CWPAP Assessment Strategies
Watershed assessment must consider interactions among natural processes, human activities, and resource conditions to assess watershed health. CWPAP recognizes that these watershed interactions are numerous, complex, non-linear, and may occur over extended periods of time and space. Furthermore, the forces or systems that drive or affect these factors may lie outside the watershed or occur at a much larger scale. Single cause-and-effect relationships may, therefore, be difficult to pinpoint.
Natural drivers and watershed activities can cause significant disturbances that affect both watershed conditions and processes. Their effects may, in turn, affect other processes, including those needed for recovery. For example, sediment from a road failure may take 30 years to work its way down many miles of stream, affecting fluvial processes, impacting water quality conditions, and altering stream substrate as it moves. As the sediment transports down stream, it can cause spatial and temporal changes channel conditions through initial aggradation, possible lateral migration that undercuts channel banks, and eventually degradation as the channel attempts to reach its initial base level. Thus, this additional sediment may alter channel and channel bank structures, flow hydraulics and impede riparian vegetation re-establishment.
Interactions among watershed processes, conditions and activities.