Joseph T. Kelley and Walter A. Anderson GE254 Don Whitcraft

Wells and Saco harbors Both 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 Outdated single-minded engineering practices have consequences on beaches.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 Dynamics Coastal 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 m 3 of beach lost. USACOE dredged the harbor – place sand at Camp Ellis

Saco USACOE 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 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 transfer Sand 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.

Conclusion Commerce 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 tourism Environmental concern: wildlife habitat Beach erosion continues. $2.6 Million in flood damage Engineering failures of the 19 th 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.