7832

• UCREFRP Catalog Number: 7832
• Author: U.S. Bureau of Reclamation.
• Title: A Pilot For Long-Term Monitoring Of Resources On The Colorado River In The Grand Canyon Using Geographic Information Systems.
• USFW Year: 1995.
• USFW - Doc Type: \
• Copyright Material: NO

REPORT NO.1
USING A GIS TO MONITOR SEDIMENT RESOURCES IN THE
COLORADO RIVER, GRAND CANYON, ARIZONA
M.A. Kaplinski
Northern Arizona University Geography Department
Flagstaff, Arizona
Introduction
A GIS compilation of topographic and photographic data related to sandbars along the Colorado
River in Grand Canyon is being developed at the Northern Arizona University Department of
Geology. Sandbars are a primary natural and recreational resource of the river corridor because
they are the foundation on which the fluvial ecosystem is structured (Bureau of Reclamation,
1994). The sandbar survey studies were designed to monitor the effects of current operating
strategies from GCD (Glen Canyon Dam) on Grand Canyon sandbars. This study involved the
comparison of topographic and bathymetric surveys at 30 sandbars located in each of the 11
geomorphic reaches of the Colorado River corridor (fig. 8). We have evaluated the applicability
of the GCES/GIS (Glen Canyon Environmental Studies/Geographic Information System) as an
analytical tool. The first example involves a sandbar located within GCES/GIS site No. 5, at RM
(river mile) 62.4, that underwent significant changes during winter 1993 flood events. The
second example is a preliminary hypsometric analysis of a subset of the entire sandbar survey
data base.
Methods
The sandbar survey data consist of results from two separate studies of repeated topographic
and bathymetric surveys at 30 sandbars (Beus et al., 1992; Kaplinski et al., 1994a) and daily
photographs collected at 43 camera locations (Dexter et al., 1994). The data base was initially
stored in a variety of DOS-based formats. The original data are exported from the DOS systems,
typically as ASCII text and AutoCAD DXF files, and imported into ARC/INFO format. The daily
photographic data consist of the scanned original oblique images and ERDAS.LAN files of
rectified images, arc coverages of polygons outlining the exposed portion of the sandbar, and
related tabular information. ARCANFO macro programs were developed to automate the
process of converting from DOS-based to UNIX-based ARCANFO format transfer.
State Plane coordinates of the individual site control points located within GIS reaches are
included in the GCES/GIS and were provided by the GCES Survey Division. These coordinates
were used to translate and rotate the survey information from a local coordinate system into the
State Plane coordinate system. Once projected in the State Plane system, the surveys were
overlaid with coverages of the Bureau Of Reclamation 0.5-m river corridor topography (Werth
et al., 1993).
The sandbar survey data consist of up to 17 repeated surveys at each of the 30 sites, which were
collected from June 1990 to April 1994. The analysis presented here includes surveys conducted
during the interim flow period (July 1991 to April 1994). Study sandbars located within GIS site
No. 5 at RM62.4 and RM68.2 were used as pilot studies to develop the methodologies used in
the remaining survey sites. Individual sandbar surveys include coverages of topographic and
bathymetric survey points with elevation and code attributes, arc coverages of boundary and
breakline information used in TIN (triangulated irregular network) model generation, as well
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