FLOOD08081

• County: Statewide
• Basin: Statewide
• Title: Groundwater in Colorado: A Primer
• Date: 10/1/2002
• Prepared For: State of Colorado
• Prepared By: Rock Talk
• Floodplain - Doc Type: Educational/Technical/Reference Information

Introduction
11. .CO.l orado Geological Sur-
. vey, along with consulting
partners, has recently com-
peteg. for and won a grant
from NA~A to apply remote-sens-
ing technology to geology related
water-quality impacts in the upper
Arkansas River basin. This is
CGS's first NASA grant and it
highlights the growing use of
remote-sensing data in geological
applications. The project's formal
title is hDetermining Contribution
of Natural and Anthropogenic
Acidic and I or Metalliferous
Sources to Contamination of the
Upper Arkansas River Watershedh
(NASA grant NAG13-02026). Part-
ners on the project are Peters Geo-
sciences, Spectral International,
Hendco Services, and the Colorado
Mountain College in Leadville.
The project will use hyperspec-
tral remote sensing to identify
sources of metals and acidity in

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selected portions of the watershed
in Lake County and northern Chaf-
fee County. Hyperspectral sensors
can hseeh the mineralogy of
exposed rock and identify types of
mineralogy that, through interac-
tion with surface runoff and
ground water, can adversely affect
water quality within a watershed.
Both natural and mining-related
sources will be examined and relat-
ed to changes in downstream
water quality.
Hyperspectral remote sensing
allows specific mineral types to be
identified by recording light (i.e.
electromagnetic energy) reflected
from the Earth's surface. Just as
minerals reflect different colors,
they also reflect differently in parts
of the electromagnetic spectrum
beyond the visible range. A hyper-
spectral sensor records data from
the visible (400-700 nanometers,
nm), near infrared (700--1300 nm),
and short-wave infrared (1300-2500

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Visible

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nm) portions of the electromagnet-
ic spectrum (see graph) in specific
wavelengths important in identify-
ing and differentiating minerals.
For years, this technology has been
used to find mineral deposits for
economic development, but its use
as a tool in environmental charac-
terization has been more recent.

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Relation
to Earlier Work
"'I""he project builds on recent
. work by CGS (Open-File
Report 00-16, future Bulletin 54)
that identifies several areas of nat-
ural acid rock drainage associated
with hydrothermally altered rocks
in Colorado, areas that are com-
monly characterized by acidic
streams with high concentrations
of metals. Hydrothermal alteration
is a process whereby hot water cir-
culating within the earth changes
the composition ofrocks. Com-
monly pyrite (iron sulfide) is
_emplaced in the rocks, which can
lead to acid rock drainage (see
RockTalk Vol. 3, No.2, April 2000 -
for a more complete discussion of
hydrothermal alteration and acid
rock drainage.)
The Grizzly Peak Caldera
(Oligocene), one of the areas
exhibiting natural acid rock
drainage is within the project
study area. The caldera lies south
of Independence Passin the head-
waters of Lake Cleek, a major trib-
utary to the upper Arkansas River.
The NASA grant will allow us to
look at this area in greater detail
and test the usefuiness of current
remote sensing technology for
identification of natural and
anthropogenic influences on the
environment.

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Colorado Geolog;ca1 Survey /lOCf(TAlJ(Vol. 5, No.4

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