COMPACTION AND WATER VELOCITY EFFECTS ON SOIL-EROSION IN SHALLOW FLOW

A laboratory investigation was conducted to study the effects of soil compaction and soil strength on the erodibility of a silty sand soil. A 6.1-m-long flume was designed and constructed to measure erosion. Erosion rates were determined at four soil bulk densities ranging from 1.28 to 1.52 Mg/m(3), eight shallow-flow depths ranging from 5.5 to 17.5 mm. three slopes ranging from 0.005 to 0.03 m/m, and eight flow rates ranging from 0.11 to 0.48 m(3)/(m . min). Soil shear strengths were measured using a Swedish fall-cone penetrometer. Erosion rates increased when soil air was entrapped and not allowed to escape into the atmosphere. Water velocity profiles over eroding soils were measured using a computerized pitot tube and pressure transducer apparatus. Velocity near the soil bed increased with greater bulk density. As a result, erosion rates increased as bulk density became larger.