Potential pesticide transport in Colorado agriculture: a model comparison

.30 September 1989.Includes bibliographical references (pages [50]-52)Grant no. 14-08-0001-1551, Project no. 09; financed in part by the U.S. Department of the Interior, Geological Survey, through the Colorado Water Resources Research Institute

Porewater pressure increases in soil and rock from underground chemical and nuclear explosions

A review and analysis of chemical and nuclear explosive-induced porewater pressure increases and induced rise in groundwater table elevations (groundwater mounding) is presented. Our analysis indicates that residual pore pressure increases and groundwater mounding can be induced by underground chemical and nuclear explosions to scaled distances of 879 m/(kt)1/3. This relationship is linear over eleven orders of magnitude of explosive energy ranging from a 0.01 kg chemical explosion to a 100 kt nuclear explosion and is valid for a wide variety of saturated geological profiles. Underground chemical explosions, and probably underground nuclear explosions, have the potential to induce liquefaction of water-saturated soils to scaled distances of about 260 m/(kt)1/3

Capillary pressure overshoot for unstable wetting fronts is explained by Hoffman's velocity-dependent contact-angle relationship

Pore velocity-dependent dynamic contact angles provide a mechanism for explaining the formation of fingers/columns in porous media. To study those dynamic contact angles when gravity is present, rectangular capillary tubes were used to facilitate observation of the complete interface without geometric distortion. Results show that the Hoffman (1975) relationship between dynamic contact angle and water velocity applies to gravity-affected flow fields, and that it (when adjusted for nonzero static contact angles) can be used to model dynamic capillary pressures for unstable wettings fronts in porous media by assuming that (1) pressure at the wetting front is discontinuous, (2) the flow field behind the fingertip is highly heterogeneous, and (3) the front line advances one or a few pores at the time. We demonstrate the utility of the Hoffman relationship for porous media with a published infiltration experiment by calculating the capillary pressure successfully at the unstable wetting front as a function of the flux of water in the finger and the grain size diameter

Screening methods for groundwater pollution potential from pesticide use in Colorado agriculture

31 December 1990.Includes bibliographical references.Grant no. 14-08-0001-G1551-01, Project no. 02; financed in part by the U.S. Department of the Interior, Geological Survey