Hydrologic and Climatic Responses to Anthropogenic Groundwater Extraction

Highlights:

• A scheme of anthropogenic groundwater extraction was incorporated into the Community Earth System Model version 1.2.
• Groundwater irrigation increased precipitation in Northern China Plain due to the increase of evapotranspiration, while it decreased the precipitation in Northern India because the Indian monsoon and its transport of water vapor were weaker as a result of cooling induced by groundwater use.
• Local terrestrial water storage was shown to be unsustainable at the current high groundwater extraction rate over Northern China Plain, Northern India and Central USA.

Anthropogenic groundwater exploitation changes soil moisture and land-atmosphere water and energy fluxes, and essentially affects the ecohydrologicalprocesses and the climate system. In over-exploitedregions, the terrestrial water storage has been rapidly depleted, causing unsustainability of water use and inducing climate change. Quantifying the hydrologic and climatic responses to anthropogenic groundwater extraction not only advances our understanding on the hydrological cycle with human intervention, but also benefits effective human water management for sustainable water use.

Recently, scientists from CAS institute, XIE Zhenghui and ZENG Yujin in LASG/Institute of Atmospheric Physics incorporated a scheme of anthropogenic groundwater exploitation into the Community Earth System Model version 1.2, and conducted a series of simulations over global scale to investigate the impacts of anthropogenic groundwater exploitation on the hydrological processes andclimate system around the world. The framework of the coupled model are shown in Fig. 1. The model was also applied over Heihe River Basin in northwestern China for investigating the impacts of human water regulation and groundwater lateral flow on basin-scale land surface processes, and the ecohydrological effects of stream-aquifer water interaction over riverbanks.

Their results showthat groundwater exploitation caused drying in deep soil layers but wetting in upper layers, along with a rapidly declining water table in areas with the most severe groundwater extraction, including the central United States, the north China Plains and the north India and Pakistan, as Fig. 2 and Fig. 3 show. The atmosphere also responded to groundwater extraction, with cooling at the 850 hPa level over the north India and Pakistan and a large area in the north China and central Russia. Increased precipitation occurred in the north China Plains due to increased evapotranspiration from groundwater irrigation. Decreased precipitation occurred in north India because the Indian monsoon and its transport of water vapor were weaker as a result of cooling induced by groundwater use, as shown by Fig. 4. Additionally, the background climate change may complicate the precipitation responses to the groundwater use. Local terrestrial water storage was shown to be unsustainable at the current high groundwater extraction rate. Thus, a balance between reduced water withdrawal and rapid economic development must be achieved in order to maintain a sustainable water use, especially in regions where groundwater is being over-exploited.

This research findings have been published in Journal of Climate, Journal of Advances in Modeling Earth Systems, and Hydrology and Earth System Sciences.

Figure 1.Framework of the coupled model

Figure 2.(a) global groundwater extraction rate around year 2003 and (b) the area-averaged extraction rate in the central USA, the north China Plains and in north India and Pakistan from 1965 to 2005.

Figure 3.Spatial distribution of ensemble-averaged differences between simulations with and without human groundwater exploitation averaged over 1970-2005 for annual-mean (a) groundwater table depth (m); (b) 10-cm soil moisture (m3/m3); (c) runoff (mm yr-1); (d) terrestrial water storage (cm); (r) latent heat flux (W m-2); (f) sensible heat flux (W m-2). The shaded areas indicate the regions where the difference passed the 95% confidence level in a Student’s t-test.

Figure 4.Spatial distribution of ensemble-averaged differences between simulations with and without human groundwater exploitation averaged over 1970-2005 for annual-mean (a) JJA precipitation (mm d-1); (b) JJA 850 hPa level wind field (m s-1); (c) JJA 500 hPa level wind field (m s-1); (d) JJA 200 hPa level wind field (m s-1); (e) JJA horizontal vapor flux (kg m-1 s-1). The grey shading indicates the regions where the magnitude of vector difference passed the 95% confidence level in a Student’s t-test.

Citations:
Zeng, Y., Xie, Z., and Zou, J. (2016). Hydrologic and climatic responses to global anthropogenic groundwater extraction. J. Climate.,doi: 10.1175/JCLI-D-16-0209.1.
Download: http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-16-0209.1?af=R

Zeng, Y., Xie, Z., Yu, Y., Liu, S., Wang, L., Zou, J., Qin, P., and Jia, B. (2016), Effects of anthropogenic water regulation and groundwater lateral flow on land processes, J. Adv. Model. Earth Syst., 8, 1106–1131, doi:10.1002/2016MS000646.
Download: http://onlinelibrary.wiley.com/doi/10.1002/2016MS000646/full

Zeng, Y., Xie, Z., Yu, Y., Liu, S., Wang, L., Jia, B., Qin, P., and Chen, Y. (2016), Ecohydrological effects of stream–aquifer water interaction: a case study of the Heihe River basin, northwestern China, Hydrol. Earth Syst. Sci., 20, 2333-2352, doi:10.5194/hess-20-2333-2016.
Download: http://www.hydrol-earth-syst-sci.net/20/2333/2016/hess-20-2333-2016.html

Contact: XIE Zhenghui,zxie@lasg.iap.ac.cn; ZENG Yujin, zengyj@mail.iap.ac.cn