An overview of Montana StreamStats and methods for obtaining streamflow characteristics at gaged and ungaged locations in Montana In cooperation with Montana Department of Natural Resources and Conservation ID: 480275
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Montana StreamStatsAn overview of Montana StreamStats and methods for obtaining streamflow characteristics at gaged and ungaged locations in MontanaIn cooperation withMontana Department of Natural Resources and Conservation,Montana Department of Transportation,and Montana Department of Environmental Quality
Peter McCarthy
USGS-Hydrologist
pmccarth@usgs.gov
406-457-5934Slide2
StreamStats and Scientific StudiesOne Scientific Investigations Report (SIR) with multiple chaptersChapter A: Montana StreamStats introduction Gaged sitesChapter B: Peak flow trends and stationarityChapter C: Peak-flow analyses Chapter D: Methods for improving peak flow analysesChapter E: Streamflow characteristicsUngaged sitesChapter F: Peak-flow regional regression equationsChapter G: Streamflow statistics regional regression equationsSlide3
Chapter A: StreamStats Introduction
http://water.usgs.gov/osw/streamstats/Slide4
Chapter A: StreamStats Introduction
http://water.usgs.gov/osw/streamstats/Slide5
Chapter A: StreamStats IntroductionSlide6
Chapter A: StreamStats Introduction
Basin Characteristics
Save shapefileSlide7
Chapter A: StreamStats IntroductionNational StreamStats Version 3Patch between ver. 2 and ver. 4Version 4 expected December 2015Montana StreamStats ApplicationFully implemented (January-February, 2015)Obtain flow statistics from current studiesCompute streamflow characteristics at ungaged sites using new regional regression equationsSlide8
Chapter A: StreamStats IntroductionRegulation classificationRegulated: If the conjoined drainage area of all dams is greater than or equal to 20% of the basin Major regulation: The drainage area of a single dam exceeds 20%Minor regulation: The drainage are of no single dam exceeds 20%, however the conjoined drainage area exceeds 20%.NHDPlusV2 dams databaseRegulation status as of 2011Date of regulation (when did a site exceed 20%)Slide9
Chapter B: Peak flow trends and stationarityGage selection (24 selected)75+ years of annual peak-flow records5+ years of data in the 1930’s (particularly dry period)Small urbanization or reservoir effectFour analysis periodsStart of data collection through 19401930-19761967-2011Start of data collection through 2011Slide10
Chapter B: Peak flow trends and stationaritySlide11
General Conclusions Magnitude of peak flowsUpwards trends during 1930-1976 generally stronger than downward trends during 1967-2011Annual peak flow for most long-term gaging stations can be considered stationary for peak-flow frequency analysesTiming of peak flowsEarlier peak trends (1967-2011) were generally stronger than later peak trends (1930-1976)Differences in timing are variable and not particularly strong; however 5 of 7 high-elevation gages showing trends of earlier peaksMagnitude and timing of peaks generally correspond (i.e. earlier peaks correspond to smaller peaks)Chapter B: Peak flow trends and stationaritySlide12
Chapter B: Peak flow trends and stationaritySlide13
Chapter B: Peak flow trends and stationarity06324500-Powder River at MoorheadSlide14
Chapter B: Peak flow trends and stationarityMore research and analyses are needed to better understand downward trends of peak flow magnitudes and timing in Eastern MontanaEffects of smaller dams and land use practicesEffects of climate changesHow do I proceed? Be conservative!Consider your period of record for analysisUse record extension or regression equations to adjust your analyses (more on this later)Slide15
Chapter C: Peak flow analysesPerformed analyses using Bulletin 17B725 streamflow gaging stations in and near Montana579 unregulated streamflow stations146 regulated streamflow stations100 analyzed for post-regulation period only17 analyzed for pre-regulation period only29 analyzed for both pre- and post-regulationPre-regulation analyses used for regression equationsSlide16
Chapter C: Peak flow analysesSlide17
Chapter C: Peak flow analyses
Analyses served in downloadable file
Tables 1-1 through 1-6 provide analyses info
Station analysis and plots shownSlide18
Chapter D: Improving peak flow analysesWhy do peak flow analyses need to be improved?Period of record (dry or wet period)Length of record (short period of record)Multiple stations along same stream with different periods of record and resultsHow are peak flow analyses improved?MOVE.1 Record extension methods (66 gaging stations)Weighting station analyses with regression equations (438 gaging stations)Slide19
Systematic
Record extension (MOVE.1)
Chapter D: Improving peak flow analysesSlide20
Weighting with regional regression equations
Chapter D: Improving peak flow analyses
12301800-Gold
Creek near
Rexford (1959-1969)Slide21
Streamflow characteristics using daily mean streamflowAnnual and seasonal low flowsAnnual based on climatic year (March 1-February 28)March-JuneJuly-OctoberNovember-FebruaryAnnual high flowsAnnual and monthly durations Chapter E: Streamflow CharacteristicsSlide22
Performed analyses using SWSTAT408 streamflow gaging stations in and near Montana281 unregulated streamflow stations127 regulated streamflow stations89 analyzed for post-regulation period only15 analyzed for pre-regulation period only23 analyzed for both pre- and post-regulationPre-regulation analyses used for regression equationsChapter E: Streamflow CharacteristicsSlide23
Chapter E: Streamflow CharacteristicsSlide24
Analyses served in downloadable file
Table_1 provides station information
Excel tab for each station
Chapter E: Streamflow CharacteristicsSlide25
Regional Regression Equations for unregulated annual exceedance probabilities
8 hydrologic regions
537 gaging stations
Drainage area less than ~2,500 sq. mi.
Systematic record unaffected by major regulation
No redundancy with nearby stations
Representation of peak-flow characteristics in MT28 candidate basin characteristics A, EL5000
, EL6000, ETSPR, F, P, SLP30Chapter F: Peak-Flow Regional Regression EquationsSlide26
Chapter F: Peak-Flow Regional Regression EquationsSlide27
Envelope Curves
Crippen and Bue (1977)
Regional envelope line
1% AEP
Chapter F: Peak-Flow Regional Regression EquationsSlide28
Chapter G: Regional Regression Equations for Streamflow CharacteristicsAnnual and seasonal low-flow7Q1014Q5Annual and monthlyMeanDuration values forQ20%Q50%Q80%
Explanatory Variables
Drainage area
Mean annual
precip
.
Percent of basin with slopes greater than 50 percent.Slide29
Chapter G: Regional Regression Equations for Streamflow CharacteristicsSlide30
Additional Studies Updates to Bulletin 17B EMA, low outlier, high threshold, confidence intervalsDevelop a new regional skew map Pacific Northwest, Greater Missouri BasinPaleo flood data PMF, 1964 recurrence, regional studies Flood Inundation Mapping StreamStats Regulation, high-resolution, additional BCsSlide31
StreamStats Training Sign up for training notifications at http://wy-mt.water.usgs.gov/mtwy-notices.htmlAssociation of Montana Floodplain Managers meeting-March 15-17, 2016Other Slide32
Questions?Clark Fork River at Milltown Dam, June 1908http://www.floodsafety.noaa.gov/states/mt-flood.shtmlQpeak=48,000cfs