No. 41, Spring/Summer 1997
The CCD, Part II: Asia & Americas
The photograph on this issue's "cover" was taken in the Avra Valley west of Tucson, Arizona, a few miles south of Saguaro National Park West. It shows the lush, thick vegetation growing on the upslope side of a water-spreading berm constructed roughly 60 years ago by the Civilian Conservation Corps (CCC). There are several such berms in this area. They are roughly eight feet high and were built either by hand or with the assistance of horse-drawn tools. They have been essentially unmaintained since at least the beginning of the 1940s, but are still in good shape.
These berms have been slowing and spreading water, allowing it to infiltrate slowly while leaving behind rich deposits of silt, for more than half a century. This has created a beneficial habitat for plants and wildlife. Consequently, the difference between the area upslope from the berm and the surrounding desert is striking. In the cover image, the foreground of the picture, with a creosote bush (Larrea tridentata) on the lefthand side, is representative of the typical desert vegetation in this part of the Avra Valley. The thick tangle of trees and shrubs in the background of the photograph clearly shows where the slowed-down water and silt were deposited. In the center is a palo verde tree (Cercidium spp.) in bloom. The other trees are primarily mesquites (Prosopis spp.). The plants grow so thickly that it is difficult to walk through the area. When we were there, the air was loud with the humming of bees visiting the flowering mesquites and the calls of desert birds. The ground showed ample signs of the presence of numerous rabbits and other small mammals.
The image above is a composite of several photographs taken to show more clearly the contrast between the upslope side of the berm and the surrounding desert. The berm is in the center of the photograph. To the left is the area downslope of the berm; to the right is the area of lush growth, with the flowering palo verde clearly visible. These two pictures (the composite image and the cover image) were taken by me and my colleague Michael Haseltine on 5 May 1997, with a digital camera. We took on the role of artistic designers for this issue because Merrill Parsons, artistic designer for several issues of the ALN, is no longer able to take on freelance work. [Michael and I have both discovered in the past few years that designing and maintaining web sites definitely requires one to be a "renaissance person." Our lack of experience with digital cameras shows especially clearly in the composite picture above, but we are learning!]
The picture above is from a slide taken by Tim Murphy, a permaculture designer and teacher based in southeastern Arizona. He made the slide from an aerial photograph shot in about 1986 by Cooper Aerial Survey Co., a Tucson firm. The top of the picture is north. At least nine berms and their upslope vegetation are clearly visible in this photograph, and it's possible to see how the berms were built at a slant across the water course they are interrupting. The straight line in the upper righthand corner of the photograph is the canal of the Central Arizona Project, carrying water from the Colorado River.
According to the Arizona Historical Society, the CCC was heavily involved in building Tucson Mountain Recreation Park (now called Tucson Mountain Park), whose western edge is located in the general vicinity of these berms. The Historical Society librarian I spoke with could not locate any definitive information about these berms, but speculates that they were probably built in connection with Tucson Mountain Park, and were probably intended as a flood and erosion control measure. However, even though their primary purpose was most likely not agricultural, it is easy to see from these photographs that spreader dams of this kind could be used for agricultural purposes.
Tim Murphy is a pioneer in permaculture education and design in drylands,
specializing in integrated sustainable design for dryland sites. Tim
studied for several years with Australian ecologist and environmental
designer Bill Mollison, who developed Permaculture as an interdisciplinary
approach to land use and community development. Tim founded the Sonoran
Permaculture Association, now active as Permaculture Drylands Institute, in
1986. He developed basic and advanced
permaculture design courses as an adjunct faculty member in the Prescott
College Environmental Studies Program from 1991-97, and currently serves as
a senior instructor for Permaculture Drylands Institute. He operates Tim
Murphy Design and Consulting, an ecological design firm specializing in
unique and detailed site assessments and concept studies.
Cooper Aerial Survey Co. was established as an Arizona corporation in 1966 to provide aerial photography and photogrammetric services to Tucson and the Southwestern US. With the addition of affiliate offices in Phoenix and Las Vegas in the early 1980s, their services expanded to include clients throughout the U.S. and Puerto Rico. In August 1994, their organization expanded again to include incorporation of their photo lab operation, CAPLAB, Inc., and the formation of a Mexican office, Cooper Aerial Photo of Mexico.
About the Arid Lands Newsletter