ABSTRACT
In order to allow for potential correlation between the evaluation results and the history of internal erosion in a specific dam it is necessary to categorize the dams with respect to the specific dams “operative history of internal erosion”. It should be noted that it is difficult tomake such a categorization. Inmost cases an internal erosion process is concealedwith a very slowprogress, and it can take years until signs of internal erosion surface, if ever. In the evaluation of dams that fall into categories 1* and 2* (see definitions below) both have experienced clear signs of deterioration and possibly internal erosion, but the prerequisite on category1* is a more or less “confirmed and documented” occurrence of internal erosion in the dam. Hence, the dams are qualitatively grouped as follows:
• 1* – Embankment dams with Probable occurrence of internal erosion and leakage – The dam has had incidents with visible sinkholes and settlements on the surface of the dam and leakage with cloudy water (eroded material in suspended load) or other observed signs of internal erosion.
