Colby College Digital Commons @ Colby Undergraduate Research Symposium Student Research 2006 Variation in Beach Profile and Sediment Characteristics at Popham Beach, Phippsburg, ME Kathryn Lidington Colby College Follow this and additional works at: http://digitalcommons.colby.edu/ugrs Part of the Biology Commons Recommended Citation Lidington, Kathryn, "Variation in Beach Profile and Sediment Characteristics at Popham Beach, Phippsburg, ME" (2006). Undergraduate Research Symposium. Paper 25. http://digitalcommons.colby.edu/ugrs/25 This Article is brought to you for free and open access by the Student Research at Digital Commons @ Colby. It has been accepted for inclusion in Undergraduate Research Symposium by an authorized administrator of Digital Commons @ Colby. For more information, please contact mfkelly@colby.edu.
Variation in Beach Profiles and Sediment Characteristics at Popham Beach, Phippsburg, ME By Kathryn Lidington
Outline: An introduction to beach systems An overview of Popham Beach Field work Beach profile and grain size analysis results X-ray diffraction results Conclusions
Defined as an accumulation of unconsolidated sediment situated at a boundary between land and a large expanse of water Affected by waves, winds, storms, currents, and tides Beach Systems
Beach Sediments A sediment source is required for the development of a beach: Fluvial sediments Erosion along the foreshore Seafloor sediments Marine organisms Wind-blown sand Human activities
Waves Formed by winds both locally and far offshore Move sand both to shore and offshore Three breaker types: Spilling Plunging Surging
Wave Refraction Waves are subject to refraction as they enter shallower depths Longshore drift occurs when they hit the beach at an angle
Winds Wind transports sediment by: -creep -saltation -suspension Amount of sand transported directly related to the velocity of the wind Winds also cause the formation of dunes
Storms Even extreme storms do not cause permanent shoreline retreat But a rapid succession of storms can result in significant erosion
Spring tides higher than normal tides, occur when the earth, moon, and sun are aligned Neap tides lower than normal tides, occur when the sun and moon are at right angles to one another Tides
Tide Categories Based on their spring tidal ranges, coasts may be: microtidal: < 2 meter range mesotidal: 2-4 meter range macrotidal: > 4 meter range
Currents Rip currents Longshore currents Nearshore currents may also be caused by: tides rivers estuarine circulation
Located in Phippsburg, ME, at the mouth of the Kennebec River 3640 meters long with an area of 138 hectares Popham Beach
Sediment: Major source is the Kennebec River Sand is easily eroded Heavy mineral sands Tides: 3-4 meter range: mesotidal Storms: Nor easters Popham:
Human Impact Lightly developed: no jetties, seawalls, or breakwaters But there are roads, footpaths through the dunes, and houses
Four transects measured over seven dates from September 25 to December 4 Beach profile was measured Sand samples were taken at the water line Field Work
Site 1 Little significant change Net loss of sand 0.5 0 0 5 10 15 20 25 30 35-0.5-1 -1.5-2 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4-2.5-3 -3.5
Site 1 Grain Size Analysis 70 60 50 40 30 20 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4 10 0 1 mm 710 micro 500 355 250 180 125 90 63
Site 2 Stable profile 0 0 5 10 15 20 25 30 35 40-0.5-1 -1.5-2 -2.5 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4-3 -3.5
Site 2 Grain Size Analysis 80 70 60 50 40 30 20 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4 10 0 1 mm 710 micro 500 355 250 180 125 90 63
Site 3 Beach scarps present on Sept. 25 and Oct. 1 were buried by a large influx of sediment 0 0 5 10 15 20 25 30-0.5-1 -1.5-2 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4-2.5-3
Wave Scarps
Site 3 Grain Size Analysis Site 3 Grain Size 80 70 60 50 40 30 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4 20 10 0 1 mm 710 micr o 500 355 250 180 125 90 63 Gr ain size
Site 4 Net erosion, but a large amount of deposition along the dunes from Oct. 22 to Oct. 30 Site 4 Beach Profile 0.5 0 0 10 20 30 40 50 60 70 80-0.5-1 -1.5-2 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4-2.5-3 -3.5 Distance f r om tr ansit (m)
Large Deposition of Sand at Site 4
Sandbar Located South of Site 4
Site 4 Grain Size Analysis 70 60 50 40 30 20 Sept. 25 Oct. 1 Oct. 22 Oct. 30 Nov. 6 Nov. 13 Dec. 4 10 0 1 mm 710 micro 500 355 250 180 125 90 63
X-Ray Diffraction Results The garnet sand contained quartz, garnet (variety pyrope), actinolite and hornblende. Minerals not stable in beach environments indicate that the sand is immature Sand collected at Site 2 on Oct. 30 and Dec. 4 consisted of quartz and minor albite, A more mature sand
Conclusions: Winter profile: higher energy levels coarser grain sizes steep beach profiles Summer profile: finer grain sizes more gradual beach slopes But Popham Beach did not show this change
High rainfall increased the Kennebec River discharge and caused an extremely large influx of sediment
Sources http://whyfiles.larc.nasa.gov/text/kids/problem_b oard/problems/sound/sound_waves2.html http://www.csc.noaa.gov/text/glossary.html http://www.about.com/library/bl/maps/blmainesur fmap.htm http://www.topozone.com/map.asp?lat=43.75194 &lon=- 69.785&s=50&layer=DRG25&size=l&u=2 http://www.maine.gov/dep/blwq/topic/dunes/ Thank you to Meredith Lowmaster, Katie Packard, and Dr. Bob Nelson