5.2 Impact of anthropogenic groundwater exploitation on regional climates
The global water demand is rapidly increasing as a result of economic development and population growth (Rodell and Famiglietti 2002; Rodell et al. 2009; Alvarez et al. 2012; Shi et al. 2013; Devic et al. 2014). Groundwater is widely used to supplement human demands for freshwater due to its convenience of extraction and good quality. The continuous over extraction of groundwater resources for consumption not only reduces groundwater table levels, but also changes the regional, and even global, environment and climate (Pokhrel et al. 2012b; Chen and Hu 2004). Implementation of anthropogenic groundwater exploitation in the CAS-FGOALS model was done by using a groundwater exploitation extraction forcing data set, the details of which can be found in the work of Wang et al. (2020). Figure 10 shows the simulated latent heat flux with and without anthropogenic groundwater exploitation (EXP and CTR, respectively). As seen in the figure, addition of the anthropogenic groundwater exploitation has caused the significant latent heat flux to increase (5–20 W∙m-2) in three representative over extraction regions of North India, North China, and the western coast and central regions of the USA. According to Dirmeyer et al. (2013), evapotranspiration in these three places was restricted by water availability more than in other regions. Thus, when a greater supply of water was available, more evaporation latent heat occurred. This argued for the explicit representation of anthropogenic groundwater exploitation within climate models.