Geoscience Reference
In-Depth Information
Figure 16-9.
Satellite image of Dry Lake vicinity. Dry Lake occupies an enclosed drainage basin between Pawnee
Mound and a tract of sand hills. Local relief ranges from
>
910 m elevation at Pawnee Mound to
<
870 m around Dry
Lake. Dark circles represent irrigated crops during a drought year. Landsat TM band 7 (mid-infrared); 15 August
2011. Image from NASA; processing by J.S. Aber.
or a combination of these processes (Merriam
2011). Dry Lake, near Garden City, is one such
example (Fig. 16-9). Dry Lake occupies a former
stream valley that trended from west to east. The
western drainage was cut off, presumably by
movement of buried faults that uplifted the
Pawnee Mound ridge. These faults may be asso-
ciated with the Bear Creek and Crooked Creek
fault zones of southwestern Kansas, which are
collapse structures formed by subsurface salt
solution (Miller and Appel 1997). The Dry Lake
basin is separated from another unnamed basin
to the east by a low barrier of sand dunes blown
northward from nearby sand hills.
Long-term average annual precipitation in
the vicinity of Dry Lake is approximately 50 cm
(
carbonate and sodium-halide salts around the
margin to high-salinity bitter (potassium-halide)
salts toward the center of the basin. Even when
dry, saline ground water remains just below the
surface (see Fig. 5-8). Dry Lake, thus, represents
a salina or salada wetland habitat. When it con-
tains water, migrating shorebirds and waterfowl
may be seen in abundance.
16.2.2 Biocontrol of saltcedar along the
upper Arkansas River valley
Saltcedar is a shrub or small tree that is native
to Asia, the southern Mediterranean, and north-
ern Africa. It comprises several species within
the genus
Tamarix
that were introduced in the
United States beginning in 1823 (DeLoach 2004).
During the Dust Bowl of the 1930s, saltcedar
was planted widely for windbreaks and to
control stream erosion in the Great Plains and
western United States. Since then, however, salt-
cedar has spread rapidly, becoming an invasive
plant throughout arid and semiarid portions of
the western United States (see Fig. 6-7) and
northern Mexico, where it is responsible for a
major ecological disaster (DeLoach et al. 2007).
∼
20 inches), but individual years range from
more than 90 cm to less than 25 cm precipitation
(High Plains Regional Climate Center 2011).
Given the semi-arid climate, highly variable pre-
cipitation, and relatively small size of its drain-
age basin, Dry Lake undergoes conspicuous
changes annually and seasonally from full of
water, which is a rare event, to completely
dry, which is common (Fig. 16-10). When dry,
the salt l at grades from low-salinity calcium-
