Transience of channel head locations following disturbance

We used annual re‐surveys of two populations of channel heads affected by a severe wildfire in 2012 to monitor changes in channel head location with time following disturbance. Relative to channel heads in surrounding unburned areas, the median contributing drainage area of burned channel heads decreased by two orders of magnitude immediately after the fire, but then returned to values comparable to unburned areas within four years. We distinguish three types of channel heads. Permanent channel heads, which constitute 4% of the total population, occur in well‐developed swales in association with stable features such as bedrock outcrops: these channel heads appear to have been unaffected by the fire. Persistent channel heads, which are 40% of the total population, also occur within hillslope concavities, but the exact location of the channel head moves upslope and downslope through time in response to varying inputs of water and sediment. Transient channel heads form on straight and convex slopes immediately following disturbance, but disappear as regrowth of ground cover limits overland flow and sediment movement. The majority of the position changes for persistent and transient channel heads occurred abruptly when viewed as annual time steps. Copyright © 2017 John Wiley & Sons, Ltd.