*3.2. Beach Elevation Profiles*

Elevation profiles of North Captiva's coastline from 2004–2018 are grouped based on their corresponding R-monuments, as well as approximate location on the island based on the section of island it is found in. Profiles are displayed from the northern-most region, mid-region, the breached area, and the southern tip. Figures 3–6 show the changes in elevation between 2004 post-Charley and 2018.

Figure 3 shows profiles extracted from the northernmost sector of the study area, including R-monuments 67 and 69. These profiles show a relatively stable beach with little geomorphological changes occurring from 2004–2018, aside from slight sediment accretion following Hurricane Charley and greater erosion in 2018. The orientation of this shoreline from north northeast to south southwest helps to maintain the coastal stability for this region.

Figure 4 shows profiles from the mid region of the study area including R72 and 74, which show significant erosional behavior for the region. After a slight sediment accretion post-Charley, since 2010 the shoreline has been subjected to significant erosion. In some areas along R72, specifically 75 m and 150 m onshore, the height of the beach has been eroded by about 1 m. Along R74, similar patterns are observed at 300 m and 440 m onshore where the height of the coast decreased by about 1 m since 2007 and 2010. High erosion from this area could be explained by greater exposure of this section of the island to northwesterly waves during winter storms.

**Figure 3.** R67 and R79 elevation profiles with respect to NAVD88 of North Captiva Island for 2004 post-Charley through 2018.

**Figure 4.** R72 and R74 elevation profiles with respect to NAVD88 of North Captiva Island for 2004 post-Charley through 2018.

Figure 5 depicts profiles R78a and 78c, representing the area on the island that was breached during Hurricane Charley made landfall. Data from 2004 shows evidence of the cut, as can be seen where the elevation of the island in 2004 falls below sea level on both the profiles from R-78a and for R-78c. Evidence of island recovery can be seen as the elevation increases from about −1 m to almost 2 m since 2004 post-Charley. Both of these peaks can be seen from 200–250 m. Evidence of sediment accretion from the elevation profiles began as early as 2007, showing the natural healing of the island that occurred. Sediment eroded from the beach section just north has been transported southward and helped in rebuilding this section.

**Figure 5.** R78a and R78c elevation profiles with respect to NAVD88 of North Captiva Island for 2004 post-Charley.

Figure 6 shows the southern end of the study area denoted by R-monuments 79a and 80. The southern end of the island is the recipient of materials eroded from the north and transported southward. Sediment accretion can be seen in the increase in elevation of the study area since 2004. This elevation increase spikes in 2015 and 2018.

**Figure 6.** R79a and R80 elevation profiles with respect to NAVD88 of North Captiva Island for 2004 post-Charley through 2018.

Hurricane Charley had the most notable impact on the region denoted by R-monuments 78–79. This is the area that was breached when Hurricane Charley made landfall. Additionally, it is also the region that was most impacted by sediment transport since 2004, recovering in some areas approximately 2.5 m of elevation without the influence of artificial beach recovery.
