Kiran Chinnayakanahalli David G. Tarboton

1. Predicting Hydrologic Flow Regime for Biological Assessment at Ungauged Basins in the Western United States Kiran Chinnayakanahalli David G. Tarboton Civil and Environmental Engineering Department, Utah State University, Logan, UT Charles P. Hawkins Department of Aquatic, Watershed, and Earth Resources, Utah State University, Logan, UT

2. W W hy quantify hydrologic flow regime? • Vital to the composition, structure and functioning of stream ecosystems • Classify streams and watersheds • Relate to biotic variability • Extrapolate site-specific data to stream reaches having similar characteristics • Quantify stream impairment

3. A A pproach Develop statistical models that relate streamflow statistics to climatic variables • Existing work • Streamstats http://water.usgs.gov/osw/streamstats/ • National Flood Frequency program • USGS Statistical Regionalization Methods • Kroll et al. Watershed characteristics database. watershed attributes (watershed morphology, channel network) basin geology/soils variables

4. D D ata – HCDN gauges in the west US Total number of HCDN gauges in Western US = 491. Area range: 15.7 km2 – 489346 km2 Off them 425 have area ≤ 5000km2 No. of watersheds Watershed area in km2

5. F F low regime Flow regime: Magnitude Frequency Duration Timing Rate of change M F D T R Water Quality Energy Sources Physical Habitat Biotic Interactions Ecological Integrity Figure from Poff, N. L., et al. (1997). "The Natural Flow Regime: A Paradigm for Conservation and Restoration of River Ecosystems." BioScience 47: 769-784.

6. H H ydrologic indices that define the flow regime Flow regime: Magnitude Frequency Duration Timing Rate of change BFI (%) – Base flow index M F D T R Flow regime: Magnitude Frequency Duration Timing Rate of change N –total number of years of record, QDMINy - Minimim Q in the year y, QAVEy = Mean Q in the year y, M F D T R

7. H H ydrologic indices Colwell’s index: P=C+M Predictability (P), Constancy (C), and Contingency (M) Maximum constancy, P=1, C = 1 and M = 0 Maximum contingency, P=1, C = 0 and M = 1 Flow Flow Time Time Flow regime: Magnitude – M, Frequency – F, Duration – D, Timing – T, Rate of change - R

8. W W atershed attribute derivation Digital Elevation Model Analysis Climate Soils PRISM TauDEM STATSGO • Watershed area • Main channel length • Main channel slope • Mean elevation • Relief • Drainage density - channelization threshold determined objectively using constant drop analysis • Basin shape • Hypsometric curve indices • Outlet elevation • Mean annual precipitation • Monthly mean temperature • Monthly maximum and • minimum temperature • Soil thickness • Available water capacity • Permeability • Bulk density

9. D D atabase Watershed morphology Hydrologic indices Climate Soils = f , , • Watershed area • Main channel length • Main channel slope • Mean elevation • Relief • Drainage density • Basin shape • Hypsometric curve indices • Outlet elevation • BFI • DAYCV • QMEAN • Q1.67 • ZERODAY • Colwell’s index • 7Qmin • 7Qmax • NOR • Flood frequency • Mean annual precipitation • Monthly mean temperature • Monthly maximum and minimum temperature • Soil thickness • Available water capacity • Permeability • Bulk density Response variables Explanatory variables

10. A A nalysis - Correlation between hydrologic flow regime variables

11. A A nalysis- Correlation between hydrologic flow regime and watershed attributes

12. A A nalysis – results from stepwise linear regression 1,2,3,4- parameter importance in the model with 1-most important, X- Not used

13. C C onclusions • Available methods do not quantify all the stream variables that are important to stream biota at the ungauged basins. • Selected hydrologic indices show potential to capture the different aspects of the flow regime. • Initial linear regression models showed better results for magnitude related hydrologic indices.

14. F F uture work • To classify watersheds based on hydrological flow regime variables • Quantify how effectively the classification based on hydrology performs in partitioning the naturally occurring biotic variation.

15. Thanks! Thanks!