Changing storage beneath a stationary water table—an anomaly of certain humified peats

Abstract

Abstract Previously published seepage tube test results for well-humified peats at Dun Moss showed anomalous water transmission properties only partially explained by non-Darcian behaviour found in permeameter tests. In a new suite of seepage tube recovery tests it was found that the shape of the recovery curve varied with the time taken to establish the initial displacement. This variation, which is not associated with any movement of the water table, suggests that these peats possess a pressure-sensitive storage property consistent with the elastic behaviour of a wide range of aquifer materials of current interest to hydrogeologists. This interpretation is supported by comparison with the hydrogeological ‘slug test’ and by results from a special ‘re-fill’ variant of a recovery slug test. In these tests the water level was observed to decline spontaneously while below the equilibrium level, an effect explicable only by exchanges to storage.