After the Fire: Low Cost Flooding and Erosion Mitigation Strategies

By: Lindsey Quam, Santa Clara Pueblo Forestry Director and Gabe Kohler, Forest Stewards Guild Program Coordinator

Since wildfire is inevitable, the work to develop fire adapted communities is never done. This is why it’s so important that as a network we discuss strategies for adapting to wildfire before and after the fire. A recent Fire Adapted Communities New Mexico workshop in Santa Clara Pueblo focused on strategies for protecting our communities from flooding and erosion after a wildfire has occurred. Planning for after a wildfire may help shift conversation about wildfire potential from ‘if’ to ‘when’.

On May 24th, Fire Adapted Communities (FAC) leaders and partners from Santa Clara Pueblo in Northern New Mexico, gathered for an interactive workshop. It was a small, close-knit group  with representatives from 4 different organizations including Santa Clara Pueblo Forestry, The Santa Clara Office of Emergency Management, The Forest Stewards Guild, and Padilla Logging. The diverse group of partners and community members were able to productively identify lessons learned from the ongoing response and recovery efforts in Santa Clara Canyon following the 2011 Las Conchas wildfire.

A key goal of the FACNM network is to facilitate peer-to-peer information sharing to empower people to work toward wildfire adaptation in their communities. In addition to highly engineered, state-of-the-art erosion and flooding prevention structures, the pueblo implemented many low-cost structures. These low cost methods were part of a landscape scale effort to mitigate flooding and erosion after the Los Conchas fire, and are powerful tools for response and recovery that can be used to leverage the people-power in any community and make an impact against flooding and erosion before it occurs.

The project area is contained within the Santa Clara Creek Watershed and includes over 32,000 acres, 24 miles of stream, and 5,000 feet of elevation gradient.

The project area is contained within the Santa Clara Creek Watershed and includes over 32,000 acres, 24 miles of stream, and 5,000 feet of elevation gradient.

Stream-first Wildfire Recovery

The Las Conchas wildfire burned more than 150,000 acres adjacent to the community of Santa Clara, and created extreme flooding and erosion in Santa Clara Creek (more info here). Santa Clara Creek is regarded as a sacred source of life to the people of Santa Clara Pueblo,  so the Tribe took a ‘stream-first’ approach to prioritizing natural stream function. Its flood mitigation and restoration design emphasized the use of natural materials as infrastructure, which maximized ecosystem benefits and decreased the cost.

Erosion Control

Erosion control structures were installed in tributaries to stop sediment delivery upstream, minimize head cutting, and aggrade incised channels. The structures used were cost-effective, being built by hand and using on-site materials. The low cost of these methods allowed them to be used broadly throughout the project area, and over 5,300 structures were built in the 26 tributaries since 2014.

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Contour Felling

Felling trees along a horizontal contour is an easy and effective way to keep excess water out of a main drainage. These structures encourage lateral water flow and capture water to contribute to the water table.

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Rockdam

Rocks are positioned to counteract erosion by reducing the velocity of water flow. These structures raise the level of the streambed, and create viable habitat for plants.

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Log Drop

Similar to rock dams, the log acts as a footer that is anchored into the banks of the incised channel. Rocks and dirt are placed upstream of the log and sometimes grass transplants are installed into the structure. These materials collect sediment behind the log structure and provide grade control. The sediment collected often contains organic material and other nutrients needed for healthy plant growth.

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Flow Splitter

These structures divert water flow out of a main incised channel and encourage sheet flow across the surface. These designs are most effective in wide valley bottoms where flow has space to spread and dissipate.

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Zuni Bowl

These structures are constructed at the base of a head-cut. Zuni bowls (originally used by Zuni Pueblo) armor the substrate within the channel, preventing scouring action by water over the long term. The bowl shape acts as an energy dissipater as water flows into the structure, protecting the potentially erosive substrate. The bottom of the bowl also acts as a water harvesting feature which will maintain moisture for long periods.

In New Mexico, where wildfire season is immediately followed by monsoons, planning for flooding and erosion mitigation is crucial to the resilience of our communities in the face of wildfire. Waiting for emergency assistance and outside funding may not be the best strategy for protecting our communities from flooding and erosion. The lost cost methods and materials used in Santa Clara Pueblo may be an important part of your communities after-the-fire toolkit.  

For more information about recovery after-the-fire, check out:

1.   Story map of Santa Clara’s response and recovery efforts to the Las Conchas Wildfire

 https://arcg.is/0HGPHf

2. After the Wildfire NM

https://afterwildfirenm.org/

https://afterwildfirenm.org/post-fire-treatments/treatment-descriptions/channel-treatments

3. The Burned Area Learning Network (BALN) https://www.conservationgateway.org/ConservationPractices/FireLandscapes/FireLearningNetwork/RegionalNetworks/Pages/BALN.aspx