. This method uses the sensitivity of pedogenes and fits the precipitation and temperature equation to quantitatively reconstruct the paleoprecipitation and paleotemperature changes since the Holocene, which determines the relationship between soil erosion intensity and precipitation in order to estimate soil erosion intensity since the Holocene period. Results show that the climate change in Xi'an is as follows: 10000~8400 a B.P. is the cold temperature transition stage; 8400~7000 a B.P. is the warm-cold fluctuation stage; 7000~5000 a B.P. is the warm temperature stage; 5000~3400 a B.P. is the warm-cold violent fluctuation stage; and 3400 a B.P. is the warm-semi-humid and semi-arid stage. The Holocene soil erosion intensity changes with annual average precipitation. At 9700 a B.P., the annual average rainfall is 676.6mm, the Estimate of soil erosion intensity reaches its peak value (1287.7 Mg·km−2·a −1), and the soil erosion intensity will become more serious for some time in the future. This research proposes a new method for estimating soil erosion intensity changes caused by climate change, which not only infers the relationship between soil erosion intensity and climate change, but also provides a theoretical basis for accurately processing the soil and water conservation works in the loess area.