Aquifers, Critical Contributors to Water Security, are at Risk
Water intensive farming has almost depleted a three-million-year-old aquifer in the high plains. It could be dry in less than 100 years, and would take 6000 years to replenish.
Aquifers are a key source of freshwater, supplying 30% of the global population’s water needs. According to NASA, most aquifers are being depleted faster than they can recharge, and they can take thousands of years to replenish if they become depleted.
The Ogallala Aquifer, one of the largest aquifers in the world, supplies a portion of the water needs for 8 states from Texas to South Dakota.
The aquifer system is an essential water supply source for several million people in the High Plains but the primary use of the groundwater is for farming, accounting for up to 94% of withdrawals.
As a result of this intensive use, the Ogallala is the world’s fastest disappearing aquifer, being depleted at an annual rate equivalent to the flow of eighteen Colorado Rivers. The misguided federal incentive program for farmers to grow water-intensive corn for ethanol – 1000 gallons of water or more is needed to produce one gallon of ethanol – puts a three-million-year-old asset on course to be depleted in less than 100 years, and it could take 6000 years to replenish.
Industrial Agriculture’s Antagonistic Relationship with Water Quality
The depletion of aquifers is just one of the ways industrial agriculture practices wreak havoc on water supplies and the people and ecosystems that depend on them; pollution is another problem with far-reaching consequences.
The EPA has identified farming as one of the most significant sources of water quality degradation—runoff from farms containing pesticides pollute waterways, and excess nutrients from fertilizers cause eutrophication, an excessive amount of nutrients that cause the dense growth of aquatic plants that use up the oxygen in the water. Insufficient oxygen to support life – referred to as hypoxia – results in the death of marine life. 415 sites around the globe have been identified as having some degree of eutrophication, and 40% of those experience hypoxia.
The 2,340-mile-long Mississippi River drains all or part of 32 states and 2 Canadian provinces between the Rocky Mountains and the Appalachian Mountains. This vast watershed serving 30 million people is the ill-fated recipient of chemical runoff from Midwestern farms that drains into the Mississippi and down to the Gulf of Mexico, creating a hypoxic “dead zone” roughly the size of the state of New Jersey, disrupting marine food webs and human fisheries. It is irrational that food production on Midwestern farms causes the destruction of a food source in the Gulf of Mexico.
More than 100 different pesticides are used around the world. According to Cornell University Cooperative Extension, “the cleanup of groundwater contaminated by pesticides is usually impossible. The slow movement of groundwater means that it may take decades for the contaminated water to flow beyond the affected wells.”
While some of these issues are deeply entrenched with no easy solutions, a systemic remedy is to steadily transition agricultural practices towards those that develop healthy, carbon-rich soils that increase the water-holding capacity of soil, build fertility, and enable farmers to reduce or eliminate agricultural chemicals. Learn more about these practices via our series on Regenerative Agriculture.
On-Farm Water Conservation
Given the water challenges facing the agricultural sector, especially in arid regions, conservation strategies, new technologies, groundwater recharge, and policies that take a long view of water stewardship are urgently needed. While strategies such as drip irrigation, smart irrigation, retention ponds, dry farming and the use of recycled water for irrigation are slowly being adopted, the pace and scale of implementation needs to be radically increased to avoid a serious disruption of food supply. Transitioning to a new way of thinking about water use and stewardship will be essential to sustain the capacity to grow food.
Organic farmer Tom Wiley suggested at a California Climate and Agriculture Network conference that we should rehydrate the Central Valley by allowing nature to do what it historically did prior to engineering and canalization of the natural water flow.
The pre-agricultural grassland ecosystem of California’s Central Valley was endowed by the generosity of the snowpack from the Sierra Nevada mountains. Annual snowmelt released water slowly to lower elevations and hydrated the landscape creating what Ross Noss, Chief Scientist of the Florida Institute for Conservation Science, called “one of the biologically richest and most glorious grassland regions in North America.”
