Flow Durations, Low-Flow Frequencies, and Monthly Median Flows for Selected Streams in Connecticut through 2005

Ahearn, Elizabeth A.

doi:10.3133/sir20075270

Cited by 8 publications

(7 citation statements)

References 10 publications

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“…Several studies by the USGS that provide estimates of flow-duration statistics in Connecticut have been published, including a series of basin studies (Cervione and others, 1972;Handman and others, 1986;Mazzaferro and others, 1979;Randall and others, 1966;Ryder and others, 1970;Ryder and others, 1981;Thomas and others, 1968;Thomas and others, 1967;Weiss and others, 1982;Wilson and others, 1974). Ahearn (2007) published estimates of flow durations, low-flow frequencies, and monthly median flows for selected streams in Connecticut using data through 2005. That report updated and superseded previously published flow durations, low-flow frequencies, and monthly median flow estimates in Connecticut and was a precursor to the development of regression equations to estimate the flow-duration statistics described in this report.…”

Section: Previous Studiesmentioning

confidence: 99%

“…Data from about 100 streamgages with 10 or more years of daily mean flows in Connecticut and in the neighboring states of Rhode Island, Massachusetts, and New York were retrieved from the USGS National Water Inventory System (NWIS) database at http://nwis.waterdata.usgs.gov/usa/nwis/discharge and considered for the regression study (Ahearn, 2007). Subsequently, Connecticut DEP and USGS made a rigorous effort to identify and eliminate any of the streamgages that were impacted by anthropogenic activities (such as flow augmentation, diversions, or water-supply/industrial withdrawals in the upstream drainage basin).…”

Section: Data-set Developmentmentioning

confidence: 99%

“…The 6 short-term streamgages and 28 partial-record sites are located in Connecticut and were available for regionalization of the Q 99 without reference to a bioperiod. In a companion study that preceded the regression analysis presented in this report, several low-flow statistics, including the Q 99 , were estimated for the short-term streamgages and partial-record sites (Ahearn, 2007).…”

Section: Data-set Developmentmentioning

confidence: 99%

“…Previously derived flow-duration statistics for the Q 99 from short-term streamgages and partial-record sites were used in conjunction with the 39 continuous-record streamgages in the regression analysis of the non-bioperiod Q 99 . In a previous study (Ahearn, 2007), the Q 99 was derived using the MOVE3 method (Vogel and Stedinger, 1985) for 7 short-term continuous-record and 31 partial-record sites in Connecticut; flow-duration statistics were not computed for the bioperiods. The flow-duration statistics at the short-term continuous-record streamgages and partial-record sites were calculated based on the relation between same-day flows at the short-term streamgages and partial-record sites and concurrent daily mean flows at a nearby continuous-record streamgage with natural flow conditions.…”

Section: Calculation Of Flow-duration Statistics At Streamgagesmentioning

confidence: 99%

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Regional Regression Equations to Estimate Flow-Duration Statistics at Ungaged Stream Sites in Connecticut

Ahearn¹

2010

Scientific Investigations Report

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Multiple linear regression equations for determining flow-duration statistics were developed to estimate select flow exceedances ranging from 25-to 99-percent for six "bioperiods"-Salmonid Spawning (November), Overwinter (December-February), Habitat Forming (March-April), Clupeid Spawning (May), Resident Spawning (June), and Rearing and Growth (July-October)-in Connecticut. Regression equations also were developed to estimate the 25-and 99-percent flow exceedances without reference to a bioperiod. In total, 32 equations were developed. The predictive equations were based on regression analyses relating flow statistics from streamgages to GIS-determined basin and climatic characteristics for the drainage areas of those streamgages. Thirty-nine streamgages (and an additional 6 short-term streamgages and 28 partial-record sites for the non-bioperiod 99-percent exceedance) in Connecticut and adjacent areas of neighboring States were used in the regression analysis. Weighted least squares regression analysis was used to determine the predictive equations; weights were assigned based on record length. The basin characteristics-drainage area, percentage of area with coarse-grained stratified deposits, percentage of area with wetlands, mean monthly precipitation (November), mean seasonal precipitation (December, January, and February), and mean basin elevation-are used as explanatory variables in the equations. Standard errors of estimate of the 32 equations ranged from 10.7 to 156 percent with medians of 19.2 and 55.4 percent to predict the 25-and 99-percent exceedances, respectively. Regression equations to estimate high and median flows (25-to 75-percent exceedances) are better predictors (smaller variability of the residual values around the regression line) than the equations to estimate low flows (less than 75-percent exceedance). The Habitat Forming (March-April) bioperiod had the smallest standard errors of estimate, ranging from 10.7 to 20.9 percent. In contrast, the Rearing and Growth (July-October) bioperiod had the largest standard errors, ranging from 30.9 to 156 percent. The adjusted coefficient of determination of the equations ranged from 77.5 to 99.4 percent with medians of 98.5 and 90.6 percent to predict the 25-and 99-percent exceedances, respectively. Descriptive information on the streamgages used in the regression, measured basin and climatic characteristics, and estimated flow-duration statistics are provided in this report. Flow-duration statistics and the 32 regression equations for estimating flow-duration statistics in Connecticut are stored on the U.S. Geological Survey World Wide Web application "StreamStats" (http://water.usgs.gov/osw/streamstats/index.html). The regression equations developed in this report can be used to produce unbiased estimates of select flow exceedances statewide. Habitat Forming March-April High Maintain natural habitat and connectivity with flood plain, channel formation, and flushing and transport of fine-grained sediment. Clupeid Spawning May Medium Increased flows...

