3.2. Reference Reach Delineation
For both reference reaches, imagery for 2009 (pre-valley plug) was
collected in August when flows were at 8.07 cms, and imagery for 2015
was collected in July when flows were at 0.26 cms. The slope of our
Spring Canyon reach was .0015 (Table 1). The valley bottom measured 2.26
km2, of which ~5% (112,676
m2) was inundated by free-flowing river in 2009. The
river rerouted and cut off an >800 m stretch of river
between 2010 and 2012, and in 2015 ~3% (85,199
m2) of the valley bottom was inundated. We found that
the valley plug contained 3% more inundated habitat as compared to the
Spring Canyon reference reach in 2009, and had ~1,577%
more inundated habitat in 2015 (Figures 3A and 3B). The valley plug also
contained ~0.67 km2 more riparian
habitat as compared to the Spring Canyon reference reach in 2009, and
0.7 km2 more riparian habitat in 2015 (Figures 4A and
4B).
We found that the Moonshine Wash reference reach had a slope of .0016
(Table 1), with ~75,227 m2 of
inundated habitat in 2009, occupying ~6% (75,227
m2) of its 1.13 km2 valley bottom.
In 2015, inundation was reduced to ~5% (60,556
m2) of the valley bottom. The valley plug contained
54% more inundated habitat as compared to the Moonshine Wash reference
reach in 2009, and ~2,259% more inundated habitat in
2015 (Figures 3A and 3C). We observed an increase in the number of
geomorphic units found in the Moonshine Wash reference reach, containing
43 riffles and 27 large woody debris structures in 2015, compared to
zero in 2009. Riparian habitat did not change significantly between 2009
and 2015 in the Moonshine Wash reach, and the valley plug contained an
average 0.7 km2 (Figures 4A and 4C) more riparian
habitat than the Moonshine Wash reach during both 2009 and 2015.