Abstract
Landscape water conservation and potential evapotranspiration (PET or ET[p]) based irrigation programs are hindered by a lack of data on actual evapotranspiration (ET[a]) rates of multiple plant species landscapes. Irrigation coefficients are commonly used in potential ET based irrigation programs for turf but little in situ water use information exists for trees, shrubs, or ornamental plants. The objectives of this research were to evaluate the soil water dynamics within a multiple species landscape and to determine the relationship between ET[a] and ET[p] to develop a landscape irrigation coefficient. An additional objective was to assess the effects of several landscape species on soil water dynamics in an irrigated South Texas landscape. Soil moisture sensors were installed at 64 locations at depths of 0 to 20, 20 to 40, and 40 to 60 cm to record volumetric soil water content at 30 min intervals. Changes in volumetric water content between 0 hr of successive days were used to determine daily ET[a] and compared with ET[p]. The ratio of actual to potential ET was used to calculate a landscape irrigation coefficient. The daily landscape irrigation coefficients ranged from 0.05 to 1.00 and were influenced by soil moisture levels and season of the year. Monthly landscape coefficients (L[c]) ranged from 0.51 to 0.67 and the upper 20 cm of soil supplied the greatest percentage of ET[a] for all landscape species and the landscape as a whole.
Havlak, Roger Dale (2004). Combined water use of turf and woody ornamentals in an irrigated South Texas landscape. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2004 -THESIS -H28.