Preprints
https://doi.org/10.5194/cp-2021-55
https://doi.org/10.5194/cp-2021-55

  03 Jun 2021

03 Jun 2021

Review status: this preprint is currently under review for the journal CP.

Different facets of dryness/wetness pattern in southwestern China over the past 27,000 years

Mengna Liao1,, Kai Li1,, Weiwei Sun2, and Jian Ni1 Mengna Liao et al.
  • 1College of Chemistry and Life Sciences, Zhejiang Normal University, Jinhua, 321004, PR China
  • 2State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, PR China
  • These authors contributed equally to this work.

Abstract. Frequently happened meta-droughts have arisen broad social attention under current global climate change. A paleoclimatic perspective is expected to gain our understanding on the causes and manifestation more comprehensively. Southwestern China has been threatened by severe seasonal droughts. Our current knowledge of millennial-scale drying/wetting processes in this region is primarily based on the variability of the Indian Summer Monsoon. However, water availability over land does not always follow the monsoonal precipitation but also depends on water loss from evaporation and transpiration. Here, we reconstructed precipitation intensity, lake hydrological balance and soil water stress index (SWSI) covering the last 27,000 yr, based on grain size, geochemical and pollen records from Yilong Lake, to discuss the long-term nexus and discrepancies of dryness/wetness patterns in meteorological, hydrological and soil systems in central Yunnan region, SW China. Our results show that the long-term change trajectories among precipitation, hydrological balance and soil moisture were not completely consistent. During periods of low precipitation, hydrological balance and soil moisture were primarily controlled by temperature-induced evaporation change. This caused opposite status of precipitation with hydrological balance and soil moisture during the Last Glacial Maximum and Younger Dryas. During periods of high precipitation – the early to late Holocene, intensified evaporation from the lake surface offset the effects of increased precipitation on hydrological balance. But meanwhile, abundant rainfall and dense vegetation canopy avoided soil moisture deficit that might result from rising temperature. To sum up, hydrological balance in central Yunnan region was more vulnerable to temperature change while soil moisture could be further regulated by vegetation changes on millennial scale. As such, under future climate warming, surface water shortage in central Yunnan region can be even more serious. But for soil systems, efforts to reforestation may bring some relief to soil moisture deficit in this region.

Mengna Liao et al.

Status: open (until 29 Jul 2021)

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Mengna Liao et al.

Mengna Liao et al.

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Short summary
The long-term trajectories of precipitation, hydrological balance and soil moisture are not completely consistent in southwest China. Hydrological balance was more sensitive to temperature change on a millennial scale. For soil moisture, plant processes also played a big role in addition to precipitation and temperature. Under future climate warming, surface water shortage in southwest China can be even more serious and efforts to reforestation may bring some relief to soil moisture deficit.