Activity #33
Reflection Questions
Question #1
• Describe how each of the landforms below
contribute sediments to the Town Beach in
Boomtown.
• Seaside Cliff – Seaside cliff is located above
and just to the north of the Town Beach.
When erosion moves sediments off of the cliff,
they fall down to the beach area, adding
material to the beach.
• Delta Wetlands – The Delta Wetlands feeds
sediments directly from the Rolling River to
the Town Beach. Since the beach is north of
the mouth of the river, it is likely that the
shoreline cureent runs south to north.
• Green Hill – Sediments that are eroded from
Green Hill are washed into the Rolling River
and then transported to the beach.
• Rolling River – The Rolling River transports the
sand and sediments from Green Hill and
beyond to the ocean, where they make up the
beach.
Question #2
• The constructive force of deposition is greater
than the destructive force of erosion. The
evidence for this is that the topographical
maps show that the coastline at the Delta
Wetlands is moving towards the ocean,
indicating that the sediments from the Rolling
River are building up faster than the ocean
waves can erode them.
Question #4
• Deposition can be controlled by jetties. A
jetty has the advantage of holding back the
sand being transported in a longshore current
and preventing it from being deposited in and
undesirable location, such as a harbor. A
disadvantae, however, is that the other side of
the jetty tends to erode more than if the jetty
were not there.
• Erosion can be controlled by breakwaters. A
breakwater has the advantage of reducing
erosion on the shoreline. It has the
disadvantage of increasing the amount of
deposition between the breakwater and the
shoreline.
Method
Advantages
Disadvantages
Dredging
Removes unwanted sand
Hard work, expensive
Opens up silted areas, such Deposition can return
as channels and harbors
Sediments can be
contaminated
Can destabilize the land
Jetty
Easy to build
Keeps harbors from filling
in
Accelerates erosion on the
other side of it
Eventually sand may have
to be moved if too much
builds up
Breakwater
Slows down erosion of
cliffs and beaches
Increases deposition of
sand between breakwaters
and shore
Seawall (riprap)
Can be easy to build
Reduces rate of erosion
More erosion around the
sides of the wall.