Climate changes impact on the terrestrial water cycle and water resource
Groundwater is a critical freshwater resource for humans and ecosystems. This international cooperation research led by the Department of Atmospheric Sciences, College of Science, National Taiwan University, investigates the potential groundwater storage changes in the 21st century. The study is published online in Nature Communication in July 2020.
Groundwater provides critical freshwater supply, particularly in dry regions where surface water availability is limited. This research used a fully coupled climate model to investigate groundwater changes over seven vital aquifers identified as significantly distressed by satellite observations in the past 14 years. Researchers assessed the potential climate-driven impacts on groundwater water storage changes throughout the 21st century under the business-as-usual scenario. Results show that the climate-driven effects on groundwater changes do not necessarily reflect the long-term trend in precipitation; instead, the trend may result from an enhancement of evapotranspiration, and reduction in snowmelt, which collectively lead to divergent responses across different aquifers.
In theory, anthropogenic pumping should not overwhelm natural replenishment. However, satellite observations have detected severe groundwater depletion in several aquifers. Using satellite observations and modeling results, researchers found that reduction in groundwater is mainly due to the combined impacts of over-pumping and climate effects; however, the contribution of pumping could easily exceed the natural replenishment. This research provides guidance for sustainable groundwater management.
a Schematic of land hydrological processes. b controlling factors affecting divergent groundwater responses.
Attribution of future groundwater recharge to three climate-driven factors (rainfall, snowmelt, and evapotranspiration (ET)), as derived from the regression based on CESM-LE projections (2006−2010) under the business-as-usual scenario (RCP8.5). The color in the triangle quantifies the relative contribution of each factor based on relative hue in red (snowmelt), green (ET), and blue (rainfall). Aquifer-averaged results are labeled on the triangle using the aquifer index shown in Fig. 2. For example, the results of Guarani (6) is (snowmelt: 0.0, ET: 0.4, rainfall:0.6).
Reference
Wen-Ying Wu, Min-Hui Lo, Yoshihide Wada, James S. Famiglietti, John T. Reager, Pat J.-F. Yeh, Agnès Ducharne & Zong-Liang Yang Divergent effects of climate change on future groundwater availability in key mid-latitude aquifers. Nature Communications 11, 3710 (2020). https://doi.org/10.1038/s41467-020-17581-y