2 David Low Way - Attachment 4 - Specific Engineering Assessments - Cardno 10-8-17

Long term shoreline changes were determined from linear regression analyses of the available long
term vegetation line changes. These analyses were undertaken using the Digital Shoreline Analysis
System (DSAS) developed by the US Geological Survey (Himmelstoss, 2009). Figures 1.3 and 1.4
describe results for two of these cross-sections, 6 and 14. They show gradual shoreline progradation
rather than long term erosion (recession). Note the poor fit at Cross-section 14 caused by unknown
processes in the 1970-80s period — perhaps sand mining or a blow-out. Overall the analysis results, in
terms of the linear regression rate (LRR) of shoreline change, show shoreline progradation rates in the
order of 0.73m/year at the southern end, reducing to about 0.14m/year at the northern end — the latter
affected significantly by the unknown activity at the northern end — Figure 1.4. These results are
presented in Table 1.1.
40 Profile 6

¥ = 0.002x~28.32
R= 0,734

50 °
40

30

Distance from Baseline (m)

19

0
29/06/1957 8/03/1971 14/11/1984 24/07/1998 3/04/2012
Date
Distance from Baseline (m) Linear {Distance from Baseline (my)

Figure 1.3 — Long Term Shoreline Change at Profile 6
Profile 14
45

y=0,0004x + 19.204
40 R 20.07

Distance from Baseline (m)

8/03/1971 14/11/1984 24/07/1998 1/04/2012

Distance fram Baseline (m} Linear (Distance from Baseline (m)}

Figure 1.4 Long Term Shoreline Change at Profile 14

9/12/2025

9/12/2025