Analysis and modeling of erosion hazards and sediment delivery on St. John, U.S. Virgin Islands

374 Pages·1994·10.9 MB·English

by  Anderson, D.M.

ANALYSIS AND MODELING
OF EROSION HAZARDS AND
SEDIMENT DELIVERY ON
JOHN, VIRGIN ISLANDS
ST. U.S.
Donald M. Anderson
NPS/NRWRD/NRTR-94/34
United States Department ofthe Interior • National Park Service

The National Park Service Water Resources Division is responsible for providing water resources
management policy and guidelines, planning, technical assistance, training, and operational support
to units ofthe National Park System. Program areas include water rights, water resources planning,
regulatory guidance and review, hydrology, water quality, watershed management, watershed studies,
and aquatic ecology.
Technical Reports
The National Park Service disseminates the results ofbiological, physical, and social research through
the Natural Resources Technical Report Series. Natural resources inventories and monitoring
activities, scientific literature reviews, bibliographies, and proceedings oftechnical workshops and
conferences are also disseminated through this series.
Mention oftrade names or commercial products does not constitute endorsement or recommendation
for use by the National Park Service.
Copies ofthis report are available from the following:
National Park Service [phone]
Water Resources Division
1201 Oak Ridge Drive, Suite 250
Fort Collins, CO 80525
Technical Information Center [phone]
Denver Service Center
P.O. Box 25287
Denver, CO 80225-0287
NATIONAL PARK
SERVICE
Water
Reeourifee Division
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CoZ&ttfi, Colorado
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11

M.S. THESIS
ANALYSIS AND MODELING OF EROSION HAZARDS
AND SEDIMENT DELIVERY ON
ST. JOHN, U.S. VIRGIN ISLANDS
Donald M. Anderson
Department ofEarth Resources
Colorado State University
Fort Collins, Colorado
Fall 1994
Technical Report NPS/NRWRD/NRTR-94/34
Dr. Lee H. MacDonald, Principal Investigator
Colorado State University
Dr. William Dietrich, Co-Investigator
University ofCalifornia, Berkeley
Funded by
National Park Service
Water Resources Division
CO
Fort Collins, 80525
United States Department ofthe Interior
National Park Service
Washington, D.C.
in
Digitized by the Internet Archive
in 2012 with funding from
LYRASIS Members and Sloan Foundation
http://archive.org/details/analysismodelingOOande
COLORADO STATE UNIVERSITY
July 27, 1994
WE HEREBY RECOMMEND THAT THE THESIS PREP.ARED UNDER
OUR SUPERVISION BY DONALD M. ANDERSON ENTITLED ANALYSIS AND
MODELING OF EROSION HAZARDS AND SEDIMENT DELIVERY ON ST.
JOHN, U.S. VIRGIN ISLANDS BE ACCEPTED AS FULFILLING IN PART
REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE.
Committee on Graduate Work
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ABSTRACT OF THESIS
ANALYSIS AND MODELING
OF EROSION HAZARDS AND SEDIMENT DELIVERY
ON ST. JOHN, U.S. VIRGIN ISLANDS
More than half of St. John island and much of its offshore area is managed as
Virgin Islands National Park by the U.S. National Park Service. St. John is a
popular tourist destination because of its white sand beaches, coral reefs, and
relatively undisturbed tropical forests. Increasing development on St. John has raised
concerns that soil erosion and sediment delivery to the marine environment has
accelerated. Since coral reefs are particularly sensitive to turbidity and fme sediment,
this may be damaging the marine resources that were a primary reason for the
establishment of the Park.
This study was undertaken on behalf of the U.S. Park Service to assess
existing and potential erosion threats on St. John. The primary objectives were: (1)
to identify and map areas of low, medium, and high erosion susceptibility; (2) to
predict rates of sediment delivery to the marine environment; and (3) to recommend
practices to minimize or reduce sediment delivery to the marine environment.
Historic rates of sediment delivery on the island were estimated by
investigating sediment accumulation in depositional areas and erosional characteristics
of upland areas. Present-day erosion and sediment delivery processes were assessed