Moisture (Phase 2): Site #1

Water Diversion System

We selected a physical site with a wash to allow the collection of rainwater to feed a series of gardens. The initial plan was to situate a water-collection funnel, protected by different obstacles, in the wash bed to divert liquid flows into a tank designed to dispense water to the plant material.

Paul Measeles, a hydrologist who answered our posting on the WaterForum listserve, advised us to build a gabion with a French drain directly down-stream. To avoid the need for a pump, we decided to rely solely on gravity. We connected the drain (Fig. 3) to a 1.5-in-diameter pipe that would directly feed Garden #1 (which had to be dug more than 2 ft deep) on one side and Garden #2 (which had to be dug 3.5 ft below ground level) on the other, with a water tank positioned at the halfway point. Between the gabion and the tank, we ran the pipe through a bucket to serve as a silt trap.

We researched the available water tanks on the market, but none was suited to our needs. Our proposed system required a large, flat tank. After researching different possibilities, Perroud decided to build an 8 × 4 × 1 1/4-ft 200-gallon tank out of marine-grade plywood. He then lined the tank with two layers of the thickest plastic sheeting to be found on the market. The tank had to be placed at the proper subsurface height, so we had to dig a very large hole (Fig. 4). It took a few all-day sessions with five well-fed individuals to obtain the correct depth.

On the bottom of Garden #2 we laid plastic sheeting. On the edge we installed a watering timer, and from there a net of 1/4-inch pipes covered with a layer of gravel to allow for the proper dispersal of the water. We added 1.5 feet of sand on top of the pipe system. To prevent erosion, we gave the edge a 45° slope, and at half the height we made a 1.5-ft terrace on which we positioned plants. The excavated sand was used to create berms around the garden to provide protection from runoff.

Fig. 3.

Drain and gabion: French drain is placed behind the finished gabion by the MOISTURE team, December 2003.

Photo © C. Willey

The Gardens

Our use of DriWater transformed the initial garden plan (Fig. 5). In keeping with our desire to create subtle microclimatic change, we expanded our design to establish a wider range of native plants and trees agreeable to our site's region.

In the beginning stages, the 15-acre site was measured, and plants were mapped and identified. We noticed that the existing plants grew in circular patterns with almost perfect spacing between. Upstream, and in view of the

Fig. 4.

Tank placement: C. Willey, B. Perroud, R. Frisinger and Adam Belt place the water tank into the ground, December 2003.

Photo © D. Capparelli

project site, are two 10-ft-diameter circular water troughs. These forms inspired the individual garden shapes, and the entire series of gardens mimicked the pattern of the Little Dipper, visible in the sky above. The gabion was positioned farthest upstream from Gardens #1 and #2, with Garden #1 being positioned directly below Polaris.

Fig. 5.

Planting: Deena Capparelli, using five DriWater quarts, plants a Larrea Tridentata in one of the gardens.

Photo © C. Willey

Each garden, designed to be 10 ft in circumference, was dug through crusts of compact soil to a depth of 2 ft. The plan was to boost the development of grasses and perennials by adding small amounts of gypsum to reduce the high alkali levels in the soil. Holes for the trees were dug to depths of 3 ft to break through the caliche, thus allowing their roots the opportunity to search for water at deeper levels.

The Center Gardens (Gardens #1 and #2) are to...