Effect of logging on subsurface pipeflow and erosion: coastal northern California, USA

Three zero-order swales, each with a contributing drainage area of about 1 ha, were instrumented to measure pipeflows within the Caspar Creek Experimental Watershed in northwestern California, USA. After two winters of data collection, the second-growth forest on two of the swales was clearcut logged. The third swale remained as an uncut control. After logging, peak pipeflow was about 3.7 times greater than before logging. Before logging, little sediment was transported through the pipes. Suspended sediment concentrations before logging were less than 20 mg l and coarse-grained sediment was rare. After logging, there was great spatial and temporal variability in sediment transport. Sediment loads increased dramatically from some pipes during some storms, but from other pipes, sediment discharge remained unchanged after logging.