Task 5: Stream channel restoration
The objective of this task is to accelerate channel evolution toward more stable states, using different kinds of treatments. This will result in increased watershed stability and improved water quality. There are some sites in the Rio Puerco or its tributaries where the basic elements of stream dimension, pattern and profile are not in equilibrium with desired stable stream conditions. For example, straight channel segments or deeply incised channels downstream suggest accelerated erosion. River morphology efforts, such as restoring proper gradient, channel dimension, width/depth ratio, sinuosity, and bioengineering, are undertaken. Different approaches are used and assessed.
Conventional Channel Restoration with Bioengineering Applications
In some cases, a studied geomorphic approach is being used to design channel restoration projects. Longitudinal surveys, cross-sections, and other tools are used to guide the construction and implementation of projects. Heavy equipment and highly engineered in-channel structures are employed, as they are the most suitable options. A modification of this approach, soil bioengineering, is being used to treat a series of tortured meanders in the Rio Puerco adjacent to the 19th-century village of Cabezon.
Soil bioengineering is a restoration technique based on the idea that healthy vegetation can serve as the best, and most flexible, armoring available for stream stabilization. This technique reinforces conventional bank stabilization engineering designs with plants and plant materials (trunks, root wads, etc.). Ultimately, the organic components will provide the natural, long-term bank stability needed to keep a stream channel healthy.
This modification of the conventional geomorphic approach is new to the region.
Induced meandering is a mechanism for adding channel sinuosity while creating or restoring a floodplain. This provides a better opportunity for vegetation to become established, promoting long-term bank and channel stability. Streams can be induced to meander at a relatively low cost because the structures are low-tech and built using local and native materials. This approach is being used to reconnect the Arroyo Arañal in La Jara with its former floodplain.
A recently published booklet on the subject, An Introduction to Induced Meandering (EWI, QC, B. Zeedyk, 2003), is available for free through the RPMC.