[A-GE28] Energy-Environment-Water Nexus and Sustainable Development

[AGE28-P09] Identification of environmental controls on the actual evapotranspiration of Artemisia Ordosica in Mu Us Desert, China

*Zaiyong Zhang^1,2, Wenke Wang^1,2, Bin Ran^1,2, Chengcheng Gong^1,2, Da Xu^1,2 (1.Key Laboratory of Subsurface Hydrology and Ecological Effects in Arid Region, Chang'an University, Ministry of Education, China, 2.School of Water and Environment, Chang'an University, China)

Keywords:Evapotranspiration, Soil moisture, Mu Us Desert, Artemisia ordosica

The Mu Us Desert, which covers a large area of China, is prone to drought. Currently, most of the shrubs in the Mu Us Desert are rainfed and are therefore vulnerable to interannual climate variability and future climate change. However, the controlling factors of evapotranspiration in arid and semi-arid regions are still largely uncertain. Here, we used a lysimeter under the condition of Artemisia ordosica (AO) condition in the Mu Us Desert, which is well represented for the current rainfed part of the shrub. We used a multiple linear regression model to quantify the influence of the six environmental factors (namely, air temperature (Ta), net radiation (Rn), wind speed (WS), soil moisture (θ), vapor pressure deficit (VPD) and heat flux (HF)) on the evapotranspiration. In addition, we applied the boosted regression tree (BRT) method to determine the relative contribution of evapotranspiration. Our results showed that the annual evapotranspiration was 444.46 mm/year, which mainly affected VPD during the dry season and the Rn during the rainy season. We reconciled our results with the previously emphasised importance of soil moisture and Ta. Using BRT analysis, we found that VPD and Rn mainly controlled evapotranspiration in water-limited areas. Furthermore, evapotranspiration decreased significantly when soil moisture was less than 0.063 cm³/cm³. Evapotranspiration increased by 92.3% on days after precipitation compared to days before precipitation. With increasing aridity under climate change, increased shrub water stress can be expected in the future for the Mu Us Desert. Our results highlight the need for a better understanding of how environmental factors and soil moisture dynamics impact the evapotranspiration of AO.