Coast Line Erosion - Virginia Beach Fill EarthCache

The Virginia Beach, beach fill occurs on a regular basis. It is the oldest continuous fill program (beginning in 1949) on the East Coast. Every year between 1949 and 2001, Virginia Beach added sand to its resort strip, to attract tourists and protect visitor-serving hotels and businesses. The local government pays for much of the fill program, and it is actually a part of the annual budget. The city's cost for annual maintenance dredging of Rudee Inlet was $394,000 in 2002 (the federal government provides additional funds). In addition, the City owns a cutterhead dredge and has 21 employees working three shifts, seven days per week to maintain safe navigation in Rudee Inlet and to bypass sand to the Resort Beach. With a general south to north littoral transport, approximately 250,000 cubic yards of sand is dredged each year from Rudee Inlet and placed on the Resort Beach.

Dredging barge.

Our modern coastline has been shaped by sea level changes that have been occurring over the past 2 million years as the result of the development and demise of huge ice sheets that covered much of the world's high latitudes. Although these vertical sea level changes had a maximum range of more than 100 meters, the shoreline migrated horizontally up to 200 kilometers in some places. In doing so, important sedimentary deposits accumulated along the shorelines. Along the Atlantic and Gulf Coasts, many were in the form of barrier islands.

The most recent stage of sea level change is also the most important. Up until approximately 20,000 years ago, when glaciers were at their maximum extent, sea level was some 125 meters below its current level, and nearly all of the present-day continental shelf was exposed. As the glaciers melted, all of the water released caused a rapid change in sea level. Between 20,000 and 7,000 years ago, sea level rose at a rate of about one centimeter per year. Although this may seem to be a small rate of increase, it is comparable to the planet's highest modern day rate of sea level rise occurring in the Mississippi Delta area of Louisiana. Beginning about 7,000 years ago, the rate of rise dropped to about two millimeters per year, similar to the present global rate. This permitted barrier islands to form by giving time for waves and currents to accumulate sand along the coastlines.

Also about this time, rising ocean waters began flooding river valleys that were cut through the continental shelf during the low-stand of sea level. These drowned river systems comprise the numerous estuaries along both the Gulf and Atlantic Coasts. The rivers along the coastal plain have carried tremendous volumes of sediment to the coast, much of it sand. The combination of slow sea level rise and wave action with rivers carrying sediment to the coast has produced a huge volume of sediment along the coastal zone. Much of this sand has been molded into the beaches and barrier islands that extend along most of the Atlantic and Gulf Coasts. Dams and river dredging have caused a substantial reduction in the volume of sediment delivered to the coast. The reduction in sediment supply to the coast, along with a rising sea level, has resulted in extensive erosion along the modern beaches.

Data compiled from surfrider.org and csc.noaa.gov.

To log this cache you will need to do ALL of the following.

• During high tide measure the distance between the center yellow line of the bike path (as seen in picture) and the shoreline due East. Please post the distance you have come up with. Distances will be compiled and we will see if the position of the coastline changes over time. Please note the variance in you GPS accuracy.
• Take a picture of your GPS/caching party at the above coordinates of the inlet.
• Attempt to locate the dredging barge at the inlet. It does move around so do your best to find it. You can still claim this cache without seeing the barge since it really could be anywhere in the inlet.
• Locate the output pipe. It's near (north on the beach) the posted coordinates on the beach. Send me the coordinates of this location. Please do not post the coordinates.