erosion and sediment control - faga’alu, american samoa
TRANSCRIPT
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Outline
Introduction and Objectives -
American Samoa -
Stream Sampling -
Land-Based Sources of Pollution -
Impacts -
Environmental Management Practices -
Summary -
Acknowledgements -
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Introduction
• Steven Curtis
• The Pennsylvania State University
• Environmental Meteorology
• National Ocean Service (NOS)
– Fagatele Bay National Marine Sanctuary (FBNMS)
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Introduction
• FBNMS a member of the Governor’s Coral Reef Advisor Group (CRAG)
• Addressed Land-Based Sources of Pollution to mitigate impacts on coral reef within Faga’alu Bay, American Samoa
• Supports NOAA’s objective
• Emily Gaskin (FBNMS) • Lauren Wetzell (AS-CMP) • Phil Wiles (AS-EPA) • Hideyo Hattori (CRAG Lead) • Rocco Tinitali (ASCC)
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American Samoa
• Consists of Five (5) Islands
• Latitude / Longitude: 14.30S 170.70W
• Population: ~60,000
• Capital City: Pago Pago
• Faga’alu Village
http://www.nationsonline.org/map_small/samoa.jpg http://www.infoplease.com/atlas/state/americansamoa.html
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Faga’alu
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Faga’alu
• Population: 1,006
• Rainfall: 155-165 inches / year
• Nestled in valley of Matafao Peak
• Observable impacts from sediment throughout stream and on reef flat
• During heavy rain events, the problem was exacerbated
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Objectives
• Hypothesis: There are statistically significant land-base sources of sediment that affect the stream and coral
• Identify potential land-based sources of pollution
• Statistically significant contributors of sediment to Faga’alu Stream
• Suggest environmental management practices to mitigate impacts on coral reef
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Methods
• Participatory, Learning, and Action (PLA) – Community outreach
– Understand potential land-based sources of sediment
– Educate community and promote environmental stewardship
• Worked with intern at American Samoa Community College to help build local capacity
• Supports NOAA’s objective on “engaging local stakeholders in coastal and marine management planning” while improving “community readiness to cope with natural and human-induced coastal hazards.”
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Methods
• Identify potential land-based sources of sediment
• Utilize YSI Sonde to measure turbidity
• Turbidity – measured in Nephelometric
Turbidity Units (NTU)
– The sensor uses optics to calculate the clarity of the water.
– Often used as an indicator of how much sediment is in the water.
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• Land-Based Sources of Pollution
• LBJ Hospital
• Bridge and Road Construction
• Quarry
• Matafao Landslide
• Nine (9) Sample sites were selected
• Study commenced June 2, 2011
• Two-Hundred Fifteen (215) samples
Sampling Strategy
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Site #9
Site #8
Site #7
Site #6
Site #5
Site #2 & 3
Site #4
Site #1
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• Clean Water Act states turbidity measurements SHOULD NOT exceed FIVE (5) NTU
• Turbidity measurements ranged from 0 – 735 NTU
• One-Hundred Ten (110) out of Two-Hundred Fifteen (215) samples failed ASEPA Standards
Results
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• Statistics
– Descriptive Statistics
– Box-and-Whisker Plots
– Kruskal-Wallis Test
– Mann-Whitney Test
Results
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• Quarry and Construction have the HIGHEST mean and median turbidity measurements
• Sample sites upstream from the quarry have lowest turbidity measurements
Matafao landslide may not be significant source of sediment
Results
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• Kruskal-Wallis Test
– Compares median turbidity measurements between ALL site
• Are sample populations the same or do other factors influence turbidity measurements?
Results
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• Given the Kruskal-Wallis test, with 95% confidence, we can accept the alternative hypothesis that the sample sites have differing median values and do not belong to the same population.
