The Rio Grande-Rio Bravo River is the second longest river in the US and is a critical drinking water source for more than 13 million people. It flows south from the snow-capped mountains of Colorado through the New Mexico desert, forms the border between Texas and Mexico, and empties into the Gulf of Mexico at Brownsville, Texas. The multi-national, multi-state, ecologically diverse nature of this river makes management of the resource a complex task, especially in the context of more frequent droughts, changes in land use patterns, and increasing water use needs.
The purpose of this project was to review scientific monitoring and research reports and provide an overview of the state of the knowledge of the Upper Rio Grande-Rio Bravo Basin. The project researchers developed a report that synthesizes historical and geomorphic studies that describe the river’s characteristics in the 1800s, its subsequent transformation caused by consumptive water use, dams, and physical manipulation of the channel, and a modern understanding of the natural and transformed flow regime. An extensive second section of the report focuses on aquatic ecology of the four major river segments of the Basin. In that section, the researchers summarize current understanding of the historical state compared to the contemporary state of the ecosystem, identify causes of ecosystem degradation, with an emphasis on those factors most affected by flow, and identify existing efforts to reverse ecosystem degradation, however intractable and dynamic these efforts may be. Finally, the project team summarized the state of knowledge of potential “knobs” that can be “turned” relating an ecological response to some component of flow management. They also seek to identify information gaps.
Realizing the need to define novel, new targets for desirable ecosystems places a great challenge on applied river science. To date, river science is pursued piece meal and focused on discrete segments of the watershed. This work helps to build a connection between politically-acceptable water management compromises, and the environmental flows needed to achieve river ecosystem objectives.
This project is associated with similar work being conducted in the Lower Rio Grande-Rio Bravo Basin: Assessing the State of Water Resource Knowledge and Tools for Future Planning in the Lower Rio Grande-Rio Bravo Basin