This work provides a comprehensive analysis of soil water dynamics in Australia for the climate projections of the Coupled Model Intercomparison Project 6 (CMIP6). We modelled the historical soil water dynamics from 1981 to 2018 at various depths within and below the root zone using the BRTSim computational solver to generate the "current conditions". We then investigated how the CMIP6 scenario can affect water accessibility by plants, and hence their potential impact on croplands and native ecosystems. We found that surface soil moisture can decline by 7% across Australia between 2020 and 2050, with the 2030 decade projected to experience the greatest soil water loss. Above-average precipitation during the 2040s will still lead to 2% soil moisture decline relative to current conditions, with about 1 million km² projected to recover from this deficit later on. Seasonally, our results inferred drier summers and winters with 13% and 5% loss in soil water, respectively. Shrublands and savannas were the most affected native ecosystems with a moisture decline between 16% and 7% within the root zone, respectively. More importantly, 36% to 52% of croplands were found to undergo a 7% decline in soil moisture within the root zone, which was spatially and temporally heterogeneous across crop types. Within the crop calendar, wheat-growing regions were affected by soil moisture deficiencies from sowing to harvest in almost the entire time frame of our assessment.

这项工作为耦合模型比较项目6（CMIP6）的气候预测提供了澳大利亚土壤水分动力学的综合分析。我们使用BRTSim计算求解器对1981年至2018年在根区内和下方不同深度的历史土壤水分动力学进行了建模，以生成“当前条件”。然后，我们研究了CMIP6方案如何影响植物的水可及性，以及它们对农田和原生生态系统的潜在影响。我们发现，到2020年至2050年，澳大利亚的表层土壤水分将下降7％，而2030年预计将经历最大的土壤水分流失。在2040年代，高于当前水平的降水仍将导致土壤水分相对于当前状况下降2％，约为100万平方公里²预计以后可以从赤字中恢复过来。从季节性上看，我们的研究结果推断夏季和冬季较干燥，土壤水分损失分别为13％和5％。灌木丛和热带稀树草原是受影响最严重的原生生态系统，其根部区域的水分下降分别在16％和7％之间。更重要的是，发现36％至52％的耕地根部土壤水分下降了7％，而根际区域在作物类型上时空异质。在作物日历中，几乎在我们评估的整个时间范围内，从播种到收获期间，小麦生长地区都受到土壤水分缺乏的影响。