Evaportranspiration studies for protective barriers: FY 1989 status report

This document describes the results of technological developments and experiments at the Small Tube Lysimeter Facility. The objective of this research is to develop the capability to predict evapotranspiration in support of studies of water infiltration control for the Hanford Protective Barrier Development Program. Evapotranspiration is the combined loss of water from plants and soil surfaces to the atmosphere. This process must be predictable to adequately model soil water dynamics. We develop a miniature greenhouse (gas exchange chamber), where internal temperature and relative humidity can be controlled. With this device we measured evapotranspiration, transpiration, and carbon dioxide exchange rates from lysimeters with various surface and plant characteristics. We tested the effect on gas exchange rates and sand, gravel, admix, and soil surfaces in lysimeters where, cheat-grass, Bromus tectorum, had been seeded. Results showed that evapotranspiration was unaffected by the surface treatments. Estimated transpiration rates were higher for plants growing in sand compared with rates for plants growing in the admix and soil treatments. Soil evaporation rates were higher in the gravel treatment than in the sand treatment. Future research will entail parameterization of relationships between evapotranspiration, transpiration, soil evaporation, carbon dioxide exchange, and the abiotic and biotic factors that drive these processes for model development

An analytical solution for response of a porous seabed to combined wave and current loading

In this paper, an analytical approximation for the evaluation of the pore pressure and effective stresses in marine sediments under combined wave and current loadings is derived. Unlike previous investigations, non-linear interactions between waves and currents are considered in this study. An analytical solution for the wave-current induced oscillatory soil response in marine sediment is presented first. Based on the proposed analytical solution, a parametric study for the liquefaction potential will be carried out. Parametric study results indicate that the influence of current and non-linear waves on the maximum liquefaction depth is significant