3.4. Valley Plug Geomorphic Units and Vegetation Survey
We found that the valley plug underwent a 641% increase in more diverse geomorphic units from 2015 to 2021 (Figure 7). Specifically, we observed a 657% increase in confluences, a 371% increase in diffluences, an ~861% increase in large woody debris structures and a 225% increase in riffle habitat. The riparian zone increased >5% between 2009 and 2015, occupying ~16% of the valley bottom (Figure 8). Between 2015 and 2021, riparian vegetation increased by >238%, occupying ~55% of the valley bottom. In total, the riparian zone increased by 2.2 km2 or by >258% after the arrival of the 2010 sediment pulse and corresponding plug. The amount of upland vegetation in the valley bottom shrank by ~96% between 2009 and 2021.