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Section: Previous Studiesmentioning

confidence: 99%

Section: Data-set Developmentmentioning

confidence: 99%

Section: Data-set Developmentmentioning

confidence: 99%

Section: Calculation Of Flow-duration Statistics At Streamgagesmentioning

confidence: 99%

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Regional Regression Equations to Estimate Flow-Duration Statistics at Ungaged Stream Sites in Connecticut

Ahearn¹

2010

Scientific Investigations Report

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“…Since 2005, when the General Assembly required CT DEEP to update streamflow standards, the U.S. Geological Survey (USGS), in cooperation with CT DEEP, conducted several studies that contributed to planning and management of Connecticut water resources (Ahearn, 2008(Ahearn, , 2010. As part of the ongoing process of implementing streamflow standards, new methods and tools are needed for describing and quantifying streamflow and sustainable water use.…”

Section: Introductionmentioning

confidence: 99%

The Connecticut Streamflow and Sustainable Water Use Estimator—A decision-support tool to estimate water availability at ungaged stream locations in Connecticut

Levin¹,

Olson²,

Nielsen³

et al. 2018

Scientific Investigations Report

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A novel method to evaluate stream connectivity using trail cameras

Bellucci

Becker

Czarnowski

et al. 2020

River Research & Apps

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Stream connectivity is important for the ecological health of the stream and downstream waters. In this study, we use the term stream connectivity to mean hydrologically connected pools and riffles that link stream habitat along a longitudinal continuum (upstream to downstream), while also recognizing the lateral dimension (connection to flood plain) and vertical connection to groundwater. There are thousands of man-made structures (i.e. dams, culverts, surface and groundwater withdrawal locations) in Connecticut which negatively impact stream connectivity and can result in aquatic habitat fragmentation. Cost-effective techniques are needed to assess human alteration to streams in order to prioritize management actions to restore stream connectivity. We developed a method to characterize stream connectivity using commercially available trail cameras that cost less than approximately $500 per deployment. We developed a six-category system to describe the variations in stream connectivity observed using the trail camera images. We then used the categorical data to calculate metrics that quantify stream connectivity. To pilot this approach, we evaluated reference locations with minimal anthropogenic influence on stream connectivity in comparison with stream reaches likely to be impacted by nearby groundwater wells. We found that metrics derived from trail camera images were useful to quantify stream connectivity. We anticipate that the methods outlined herein is a useful stream connectivity assessment tool that can be effectively communicated to scientists and non-scientists. All source

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Flow Durations, Low-Flow Frequencies, and Monthly Median Flows for Selected Streams in Connecticut through 2005

Cited by 8 publications

References 10 publications

Regional Regression Equations to Estimate Flow-Duration Statistics at Ungaged Stream Sites in Connecticut

Regional Regression Equations to Estimate Flow-Duration Statistics at Ungaged Stream Sites in Connecticut

The Connecticut Streamflow and Sustainable Water Use Estimator—A decision-support tool to estimate water availability at ungaged stream locations in Connecticut

A novel method to evaluate stream connectivity using trail cameras

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