Newport Beach/Santa Ana Rivermouth Beach Profile Study - A comparison of the summer and winter beach profiles of a high traffic area

of beach containing semi-natural dunes. Background: There are many forces affecting the sand beaches that surround the Santa Ana rivermouth. These forces include a reduction of sediment flowing downriver from the mountains due to dams and reservoirs, the constant longshore drift that tends to move sand southward, natural coastal erosion, homes built within a hundred meters of the high tide waterline, and the constant intrusive forces by humans like groins, sand grooming, sand replenishment and dune rehabilitation. All of these affect the profile of the beaches year after year.

Figure B: The Santa Ana River Mouth aerial view

Significant and constant change in beaches is a geological fact. Coasts are meant to erode and fall prey to the forces of wind and water that are always acting on them. However, due to the fact that we have built communities and the economic basis of our local cities on having pristine, visitable, and unchanging beaches means that we need to slow or halt this natural process of change. There are many ways in which this has been attempted at this particular stretch of beach.

Study aims and objectives: The aim of this study is to compare the summer profile of a local beach to its winter profile. This is one of the few area beaches that has been enabled to retain (in part) its dune character making it a better indicator of natural conditions. In the analysis, several contributing factors will be considered including human impacts, storm activity and rainfall. The eventual aim is to create a longitudinal profile of the changes in this area.

Study Methods: Students will use the Emery Beach profile method with 2 x 2-m marked poles with horizon eyeholes and a 5-m line with a bubble line level. Markings will be made every 2 meters on sand pack that is quickly changing elevation and every 5 meters once fairly level beach has been reached. Data/Analysis: Students will first share their elevation and distance data for both the summer and winter profiling studies on a google document. They will then graph the elevation and distance data on 2 separate 3 dimensional bar graphs in excel. One graph will be the summer profile data and the second will be the winter profiling data.

Students will research and record and human impacts (dredging, pumping sand onto the beach, building of jetties, groins or other structures) that have occurred within the calendar year prior to the profiling study.

Students will research and record the natural phenomena (storm/high surf events including swell size and direction, significant precipitation events responsible for bringing sediment from the river) that have occurred within the calendar month prior to the profiling study.

Any images that were taken at the time of profiling should be included and captioned appropriately.

[for the years 2015 and following]: Students will record the range and the average of grain sizes found at the back dune, fore dune and berm area of the beach profile.

Students will make a comparison of the summer vs winter profiles. What is different? What is the same?

Discussion: The following questions should be considered in writing the discussion section of this paper.1. What are the direction of the longshore currents throughout the year? How do they change and how do they affect sand deposition?2. How have the human created solutions to loss of sand and sediment benefited and harmed the beaches?3. Based upon your understanding of timing of the addition of sand through dredging and pumping, is this a reasonable solution to beach erosion?4. What differences are their in human (and canine) beach traffic from summer to winter? How might this affect the dunes?5. What (if any) events of note may have impacted the summer and winter beach profiles?6. What would your recommendations be for solving the beach erosion issue long term?