Compendium Vol. 2 No. 2: Introduction

While previous issues of the Compendium have addressed ecosystem strategies to reverse global warming, here we discuss ecosystem restoration to adapt to the consequences of climate change. From drought in Cape Town and wildfire in California and Greece to flooding in Beijing, Paris, Houston and North Carolina, each new report of catastrophe makes climate change more real and more frightening. And while taking the giant steps required within the next 12 years to avert climate catastrophe as the IPCC advises^[3] may seem out of reach for everyday people, anyone can act locally and regionally to restore the ecosystems that protect our homes and communities. Happily, healthy ecosystems contribute both to mitigation and resilience.

Slowing down water and the art of survival

Managing rainwater within a landscape so that neither heavy storms nor long dry spells devastate human endeavors and constructions is referred by Yu Kongjian as the “art of survival” [Yu 2012]. This Chinese landscape architect with an ecological mindset learned the art of survival by studying the ways of ancient peasant farmers. He contrasts the wisdom embodied in their simple structures, such as terraced crop fields on sloping land designed to capture and hold storm water for later use with the modern “art of pleasure making and ornament.”

Modern urban design tends to favor non-functional decorative features – “monumental architecture” like a grand stadium, manicured lawns, or fruit trees grown for their blossoms rather than their fruit, for example. Such investments are pretty, but expensive and “easily superseded,” according to Yu. Equally beautiful urban designs such as green rooftops and boardwalk-accessible urban wetland parks, on the other hand, can be affordable, high-performing features designed to withstand environmental extremes.

World cities, and especially those in China, face deepening environmental problems: flood, drought, pollution, aquifer drop, loss of natural habitat and cultural heritage. A low-culture approach using what I term ‘adaptive design’ provides a technique for solving problems in an economical and ecological way [Yu 2012: 72].

For Yu, design is adaptive “when it responds elegantly and efficiently to its environmental setting so that new uses can endure” [Yu 2012: 72], meaning a design for urban resilience in the face of ever more severe weather.

It’s not only Chinese peasants who understood water cycles and how to manage them. Ancient peoples of the Middle East actually depended on seasonal flooding. Like we do today, these ancient farmers grew crops on river floodplains. Yet unlike today’s practices of diking off the river to keep croplands dry, they allowed annual flood pulses onto their fields.

Annual flood pulses are so predictable and long-lasting that plants, animals, and even human societies have adapted to take advantage of them. In ancient Egypt and Mesopotamia, the fertility of the soils was renewed each year by the annual overflow of the rivers, thereby sustaining large populations in one place for millennia and permitting the development of great civilizations [Sparks 1995: 168].

In India’s Rajasthan region, where the monsoon cycle brings torrents of rain all at once, after which begins a long dry season, rural farming communities built johads. These are small earthen dams on sloping land that create ponds or wetlands by harvesting stormwater during the rainy season. This water reserve then becomes a vital resource during the dry season. However, johads were abandoned in favor of more modern borehole wells, which are deep, not wide like a basin, and therefore not able to catch rainwater, which instead simply ran off the landscape. By the 1980s the johads were gone, wells were dry, people walked 9km in search of drinking water, and farmers left town in search of other employment. But then communities throughout the region started to rebuild johads, which raised the water table enough to refill wells, support agriculture and wildlife, and for streams to flow again [Singh 2015, SIWI 2015].

Similarly, severe drought in Burkina Faso in the Sahel region bordering the Sahara Desert presented farmers with a simple choice: find a way to restore the land and farm again, or migrate. As in Rajasthan, these farmers were prompted in desperation to rediscover their region’s own traditional techniques for water conservation. They dug rows of small pits in their fields to capture rainfall, which they filled with compost and manure, and into which they planted crops. Other farmers built stone terraces along the contours in their fields to capture rainfall and prevent runoff; some farmers did both. Over time, at least 140,000 farming households over 200,000 hectares or more were practicing these techniques, resulting in the revival of crop production, reestablishment of trees, shrubs and grasses, and the recharging of the area’s water table by a depth of five meters [Reij 2009].  

