Rainwater Harvesting for Drylands and Beyond, Volume 2
Review by Doug Pushard
Rainwater Harvesting for Drylands and Beyond, Volume 2 Water-Harvesting Earthworks, is Brad Lancaster’s recently published book on passive rainwater collection. It is a practical guide to holistic rainwater management, also refer to as earthworks or living water harvesting systems. This new book features information on passive rainwater harvesting strategies; including site planning with entire chapters on berms, basins, terraces, mulching and much, much more. The 419 page guidebook is packed with detailed examples, stories, data, sample calculations and illustrations.
Each chapter of the book includes information about the concept being covered (i.e. infiltration) as well as sidebars covering important tips and real world examples on each topic. The entire guide book can be read or individual chapters can be referred to gain a deep insight into on a specific topic (i.e. imprinting). Either way for those interested in landscaping or earthworks it is likely to become a handy reference manual that will be referred to again and again.
Rainwater Harvesting for Drylands and Beyond, Volume 2 includes chapters on Berms and Basins, Terraces, French Drains, Infiltration Basins, Imprinting, Mulching, Permeable Paving, Diversion Swales, Check Dams, Vegetation and a very brief chapter on Greywater Harvesting. This guidebook is written in a very personable manner that is easy to read and includes nearly 500 illustrations and sidebars. It is very well cross-referenced, contains dozens of real life examples, provides a list of tools and materials required to build each type of earthwork, the best sites to use each technique and a extensive list of additional resources.
The book includes numerous nifty factoids. These fun facts add lots of interesting color and humor. A few include:
- Based on typical water usage in the United States, a single person generates up to 40 gallons (152 liters) of greywater per day.
- The U.S. Environmental Protection Agency ranks urban runoff and storm-sewer discharges as the second most wide-spread source of water quality impairments for the nation’s estuaries.
- A 30-foot wide paved street will drain 83,500 gallons of runoff per mile in a one inch rainstorm.
- Sleeping on cold bare ground will such the heat out of your body and make your hips and shoulders ache.
- Soil with as little as 2% organic matter can reduce the irrigation needed by 75% compared soil with 1% organic matter.
- Approximately 10 gallons of water are required to manufacture 1 gallon of gasoline.
- Gabions are check dams in which the rocks are encased in a wrapping of wire fencing or a wire basket that holds everything together – sort of a rock burrito in a wire tortilla.
One of the book’s appendices is a list of handy calculations. Some of these include equations for calculating: catchment area of a triangular surface, estimating maximum runoff using rules of thumb, Berm ‘n Basin water-holding capacity, terrace capacity, circular infiltration basin holding capacity, and diversion swale sizing.
A very short excerpt on the chapter on Mulch, provides a good example of what is inside this excellent, well organized guide. This is from the chapter on Mulch.
Mulch happens. See it. Understand it. Mimic it. Benefit from it. Under trees and shrubs in a healthy forest you always find a rich humus created from accumulated leaves, bark, and twigs: mulch. The particles comprising mulch protect the soil from the compacting force of raindrops. They act as countless tiny water harvesting sponges intercepting those drops before they have a chance to become erosive runoff, and they allow the moisture to infiltrate into adjacent soils.
Once rainwater has infiltrated into the soil, the mulch layer helps retain that precious moisture by greatly reducing the loss of water to evaporation. In drylands, evaporation from the upper 4 inches (10 cm) of soil is typically very rapid. High temperatures, drying winds, and capillary action move water quickly upward within the soil to the surface where liquid water changes to water vapor and moves out of the soil into the atmosphere. Mulch shelters soil and shallow roots, lowering their temperature in hot climates. This enables earthworms and other beneficial soil life to thrive. Thee life forms and the mulch build soil as it gradually decomposes into humus. This nutrient-rich humus feeds trees and other plants. Birds and other animals come for the food and shelter offered by the vegetation, and leave little fertilizing packets of their own in the form of manure. Everything falls to the ground and decomposes to be taken up again by flourishing plant and animal life, creating a wonderfully sustainable nutrient loop.
In the human-built environment, fallen leaves are often snatched up with a rake or hit by a gust from a gas blower, then bagged in plastic, and carted off to the dump. The resulting bare earth is scorched in summer, frozen in winter, and prone to erosion and high evaporation year round. In additional, far less water is absorbed into the soil, and water is more likely to wastefully puddle, because exposed soil often forms a cap-like layer of compacted, less permeable earth. Advertisers and landscape companies then turn around and sell manufactured fertilizer and imported mulch to replace the free, local nutrients that are routinely removed. You can save work and expense by letting leaves fall and naturally decompose under your plants. Leaves on paths and patios can be raked or swept into sunken basins nearby.
Hopefully, Brad will continue writing and bring his holistic approach to green roofs, greywater systems and other water-related topics. Both greywater and green roofs, like rainwater harvesting, have been around for centuries but are just now starting to come into vogue due to market realities and new technologies. It is understanding these systems and integrating them into an overall holistic water system emphasizing natural processes that would benefit from Brad’s hands on natural systems hands on approach. Rainwater Harvesting for Drylands and Beyond, Volume 2 Water-Harvesting Earthworks, is bound to be a reference manual used by many. Passive rainwater harvesting should be the first step of any rainwater harvesting plan and I highly recommend this guidebook for anyone serious about living a more sustainable lifestyle or those that are helping others live more lightly on our planet.