ALKALI FLATS

The Alkali flats region is located between Hot Creek to the west and Lake Crowley to the east in Long Valley Caldera (click here to see location). It is a region of small shallow lakes and limited surficial flow of thermal waters. The waters of the lakes support an ecosystem of small brine shimp and water fowl, as well as marsh type vegetation at the edges.



The image above is of a small alkali lake located to the west of Little Alkali Lake. The orange color of the water in the forefront of the image is due to populations of cyanobacterias in the muds of the lake bottom. Below is a spectral profile of the lake waters in the vicinity of this photograph. The spectra has been extracted from a 1992 AVIRIS image and is corrected to reflectance using ATREM.


The next plot is a spectra of cyanobacterias taken from Hot Creek waters using a handheld spectroradiometer. Included, is a spectra of a nettle plant to illustrate the fundamental differences in spectral geometry between bacterias and green vegetation. The cyanobacteria is in white, while the nettle is in red.

The spectra extracted from AVIRIS data of the alkali lakes resemble the spectra of cyanobacterias taken in Hot Creek located to the west.


The image below is of Little Alkali Lake looking to the SE. The color of this lake is not orange, but instead a pink color. More green vegetation grows in its waters. It is a larger body of water than the lake pictured above. Perhaps the waters of Little Alkali lake are more dilute and therefore don't support the dense bacteria populations as the previous lake does. Another possibility is that this lake posesses different kinds of bacteria than Big Alkali Lake.



Below is a classification of only bacteria/algae laden sediments/waters in the Alkali Lakes region from 5m HyMap data. North is to the left. The spectra used in this classification follow the image at the bottom. Following this is a directed color composite RGB image singling out the bacteria in red/majenta/maroon colors. This was accomplished by isolating a particular absorption feature that might be unique to bacteria. It's centered around 1.23um or Band 54.







This line is just to the north. Keep in mind that this image is rotated 180 degrees from the previous. The pink lake is the same one that pink was showing up in the previous line for reference. Little Hot Creek is the feature at the top of the image. The wierd (incorrectly spelled) water spectra is not classified in the image, but I found this particular spectra in the center of the mostly yellow classified lake. I have absolutely no idea...