The Maine Shore and the Army Corps:

Joseph T. Kelley and Walter A. AndersonGE254

Don Whitcraft

Wells and Saco harborsBoth are summer tourist destinations as well

as commercial harbors.Army Corps of Engineers initially called in to

improve commercial navigation. The USACOE built a jetty perpendicular to the coast so that sediment would not get deposited at the delta.

Outdated single-minded engineering practices have consequences on beaches. In image on next slide. North Beach is retreating rapidly due to erosion.

The problem faced today is of our own doing.Beachfront properties at risk of being lost to

the ocean in Maine.

Jetties at Camp Ellis extend 2 km to sea, and were put in place to make navigation into Saco Harbor easier. (image from Google Earth)

Beach DynamicsCoastal processes of erosion and deposition

require waves.Waves are driven by wind.Winds and waves are greatest in storms.

Erosion is prevalent at these times.The beach responds at different rates. E.g.

digging a hole in the beach, build a jetty, will have different impacts.

Human interference with a specific point can have widespread consequences.

Longshore Drift (LD)Is the movement of particles along a beach.LD caused by waves approaching beach at angle.Sand moves up and down the beach from the

swash and backwash of the wave.LD is the primary reason for erosion at Wells and

Saco, sand constantly moving.

Camp Ellis, Saco Saco River is a large river (originates in the White Mountains) exits

at Saco Bay at a small delta. Saco Beach is one of the largest beaches in Maine. European visitors struggled with navigating past tidal deltas into

Saco. Engineers erected a rock jetty to the north which blocks movement

of beach sand Believed sand was moving from N-S Jetty extended to sea 1280 m then to 2000 m Analysed Benefit/Cost ratio. This determines if they build anything. If

the ratio is greater than 1, then the cost of building is worth it. Sand continued to clog channel dredged Camp Ellis beach initially moved forward, then began to retreat Sea claimed houses and roads Study concluded that sand for the beach originated from Saco River 6 million m3 of beach lost. USACOE dredged the harbor – place sand at Camp Ellis

SacoUSACOE rejected the idea that they did

anything wrong.It took a long time before they even

recognized a problem.Solution to Erosion: build a breakwater

parallel to coast, 914 m long. Benefit/ cost ratio was calculated as 0.2 - not worth it.

Wells Harbor Lies between Wells beach and Drakes

Island beach, separated by Webhannet river.

Anchorage was choked with salt marshes. Sand deposited formed a flood-tidal delta.

The jetties were built to accomodate larger fishing boats into the harbor.

Army Corps was requested to build a small boat anchorage at the river mouth.

Built 2 jetties > 200 m long Sand built up between the jetties &

in harbor Ceaseless channel-dredging between

jetties for boats to travel into the harbor.

Here is me standing on one of these jetties during Thanksgiving.

At Drakes Island Beach and on Wells Beach there is deposition next to the Jetty, while other parts of the beach are eroding. A lot of the deposited sand gets tied up in dunes.

Sediment transferSand began to collect adjacent to the jetties.Wind blew deposited sand into dunes farther

inland.This causes a loss of beach sand, as more of

it gets tied up in dunes.Property falls into the ocean, when erosion is

dominant. This occurs during a storm event.

ConclusionCommerce in Saco, recreation in Wells. On one hand the

jetties are needed for fishing, a major source of income for Maine. But at the same time, each summer copious numbers of tourists flock to the beaches in Maine. What would happen if the beaches are completely eroded? Which is more important?

Economic consideration: fishing and tourismEnvironmental concern: wildlife habitatBeach erosion continues. $2.6 Million in flood damageEngineering failures of the 19th century are excusable, but

the same mistakes were made up to the 1980s- inexcusable.

The local communities are getting annoyed at the Engineers, but it is wishful thinking that there would be no problem resulting from modification of the natural system.