The importance of road design
Our results show the importance of the road drainage system in a post-fire watershed in altering surface hydrologic and soil loss processes. A field survey confirmed the LiDAR topography with road 1 flat and lacking culverts or an inside drainage ditch within the eastern part of the burnt area. Much of the upslope runoff either followed or crossed over the road surface, depositing sediment as it passed. Conversely, there were several ditches defined by the LiDAR DEM and verified by our field visit along road 2. Road-intercepted runoff was channeled along the ditches to culverts and downhill sediment basins rather than flooding over the road surface. Therefore the land surface below road 2 was not impacted by upslope runoff and the erosion risk was limited to channels which tended to be more armored than the burned hillslope (Figure 5). The upslope ditches and regularly spaced culverts on road 2 demonstrate the potential for road networks to reduce erosion risks in forests following wildfire.