Performance of Evapotranspirative Covers Under Enhanced Precipitation: Preliminary Data.

Desotell, L. T. ; Hudson, D. B. ; Anderson, D. ; Yucel, V. ; Shott, G.

Technical Information Center Oak Ridge Tennessee

关键词: Lysimeters;    Landfill covers;    Evapotranspiration;    Nevada test site;    Precipitation;   

RP-ID  :  DE2007914420

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Since January 2001, drainage lysimeter studies have been conducted at Yucca Flat, on the Nevada Test Site, in support of an evapotranspirative cover design. Yucca Flat has an arid climate with average precipitation of 16.5 cm annually. The facility consists of six drainage lysimeters 3 m in diameter, 2.4 m deep, and backfilled with a single layer of native soil. The bottom of each lysimeter is sealed and equipped with a small drain that enables direct measurement of saturated drainage. Each lysimeter has eight time-domain reflectometer probes to measure moisture content-depth profiles paired with eight heat-dissipation probes to measure soil-water potential depth profiles. Sensors are connected to dataloggers which are remotely accessed via a phone line. The six lysimeters have three different surface treatments: two are bare-soil; two were revegetated with native species (primarily shadscale, winterfat, ephedra, and Indian rice grass); and two were allowed to revegetate naturally with such species as Russian thistle, halogeton, tumblemustard and cheatgrass. Beginning in October 2003, one half of the paired cover treatments (one bare soil, one invader species, and one native species) were irrigated with an amount of water equal to two times the natural precipitation to achieve a three times natural precipitation treatment. From October 2003 through December 2005, all lysimeters received 52.8 cm precipitation, and the four irrigated lysimeters received an extra 105.6 cm of irrigation. No drainage has occurred from any of the nonirrigated lysimeters, but moisture has accumulated at the bottom of the bare-soil lysimeter and the native-plant lysimeter. All irrigated lysimeters had some drainage. The irrigated baresoil lysimeter had 48.3 cm of drainage or 26.4 percent of the combined precipitation and applied irrigation for the entire monitoring record. The irrigated invader species lysimeter had 5.8 cm of drainage, about 3.2 percent of the combined precipitation and applied irrigation. An irrigation valve failure caused an additional 50.8 cm of irrigation to be applied to the irrigated native plant lysimeter. There has been 29.3 cm of drainage from this lysimeter, which is 11.5 percent of the total applied water. Approximately 40 percent of the drainage from the irrigated native plant lysimeter occurred within four weeks of the valve failure.