Geoscience Reference
In-Depth Information
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Figure 17-18.
Two-year continuous record of soil temperature in the beaver mire near Bear Lake, Culebra Range,
south-central Colorado, United States. The record begins in June 2007 and continues until June of 2009. Note that
freezing never occurs at shallow depth in the mire.
A
B
Figure 17-19.
Lower Blue Lake in the Blue-Bear Lakes moraine complex, Cucharas Creek valley, Culebra Range,
south-central Colorado, United States. A. June 2002, a drought year, in which the lake was completely dry and many
forest i res occurred nearby. B. June 2003 with the lake full of water. Note beaver-cut aspen in foreground. These
trees were cut
∼
2 m above the ground, presumably when snow pack was present. Photos by J.S. Aber.
into alluvial fans and sand dunes, and ground
water migrates toward the low point at San Luis
Lake (Fig. 17-21). Abundant ground water gives
rise to many lakes, springs and l owing wells,
and supports considerable irrigation in the
valley. Throughout most of the valley, ground
water is less than 12 feet (3.6 m) below the land
surface (Emery 1971). Irrigation is also carried
out with water diverted from the Rio Grande via
canals (Fig. 17-22), Culebra Creek (see Fig. 11-
20), and other streams. Meanwhile, the state of
Colorado is obligated to supply water south-
ward under terms of the Rio Grande Compact
with New Mexico and Texas (Emery 1971). In
order to do so, ground water is salvaged via
deep wells in the northern portion of the valley
and transported via canal southward to New
Mexico (Fig. 17-23).
The abundance of ground and surface water
gives rise to many wetland habitats, as evi-
denced by Great Sand Dunes National Park and
Preserve, as well as Monte Vista, Alamosa, and
Baca national wildlife refuges, and several state
wildlife areas. Access to a state wildlife area
requires a Colorado Wildlife Habitat Stamp,
funds from which are used to improve and
maintain the wildlife areas. Spring and fall are
migration seasons for vast l ocks of waterfowl,
including some 25,000 sandhill cranes (U.S.
Fish and Wildlife Service 2010b). In fact, a
Crane Festival is held each March in Monte
Vista (Fig. 17-24). Summer is time for shorebird
breeding and nesting, including American
avocet, Wilson's phalarope, white-faced ibis,
and many others (see Fig. 7-22). The modern
abundance and diversity of waterfowl and