• Suggests that there are factors influencing turbidity measurements
Results
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• Mann-Whitney Test – Similar to a rank-sum test, a non-parametric test to
determine if two samples differ
– Used to determine if two sample sites have statistically different turbidity measurements
– Test utilized to assess whether QUARRY or CONSTRUCTION are statistically significant sources
Results
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Results
Quarry
• With 95% confidence, we can accept the alternative hypothesis that turbidity measurements at the quarry tend to be greater than the turbidity measurement above the quarry
= Quarry is a statistically significant source of sediment
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Results
Construction
• With 95% confidence, we can accept the alternative hypothesis that turbidity measurements at the construction site tend to be greater than the turbidity measurement upstream
= Construction is a statistically significant source of sediment
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Impacts - Construction
• Construction can increase erosion
upwards of 200 times that of vegetated
land (Georgia Soil and Water Conservation Commission)
• Uncovered land increases runoff directly into the stream culvert
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Impacts - Quarry
• Uncovered land increases impacts of erosions
• Other impacts:
• Loss of habitat
• Noise
• Dust and air quality
• Chemical spills and heavy metals
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Impacts – Faga’alu Bay
• Sediment enters the bay continually from the stream
• Settles and destroys coral habitat
• Siltation harms coral and transition from coral dominated to algal dominated community
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Environmental Management Practices
• Riparian zone in need of management practices
• Coastal Vegetation – Vetiver Grass
• Sediment Traps
• Organic Matter Cover
• Silt Fences
http://www.flickr.com/photos/normvanthoff/sets/72157622408840550/detail/ http://midwestboatparty.com/forum/showthread.php?23264-Acreage-Home-Construction-Project
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Environmental Management Practices
• Ideally, in order to be in compliance with American Samoa Environmental Protection Agency protocol, the quarry should move machinery to at least fifty feet from the stream bank.
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Follow-Up
• My research has alerted CRAG and the PNRS Board.
• Beginning enforcement of environmental management practices throughout the island
• PNRS Board reviewing quarry and construction permit
• Quarry and construction representatives asked to conduct Environmental Assessment and make improvements of management practices or permit will be revoked
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Summary
• The QUARRY and CONSTRUCTION are statistically significant sources of land-based pollution
• Steps are being taken throughout community to mitigate impacts of land-based sources of pollution
• Project succeeding in addressing key NOAA mandates from the National Marine Sanctuaries Act, the Coastal Zone Management Act, and the Coral Reef Conservation Act
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Acknowledgements
NOAA Office of Education
Lauren Wetzell (ASCMP)
Emily Gaskin (FBNMS)
Phil Wiles (ASEPA)
Christin Reynolds
(GIS Lead)
Hideyo Hattori (CRAG Lead)
Rocco Tinitali
NOAA
AS-DOC
FBNMS
AS-EPA
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References • American Samoa Department of Commerce.
(2006). Statistical Yearbook 2006. Retrieved 6 29, 2011, from Statistics Division: http://www.spc.int/prism/country/as/ stats/fnl06yrbkhome.pdf
• Craig, P. (2009). Natural History Guide to American Samoa. In P. Craig (Ed.). Pago Pago: National Park Service.
• DiDonato, G. T. (2005). Nitrogen and phosphorus concentrations in tropical Pacific insular streams: historic data from Tutuila, American Samoa. Micronesica , 37 (2), 235-247.
• Georgia Soil and Water Conservation Commission. (2002). Erosion and Sediment Course Manual .
• Hirsch, D. H. (2010, March 23). Statistical Methods in Water Resources. Retrieved July 13, 2011, from USGS: http://pubs.usgs.gov/twri/twri4a3/ht ml/pdf_new.html
• Langer, W. H., & Arbogast, B. F. (1998). Environmental Impacts of Mining Natural Aggregate. In A. G. Fabbri, G. Gaal, & R. B. McCammon (Eds.), Deposit and Geoenvironmental lModels for Resource Exploitation and environmental Security (pp. 151-168). Netherlands: Kluwer Academic Publishers.
• US Environmental Protection Agency. (2010, February 26). Water. Retrieved July 13, 2011, from http://water.epa.gov/lawsregs/lawsgu idance/cwa/tmdl/overview.cfm
• Wong, M. (1996). Analysis of Streamflow Characteristics for Streams on the Island of Tutuila, American Samoa. Honolulu: U.S. Geological Survey.
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Kruskal-Wallis Test
• Null Hypothesis (Ho) = All the sample sites have no variation amongst measurements
• Alternative Hypothesis (Ha) = At least one sample site has a different distribution and the sample comes from different populations.
Degrees of Freedom
Χ20.95(8) K
8 15.51 142.18
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Mann-Whitney Test
• Null Hypothesis (Ho): Turb(Site#6) = Turb(Site#7) The turbidity values measured downstream the quarry are equal to those turbidity values measured above the quarry
• Alternative Hypothesis (Ha): Turb(Site#6) > Turb(Site#7) Turbidity values measured downstream of the quarry tend to be higher than those turbidity values measured at above the quarry
U-value Z-score(0.95)
Converted Z-value
594 1.645 5.87
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Mann-Whitney Test (2nd)
U-value Critical U-Value
25 <25
• Null Hypothesis (Ho): Turb(Site#5)= Turb(Site#7) The turbidity values measured downstream the construction are equal to those turbidity values measured above the quarry
• Alternative Hypothesis (Ha): Turb(Site#5) > Turb(Site#7) Turbidity values measured downstream of the construction tend to be higher than those turbidity values measured at above the quarry