Soil-water movement under natural-site and waste-site conditions: a multiple-year field study in the Mojave Desert, Nevada

• Published in: Water resources research 1997-08, Vol.33 (8), p.1901-1916
• Main Author: Andraski, B.J. (U.S. Geological Survey, Carson City, NV.)
• Format: Article
• Language: English
• Subjects: ARID CLIMATE; CARACTERISTICAS MORFOLOGICAS SUELO; CLIMA ARIDO; CLIMAT ARIDE; DEPTH; DESERT; DESERT SOILS; DESERTS; DESIERTOS; ELIMINACION DE DESECHOS; ELIMINATION DES DECHETS; MOUVEMENT DE L'EAU DANS LE SOL; MOVIMIENTO DEL AGUA EN EL SUELO; NEVADA; POTENCIAL HIDRICO DEL SUELO; POTENTIEL HYDRIQUE DU SOL; PRECIPITACION ATMOSFERICA; PRECIPITATION; PROFONDEUR; PROFUNDIDAD; SIMULACION; SIMULATION; SOIL MORPHOLOGICAL FEATURES; SOIL TEMPERATURE; SOIL WATER MOVEMENT; SOIL WATER POTENTIAL; SOIL WATER STORAGE; SOL DE DESERT; SUELO DE DESIERTOS; TEMPERATURA DEL SUELO; TEMPERATURE DU SOL; TEMPORAL VARIATION; TRAIT MORPHOLOGIQUE DU SOL; VEGETATED SOILS; WASTE DISPOSAL; WASTE DISPOSAL SITES; XEROFITAS; XEROPHYTE; XEROPHYTES
• ISSN: 0043-1397; 1944-7973
• DOI: 10.1029/97WR01502

Soil-water movement under natural-site and simulated waste-site conditions were compared by monitoring four experimental sites in the Mojave Desert, Nevada, during a 5-year period: one vegetated soil profile, one soil profile where vegetation was removed, and two nonvegetated test trenches. Precipitation ranged from 14 to 162 mm/yr. Temporal changes in water content measured by neutron probe were limited to the upper 0.5-1 m; values ranged from 0.01 to 0.19 m3/m3. Water potential and temperature were measured by thermocouple psychrometers; 77% remained operable for greater than or equal to 4.5 years. For vegetated soil, precipitation that accumulated in the upper 0.75 m of soil was removed by evapotranspiration: water potentials decreased seasonally by 4 to 8 MPa. During 2 years with below-average precipitation, water potentials below the apparent root zone decreased by 2.3 (1.2-m depth) to 0.4 MPa (5-m depth), and the gradients became predominantly upward. Water potentials then rebounded during 2 years with near- and above-average precipitation, and seasonally variant water potential gradients were reestablished above the 4.2-m depth. Under nonvegetated waste-site conditions, data indicated the long-term accumulation and shallow, but continued, penetration of precipitation: water potentials showed moisture penetration to depths of 0.75-1.85 m. The method of simulated-waste drum placement (stacked versus random) and the associated differences in subsidence showed no measurable influence on the water balance of the trenches: subsidence totaled less than or equal to 13 mm during the study. Water potentials below the trenches and below the 2-m depth for the nonvegetated soil remained low (approximately -5.5 to -7.5 MPa) and indicated the persistence of typically upward driving forces for isothermal water flow