Given competing interests for floodplain property, some have argued for strategic partial reconnection of floodplains to the river by allowing portions of floodplain to flood, so that pressure elsewhere along the river during a flood may be alleviated [Opperman 2009].
For example, California’s Yolo Bypass was created in the early 1900s after the Sacramento River flooded several times and levees proved inadequate to protect the city [Sommer 2001]. The site of the bypass was historically the vast wetland floodplain of the Sacramento River and other nearby rivers and streams that had since been converted to agriculture. Today, the bypass reconnects the river to its floodplains.
Since 1997, Yolo Bypass also features more than 16,000 acres of wildlife area, including seasonal and perennial wetlands, riparian forest, pasture, and seasonal crop production where fields are allowed to flood during winter. This solution has not only kept Sacramento dry during numerous high water events, it has also restored diverse populations of fish, bird, snake, mammal and other species to the area, while providing recreational and educational opportunities to nearby communities.
While the Yolo Bypass Wilderness Area exemplifies the large-scale engineered reconnection of a major river to its floodplain, many smaller stream floodplains benefit from the work of non-human engineers. Long considered the nemesis of ranchers and farmers alike, beavers caught damming irrigation ditches or flooding fields are often summarily trapped and killed. Yet in Elko, Nevada, beavers and altered livestock grazing regimes have brought stream beds back to life [Goldfarb 2018, Evans & Griggs 2015].
One rancher’s management change began by excluding cattle from grazing along Elko’s Suzie Creek – just during the hot season when plants are vulnerable. This allowed rushes, sedges and other vegetation to grow back, slowing water down enough for sediment to fill in the gouged out gully and raise the streambed back up to the level of its floodplain. Once beavers discovered their favorite food – willow – growing again at Suzie Creek, they moved in and have since built 139 dams there. These dams, in turn, raised the water table by about two feet, becoming the natural irrigation system for the ranch’s now lush riparian pastureland. The beaver dams proved vital in 2012-2015 when Suzie Creek kept flowing despite several summers of drought that left the rest of the region parched.
The beaver dams proved vital in 2012-2015 when Suzie Creek kept flowing despite several summers of drought that left the rest of the region parched.
At around the same time as Suzie Creek’s revitalization, across the Atlantic in Devon, England, a pair of Eurasian beavers were introduced to a wooded stream at the headwaters of the Tamar River [Puttock 2016]. A few years and 13 dams later, the beavers’ activity was filtering pollutants out of water passing through the dam sites and slowing the flow so as to minimize downstream flooding during storms. As in North America, beavers were once abundant in Europe, but by the 16th Century were wiped out in the UK. In recognition of beavers’ beneficial effects on hydrological systems, multiple reintroduction programs have begun establishing colonies across Europe and North America.
“Because of their abilities to modify streams and floodplains, beavers have the potential to play a critical role in shaping how riparian and stream ecosystems respond to climate change,” explain the authors of a recent study of potentially suitable beaver reintroduction sites [Dittbrenner 2018: 2]. The authors continue:
By damming streams, beavers create pond and wetland complexes that increase … species and habitat diversity, and therefore ecosystem resilience to climate-induced environmental change. Beaver impoundments slow stream velocity allowing sediment suspended in the water column to settle, aggrading incised stream systems, and reconnecting streams with their floodplains. The increase in surface water promotes groundwater recharge, storage, and supplementation during base flows. The increased geomorphic complexity also promotes higher thermal variability and cold-water refugia in deeper waters and in areas of downstream upwelling [Dittbrenner 2018: 2].
Furthermore, by repairing hydrological functioning and increasing a landscape’s overall level of moisture, beaver populations could literally dampen conditions for wildfire, which is intensified by drought [Maughan 2013].
Such vital ecosystem services provided by a keystone species like beaver in the era of climate change are nothing to scoff at. And while beavers are still trapped and killed for sport and by hunters or land managers who consider them a nuisance [Goldfarb 2018], castor canadensis is also increasingly accepted, as evidenced by more pro-beaver attitudes within the fish and wildlife departments of western states that had previously considered them mainly as pests. Beavers are discussed on state wildlife agency websites in terms of “living with wildlife,” where beaver life histories are described, along with explanations of the benefits of beaver dams for landowners and for the landscape overall.
