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Transport assessment - arid: measurement and prediction of water movement below the root zone

Conference ·
OSTI ID:6432689

The amount of water transported below the root-zone and available for drainage (recharge) must be known in order to quantify the potential for leaching at low-level waste sites. Under arid site conditions, we quantified drainage by using weighing lysimeters containing sandy soil and measured 6 and 11 cm of drainage for a 1-yr period (June 1983-May 1984) from grass-covered and bare-soil surfaces, respectively. Precipitation during this period at our test site near Richland, Washington, was 25 cm. Similar drainage values were estimated from neutron probe measurements of water content profile changes in an adjacent grass-covered site. These data suggest that significant amounts of drainage can occur at arid sites when soils are coarse textured and precipitation occurs during fall and winter months. Model simulations predicted drainage values comparable to those measured with our weighing lysimeters. Long-term, 500- to 1000-yr predictions of leaching are possible with our model simulations. However, additional studies are needed to evaluate the effect of soil variability and stochastic rainfall inputs on drainage estimates, particularly for arid sites. 15 references, 9 figures, 1 table.

Research Organization:
Pacific Northwest Lab., Richland, WA (USA)
DOE Contract Number:
AC06-76RL01830
OSTI ID:
6432689
Report Number(s):
PNL-SA-12508; CONF-8409115-10; ON: DE85000834
Country of Publication:
United States
Language:
English