Water Retention Techniques for Vegetation Establishment in Arid Regions of Texas

Project Description

Water harvesting — the collection of storm water runoff and rainfall for later use — is essential to the practice of roadside vegetation management and the associated control of erosion. The practice has become increasingly important in light of decreasing groundwater supplies for irrigation and shifts in regional rainfall patterns, and this is especially true in arid regions. Although West Texas fits the arid description because of its limited and periodic rainfall, the area does experience some very high short-term rainfall events, causing considerable runoff from the roadway surface. Consequently, West Texas provides an ideal research environment to assess the best water harvesting techniques for arid regions. TTI researchers evaluated management practices at four sites near Childress, Canyon, El Paso and San Angelo to improve vegetation establishment through maximizing harvesting via physical options, maximizing water retention using soil amendments/techniques, and identifying biological approaches that improve water availability to vegetation. The researchers saw promising results in the use of asphalt emulsions, improved infiltration, reducing soil compaction, retentive grading, diversion channels, and installations of level spreaders and a variety of berms, finding that various combinations of these strategies would support early seed germination and moisture retention. In addition, the research team performed a cost / benefit analysis. Requirements of the Texas Commission on Environmental Quality stipulate that vegetation must be established on roadway construction sites. Consequently, these research findings have far-reaching applicability for the Texas Department of Transportation, not only in terms of regulatory compliance, but also to ensure the essential maintenance, safety and aesthetic quality of the state's roadway environment.

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