2006 Progress Report: Linking Watershed Characteristics with Flow Regime and Geomorphic Context to Diagnose Water Quality Impairment at Multiple Spatiotemporal Scales

EPA Grant Number: R831367
Title: Linking Watershed Characteristics with Flow Regime and Geomorphic Context to Diagnose Water Quality Impairment at Multiple Spatiotemporal Scales
Investigators: Poff, N. LeRoy
Current Investigators: Poff, N. LeRoy , Bledsoe, Brian P. , Dean, Denis
Institution: Colorado State University
EPA Project Officer: Hiscock, Michael
Project Period: November 1, 2003 through October 31, 2007
Project Period Covered by this Report: November 1, 2005 through October 31, 2006
Project Amount: $897,798
RFA: Development of Watershed Classification Systems for Diagnosis of Biological Impairment in Watersheds and Their Receiving Water Bodies (2003) RFA Text |  Recipients Lists
Research Category: Water and Watersheds , Water

Objective:

Objective 1: Quantify interaction between watershed characteristics, flow regime components, and geomorphic settings that explain variation in sediment and biological indicators of water quality impairment in EMAP datasets.
Objective 2: Create a national classification of water quality impairment in terms of flow regime components and land use.
Objective 3: Regionally test flow regime-water quality linkages by conducting field studies in Rocky Mountain streams.

Progress Summary:

We made substantial progress on Objectives 1 and 2 in 2005-6 with regard to development of modeling tools for predicting streamflow regimes and geomorphic context at EMAP biomonitoring sites across the western US. These activities are summarized in bullet form below:

  • Continued extending the analysis of flow regime-biotic linkages to the entire western US through developing input matrices required for artificial neural network models of 1) hydrologic regimes at ungauged EMAP sites, and 2) biological variation (taxonomic and functional) in relation to a robust set of hydroclimatic, geomorphic, and land use descriptors of western EMAP watersheds.
  • Generated hydrologic metrics using USGS daily gauge data for four large hydrologic regions of the US and analyzed relationships between landuse / landcover and hydrologic change among regions.
  • Compiled all USGS streamflow records in the western US and assessed for record length, dates, completeness, and quality.
  • Continued computing hydrologic metrics for all streamflow gages in the western US with with flow data for at least 12 of the last 30 years. Tools were developed to compute over 100 hydrologic metrics per gage by analyzing records in batch mode.
  • Generated watersheds and clipped 10m digital elevation models (DEMs) along with coverages of hydroclimatic (e.g. PRISM), geomorphic, and land use descriptors for all western EMAP sites.

Preliminary Results from Study of Flow Regime Alteration in Four Hydroclimatic Regions
Using daily discharge data from the USGS, we analyzed how hydrologic regimes vary with land use in four large hydrologic regions that span a gradient of natural land cover and precipitation across the continental United States. In each region we identified small streams (contributing area < 282 km2) that have continuous daily streamflow data. Using a national database, we characterized the composition of land cover of the watersheds in terms of aggregate measures of agriculture, urbanization, and least disturbed (“natural”). We calculated hydrologic alteration using 10 ecologically-relevant hydrologic metrics that describe magnitude, frequency, and duration of flow for 158 watersheds within the Southeast (SE), Central (CE), Pacific Northwest (NW), and Southwest (SW) hydrologic regions of the United States. Within each watershed, we calculated percent cover for agriculture, urbanized land, and less disturbed land to elucidate how components of the natural flow regime inherent to a hydrologic region is modified by different types and proportions of land cover. We also evaluated how dams in these regions altered the hydrologic regimes of the 43 streams that have pre-and post-dam daily streamflow data. In an analysis of flow alteration along gradients of increasing proportion of the three land cover types, we found many regional differences in hydrologic responses. In response to increasing urban land cover, peak flows increased (SE and CE), minimum flows increased (CE) or decreased (NW), duration of near-bankfull flows declined (SE, NW) and flow variability increased (SE, CE, and NW). Responses to increasing agricultural land cover were less pronounced, as minimum flows decreased (CE), near-bankfull flow durations increased (SE and SW), flow variability declined (CE). In a second analysis, for three of the regions, we compared the difference between least disturbed watersheds and those having either >15% urban and >25% agricultural land cover. Relative to natural land cover in each region, urbanization either increased (SE and NW) or decreased (SW) peak flows, decreased minimum flows (SE, NW, and SW), decreased near-bankfull flows (SE, NW, and SW), and increased flow variability (SE, NW, and SW). Agriculture had similar effects except in the SE, where near-bankfull flow durations increased. Overall, urbanization appeared to induce greater hydrologic responses than similar proportions of agricultural land cover in watersheds. Finally, the effects of dams on hydrologic variation were largely consistent across regions, with a decrease in peak flows, and increase in minimum flows, an increase in near-bankfull flow durations, and a decreased in flow variability.

In 2006, we also analyzed hydraulic data from the field study (Objective 3). In general, flow diversions at the 13 study sites resulted in 1) significantly lower channel velocities (channel averaged and thalweg velocities), and 2) decreases in fast habitat coupled with a significantly greater accumulation of fine sediment in riffles and runs. In accordance with EPA’s goal of identifying sensitive flow metrics to predict water quality impairment, we performed a multivariate regression to determine the best subsets of predictor variables for each fine sediment measure. We measured fines as mass in our cylinder samples, as coverage on the surface of the bed using a grid count, and as part of the overall pebble count. We found that the volumetric measure of fine sediment in the fast flowing habitats provided the most robust models. This linked with the significant difference in amount of fines in fast flowing habitats above vs. below all diversions indicates that fast flowing habitats are the most sensitive regions to reach averaged changes in hydraulic conditions.

