Spatial and Temporal Variations in Moisture Content at a Sandy Beach and the Impact on Sediment Strength

The impact of moisture content on the strength of sediments at a sandy beach is explored. Surficial beach sediments with limited variability in size (0.34–0.37 mm median grain size) were tested for moisture contents and quasi-static bearing capacities. Moisture contents and grain sizes were found from push core samples and in situ sediment strength was assessed from deployments of a portable free-fall penetrometer. Moisture contents ranged from 4.5–21%, and estimates of quasi-static bearing capacities varied from 14.3–43.7 kPa over a single transect during one sampling period (~30 minutes). Over a survey period of three days, moisture contents varied from 4.7–19.9%, and quasi-static bearing capacities ranged from 13.0–38.1 kPa for one exemplary location. Higher moisture contents generally resulted in higher strengths in the intertidal zone. With other variables remaining constant, the results indicate a spatiotemporal relationship between sediment strength and moisture content of sandy foreshore sediments.