Multi-Scale Approach to Hydrological Classification Provides Insight to Flow Structure in Altered River System

The flow regime is considered a master variable in structuring lotic systems across multiple scales. Research has focused on quantifying flow characteristics across large spatial scales and also integrating such measures of flow variation with biological responses (e.g., fish survival and somatic growth). However, the scale at which quantitative measures of flow are derived may alter the interpretation of fish population response to changing flow conditions, and thus alter prescription of conservation and management activities. We quantify flow conditions in the Lower Platte River (LPR), NE at two different scales (i.e., annual and sub-daily) and show how flow variables derived at the annual time step may “average-over” important sub-daily flow structure within the LPR. Flow variables at the annual time-step responded well to large changes in climatic patterns (i.e., wet vs. dry cycles), whereas, flow variables derived at the sub-daily time-step were more sensitive to anthropogenic alteration (i.e., hydropeaking).