Similarly, Holland is learning new ways to live with water. In the Netherlands, literally “low country” due to much of its land area being at or below sea level, there is an age-old struggle with water and flooding, notably through the use of dikes. However, alarmed by recent flooding and the prospects of sea-level rise from climate change, the nation is undergoing a paradigm shift wherein the guiding principle for water management has become “make room for the river” [Pahl-Wostl 2006]. Among other tactics, certain areas are being “depoldered,” meaning dikes removed from low-lying areas and the land returned to wetland; people living in those areas are assisted in relocating [Bentley 2016].
Similarly, several cities in China are striving to “make friends with water” through adoption of the concept of “sponge cities” that aim to “retain, adapt, slow down and reuse” stormwater by increasing the porosity of urban surfaces, including increasing the amount of ecologically functional urban green space [Guardian 2018].
In our panic over increasing numbers of extreme weather events, we may grasp at familiar solutions – extra air-conditioning to shelter from the heat, higher levees to hold back floodwaters, more irrigation to combat drought, or logging forests to reduce wildfire fuel. While these measures may (or may not) temporarily bandage the situation, they increase the fragility of our built environment and usher us further down the path of climate chaos though unrelenting energy consumption and increasingly hobbled ecosystems. For our own sake, it’s time to make friends with nature and to acknowledge her superior power by partnering with instead of continuously fighting her.
Bentley, Chris, 2016, Holland is relocating homes to make room for high water, Public Radio International, June 22, 2016, https://www.pri.org/stories/2016-06-22/holland-relocating-homes-make-more-room-high-water.
Delaney, Brigitte, 2018, Turning cities into sponges: how ancient Chinese wisdom is taking on climate change, The Guardian, March 21, 2018, https://www.theguardian.com/artanddesign/2018/mar/21/turning-cities-into-sponges-how-chinese-ancient-wisdom-is-taking-on-climate-change.
Dittbrenner, Benjamin J., Michael M. Pollock, Jason W. Schilling, et al., 2018, Modeling intrinsic potential for beaver (Castor canadensis) habitat to inform restoration and climate change adaptation, Plos One, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0192538.
Evans, Carol & Jon Griggs, 2015, Miracle in the Nevada desert, Restoring Water Cycles to Reverse Global Warming conference October 16th-18th, 2015 at Tufts University, Biodiversity for a Livable Climate, https://www.youtube.com/watch?v=lR7w9Tritj8&feature=youtu.be.
Goldfarb, Ben, 2018, Beaver dams without beavers? Artificial logjams are a popular but controversial conservation tool, Science, https://www.sciencemag.org/news/2018/06/beaver-dams-without-beavers-artificial-logjams-are-popular-controversial-restoration.
Goldfarb, Ben, 2018, Eager: The Surprising, Secret Life of Beavers and Why They Matter, Chelsea Green Publishing: White River Junction.
Maughan, Ralph, 2013, Beaver restoration would reduce wildfires, The Wildlife News, October 25, 2013, http://www.thewildlifenews.com/2013/10/25/beaver-restoration-would-reduce-wildfires/.
Opperman, Jeffrey J., Gerald E. Galloway, Joseph Fargione, et al., 2009, Sustainable floodplains through large-scale reconnection to rivers, Science 326, http://science.sciencemag.org/content/326/5959/1487.
Puttock, Alan, Hugh A.Graham, Andrew M.Cunliffe, et al., 2016, Eurasian beaver activity increases storage, attenuates flow and mitigates diffuse pollution from intensively-managed grasslands, Science of the Total Environment 576, https://www.sciencedirect.com/science/article/pii/S0048969716323099.
Sommer, Ted, Bill Harrell, Matt Nobriga, et al., 2011, California’s Yolo Bypass: evidence that flood control can be compatible with fisheries, wetlands, wildlife, and agriculture, Fisheries 26:8, https://afspubs.onlinelibrary.wiley.com/doi/abs/10.1577/1548-8446%282001%29026%3C0006%3ACYB%3E2.0.CO%3B2.
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