Effects of initial aquifer conditions on economic benefits from groundwater conservation
Authors: Timothy Foster, Nicholas Brozovic, Adrian Butler
Journal: Water Resources Research
Publication Date: 22 January, 2017
Department of: Mechanical, Aerospace and Civil Engineering
Extending the life of aquifers to support long-term food security
Groundwater-fed irrigation underpins agricultural productivity worldwide, providing farmers with a reliable buffer against climate variability and drought. This natural insurance is threatened, however, by rapid and alarming rates of depletion of groundwater storage in many major aquifers.
Researchers from the University of Manchester, the Water for Food Global Institute, and Imperial College London have developed a new integrated modelling tool to predict where and when groundwater conservation programs should be targeted to maximise benefits for future generations. Unlike previous modelling approaches, the tool developed considers for the first time the negative impacts of aquifer depletion on farmer livelihoods through both increased pumping costs and reduced well yields that limit farmers’ ability to reliably satisfy crop water requirements.
Applying the model to the High Plains Aquifer, one of the world’s largest aquifers and a critical global breadbasket, the authors showed that there is an optimal point along an aquifer’s depletion pathway at which regulations should be triggered to limit further over-pumping. The findings demonstrate that appropriate targeting of groundwater conservation efforts can be used to effectively prolong the usable lifetime of groundwater resources for agricultural production, and, in turn, help to enhance long-term food security and the health of rural economies.
- Groundwater provides over 40% of the water used globally for irrigated agriculture
- Current groundwater withdrawals for irrigation are unsustainable in many regions. For example, the High Plains Aquifer in the United States, which provides water to grow crops worth in excess of $35 billion each year, has experienced reductions in aquifer storage of over 400 km3 since the 1930s.
- An important consequence of aquifer depletion is the reduction in well yields, which determine the rate at which water can be supplied by a well. Declining well yields have large negative impacts on farmers resilience to drought (Foster et al. (2014), Water Resources Research, 50(8), 6370-6389), but implications for optimal groundwater management had not been previously evaluated.
- Our findings help policymakers to target conservation programs (e.g. land retirements, water use quotas) to maximise long-term resilience of agriculture to climate variability and change.
- Future work will use the model developed to map optimal management points for the entire High Plains Aquifer and other groundwater systems worldwide