Wiley’s suggestion to allow seasonal flooding seemed risky to farmers who feared that their perennial crops would be damaged by sitting in water, but since then, winter trials performed in vineyards and nut orchards allowed as much as 2 feet of water onto fields for 2 weeks to percolate into the ground to recharge the water table, and no harm was done to the vines or trees.
Mike Montgomery of Monterey One Water highlights another solution, the use of recycled water: “Agriculture makes up about 92% of all the water that is pumped out of the ground in Monterey County. When seawater intrusion was making its advances down the Salinas Valley, most crops couldn’t tolerate the high levels of salinity in the water.
Now, with recycled water in the mix, water quality has improved, and farmers are able to grow more high-value food crops such as strawberries, lettuce, celery, broccoli, cauliflower, Brussels sprouts, etc. In the county, in most of the areas that directly make use of the recycled water, seawater intrusion has slowed significantly, but in the areas where they’re still pumping a lot of groundwater, it has continued to get worse.”
Over the next twenty years, California’s Central Valley is projected to lose hundreds of thousands of acres of farmland due to the pressures of urbanization, the challenging economics of farming and the multiple stresses of climate change. That loss poses potentially dire consequences for the nation’s food supply. Implementing practices for on-farm water security will be paramount to adapting agriculture to a hotter, drier climate.
Seven Strategies for On-Farm Water Conservation
Scroll through to explore strategies
Implementing efficient water use strategies in arid regions is essential to sustaining their capacity to grow food. As climate change worsens, dry periods are more frequent and last longer. In 2000 the Western U.S. entered into a megadrought – a drought that lasted 2 decades or more. It was the 2nd worst drought in the region in 1200 years. In some of those years, California farmers experienced 80-100% cutbacks of water allotments from the State Water Project – which delivers water from Northern California rivers to Central Valley farmers and Southern California cities – and from the federal system of dams and canals. Those cutbacks are driving farmers to drill deeper wells and further exacerbate the unsustainable over-drafting of the aquifer, potentially pushing it beyond its ability to recover. There are some key strategies that will help.
Drip irrigation can save up to 35-65% of water compared to spray irrigation systems. Drip is not affected by wind drift, which carries water away from its target, and by sending water directly to the root zone and not watering between plants, drip irrigation reduces runoff and evaporation.
Smart irrigation systems have monitors in the ground that measure specific moisture and temperature ranges. The sensors send signals to open valves when conditions require it, and communicate with a central system to identify wet or dry spots in the field, helping farmers plan the most efficient irrigation schedules.
Retention ponds capture water during the rainy season and store it for use throughout the year for irrigation and to provide water for livestock and wildlife. During heavy rainfall, ponds capture runoff mitigating erosion and flooding. Riparian and aquatic plants grown around and in the pond can capture excessive nutrients from fertilizers that runoff from farm fields and cause toxic loads downstream.
Dry farming, instead of irrigating, uses techniques to optimize the moisture in the ground. The soil must have good water-holding capacity and a good water table, and plants must have wider spacing to access enough water. Dry farmed crops can be lower in yield, but they typically have more flavor.
Intentional Groundwater Recharge
Intentional or “artificial” groundwater recharge is the process of diverting water during times of high flows in streams and rivers to fallow fields, open space or other landscapes. Recycled water can also be pumped into injection wells to supplement natural recharge.
Recycled water is wastewater that has been treated to safe standards. It is used worldwide for agriculture, groundwater recharge, landscape irrigation, and even drinking water. Recycled water saves energy compared to pumping water from long distances and is cost effective in the long run despite high upfront costs.
Choose the Right Crop
Choose the right crop for the local ecology and the changing climate conditions. With mega-droughts in arid regions, farmers no longer have the luxury of growing water-intensive crops in the desert. Looking to newly developed drought resilient varieties as well as arid-region heirloom crops can help farmers continue to produce food while using less water.
Growing Food in a Hotter Drier Climate
An interview with Gary Paul Nabhan, Ph.D., a world-renowned, Arizona-based Agricultural Ecologist, Ethnobotanist, Ecumenical Franciscan Brother and author whose work has focused primarily on the interaction of biodiversity and cultural diversity in the arid, bi-national Southwest.
Your browser does not support iframes.