Maddie

Figure 7: Individual beach profiles 1-7 from Location 2 in Guana Reserve Middle Beach dated from November 9, 2020 to March 24, 2021 with linear trendlines shown.

Figure 10: Profiles 7, 13, 15, 16, and 17 from Location 1, 2, 3, 4, and 5 respectively on March 24, 2021. The tidal coefficient on this day was 54.

This project studied five different coastal locations in the north Florida area surrounding Jacksonville, Florida. A solo beach profiling tool was designed and created to track beach profiles over time in these locations.

The differing beach profiles suggest that beaches are not static. None of the profiles are identical in any location which supports the idea of a dynamic beach as a result of sand movement (Figure 6, 8).

At Location 2, the profiles 1, 2, and 3 taken in early winter have steeper slopes than profiles 4 and 5 taken in mid-winter but profiles 6 and 7 taken in early spring were steeper again (Figure 7). At Location 1, profiles 8, 9, 10, and 11 taken in mid-winter followed a similar pattern towards profiles 12 and 13 taken in early spring, like seen in Location 1 (Figure 8). The differences between each profile over time supports the idea of sediment changes on the beach (Figure 6, 8). These similar changes at both locations reinforces this conclusion. The differences in beach profiles in all five locations supports the idea that even on the coast, beaches are not constant (Figure 10). No matter how long the beach itself was on a day, the total level difference never exceeded 5.5 meters (Figure 10).

The City of Jacksonville sponsors beach renourishment projects every five to six years (1). The last major one was conducted in 2017 (1). As noted in Figure 1, Location 4 and 5 both exist in areas that participate in these beach nourishment projects. Additional, smaller beach nourishment projects have occurred in these areas after major storms since—for example, after hurricanes and tropical storms in recent years. The increased need for artificial beach nourishment in these coastal communities is reflected in their general lack of sand dunes. Many commercialized areas on the beach dig out their sand dunes, when in fact these dunes are critical to mitigating storm surges and beach erosion. Dunes protect inland areas yet carry a cultural disbelief in their appeal, at least in urban coastal neighborhoods and commercial areas. Beach nourishment campaigns help beaches that have little sand dunes and/or high erosion repair and be protected by a larger amount of coastal sediment of sand.

In addition to human activity, another factor supporting the idea of a dynamic beach is storm sand movement. As tropical and rain storms happen near the field site, rainfall and wind affect the coast with stronger tides, shifting the level of sand in different areas of the beach. Onshore wind can move the sand on the coast from location to location, and offshore winds can move water away from or towards coastlines. Additionally high and low pressure weather systems can impact the tidal action (can cause higher and lower tides than expected) and therefore impact the shape of the beach profile.

Wave cycles are determined by gravity and there are multiple wave behavior cycles that differ depending on time and location on Earth. For example, there are wave cycles over the course of a day, a week, a year, and even a decade as well as wave cycles which are geographically unique to the coast they border. Sand distribution by waves differs by season because of the tilt of Earth in relation to the bodies which surround it, such as our sun and moon. The longshore current is an ocean current that parallels the shoreline. As waves push against the beach at an angle, sand is transported down the beach in that direction.

This study was intended to better understand the nature of the profile of the beach over time and will be both valuable and interesting to consider how the beach continues to shift as the spring and summer approach, when more conclusive trends in the slope of the beach can be reached in hand with tidal levels. As more and more people choose to live on the coasts, it has become more and more important to understand how weather patterns impact the land and sand they live near. In order to protect our coasts, we need to first understand beach sediment transportation and second learn to balance the needs of our people with the needs of our planet.