Measuring Soil Water Retention Curves with an Automated Multistep Outflow System

Understanding the behavior of water flow in unsaturated soil is important for predicting groundwater recharge as well as nutrient and contamination transport. The soil water retention curve, which relates the volumetric water content to soil water pressure head, is a key input for numerical models used to predict flows. To determine this relationship, one can use in-situ or laboratory methods. In this work, the soil water retention curve is measured in the laboratory for three undisturbed samples from the Dry Creek Experimental Watershed. The retention curve will be determined using an Automated Multistep Outflow (AMSO) test apparatus which can saturate, drain, and re-wet samples so that drainage and wetting curves can be developed. Results will be used to support a larger project in which the spatial and temporal trends of soil moisture are being studied along a transect in the watershed.