San Antonio River Valley Changes Over Time: Analysis and Implications
Situation:
The city of San Antonio is located in a unique ecological area. The Edwards Plateau, Oak Woods and Tallgrass Prairie, and Tamaulipan Thornscrub ecosystems meet in the city. The conjunction of this variety of ecosystems plus the presence of numerous streams and associated riparian vegetation offer support for a diversity of plants, animals, and ecological environments that characterize the San Antonio River Valley.
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Much of the land area in and around the San Antonio National Park is referred to as "disturbed lands," or land areas that have been human engineered for human habitat functions. For example, in the vicinity of the park, the San Antonio River was channelized to assist with flood protection in the late 1950s. Many of the currently plowed fields and old fields (succeeding to huisache tree uplands) are located where historic labores (fields) were tended during Spanish colonial times. And, areas where the historic acequiasare located were at one time dry scrublands. Today, because of the presence of water, thick riparian vegetation with tall trees have replaced scrubland habitat in those areas.
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Image (at left) show
s the Espada Aquiduct.
Since its cr
eation in 1978, the park has acquired many acres of property to restore the landscape and protect the cultural resources. Much of this land was occupied by modern homesteads in various stages of use and was heavily disturbed. The park has restored most of the areas acquired by removing buildings and debris. This is done to recreate the appearance of the landscape during the Spanish colonial period and for health and safety purposes.

Resources

San Antonio River Authority - Bexar Flood Map

San Antonio River Authority - Initiatives:
San Antonio River Foundation - Making Our River Beautiful From North to South

USGS - Water Resources of the United States: This website provides access to regional data for eight types of water resource topics.

Global Change Master Directory: Discover Earth Science data and services: gcmd.nasa.gov

CEOS Climate Diagnostics: http://idn.ceos.org

Global Climate Change: Key Indicators
This site includes interactive data sets and animations that demonstrate evidence of global climate changes. PDF file gives step-by-step instructions for ways to use NASA’s Global Climate Change Websites.

ClimProb: Web Based Climate Analysis for the Continental US
Entry ID: 01-ClimProb-99

Psychology & Global Climate Change
addressing a multifaceted phenomenon and set of challenges: A Report of the American Psychological Association Task Force on the Interface Between
Psychology and Global Climate Change
Link to Animation of U.S. Stream Flow Maps
From NASA Earth Observatory
external image Texas_floods.TMO2002189.jpgSoutheast of San Antonio, Texas, rivers that were barely discernible in satellite imagery acquired in late June 2002 stand out clearly in images from early July 2002. Heavy rains during the first week of July brought as much as 2 feet of rain to some places in southeastern Texas, and this pair of images from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra satellite shows the result: massive flooding of three major river systems along the Gulf of Mexico.

From Present Hydrogeology of the Edwards Aquifer by Gregg EckhardtAfter the Buda and Eagle Ford groups of limestones were deposited on top of the Edwards formation, the Tertiary and Quaternary periods of the Cenozoic era (beginning about 70

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million years ago) saw the rejuvenation of the Rocky mountains by activi
ty of tectonic plates colliding and overriding. During this time millions of tons of sediments were being deposited by wind and water across Texas. The thickness of these sediments increases towards the coast, and their tremendous weight caused a series of parallel faults to form between the Edwards Plateau and the Gulf. The limestone layers that had been laid down flat became tilted, forming narrow bands at the surface. This is the geology we have at present (see Figure 4 below). The Edwards limestone is between 300-700 feet thick, outcrops at the surface in a narrow band, is tilted downward toward the south and east, and is overlain by younger limestone layers and thousands of feet of sediments. Figure 4 is a cutaway view of the Edwards Group near San Antonio. Note how t
he Edwards limestone outcrops at the surface north and west of San Antonio and then plunges deep under the city toward the south and east.


Image (below) from: The San Antonio River Valley**:** Native American Uses and European Discovery
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external image aep-txs18.jpgWhat plants and other environmental features have changed over the last 200 years? Here is a photo of the botanical scientific name: Carya illinoinensis
botanical common name: Pecan
which was common in the Bexar County area between 1891 and 1934.