Land management and hydrology

The concept of hydrological drought (as distinct from meteorological drought) helps explain the success of these age-old techniques to enhance surface and groundwater supply. Meteorological drought is the occurence of abnormally low rainfall for a given region. Hydrological drought is a consequence of meteorological drought – it happens when surface and ground waters run low thanks to a prolonged rainfall shortage compared to historical conditions for a region. Human water consumption for irrigation, industry and household use intensifies hydrological drought [Wada 2013].

Yet, as seen in the examples above, proper land management can raise the water table in an area in spite of occasional episodes of meteorological drought. In other words, while we cannot directly control when and how much rain falls, we can manage what happens to water once it reaches the ground.

Rain falling on much of our modern built environment is managed with ditches, gutters, drains and sewers designed to whisk it away as quickly as possible, rather than absorbing it in place. Farmland too is sometimes fitted with underground “tiles” (pipes) to drain fields, or with dikes to keep water out. Moreover, by the very absence of design, nearly all conventional farmland is so lacking in organic matter that it can barely absorb rainfall, which instead runs off the soil surface carrying soil with it.

In short, water hitting the ground in today’s world moves quickly. Stormwater moves in torrents over land seeking an outlet. That is until the outlet is full, at which point the water stagnates, rising like a bathtub, soaking and rotting property.

Ironically, the water we seek to drain away when there’s plenty becomes desperately lacking after the rain has stopped. Two sides of the same coin, flooding and drought often go hand in hand. By the same token, because a surfeit of impervious surfaces is at the root of these twin challenges, the solution of turning more land into a spongy surface helps resolve both problems at once. Spongy surfaces slow down water, allowing it to percolate into groundwater reserves.

Two sides of the same coin, flooding and drought often go hand in hand. By the same token, because a surfeit of impervious surfaces is at the root of these twin challenges, the solution of turning more land into a spongy surface helps resolve both problems at once. Spongy surfaces slow down water, allowing it to percolate into groundwater reserves.

Ecosystem restoration creates a spongy land surface by protecting soil with vegetation, thus allowing the soil to repair itself with biodiversity and organic matter, key ingredients of a good soil sponge. And beyond fostering drought and flood resilience, healthy ecosystems serve a myriad of protective functions, including cooling their surroundings, cleaning polluted water, drawing down CO2, and harboring the biodiversity that is the magic making ecosystems perform so many vital functions.

However, because the services rendered by nature go widely unrecognized or taken for granted, nature’s power as an ally is often shackled.

Human societies tend to value the potential benefits that a landscape might provide in a limited way, adjusting management practices towards desired outputs by maximizing the benefits gained from one or some of the services (often the provision of goods) leading to the loss of multifunctionality and the degradation of natural capital at the expense of human welfare [Schindler 2014: 230].

An example of a landscape with undervalued ecosystem function is a river floodplain. Because floodplains are often favored for agricultural, industrial, commercial or residential uses, rivers are constrained to their channels and their banks leveed, despite that a river and its floodplains are members of a single interdependent ecosystem. Through seasonal pulses of floodwater over the banks, like a heart pumping blood through a body, a river replenishes groundwater and nutrients throughout its floodplains, making these areas some of the planet’s most productive and biodiverse ecosystems [Sparks 1995]. Consider, for example, that the Amazon Basin is a floodplain, where fish biodiversity actually depends on riparian forest cover [Arantes 2017]. Fish swim into flooded forests during flood pulses and directly consume terrestrial floodplain vegetation (seeds, fruits, detritus).

…a river and its floodplains are members of a single interdependent ecosystem. Through seasonal pulses of floodwater over the banks, like a heart pumping blood through a body, a river replenishes groundwater and nutrients throughout its floodplains, making these areas some of the planet’s most productive and biodiverse ecosystems.

In addition to supporting robust biodiversity, floodplain ecosystems give water somewhere to go during severe flooding events rather than damaging cropland, houses or other properties. By allowing water time to infiltrate into the ground, floodplains recharge groundwater, thus alleviating future droughts [Opperman 2009]. Riparian ecosystems also serve as a migration corridor for birds and fish especially, and also as a refuge from the heat of more exposed areas.

In other words, intact river-floodplain ecosystems perform multiple ecosystem services and thus help us manage some of our most pressing societal problems if only we acknowledge the value of floodplains in these terms.

Making space for water

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,”^[4] 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.