Lesson Title: San Antonio River Valley Changes Over Time: Analysis and Implications
Grade Level: 11-12 grades
Subject: Environmental Science, Earth Science
Author/s: Laurie Ruberg, Ph.D., WJU; Colleen Quirk, San Antonio Missions National Park
Email: lruberg@cet.edu
(Adapted from Missions Education Committee, San Antonio Missions National Historical Park: A Guidebook, San Antonio Junior League of San Antonio, 1986)
(Adapted from Missions Education Committee, San Antonio Missions National Historical Park: A Guidebook, San Antonio Junior League of San Antonio, 1986)

Situation
The city of San Antonio is located in a unique ecological area that includes three different types of ecosystems. 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.

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. The process of human engineering of the land and water in the San Antonio River Valley dates back to two Spanish missionary settlements between 1718 and 1720, and the Spanish added three new missions in the valley in 1731.

San Antonio Missions National Historical Park
San Antonio Missions National Historical Park
Mission settlements of the southwestern frontier have had significant and far-reaching effects on the development of the United States. The missions were directly involved in the governing policies, military, religious, and cultural development of the Texas frontier. The contribution of the missions to agriculture, cattle industry, and commerce greatly influenced the growth of the state of Texas and the San Antonio region. The mission buildings constitute a unique record of the architecture, art, and sculpture of the Spanish colonial period in Texas.

Espada Aqueduct and Acequia
Espada Aqueduct and Acequia
The dry climate of southwest Texas made irrigation crucial for growing crops that life in the early missions required. In the missions developed in eastern and southern Texas, the Spanish settlers applied their knowledge of acequias (ah-SAY-key-ahs), a system of ditches that the Moslems had introduced to Spain. Missionaries and Indians built seven gravity-flow ditches, five dams, and an aqueduct in order to distribute water from the San Antonio River over a 15-mile network that covered 3,500 acres of land. (Photo credit (image at right): San Antonio Missions Historical Park)

Human reconfiguring of the land continued through the 1950's when, for example, in the vicinity of the park, the San Antonio River was channelized to assist with flood protection. Today, human engineering of this San Antonio River Valley continues and is necessary to provide water to support the growing San Antonio population. Human changes to the historic San Antonio missions area has been underway since the creation of the National Park in 1978 to support historic preservation of the area. 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. 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 acequias are 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.
Key Concepts Addressed

Earth Systems Science concepts:
  • The interacting components of Earth's system change by both natural and human-influenced processes. Natural processes include hazards such as flooding, earthquakes, volcanoes, hurricanes, meteorite impacts, and climate change. Human-influenced processes include pollution and nonsustainable use of Earth's natural resources that may damage Earth's system.
  • Topics include climate change, soil erosion, air and water pollution, and biodiversity loss. The time scale of these changes and their impact on human society must be understood to make wise decisions concerning the use of the land, water, air, and natural resources. Proper stewardship of Earth will prevent unnecessary degradation and destruction of Earth's subsystems and diminish detrimental impacts to individuals and society.

Skills:
Obtain, interpret, and analyze changes over time using a various types of satellite imagery of the Earth.


This image, from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, compares plant health between April 7 and April 14 to average conditions seen between 2000 and 2010.  Satellite sensors measured the amount of leafy green plant matter at the surface. Brown colors depict places where plants were less leafy or more sparse than normal, while better-than-normal conditions are green. In mid-April, plants throughout the state showed clear signals of drought stress.
This image, from the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite, compares plant health between April 7 and April 14 to average conditions seen between 2000 and 2010. Satellite sensors measured the amount of leafy green plant matter at the surface. Brown colors depict places where plants were less leafy or more sparse than normal, while better-than-normal conditions are green. In mid-April, plants throughout the state showed clear signals of drought stress.

Task
In 2011, higher than normal temperatures and dry vegetation combined with high winds and low humidity to create extremely dangerous fire conditions in Texas. Are the summer of 2011 draught conditions a consequence of global climate changes, or a weather anomaly for this area? Develop a historical narrative that describes the climate patterns for San Antonio River and immediate surrounding areas. Include an Earth Systems Science analysis that examines the surface sea temperatures and ground surface temperatures as climate change factors possibly impacting climate conditions in this areas. Use the evidence you collect to project the consequences of these climate factors and how they would cause ecology and environmental changes from this time forward.

The Park Service is interested in your analysis of data available from NASA and other scientifically valid sources. Your results may suggest how climate change indicators and prediction models are useful to explain changes in historic, present, and future San Antonio water capacity models. Using the results (causes and the consequences) of your ESS analysis, the National Park Service is interested in the implications of your research as it applies to ecological areas beyond the park to other local, regional, and the nation as a whole.
Start-up investigations

San Antonio Missions: Spanish Influence in Texas
(Historical Context)

Investigating Factors that Influence Climate
- employs inquiry methods to investigate how latitude and longitude (and distance from oceans) impact climatic factors such as temperature range, average temperature, and precipitation.
(Hydrosphere)

Drought and Heat Create Hazardous Fire Conditions in Texas- Uses satellite data from NASA Terra - MODIS satellite.
(Lithosphere)

Drought in Texas - Satellite sensors measured the amount of leafy green plant matter at the surface. Brown colors depict places where plants were less leafy or more sparse than normal, while better-than-normal conditions are green. In mid-April, plants throughout the state showed clear signals of drought stress.
(Biosphere)
Prior Knowledge, Learning Objectives, Skills Required
Standards Targeted

National Standards:
  • Geography: The World in Spatial Terms
  • Math: Data Analysis and Probability
  • Science Content: A Science as Inquiry
AP Environmental Science Topics
  • Climate shifts
  • Latitude
  • Major terrestrial and aquatic biomes


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Resources
A Student's Guide To Global Climate Change

Implementation
Student Assignments
Assessment and Evaluation
Rubrics

Teacher Guides for Student Assignments
Teacher Reflections, Portfolios, and Sharing

Background and Relevance for Students: Why should it matter to you if your regional climate is changing? Two of the indicators of climate change that scientists study are land and water surface temperatures, which are monitored at various locations around the globe. Analysis of these world-wide temperatures show that the global average temperature has been increasing for many years. This trend is called global warming. Climate science modeling systems show that rising global temperatures may to lead to other changes around the world, such as stronger hurricanes, melting glaciers, increased areas of drought, and the loss of wildlife habitats. That's because the Earth's air, water, and land are all related to one another and to the climate. This means a change in one geographic location can lead to other changes somewhere else. Most important for making climate changes relevant to you is the research by meteorological hydrologists that shows rising sea surface temperatures in the North Atlantic are likely a major driver of recent and century-long weather patterns including droughts in the Great Plains and the southwest North America.