Future Activities:

We will extend the regional analysis described above to the entire western US in 2007 to evaluate 1) the relative degree to which land use has altered flow regimes across regions in the US with naturally varying climate and natural land cover, and 2) the geomorphic and ecological implications of such flow modification. The preliminary analysis suggested that ecological and geomorphic responses to human alteration of land cover will have to be calibrated to the regional hydroclimatological, geologic, and historical context in which the streams occur, in order to determine the degree to which stream responses are region-specific versus geographically independent and broadly transferable. We plan to complete development of artificial neural network (ANN) models for predicting streamflow regimes at ungauged EMAP sites and quantifying departures from least disturbed hydrologic conditions across the western US in 2007. After the ANN models are tested and verified with USGS gauge data, model predictions will be used to develop a classification of hydrologic alteration and to examine associations between departures from least disturbed hydrologic conditions and stream biota at western EMAP sites.

We will also work to submit articles in preparation and begin preparation of final articles from the research.


Journal Articles on this Report : 8 Displayed | Download in RIS Format

Other project views: All 47 publications 15 publications in selected types All 13 journal articles
Type Citation Project Document Sources
Journal Article Craig LS, Palmer MA, Richardson DC, Filoso S, Bernhardt ES, Bledsoe BP, Doyle MW, Groffman PM, Hassett BA, Kaushal SS, Mayer PM, Smith SM, Wilcock PR. Stream restoration strategies for reducing river nitrogen loads. Frontiers in Ecology and the Environment 2008;6(10):529-538. R831367 (2006)
R831367 (Final)
X3832206 (2006)
  • Abstract: Ecological Society of America-Frontiers in Ecology & the Environment abstract
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  • Other: Journal of Lake Sciences pdf
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  • Journal Article Flores AN, Bledsoe BP, Cuhaciyan CO, Wohl EE. Channel-reach morphology dependence on energy, scale, and hydroclimatic processes with implications for prediction using geospatial data. Water Resources Research 2006;42:W06412, doi:10.1029/2005WR004226. R831367 (2005)
    R831367 (2006)
    R831367 (Final)
  • Abstract: American Geophysical Union-Abstract
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  • Journal Article Olden JD, Poff NL, Bledsoe BP. Incorporating ecological knowledge into ecoinformatics: an example of modeling hierarchically structured aquatic communities with neural networks. Ecological Informatics 2006;1(1):33-42. R831367 (2005)
    R831367 (2006)
    R831367 (Final)
  • Abstract: ScienceDirect-Abstract
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  • Other: Colorado State
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  • Journal Article Poff NL, Olden JD, Pepin DM, Bledsoe BP. Placing global stream flow variability in geographic and geomorphic contexts. River Research and Applications 2006;22(2):149-166. R831367 (2005)
    R831367 (2006)
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  • Full-text: Colorado State University-Full Text PDF
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  • Abstract: Wiley InterScience-Abstract
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  • Journal Article Poff NL, Bledsoe BP, Cuhaciyan CO. Hydrologic variation with land use across the contiguous United States: geomorphic and ecological consequences for stream ecosystems. Geomorphology 2006;79(3-4):264-285. R831367 (2005)
    R831367 (2006)
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  • Full-text: Geomorphology
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  • Abstract: ScienceDirect-Abstract
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  • Journal Article Poff NL, Olden JD, Merritt DM, Pepin DM. Homogenization of regional river dynamics by dams and global biodiversity implications. Proceedings of the National Academy of Sciences 2007;104(14):5732-5737. R831367 (2006)
    R831367 (Final)
  • Full-text from PubMed
  • Abstract from PubMed
  • Associated PubMed link
  • Full-text: PNAS full text
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  • Abstract: PNAS abstract
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  • Other: PNAS PDF
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  • Journal Article Sanborn SC, Bledsoe BP. Predicting streamflow regime metrics for ungauged streams in Colorado, Washington, and Oregon. Journal of Hydrology 2006;325(1-4):241-261. R831367 (2004)
    R831367 (2006)
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  • Full-text: ScienceDirect-Full Text HTML
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  • Other: ScienceDirect-Full Text PDF
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  • Journal Article Wohl E, Angermeier PL, Bledsoe B, Kondolf GM, MacDonnell L, Merritt DM, Palmer MA, Poff NL, Tarboton D. River restoration. Water Resources Research 2005;41:W10301, doi:10.1029/2005WR003985. R831367 (2005)
    R831367 (2006)
    R831367 (Final)
  • Abstract: American Geophysical Union-Abstract
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  • Supplemental Keywords:

    aquatic environment, ecology, watersheds, indicators, EPA Regions 8, 9, 10, channel-reach morphology, scale, hydroclimatology, flow regime, stratification, regression analysis, cluster analysis, discriminant analysis, CART, RFA, Scientific Discipline, Water, Hydrology, Water & Watershed, Environmental Monitoring, Ecology and Ecosystems, Watersheds, ecosystem modeling, watershed classification, hydrogeomorphic categories, geomorphic, GIS, water quality, spatial & temporal scaling

    Relevant Websites:

    http://rydberg.biology.colostate.edu/~poff/ Exit
    http://www.engr.colostate.edu/~bbledsoe/ Exit

    Progress and Final Reports:

    Original Abstract
  • 2004 Progress Report
  • 2005 Progress Report
  • Final Report