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Big Cypress/Caddo Watershed Geomorphic Classification

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Presentation on theme: "Big Cypress/Caddo Watershed Geomorphic Classification"— Presentation transcript:

1 Big Cypress/Caddo Watershed Geomorphic Classification
Ryan Smith The Nature Conservancy of Texas

2 Utility of River Classification
Understand watershed context of the river Understand normal channel, habitat, and biological characteristics Understand impacts on natural characteristics Selection of reaches for studies of habitat, water quality, riparian, etc

3 River Styles Brierly and Fryirs 2000 Developed in Australia
Selected by TCEQ, TPWD, and TWDB for Texas Instream Flows Program Meets recommendations of NAS review Physical basis Channel morphology Hierarchical structure Physiographic/hydrologic setting Floodplain and riparian zone

4 Stages of a River Styles Procedure
Stage 1 Data Compilation (description and mapping) • Derive watershed boundary conditions • Determine landscape units • Assess river character Stage 2 Data Analysis • Define and interpret River Styles • Explain contemporary character/behavior • Assess river history Stage 3 Predict future river structure Stage 4 Prioritize watershed management issues Stage 5 Identify target conditions for river

5 River Styles Hierarchy
Watershed Watershed area determined by drainage divide. Determines the boundary conditions within which rivers operate. Landscape Unit Topographic unit determined on the basis of local relief, valley slope and morphology. Defines the valley-setting. River Style Length of channel with a characteristic assemblage of geomorphic units. Geomorphic Unit Instream and floodplain landforms (pools, bars, levees, backwaters, etc.) that reflect distinct form-process associations. Hydraulic Unit Uniform patches of flow and substrate material within a geomorphic unit. Microhabitat Individual elements (e.g., logs, rocks, gravel patches) within a stream.

6 GIS Data Atlas TNC NFWF grant
GIS data atlas for the Caddo Lake watershed West Gulf Coastal Plain aquatic conservation priorities Considering development of data for River Styles Stage 1 analysis of Big Cypress Bayou watershed TNC aquatic ecosystems classification Many river characteristics calculated in a GIS Consider data’s usefulness for River Styles Consider developing additional data in the data atlas work

7 TNC Aquatic Ecosystems Classification
Mapped in 1:100K National Hydrography Dataset Variables: Watershed area Gradient Contributing area geology Longitudinal connectivity

8 River Styles for Big Cypress Watershed?
Undertake a River Styles analysis for Big Cypress Bayou watershed? Value added? Relationship to other studies (e.g., channel cross-sections)? Relationship to characterization, classification of hydrologic regime What are the most important aspects of river characteristics in the area that would need to be included in the development of River Styles here? Watershed characteristics? Landscape, geomorphic unit characteristics? What data are needed? Is TNC’s data useful? What else needed? Limitation of geomorphology expertise

9 River Styles: Australian Example
Watershed Namoi River Basin, New South Wales Macdonald/Manilla Sub-basin Lower Namoi Sub-basin Peel Sub-basin Middle Namoi Sub-basin 25 50 75 100 Kilometers Mooki Sub-basin

10 River Styles: Australian Example
Watershed Namoi River Basin, New South Wales Landscape Unit 25 50 100 Kilometers Legend – Landscape Units Liverpool plains Pillaga outwash Lowland plains Rugged metasediments Mid to lower Peel Rugged volcanics Pillaga Uplands

11 Vertically Accreated Floodplain River Style Floodplain Accumulation
Landscape Unit Uplands Escarpment Base of the Escarpment Rounded Foothills Lowland Plain Channel Slope Channel and Valley Width Planform Valley Cross Section Head-water Cut & Fill (Incised) Vertically Accreated Floodplain River Style Floodplain Accumulation Fan Cut & Fill (Intact) Floodout Gorge Throughput Transfer

12 River Styles: Australian Example
Watershed Middle Namoi Sub-basin Landscape Unit River Style 25 50 Kilometers

13 Geomorphic Unit Hydraulic Unit Microhabitat
Trailing Vegetation Backwater Rippled flow on cobbles Submerged Macrophyte Riffle Barely perceptible flow on sand Cobbles Smooth surface flow on cobbles/sand Floodplain Large Woody Debris Pool Smooth surface flow on cobbles Run Bar Secondary Channel Boulders Sand Pool Barely perceptible flow on sand/boulders Leaf Pack

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