WARSSS & Monitoring
Watershed and river assessments involve complex process interactions, making accurate predictions somewhat precarious. Monitored data reflecting specific stream, watershed and biotic processes will continually improve our understanding and prediction of those processes and the relationships among them. Another great benefit resulting from well-planned monitoring is the demonstration of reduced sediment and improved river stability due to management/mitigation.
Monitoring is generally recommended for the following reasons:
- Measure the response of a system from combined process interaction due to imposed change
- Document or observe the response of a specific process and compare to predicted response for a prescribed treatment
- Define short-term versus long-term changes
- Document spatial variability of process and system response
- Ease the anxiety of uncertainty of prediction
- Provide confidence in specific management practice modifications or mitigation recommendations to offset adverse water resource impacts
- Evaluate effectiveness of stabilization, or restoration approaches
- Reduce risk once predictions and/or practices are assessed
- Build a data base to extrapolate for similar applications
Because of the complexity and variability of hydrologic, hillslope, and channel processes, some uncertainty is inevitable in WARSSS assessments. Iterative use of monitoring in connection with the RRISSC and PLA phases plays particularly important roles in validating the assessment's calculations and setting the stage for providing future feedback on management practices that are implemented.
Monitoring in conjunction with the RRISSC phase is critical in order to
- Move the reaches or sub-watersheds that were given a ranking of moderate risk directly into improved management practices with monitoring to provide feedback for adaptive management, where feasible.
Monitoring in conjunction with the PLA phase outcome is critical in order to
- Verify the relations used to predict sediment and stability change
- Determine the future effectiveness of process-specific mitigation measures, stabilization, restoration enhancement, and
- Document short-term as well as long-term sediment stability and related effects on beneficial uses.
The state of the science cannot be advanced, nor can our understanding of complex processes be improved, without monitoring. Because selection of monitoring techniques can be very case-specific due to differences in regional climate, land use, stream type and many other factors, WARSSS provides only an overview of the elements that transcend these differences. Nonetheless, numerous specialized sources of monitoring guidance already exist. For example, an excellent summary of the nature and design of monitoring, statistical guidance, methods, parameters, various strategies, and biological monitoring appears in Monitoring guidelines to evaluate effects of forestry activities on streams in the Pacific Northwest and Alaska [BROKEN] (MacDonald et al. 1991). Monitoring Guidance for Determining the Effectiveness of Nonpoint Source Controls (USEPA, 1997) is also an excellent reference. Riparian vegetation monitoring is also described in detail in Monitoring the vegetation resources in riparian areas, a US Forest Service guidance document (Winward 2000).
This chapter addresses the use of monitoring in WARSSS in an overview discussion that is divided into three parts:
- Effectiveness monitoring (response of a process or system to imposed change)
- Validation monitoring (matching predicted to observed response; includes model calibration and model validation)
- Field methods/procedures (a summary of techniques specific to WARSSS assessment steps.)