The Permaculture Earthworks Handbook

How to Design and Build Swales, Dams, Ponds, and other Water Harvesting Systems

Douglas Barnes

• Publisher: New Society Publishers
• Year: 2017
• ISBN:
  9781771422345
• Topic: Technology & Engineering
• Subtopic: Sustainable Agriculture
• Index: Technology & Engineering

Maximize your water harvesting potential with efficient, cost-effective earthworks

In the face of drought and desertification, well-designed, water harvesting earthworks such as swales, ponds, and dams are the most effective way to channel water into productive use. The result can be increased food production, higher groundwater levels, reduced irrigation needs, and enhanced ecosystem resilience.

Yet, due to a lack of knowledge, designers, and landowners often build earthworks that are costly, inappropriately sized and sited, or even dangerous. The Permaculture Earthworks Handbook is the first dedicated, detailed guide to the proper design and construction of water harvesting earthworks. It covers the function, design, and construction methods for nine main types of water harvesting earthworks across a full range of climates.

Coverage includes:

• Swales, ponds, dams, hugelkultur, net-and-pan systems, spate irrigation, and more
• Cost versus benefit of different earthworks
• Assessing site needs and suitability
• Soil types and hydrology
• Designing for maximum efficiency and lowest cost
• Risk assessment and safe construction
• Stacking functions and integrating earthworks into a design

This practical handbook is the essential resource for permaculture designers, teachers and students, landowners, farmers, homesteaders, landscape architects, and others involved in maximizing the water harvesting potential of any landscape at the lowest cost and impact.

Douglas Barnes is a permaculture designer trained in Australia by Bill Mollison and Geoff Lawton. He has designed and built earthworks in North America, Japan, and Andra Pradesh, India. He lives in Tweed, Ontario in a passive solar house he designed and built, and he blogs at permaculturerelections.com.

1

The State of Water

The Colorado

On March 25, 2014, near the Sea of Cortez in the Sonoran Desert, a jovial crowd gathered in a dry, sandy riverbed flanked by cottonwood and willows on either side. They were there to witness a rare event. The occasion that attracted so much attention was a trickle of water moving along the dry riverbed at the speed of a lazy stroll. Two days earlier, the Morelos Dam had slowly opened the gates to the Colorado River.

This artificial mimicking of the natural spring flows that used to occur was a result of Minute 319 of the International Boundary and Water Commission. On November 20, 2012, both the United States and Mexico agreed to the goal of working toward the restoration of the Colorado River. This was the first time that a water allocation on an international river was made strictly for the environment.

Two months after the release from the dam, the flow of water, dubbed “the pulse,” finally reached the Sea of Cortez on May 15. Three days later the Morelos Dam was once again closed, and the pulse ended. While the next four years were to see additional base flows released, these smaller allocations were, in total, less than the pulse flow of 2014. The ongoing base flows have helped to rejuvenate the lower Colorado, and in July of 2016 a sea lion was spotted in the upper estuary for the first time.

What made the pulse so special? Why was an international agreement necessary to restore a fraction of the water that had once fed a thriving, 3,000-square-mile delta? Since the completion of the Hoover Dam in 1936, ten dams have been built along the main stem of the Colorado River—this in addition to the three dams that preceded the Hoover Dam. Add to this the thirty-one major dams along the tributaries of the Colorado, as well as the irrigation channels built into the river system, and it becomes easy to see how the Colorado’s flow never reached the sea.

Over the course of the 20th century, the river had come to be claimed for a human population that would grow to 30 million people. It became the source of power generation, irrigation, and municipal water supplies, but the success of these engineering projects came at the expense of the natural environment that ultimately supports those same people.

The Aral

Though the Colorado story has a glimmer of hope to it, a similar story on the other side of the world is an ongoing crisis on a far greater scale. In the 1950s, the Soviet Union redirected the Amu Darya and Syr Darya rivers in order to support desert agriculture in the area around the Aral Sea. The Aral Sea itself was dependent on those rivers to maintain its volume. Without the flow from the rivers, the Sea started to evaporate, leaving behind negative health effects and a ruined economy for tens of millions in the region. Infant mortality rose to a staggering 1 in 10; tuberculosis deaths rose 21 times higher; cancer saw a 10-fold increase; kidney disease rose 15 times higher; and gastritis deaths went up by 15 percent. To add insult to injury, up to 75 percent of the redirected water was wasted.

