Field Measurement of the Soil-Water Storage Capacity of Evapotranspiration Covers Using Lysimeters

Abstract

Three soils were tested as possible substrates for an evapotranspiration cover for a Uranium mill tailings disposal site in Moab, Utah. Small weighing field lysimeters were used to determine the field capacity of soils with the effect of a coarse-grained capillary barrier placed beneath the soil to increase water retention. Water was ponded on each lysimeter and then covered with plastic to prevent evaporation. Lysimeters were drained and weighed periodically throughout the experiment. Field capacity was determined by the weight of the lysimeter when drainage stopped. Results were compared to a mathematical model for estimating water storage of capillary barriers. Results from particle size analyses were also compared to water storage results and we found that both sand and clay were significant factors (p <0.05) in explaining water storage. After determining the water-holding capacity of the soils, recommendations on the most suitable soil for the Moab evapotranspiration cap will be made.