For the assessment of dike and levee strength as part of flood reduction studies, dike/levee composition is generally deducted from drilling samples and cone penetration tests (CPT’s) taken at various locations. For the improvement of geotechnical profiles and the exploration of very local – and therefore sometimes overlooked – geological features or layers, non-intrusive geophysics can be invaluable. For the water board of Rijnland, a series of surveys were conducted, using frequency and time-domain electromagnetics, (continuous vertical) electrical soundings, and microwave surveying.
