Figure 33. Spatial comparison of headward and lateral recession monitored at selected hub-line stake
erosion sites.
symmetrical, retreat patterns governed by rapid
Comparison of the recent erosion (Table 8) and
headwall recession. Moving further inland,
historical data (Table 9) shows considerable an-
Tanker and In-Between gullies have also experi-
nual variability over the short term, but over the
enced unequal headward and lateral erosion and
long term (approximately decades), rates appear
recession. The rates of erosion at sites north of
relatively consistent. The high rates of headwall
Parachute Gully appear to be mirrored on either
recession at Bread Truck (33 m in approximately
side of the Eagle River. The reasons for this sym-
2 years) and Coastal 5 (26 m in approximately 1.5
metry are unknown, but are probably related to
years) are close to the 11-year average rates of
21.6 and 18.4 m/year, respectively, as determined
and how effectively water is channeled into in-
from historical photograph analyses (Fig. 32). Sim-
cipient feeder channels inland of the gully heads.
ilarly, the headward recession of 12.1 m in 3 years
43
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