Capillary action (Wicking) is possible. The extent of the 'wicking' is dependent on several factors. In this case, it would depend mainly on the type of stone that you used for construction. The greater the porosity of the stone the greater the 'wicking' action. However, based on your description, it sounds like you trimmed the liner too close to the water level. This is asking for trouble. In a heavy rain you will easily get overflow and the resulting erosion, especially in a stream. In most cases, I will leave at least 3-4 inches of liner above the water level. Water will not usually 'wick' this high if you use the proper stone.
Last edited by tadpole; 07-29-2010 at 02:47 PM.