Quick response small catchment monitoring techniques for comparing postfire rehabilitation treatment effectiveness

Robichaud, P.R.; Brown, R.E. 2003. Quick response small catchment monitoring techniques for comparing postfire rehabilitation treatment effectiveness. First interagency conference on research in the watersheds. Agricultural Research Service. 663-667.

Keywords: erosion, sedimentation, paired watersheds, instrumentation, data logger

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Abstract: Increased runoff and erosion commonly occur after wildfires with the onset of precipitation events. Various erosion mitigation treatments are often used after wildfires to reduce flooding and sedimentation. The effectiveness of these treatments has not been well documented in the literature; therefore we undertook a rapid response approach (within four weeks following fire suppression) to install small catchment monitoring systems to compare treatment effectiveness. A paired watershed approach uses two adjacent and similar catchments (5-20 ac) after wildfires, treating one catchment and using the other catchment as a control. We developed a rapid response monitoring system that can be installed in a few weeks to monitor sediment yield and runoff response. These systems are usually left in place for three to five years.

Each installation has a complete weather station and electronic measuring devices to record streamflow and sediment accumulation in a storage basin. The sediment basins are cleaned out manually after each storm event in order to relate the event (intensity, amount and duration) to runoff and sediment yield. The data is automatically transmitted each day via cell phone or radio transmission to our computer server, thus making the data available daily on our web page. We have installed six paired catchments to date in Colorado, Washington, two in California, and two in Montana. Preliminary results suggest that 1) first year storm events produce the largest runoff and sediment response and 2) treatment effectiveness is less with high intensity short duration storm events. This rapid response protocol allows for quick installation of a monitoring system to provide an assessment of treatment effectiveness.

Moscow FSL publication no. 2003s