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Home My WebLink AboutRTI_Flow_AlterationRTI International RTI International is a trade name of Research Triangle Institute.www.rti.org Flow Alteration – Biological Response Relationships to Assist with the Determination of Ecological Flows RTI Internal Research and Development Project RTI International Outline of Presentation Objectives Methods: –Aquatic biota –Flow metrics –Statistical analyses RTI International Project Objectives: To use a combined approach of: –unaltered and current flows determined with WaterFALL model –large, state-wide aquatic biota datasets (monitoring programs) to determine species- specific flow alteration – biological response relationships that are useful to water managers. RTI International Project Objectives: Time for Time Approach Space for Time Approach Time 1 – Sp. Count = 25 Time 2 – Sp. Count = 8 Flow alter. = 10% Sp. Count = 25 Flow alter. = 45% Sp. Count = 17 Flow alter. = 80% Sp. Count = 5 RTI International Project Objectives: “transferable quantitative relationships between flow alteration and ecological response” cannot be easily developed, and “large databases, if analyzed with an eye toward degree of flow alteration, carefully selected response metrics, stream typology, and multiple environmental drivers, hold the potential to reveal important relationships” – Poff and Zimmerman (2010) RTI International Project Objectives: Studies that have adopted this approach: –Middle Potomac Environmental Flows –Virginia DEQ Environmental Flows –Carlisle et al. (2011) – USGS effort across U.S. TNC – Middle Potomac 090811 Webinar RTI International Methods: • Species • Flow metrics • Statistical analyses RTI International Methods: • Species RTI International Methods – Biological Response: Fish: –Top of the food chain integrators –Relatively fast recovery time to climatic events that may cause local extirpation –Valued by wide segments of society Datasets: –NC DWQ Fish Community –USGS National Water Quality Assessment Program (NAQWA) RTI International Methods – Biological Response: Species: –Individual species –Assigned to guilds indicative of flow requirements RTI International Methods – Biological Response: Guilds (Persinger et al., 2010): –based on study in North Fork Shenandoah River, VA Guilds Fast-generalist Riffle Pool-run Pool-cover RTI International Methods – Biological Response: Species: –Individual species –Connected to guilds indicative of flow requirements –Species – Guild Approach: identifies “canaries” within guilds assign significant flow metrics to guild for management purposes –Up to 20 species RTI International Methods – Biological Response: Species: –Up to 20 species: Riffle guild Well distributed (state or regionwide) Large number of records (i.e., > 50) Life history stages and requirements well known Single guild through-out life Exploratory statistical analyses to identify species (and associated flow metrics) with significant responses to altered flows RTI International Methods: • Flow metrics RTI International Methods – Flow metrics: Selection criteria: –Biologically relevant –Amenable to management –Can be expressed as % change –Can be effectively modeled with WaterFALL RTI International Methods – Flow metrics: Biologically relevant: –Review of flow-biology hypotheses for fish: Increases and decreases in low, high and median/stable/base flows Important events all months of the year –Represent the five components of flow Magnitude, timing, duration, frequency, rate of change Amenable to Management: –Magnitude, timing, duration, frequency, rate of change –Focus on low flows and reductions in flow RTI International Methods – Flow metrics: Selection criteria: –Biologically relevant –Amenable to management –Expressed as % changes –Can be effectively modeled Flow metrics –TNC Indicators of Hydrologic Alteration (IHA) = 67 metrics –Additional metrics RTI International Methods – Flow metrics Monthly Measures Annual Measures Extreme low flow (10th percentile) 3-, 7-, 30-, and 90-day minimum Low flow (25th percentile)3-, 7-, 30-, and 90-day maximum Median/Base flow (50th percentile) Extreme low flow (10th percentile) High flow (75th percentile)Extreme low flow count Extreme low flow duration (longest duration during year) bold = IHA metrics RTI International Methods – Flow metrics: Flow metric calculations: –WaterFALL hydrographs for unaltered/historic and current condition: Unaltered/Historic = Potential Natural Vegetation (PNV) or 1970s land-cover Current = 2006 NLCD + sources of instream flow alteration (dams, withdrawals, discharges) –30+ years of climate data –Expressed as % change –Focus analyses on reductions in flow RTI International Methods: •Statistical analyses RTI International Methods – Statistical analyses: Multiple and Single Predictor Analyses: RTI International Methods – Statistical analyses: Multiple Predictor Analysis Single Predictor Analysis Predictor 1 Re s p o n s e Y = a + b1*X1 + b2*X2 +..+ bp*Xp RTI International Methods – Statistical analyses: Multiple and Single Predictor Analyses: –Multiple Predictors: Multiple regressions (or comparable non-parametric analyses) Benefits: gain a better understanding of the degree to which species is influenced by altered flows versus other factors reduces the amount of error (i.e., accounts for a larger proportion of the variance in the relationship) Y = a + b1*X1 + b2*X2 +..+ bp*Xp RTI International Methods – Statistical analyses: Multiple and Single Predictor Analyses: –Multiple Predictors: Negatives: Application of relationship is restricted to locations where have data for the other factors (or need to assume default or average values for factors) Complicates the flow alteration – biological response relationship Co-variates included in analysis = measures of water quality, channel morphology, habitat, climatic events, sampling date, interspecific interactions RTI International Methods – Statistical Analyses Component Attribute/Dataset Water Quality DO, pH, conductance (DWQ Habitat and USGS NAQWA datasets) 303d listing Channel Morphology Sinuosity/Linear Length Slope Physiographic Region Habitat NC Habitat Score (DWQ Habitat dataset) Fragmentation x 2 (stream length between obstructions) – same stream length and summed stream length of network RTI International Methods – Statistical Analyses Component Attribute/Dataset Climatic Events Preceding year total precipitation Average of preceding 3 years of total precipitation Date Sampling Month Interspecific Interactions Influence of exotic and injurious introduced/ exotic fish species RTI International Methods – Statistical analyses: Multiple and Single Predictor Analyses: –Single Predictor: linear or quantile regressions (or comparable non- parametric analyses) RTI International Methods – Statistical analyses: Linear Regression Predictor 1 Re s p o n s e Quantile Regression TNC – Middle Potomac 090811 Webinar RTI International Methods – Statistical analyses: Multiple or Single Predictor Analyses: –Singe Predictor: linear or quantile regressions (or comparable non- parametric analyses) Benefits: Only based on response to % change of flow metric, so application in water management is more straight forward Negatives: Potentially large amount of error which will reduce the strength of the relationships RTI International Methods – Statistical analyses: Multiple or Single Predictor Analyses: –Combination of analyses provides: water managers with an understanding of the relative importance of flow alterations and other influential variables for each species Flow-biology relationships with which to model/predict the impacts of flow alteration on biological responses RTI International Questions: Fall Creek