The water problems didn’t end with an evaporating sea. The loss of volume of the sea had a corresponding loss of groundwater levels. This loss of groundwater, in turn, led to increased salinization of the soils of the region. This hindered local plant growth, contributing to erosion, which in turn led to a dependence on fertilizers for agriculture.

Dust storms are now a regular occurrence, with the salt content in the dust being as high as 90 percent, increasing respiratory illness. This salt can be carried a long distance, having harmful effects on agriculture far from the sea itself.

Through evaporation, the Aral split into the North and South Aral Seas in 1990. At that point, the Royal Geographical Society called the Aral Sea “the world’s worst disaster.” In an attempt to prevent the North Aral Sea from draining, a sand dam was built in the mid-1990s, though it had failed by the end of the decade. With funding from the World Bank, a new dam was completed in 2005, and since that time, the North Aral Sea has risen over 10 meters (32.8 feet), which has led to a revitalization of the fishing industry.

Talupula

Water crises also strike many communities on a local scale. Such is the case for Talupula, a remote village in Andra Pradesh, India. Once a dry tropical region, it has been growing increasingly arid over the decades, and the life-giving monsoons have become less reliable. Overgrazing and the harvesting of forests for fuel has denuded most of the landscape. During the dry season, the region has the look of a desert. This loss of vegetation has reduced the land’s capacity to capture and store water. This, in turn has reduced the rate of groundwater recharge. The town relies on an aquifer over 1,000 feet deep; and the rate of abstraction is lowering the water level year by year. The biotic pressures on the landscape have diminished the recharge rate of the aquifer. While redirecting and damming river flows are not the culprits here, anthropogenic changes to the watershed are.

To compound problems, fluorite, fluorapatite, and other minerals in the rock leave the water heavily fluoridated, making fluorosis a health concern. From a health standpoint, the water is considered unsuitable for drinking, yet it is the only current option for the town’s supply. High fluoride levels can also affect livestock reproduction and plant germination and growth. The high evaporation rate and low rates of recharge are suspected of compounding the fluoride issue.

Like every place in the world with a crisis looming over it, life chugs on, albeit with a sense of hopelessness in many of the residents. The environmental changes are progressing at a rate that even the young can perceive. And yet, as we will see in Chapter 7, Talupula offers an exciting ray of hope. As part of a cooperative project with the Green Tree Foundation of AP, India, we were able to turn a barren hillside into a mango orchard for under $1,000, using very simple earthworks.

Worldwide

Globally, humans use 4,000 km³ of water each year. Of this, 70 percent is used for agriculture, 20 percent for industrial purposes, and 10 percent for domestic use. It should be noted that a portion of the agricultural usage is now tied into energy production with biofuels.

With population increasing and climate change growing more severe, the World Bank estimates that Central Africa and the Middle East will lose 6 percent of their GDP to water scarcity. For with a 2°C increase in global average temperature, the percentage of the global population affected by absolute water scarcity (meaning that individuals have less than 500 m³ water per year) is predicted to increase by 5 to 20 percent, and the population experiencing water scarcity (less than 1,000 m³ per year per individual) is predicted to increase by between 40 and 100 percent, depending on population rates and warming rates.

To meet the needs of decreasing water supplies, groundwater is being drawn on at increasing rates. Currently, 48 percent of agriculture globally relies on declining supplies of groundwater for irrigation. Over the coming decades, the declines in groundwater supplies will severely limit agriculture in many regions. In addition to human depletion of groundwater, climate change is also threatening supplies.

The rate of abstraction globally has increased threefold over the past 50 years and is increasing at 1 to 2 percent per year. It is estimated that abstraction will increase by a further 55 percent by 2050. Currently, 26 percent of the global water supply is provided by groundwater, and almost half of the water extracted is used to meet the need for potable water. This rate of withdrawal currently amounts to 8 percent of the mean global aggregate of groundwater recharge, but reliance on groundwater abstraction is greatest in regions of water scarcity. It is in these regions that recharge is often less than abstraction. Over-abstraction puts tremendous pressure on agriculture, threatening the food security of already impoverished nations. The result is often environmental refugees fleeing land that can no longer support them. For instance, roughly two thirds of India’s irrigation needs are met by groundwater, and wells are being abstracted at a rate greater than they can recharge.

Degradation of groundwater is also an increasing problem. Over-abstraction in some coastal areas has allowed saltwater to backfill, contaminating the groundwater. Here, too, climate change is expected to exacerbate the problem as sea levels rise, putting more water systems at risk.

