Failure of a dam in Lesotho caused by internal erosion.
Drag forces caused by seepage water can significantly endanger the stability of dams. Changes in the flow conditions within embankment dams usually occur over long time spans, and are often not visible at the surface. The onset of internal erosion can very rapidly compromise the stability of the dam and potentially lead to its failure. By detecting problem zones during the early stages, timely and carefully targeted repair works can be undertaken. For the detection of these problem zones temperature measurements are most suitable. More than 500 linear kilometres of dam and many other types of hydraulic structures have been investigated and monitored successfully using this thermometric method. Many leaks and zones of increased permeability have been detected and accurately located. In addition, zones of increased flow within the foundations of dams have been identified. The technique can also be used to undertake quality assurance investigations, following new constructions or remedial work.

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     - Temperature Sounding Method (TSM1.pdf, 307kb)