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.