Reclamation Information Sharing Environment (RISE)

Internal erosion events account for the majority of canal and dam embankment incidents. Index testing has been used to estimate the erodibility of different compacted embankment soils. Index tests include Hole Erosion Tests (HET) and Jet Erosion Tests (JET). These tests provide an indication of different circumstances (such as water content at placement, density, soil type) that impact a soil’s erodibility. The results of these tests are often used in risk analyses to help evaluate the likelihood of failure for Reclamation’s embankment dams. Recent large-scale erosion tests were completed and compared to HET and JET results. Results from the large-scale tests indicate water content, density, void ratio, and percent saturation have a significant impact on a soil’s erodibility. Testing on non-plastic silts and high-plasticity clays revealed surprising results. Under various conditions the erosion rate in the clay was found to be similar to the highly erodible non-plastic silts and under other variations the non-plastic silts eroded as slowly as high-plasticity clays. Results from these tests will be used in the evaluation of embankment erodibility.