OOSKAnews Voices is a series of guest “opinion columns” on water, written by senior participants in different parts of the international water community. The columns provide a global platform for organizations and individuals to promulgate their views and messages.
In this piece, Guillaume Gruère, who leads the work on agriculture and water policy issues at the Organization for Economic Cooperation and Development (OECD), details the findings of his recently completed two-year project that looked at policies to manage groundwater use in OECD countries.
Gruère is a Senior Policy Analyst at the OECD. He was previously a Senior Research Fellow at the International Food Policy Research Institute (IFPRI) in Washington, DC, where he worked on agro-environmental policy issues in developing countries. He holds a PhD in agricultural and resource economics from the University of California, Davis, USA, and a dual MS in environmental and natural resource economics and agriculture engineering from AgroParisTech, Paris, France.
The opinions expressed in this article represent the views of Guillaume Gruère; they do not necessarily reflect the official views of the OECD or its member countries, and are not endorsed by OOSKAnews Inc.
Groundwater sustains a significant and increasing share of irrigated agricultural production. On a global scale, groundwater now represents over 40 percent of water use for irrigation. It has become indispensable for agriculture production in many countries; in particular, it accounts for half of South Asia’s irrigation and supports two-thirds of grain crops supplied in China.
In OECD countries, groundwater is primarily used for agricultural irrigation in semi-arid areas, covering approximatively 33 percent of total irrigated area, for an estimated annual withdrawal of 123.5 cubic kilometers (56 percent of total OECD groundwater withdrawals). In the United States, over 60 percent of irrigated agriculture and nearly half of farmers use groundwater. Irrigation represents over 70 percent of Spain’s total groundwater abstraction, and a third of the water used for irrigation in Mexico comes from groundwater. This trend has been increasing in the leading groundwater-irrigating OECD countries over the past 20 years.
The development and expansion of groundwater irrigation can largely be explained by its relative insulation from climate variability and the ability to provide affordable, on-demand water for millions of farmers. Groundwater irrigation is also a central reason why the recent drought in California -- the worst in 500 years -- was accompanied by record-high agricultural revenues in 2014.
However, intensive groundwater pumping for irrigation, as observed in many semi-arid agricultural areas -- and particularly the central coast of California -- depletes aquifers and causes environmental damage that can affect all water users and ecosystems. In particular, it can result in stream depletion and saline intrusion in coastal areas, and is responsible for land subsidence that causes significant and costly damage to rural and urban infrastructure.
These dramatic effects and the threat of even further deterioration in the future require a swift and sound policy response.
The recent report “Drying wells, Rising Stakes: Towards Sustainable Agricultural Groundwater Use,” analyzes the economic underpinning of a large range of management instruments, and reviews policy in OECD countries and key agricultural irrigating regions based on a 2014 survey (see the results by country).
The report finds that there is wide diversity in national and sometimes regional policies to manage groundwater use in agriculture in OECD countries. Policies are founded on different legal systems; they focus on the demand side (decreasing water use), supply side (providing additional water resources) or both; and they use direct or indirect approaches to regulatory, economic or collective management. Interestingly, this diversity does not appear to reflect the constraints of country-specific agricultural groundwater irrigation systems.
These policies have been unable to address groundwater depletion and control pumping-induced externalities in certain OECD regions. There is still insufficient information on groundwater resources and their use. Some policies are incompletely enforced, others are ineffective, and some even provide incentives for unsustainable groundwater use.
To respond to these issues, the report proposes a three-layer package of policy measures. First, it calls for more robust information systems, enforcing existing regulations, and removing perverse incentives in all countries that use groundwater for irrigation. To be successful, groundwater management should account for surface and groundwater interactions and favor demand-side instruments directly focused on withdrawals.
Second, the report recommends a “tripod” of regulatory, economic and collective-action measures to curb the above-mentioned impacts of intensive groundwater use. Third, it suggests agronomic tools aimed at increased water use efficiency and supply side measures for regions under very high water stress. All these measures are intended to be adapted to specific local aquifer systems.
With climate change expected to induce increased water stress in more OECD regions, groundwater issues are expected to become more pressing. Surface water volatility and weather shocks will greatly expand the role of groundwater in current and future potentially irrigated areas.
Policies to manage groundwater use will therefore have an increasing role to play in tackling these challenges, and help transform groundwater resources from a productive input for agriculture to a long-term, climate-insulated reservoir. If well managed, groundwater can and should act as a powerful climate change adaptation option and a natural insurance mechanism, not just a component of freshwater resource supplies.