Requirements for logging this cache are simple, send me a note . . .
1. Standing at GZ facing the ocean, what direction are you facing? Do you think beach orientation has an effect on sand erosion?
2. How far away do you estimate the dunes are? Do you think wave action could reach the dunes?
3. What beach warning flag(s) is flying on the lifeguard station to your right? What does that tell you about the wave action?
4. (optional) Post a picture of the beach from GZ. How many beach goers are there? What effect do you think tourism has on the local economy? Anybody playing dog fight football?
Coronado has lost about 81 feet of beach over the last 22 years, and it’s eroding at the fastest rate in San Diego County, according to a report released by the San Diego Association of Governments. The current rate is a loss of 3.8 feet per year for Coronado Beach. The study was done by Sandag, a government funded regional planning organization. The group has been monitoring the sand at numerous County beaches for a number of years. They are currently planning a feasibility study for a $250M third round of sand replenishment projects to slow coastal erosion. Neither of the first two rounds (2001, 2011) included Coronado Beach. Coronado's last sand replenishment project was in 1967.
Shoreline erosion is a natural part of sand cycles driven by winter storms and ocean currents. The problem is compounded by armoring which prevents the natural erosion of coastal cliffs and rocks that creates new sand. According to a 2015 Stanford University report, 80% of the California coastline is actively eroding and one third of the coastline is armored. With regard to Coronado, the Tijuana River Valley is the major source of natural sediment replenishment for the beaches, which flows north or south, depending on the seasonal currents. This source of sand has produced a prodigous amount as the width of the beach (686 feet) is about 3 times the average for San Diego County. The river is also the source of man made pollution, which has caused water quality health alerts on numerous occasions.
Other factors affecting beach erosion include jetties, sea walls, and channel shoaling. If rising sea levels were to continue, that would exacerbate erosion, according to the Scripps Institution of Oceanography.
One of the few defenses a beach has to erosion are sand dunes. The dunes act as a reservoir of sand and a buffer for waves. The dunes at Coronado have ice plant and other vegetation growing on top. I took the picture below from a couple thousand feet above the beach. Can you make out what the letters spell? (Hint: cache name)
