7703

• UCREFRP Catalog Number: 7703
• Author: Pucherelli, M. J. and W. P. Goettlicher.
• Title: Mapping an Instream Habitat on the San Juan River Using Airborne Videography.
• USFW Year: 1992.
• USFW - Doc Type: Washington, D.C.
• Copyright Material: NO

velocity habitat. As an alternative to the more expensive aerial photographs and GIS, airborne
videography is being used.

CONCLUSIONS

This study demonstrates the utility of airborne videography to quantify San Juan River flow to
low velocity habitat relationships.

The data collected for 1991 show a strong relationship between flow and backwater and side
channel habitat. Maximum backwater habitat occurred with flow in the range of 653 to 1,210
cubic feet per second. Maximum side channel habitat was found with flow to be in the range of
2,350 to 4,530 cubic feet per second. A compromise flow derived from these data which would
provide the most of both backwaters and side channels together would be a flow in the range of
1,210 to 2,380 cubic feet per second.

Use of airborne videography is continuing to validate the findings in this report, as well as to
collect data for Navajo Dam test flow operation.

METHODS

Study Site

The entire study site is located on the San Juan River from the Hogback Diversion, 8.7 miles
east of Shiprock, New Mexico, downstream to Mexican Hat, Utah, (see location map on fig. 1).
The Hogback Diversion is located at river mile 158.8 and Mexican Hat, Utah, is at river mile
51.8, giving about 108 river miles total for the study. The study site is divided into three reaches
for this report. These reaches were chosen for three reasons: first, stream gauges are located at
or near the beginnings of the reaches so the riverflow can be specifically characterized for each
reach; second, these reaches tend to be natural breaks for habitat characteristics; and third,
these reaches are also physically easy to identify on the ground and on a map. Reach 1 starts at
the Hogback Diversion and ends at the start of river mile 119, which is at the U.S. highway 160
bridge near the Four Corners Monument. Reach 2 extends from this point to the start of river
mile 68. River mile 68 is located where the river enters the Lime Ridge anticline, which is also
near the confluence with Chinle Creek. The remainder of the study site is Reach 3, which starts
at the beginning of river mile 68 and ends at the start of river mile 52, which is close to the U.S.
Highway No. 163 bridge at Mexican Hat.

Reach 1, the most braided section of the study site, contains the most side channel area and
number of the three reaches. Reach 1 also has the most vegetation, which may account for the
lower amount of backwater habitat compared to Reach 2, where islands are less stabilized.
Reach 2 has a large quantity of side channel as well as backwater habitat. The channel is
narrower in Reach 2 than in Reach 1 as empirically noted by the number of double passes
required for the video to cover the river in Reach 1. Reach 3 is the San Juan Canyon area and

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