Tracking groundwater is difficult, and we have only a rough picture of what reserves are in place and just how much they are declining. In 2002, NASA started tracking groundwater levels with its GRACE mission (Gravity Recovery and Climate Experiment). From the data it has collected, we know that one third of the Earth’s large groundwater basins are being depleted at an alarming rate.

Spread of deserts

Two billion people live in drylands globally, most of them below the poverty line. Accounting for 41.3 percent of all land and 44 percent of cultivated land, and containing 50 percent of the world’s livestock, these areas are increasingly coming under threat of desertification. Deforestation, farming practices, mining, and climate change are increasing the spread of deserts across dryland areas.

As drylands further degrade, they are expected to lower the global production of food by 12 percent over the next 25 years, raising food prices by some 30 percent, leaving nearly a billion people hungry. We lose 23 hectares a minute (over 12 million hectares a year) to desertification.

The deforestation and degradation of Talupula has been a process many decades in the making. It took massive engineering projects to choke off the Aral Sea and to use up the Colorado River before the river could reach the ocean. The Earth’s water problems have been centuries in the making. To do the damage we have done has taken tremendous energy and billions of labor hours and machine hours. To put it succinctly, it has taken a lot of work to muck up the Earth to the extent we have.

One obvious and important lesson to be gleaned from the Aral Sea, Colorado River, and even Talupula is that what happens upstream affects what happens downstream. We also see that large-scale engineering projects can lead to large-scale problems. Both the drying of the Aral Sea and the reduction of the Colorado River have come about through inappropriate approaches to irrigation. These two stark examples are played out on a less dramatic scale throughout much of the world today.

These three examples also show us a ray of hope. The explosion of life in the Colorado Delta, the return of fisheries to the North Aral Sea, and the results of Talupula show us just how quickly systems can be rejuvenated when we add water.

Water is vital for all life on the planet. No water, no life. We need water to survive. We need water to produce the food we eat. We also use water in cooking and cleaning processes, sanitation, and to manufacture the items we need in our daily lives.

War and conflict

With growing water scarcity comes an increase in conflict over water. This conflict takes place not only between nations but also within nations as well. In January 2014, for instance, a small dam in Kyrgyzstan was targeted with mortar rounds by Tajik security forces as part of a conflict over water- and pasture-access rights. Water supply systems are also used as targets in terrorist attacks. Such was the case in an attack on Afghan schoolgirls in April 2012, when their school’s water supply was poisoned out of opposition to the education of girls. Class conflict within a nation, too, has arisen around water rights. Growing water scarcity in the small village of Rasooh, in the state of Jammu and Kashmir, India, for instance, has seen assaults on lower caste Dalit women attempting to access village well water. Police were then needed to guard the well. The well was later damaged by a group of members of the upper caste to show their disapproval of the lower caste accessing the well.

These are but three small examples of a growing number of conflicts involving water. Africa, Asia, Australia, Europe, and North and South America all have recent records of violence or attempted violence involving water. While there are major international conflicts involving water, such as the ongoing Syrian Civil War, there is a growing number of lesser national and international conflicts around water. Increased water scarcity, together with an increasing population and the spread of deserts, makes the risk of increased future conflict more and more likely. Securing sustainable water supplies for populations at risk will increasingly become a prerequisite for peace.

Where there is hope

While the sheer numbers of people and the advent of machinery have accelerated the process, the degradation of drylands has been millennia in the making. The catastrophes of the Colorado River and the Aral Sea both required massive engineering projects. Aquifer depletion has required electric and fossil-fuel–powered pumps to withdraw water at rates greater than recharging. Damaging the environment is not that easy to do. It takes tremendous concentrated effort to really muck things up. Yes, humankind has made a real mess of much of the globe, but not without expending trillions of labor hours and quadrillions of kilocalories to do so. Simply put, breaking the planet is hard work.

The really good news is that by working in cooperation with nature, we can undo most of the damage we have done with a fraction of the time and energy it took to cause the damage in the first place. I never cease to be amazed when, time and time again, degraded sy...

Table of contents

• Cover
• Title Page
• Copyright Page
• Contents
• Introduction
• 1. The State of Water
• 2. A Look at the Past
• 3. How Water Moves in the Environment
• 4. Designing for the Whole Environment
• 5. Elements of Design and Implementation
• 6. Water Storage Techniques
• 7. Interception Techniques
• 8. Applying Permaculture Strategies
• 9. Cautions
• Appendices
• Index
• About the Author
• About New Society Publishers