Yes, you’ve been reading the headlines correctly the last few weeks. There’s been so much rain in drought-stricken California that excess water has led to flooded homes, damaged roads, dangerous mudslides and tragically, several fatalities. To make matters worse, the abundant rainfall hasn’t even cured the state’s current woes: while snowpack levels are now above normal, drought persists in Southern California and rain has already exceeded the capacity of some reservoirs—meaning that much of this water can’t be stored for the future.
This is an important reminder that conditions can change rapidly, as is happening now in California. It can be hard to understand how the challenges can move so quickly from one extreme to the other, but droughts and floods are actually both symptoms of the same water problem: too much water when it is not needed and not enough when it is.
Creative, low-tech approaches to water management
Recent stories profiling managed flooding across California are encouraging, and offer strategies for better managing excess rainfall, whenever it comes. For example, researchers and farmers are working to understand how crops handle flooded conditions, experimenting whether it is possible to intentionally flood fields so that water can slowly “refill” storage underground. The challenge of managing water that is in excess at some times and absent at others is not new, but now more than ever we must continue to innovate rainwater conservation as much possible, given future projections of increased rainfall variability.
As I’ve written previously, my research is exploring precisely these questions around optimizing water management, and we’ve found very encouraging results. With intentional emphasis on conservation and ecological practices—such as cover crops, agroforestry and perennial crops—the sponge-like properties of soils to hold more water (while also letting more water drain through) can be significantly improved. This is good for farmers, it is good for crops, it is good for communities and it is good for all of us as taxpayers: floods are known to result in some of the costliest natural disasters, including four multi-billion dollar events in 2016 alone. And droughts, of course, have big price tags as well.
Water for agriculture 101: on rainfall and irrigation
We often hear much about the “water footprint” of agriculture. Agriculture is either “rainfed” or “irrigated” which is pretty self-explanatory. Rainfed regions, which make up approximately 80% of agricultural lands globally, are predominantly found the more humid areas of the planet (i.e. much of the eastern United States). Irrigated agriculture relies on additional water resources and is mainly located in the arid regions, which make up 20% of agricultural lands (and are said to result disproportionately in 40% of production). Some irrigation waters come from rivers or streams – the surface water that you can see above ground – while others come from underground aquifers that store water.
Agricultural management approaches that improve water storage in the soil can be valuable in all regions – arid or humid – as I previously noted about flooding last fall in Iowa (a region where drought is a concern, but excess water a more persistent problem). So whether the water for agriculture comes from above or below ground, getting more help from the soil to maintain and manage it is a holistic approach that can prevent extremes and reduce costly, damage impacts.
Another reminder of the climate challenges ahead for agriculture
A study out last week in the prestigious journal Nature serves as yet another reminder of how critical water management is for our future agricultural system. A group of scientists evaluated several crop models (a common method for assessing climate change impacts) and found that crop yields decline significantly for every day with temperatures over 86 degrees F during the growing season. This effect is somewhat offset in irrigated areas; however, the authors recognize that relying on irrigation as a sole solution is problematic as well, because water resources are declining around the world (including the Western United States). Given this decline, researchers suggest that by the end of the 21st century, there will be a need to shift agricultural lands predominantly reliant on irrigation to focus on rainwater. This is exactly the conversation that we can start having right now given how much proactive planning it requires to negate the impacts of floods and droughts.
Water expert Peter Gleick recently wrote a fantastic piece summarizing the complex problems associated with water management. He notes that asking if the California drought is over is the wrong question. What we ought to be asking are broader questions about the overall sustainability of water use. He refers to the situation in California aptly as “a bank account in perpetual overdraft” given how often groundwater removals exceed recharge levels.
Right now our agricultural system is dangerously susceptible to periods of either too much or too little water. The drought-to-flood conditions in California are another reminder that we must continue envisioning a system of crop and soil management that supports the water we can sustainably use for agriculture, rather than running our water bank accounts dry. Farmers, ranchers and the broader food system will not transform to be more climate-resilient overnight, but with a common-sense look toward water woes of the future, we can start planning for that future now.
CORRECTION, Jan. 26, 2017: The post originally stated that California snowpack levels were below normal. Although they were below normal earlier this month, as of the posting date this was no longer the case.
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