Speaker
Description
Approximately 13% of the Earth's land surface is devoted to agricultural cropland where the process of bare-soil evaporation is a significant, nonviable loss of soil water. In arid or semiarid settings, this process can account for more than half of the total evapotranspirative losses. Bare-soil evaporation is driven by several different variables such as radiation, temperature, and air flow. In the case of the latter, windbreaks can be used to ameliorate downwind micro-climate, thus reducing evaporation potential by impeding direct airflow above the soil surface. This study explores the use of giant rivercane (Arundinaria gigantea) as a natural agricultural windbreak. Once widespread across North America, rivercane has declined to less than 2% of its former range. It has cultural significance in Native American communities and is considered a keystone species with numerous ecosystem benefits. This plant grows in dense stands, or canebrakes, up to 160,000 culms/ha and heights of 10 m, which could provide potential wind sheltering up to 500 m downwind. As part of this work, a series of experiments were conducted to explore how canebrake density and thickness affects evaporative water loss downwind. Experimentation was performed in the U.S. Army Engineer Research and Development Center (ERDC) Synthetic Environment for Near-Surface Sensing and Experimentation (SENSE) Research Facility which is centered around a climate-controlled wind tunnel that is interfaced with large soil test-bed. Multiple 1/10th scale physical models of a canebrake with individual culms represented by vertical dowel rods were created for different density/thickness configurations; a realization with no canebrake was treated as a reference. In each experiment, these models were installed at the upstream end of the soil test-bed and exposed to identical climate conditions (air flow, temperature, and relative humidity). The soil was homogeneously packed with a well-graded sand at a uniform, initial water content. Flow measurements indicate that velocity is reduced and turbulence levels change considerably within the ‘quiet’ zone that formed within the first meter downstream of the canebrake models. Water loss and soil moisture measurements made within the soil test-bed were similarly reduced relative to the experimental scenario with no canebrake based on the density/thickness. The soil moisture distribution varied with distance downstream of the canebrake, correlated to both the mean surface shear-stress and the reattachment of the flow. Collectively, results emphasize that the wind sheltering effects of rivercane could be beneficially incorporated into agricultural water management strategies while helping restore this plant’s distribution throughout the United States.
| Country | United States |
|---|---|
| Water & Porous Media Focused Abstracts | This abstract is related to Water |
| Acceptance of the Terms & Conditions | Click here to agree |
