Enhancing Groundwater Simulation in the IMPACT-Water Model

What is the challenge?

Groundwater plays an increasingly important role in improving water supply, achieving food security, and reducing poverty. Groundwater storage can increase the resilience of water supply systems, is essential for much of global irrigated agriculture and associated agro-ecological systems in the dry season, and is an important buffer during droughts. Presently, more than a third of irrigated cropland in the world depends on groundwater. However, a significant share of irrigated areas overdraft groundwater, which jeopardizes the sustainability of irrigated agriculture in the long term, raises extraction costs, and damages groundwater-dependent ecosystems in those areas. Ceasing groundwater overuse in these areas can have negative food security and socio-economic impacts on rural communities within established agricultural systems that rely on groundwater, at least in the near term, and can also push up world food prices with adverse impacts on food and nutrition security globally. At the same time, underutilization of groundwater is not uncommon in other areas, especially in Sub-Saharan Africa, where farmers suffer crop losses during drought years despite abundant water beneath parched land. 

Various studies have examined groundwater overdraft issues at local and regional scales, using economic and hydrological models. More recently, researchers have assessed global groundwater overdraft using global-scale hydrological models and historical groundwater use records. Nevertheless, there is in general a lack of systematic understanding of global groundwater irrigation sustainability and the food security impacts of reducing or ceasing groundwater overdraft in the short and medium term. This study, jointly implemented with the International Water Management Institute (IWMI), aims to fill this knowledge gap.

Key research questions

  • To what extent does groundwater contribute to food production at present and to what extent does current food production rely on groundwater overdraft?
  • What are the local and global impacts of reducing or ceasing groundwater overdraft on water use and food and nutrition security?
  • What are promising policy options to mitigate potential consequences of ceasing groundwater overdraft for water and food security? 

Basic information about the activity

This study develops a spatially explicit groundwater balance module, including groundwater storage dynamics in shallow and deep aquifers and recharge and discharge processes taking place in shallow aquifers, using existing hydrological and hydrogeological information for major aquifers around the world. The new module is linked to the global hydrological model (IGHM) and the global water management model (IWSM) in the International Model for Policy Analysis of Agricultural Commodities and Trade (IMPACT). Scenario analysis is conducted to explore the socioeconomic consequences of reducing or ceasing groundwater overdraft, and to identify promising options that can mitigate unfavorable consequences. 

Collaborators

Outputs

  • A groundwater module developed and linked to the IMPACT global water and food projections model, which enables explicit water balance simulations for major aquifers in agriculturally important regions. 
  • Knowledge and policy insights with respect to i) where actions need to be taken to ameliorate unsustainable groundwater use and, ii) where groundwater irrigation should be enhanced for improving food security and rural livelihoods.
  • Consequences of ceasing groundwater overdraft for water and food security, under present and future conditions, and alternative mitigation options. 

Other links

The project includes links to the CGIAR Research Program on Policies, Institutions and Markets (PIM) through a groundwater project led by IWMI as a part of the Global Futures and Strategic Foresight Program under PIM.

Contact

Tingju Zhu
Research Fellow
Environment and Production Technology Division

Acknowledgements

This project is implemented under the CGIAR Research Program on Water, Land and Ecosystems (WLE).