Theory 29/Glacial lake outbursts/Threshold lens
Breach Needs a Freeboard Threshold
The claim
Outburst occurs above a threshold in the ratio of lake depth to dam freeboard, so a deep lake behind a high dam can be safe while a shallow one behind a low dam fails.
01Mechanism
Overtopping initiates incision; the ratio determines when water can reach the crest.
02Prediction
Breach should track the ratio.
03Refutation
Breach tracking lake depth would remove freeboard.