Evapotranspiration of turfgrass located adjacent to a fallow desert soil: A quantitative assessment of the "edge effect"

A field study was conducted using microlysimeters (ML) to assess the impact of advection on evapotranspiration (ET) of turfgrass in Tucson, AZ. A rectangular block (70 m × 45 m) of irrigated turfgrass ['Tifway' bermudagrass (Cynodan dactylon L. × C. transvaalinsis Davy) in summer overseeded in winter with 'Charger II' perennial ryegrass (Lolium perenne L.)] was planted in a 1.8 ha fallow agricultural field. Wind flow at the site was typically parallel to the long dimension of the block and decidedly periodic due to a mountain-valley flow regime. Parallel rows of ML were installed in the turf at varying distances from the two edges of the field subjected to advection. ET along the edge of the field subjected to afternoon advection averaged 10.8 and 8.2% higher than ET in the middle of the field in summer and winter, respectively. Enhancement of ET relative to the field middle was smaller for the turf edge subjected to evening and morning advection and averaged 6.8% in summer and 4.7% in winter. ET from MLs located 7 m from the edge of the field were typically within 5% of ET measured in the field middle, indicating the impact of advection diminishes rapidly with distance. A simple advective index computed from wind speed and vapor pressure deficit may prove useful in quantifying the impacts of advection. Copyright ASCE 2005.