IWRA Proceedings

Key message

Groundwater, if managed well, will be critical for climate resilient agriculture in the future. Managing GW requires a WEF nexus
approach.

Groundwater and climate change- Observed

• Global groundwater abstraction (∼1,500 km3 year−1) is just about 1/8th of the annual recharge (~12,600 km3) (Aeschbach-Hertig and Gleeson, 2012)
• However, groundwater depletion occurs at local to regional scales.
• Human-induced groundwater depletion at rates exceeding 20 mm year-1 (2001–2010) is occurring in the major aquifers systems:
• The High Plains and California Central Valley aquifers (USA),
  • Arabian aquifer (Middle East),
  • North Western Sahara aquifer (North Africa),
  • Indo-Gangetic Basin (India),
  • North China Plain (China).
• In humid regions, linear associations between precipitation and recharge are often observed (e.g. Kotchoni et al., 2019).
• As the aridity increases, diffuse or focused recharge dominates, leading to non-linear relationship between precipitation and recharge
• Observed episodic recharge in India and USA, or higher recharge during more intense rainfall events, is likely to make groundwater more resilient to CC in dry land regions (Asoka et al., 2018; Thomas et al. 2016).

Groundwater and climate change- Projected

• A synthesis of 40 modelling studies suggests that projected changes in groundwater storage due to climate change will lead to a general decrease in recharge in aquifers located in arid/semi-arid tropics and humid tropics (Amanambu et al., 2020).
• Groundwater recharge will increase in northwest of India and the North China Plain (Wu et al. 2020)
• In semi-arid India, the projected increase in future rainfall will increase groundwater recharge, though the expected  irrigation expansion is likely to negate this positive gain (Sishodia et al., 2018).
• However, large uncertainties remain in these groundwater models.

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