A Model of the Middle Rio Grande Valley
River of Change: Base Activity for the Middle Rio Grande Valley
Description: In a directed class activity, students build a model of a section of the Rio Grande Valley as it was before major human intervention, and then manipulate it to demonstrate today's river. In working with today's river, the students contrast the differences between managing the river for only human benefits and managing the river with broader objectives including ecosystem health and human needs.
Objective: To understand:
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the differences and similarities of the way the river was (Rio Bravo);
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the way the river has been significantly altered by humans in the last century (Rio Manso); and
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the way the river can be managed to support a healthy ecosystem (Rio Nuevo).
Time:
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Preparation: about 30 minutes
- Activity: minimum of one hour
- Activity can be paired with others and can take many class periods
Background: This activity builds a model of a section of the Middle Rio Grande Valley. Models are tools that help us understand complex systems by simplifying their components. We use models to help demonstrate ideas that are not as easy to grasp when working with a real ecosystem.
One way to understand the relationship of the bosque to the Rio Grande is to think about the Rio Grande as "different rivers" depending on time. Long ago, the Rio Grande functioned much differently than it does today. Although people have used the river's water for irrigation for probably thousands of years, they did not start harnessing the river water behind large dams or changing the river's natural hydrological functions until this past century. In the model we call this old river Rio Bravo, which is the historic name for the Rio Grande meaning wild, brave - an untamed river.
In contrast, we call the river that has been highly altered by humans Rio Manso. Manso is a Spanish word that means tamed, such as a horse that has been broken to riding. For many years, changes were made to the river system with the top priority being how the river was serving the human society. Little attention was given to the ecosystem and the other animals and plants that depended on this important riparian corridor. In 1993, an important document, the Middle Rio Grande Ecosystem: Bosque Biological Management Plan, brought a focus on the problems of prioritizing river management for human needs only. Many projects before the plan attempted to address biological issues on a small scale, and since its publication river managers have been more active in managing the river for both human needs and ecosystem health. In our model exercises, we call this third river Rio Nuevo - a new river that meets human constraints but provides a healthy ecosystem with as many of the Rio Bravo features as can be allowed. This river will always be evolving. In actuality, there will always be places along the river that are more like Rio Manso and other places that are more like Rio Nuevo. When students ask what river we have today, we can tell them we have both, depending on what features the river and bosque have where we are looking.
Special note: In the 1995 version of the Bosque Education Guide, this activity was presented with two river concepts, Rio Grande Viejo for the old river - that is the same as Rio Bravo in this activity - and Rio Grande Nuevo for the new river, which is mostly represented by Rio Manso in this activity. The activity was updated with three river concepts to help students understand that we have choices on how we treat the river and what it can become.
