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Water harvesting by wax-treated soil surfaces: progress, problems, and potential

Fink, D.H., Frasier, G.W., Cooley, K.R.
Agricultural water management 1980 v.3 no.2 pp. 125
arid zones, clay, deserts, farmers' attitudes, livestock, paraffin wax, rain, ranchers, rangelands, runoff, sandy soils, silt, soil treatment, solar energy, springs (water), water harvesting, water supply, watershed hydrology, watersheds, weathering
Water-harvesting techniques can increase the useable water supplies of arid and semiarid areas. A relatively new water-harvesting treatment is the application of paraffin wax to soils to create a water-repellent catchment surface. The first two such catchments were installed at the Granite Reef test site in 1972 by applying ground paraffin wax (0.7 kg/m2 average rate) atop smoothed, rain-compacted soils. Solar energy melted the wax into the soil. The catchments are still operational after 7 years of natural weathering. Average runoff efficiency (yearly runoff/yearly rainfall) for the two catchments averaged 87% for the 7 years. Year 7 averages were 85%, i.e., only 2% less than the 7-year average. Also, the 7-year average runoff efficiency of the two catchments was only 10% less than that of a plastic membrane, but was more than four times greater than that of a simple, cleared and smoothed soil surface and nearly six times greater than that of a small untreated, natural desert watershed. Several operational wax-treated catchments have been built to supply water to livestock on arid rangeland. Ranchers are pleased with them -- equating them to permanent springs. Both laboratory and field tests indicated that the wax treatment is most successful on sandy soils containing less then 20–25% clay plus fine silt.