HR: 0800h
AN: H41A-0397    [Abstracts]
TI: Estimation of Evapotranspiration From a Domestic Leach-Field and Surrounding Lawn Using a Combined Measurement and Modeling Approach
AU: * Stannard, D I
EM: distanna@usgs.gov
AF: U S Geological Survey, WRD, PO Box 25046, MS 413, Denver, CO 80225 United States
AU: Paul, W T
EM: wpaul@mines.edu
AF: International Ground Water Modeling Center, Colorado School of Mines, Dept. Geology and Geological Engr., 1500 Illinois St., Golden, CO 80401 United States
AU: Poeter, E P
EM: epoeter@mines.edu
AF: International Ground Water Modeling Center, Colorado School of Mines, Dept. Geology and Geological Engr., 1500 Illinois St., Golden, CO 80401 United States
AB: Residential development in areas without centralized waste-water treatment generally relies on individual sewage disposal systems (ISDS) for treatment of domestic effluent. The main components of an ISDS are one or more tanks to collect solids and a leach-field to dispose of water through percolation and evapotranspiration (ET). In arid and semi-arid regions having little recharge, the fate of water entering a leach-field can strongly affect the amount of ground-water available. Leach-field effluent that percolates to the water table is available for future withdrawal, whereas water lost to ET or to nearby streams is not available. We studied a domestic leach-field water budget in the Rocky Mountain foothills near Conifer, Colo. from June, 2004 to present. ET from the leach-field and surrounding lawn during a 1-yr period was estimated using a modified Priestley-Taylor model for each surface. The models were calibrated against occasional chamber measurements of actual ET from both surfaces. Three chamber measurement sites were established on each surface. Daily ET from the leach-field averaged 1.45 mm d^-1, about 50% greater than ET from the lawn (0.96 mm d^-1). Although this difference is substantial, it is small relative to the domestic discharge, which averaged 7.21 mm d^-1. Assuming one-dimensional vertical flow, these data indicate only about 6.8% of the domestic use was lost to ET. However, irregularities at the site compromise this assumption, suggesting ET losses from more typical sites may be greater.
DE: 1818 Evapotranspiration
DE: 1838 Infiltration
DE: 1840 Hydrometeorology
DE: 1876 Water budgets
DE: 1894 Instruments and techniques: modeling
SC: Hydrology [H]
MN: Fall Meeting 2005