Instream Geomorphic Units I. Intro → Geomorphic Units & Process-Form Associations II. Classification & Field Identification III. Your Book (River Styles) I. Sculpted, Erosional Bedrock & Boulder GUs II. Mid-Channel, Depositional GUs III. Bank-Attached, Depositional GUs IV. Sculpted, Erosional Fine-Grained GUs V. Unit & Compound GUs VI. Forced GUs IV. Continuum of GUs V. Fluvial Taxonomy GUs (Topographically Defined) I. Tier 1 – Stage II. Tier 2 – Shape / Form III. Tier 3 – Attributed VI. GUT (Geomorphic Unit Toolkit) Reminder… • In fluvial, we found over 100 different terms to describe geomorphic units, of which 68 were actually distinctive… • This is based on same units as above, but with some clarifications • Done with your Book’s Authors • The legend should include a) margins, b) geomorphic units, and c) structural elements From: Wheaton et al. (2015) – Geomorphology; DOI: 10.1016/j.geomorph.2015.07.010 Taxonomy for Mapping Fluvial Landforms • Four Tiers • Stage Height • Shape / Form • Morphology • Roughness/Vegetation • Over 100 fluvial geomorphic units found in literature, of which 68 are distinctive (3b) • Clearer, topographically based definitions From: https://riverscapes.github.io/pyGUT/ Wheaton et al. (2015) DOI: 10.1016/j.geomorph.2015.07.010 Williams et al. (2020) DOI: 10.1016/j.scitotenv.2020.136817 Instream Geomorphic Units I. Intro → Geomorphic Units & Process-Form Associations II. Classification & Field Identification III. Your Book (River Styles) I. Sculpted, Erosional Bedrock & Boulder GUs II. Mid-Channel, Depositional GUs III. Bank-Attached, Depositional GUs IV. Sculpted, Erosional Fine-Grained GUs V. Unit & Compound GUs VI. Forced GUs IV. Continuum of GUs V. Fluvial Taxonomy GUs (Topographically Defined) I. Tier 1 – Stage II. Tier 2 – Shape / Form III. Tier 3 – Attributed VI. GUT (Geomorphic Unit Toolkit) Tier 1 – Stage Height -> Leads To Geomorphic Map • The building blocks of a Valley? vs. • The building blocks of a Valley Bottom? Wheaton et al. (2015) DOI: 10.1016/j.geomorph.2015.07.010 Reading your riverscape… • The building blocks of the riverscape? • Channel is easy place to start, but then From Wheaton et al. (2019) – LTPBR Manual look for Hs, Tr and Fa to back into Fp DOI: 10.13140/RG.2.2.19590.63049/1 A Common Impact We added one more to the legend: inactive floodplain Areas that could plausibly flood, but are not currently and are not supporting riparian vegetation. What we historically do with that riverscape… We use it! Tier 1 Applied • Contrasting valley settings show different distributions of tier 1 geomorphic Units… Confined Laterally Unconfined From: Wheaton et al. (2015) – Geomorphology; DOI: 10.1016/j.geomorph.2015.07.010 Partly-Confined Wheaton et al. (2015) DOI: 10.1016/j.geomorph.2015.07.010 Instream Geomorphic Units I. Intro → Geomorphic Units & Process-Form Associations II. Classification & Field Identification III. Your Book (River Styles) I. Sculpted, Erosional Bedrock & Boulder GUs II. Mid-Channel, Depositional GUs III. Bank-Attached, Depositional GUs IV. Sculpted, Erosional Fine-Grained GUs V. Unit & Compound GUs VI. Forced GUs IV. Continuum of GUs V. Fluvial Taxonomy GUs (Topographically Defined) I. Tier 1 – Stage II. Tier 2 – Shape / Form III. Tier 3 – Attributed VI. GUT (Geomorphic Unit Toolkit) Tier 2 – Applied Shape From: Wheaton et al. (2015) – Geomorphology; DOI: 10.1016/j.geomorph.2015.07.010 Assemblages Wheaton et al. (2015) DOI: 10.1016/j.geomorph.2015.07.010 If I land on a riffle, but don’t know it TIER 1 – ON THAT RIFFLE • Not so bad… TIER 2 - SHAPE • d Tier 2 - Shape • Just add a verb to tier 1, so it’s a Concave In Channel Unit (i.e. concavity) Concave Planar Convex Tier 2 – Shape & Form • Just add a verb to tier 1, so it’s a Concave In Channel Unit (i.e. concavity) Concave Planar Convex SADDLE Tier 2 - Form • Differentiating shape longitudinally (i.e. stream-wise), vs. laterally (i.e. cross sectional) e.g., bars e.g., riffles e.g., banks/ avalanche e.g., plane e.g., chute, e.g., pools faces bed, run, glide, shallow Edges rapid thalwegs Mound Saddle Wall Plane Trough Bowl XS Convex Concave NA Planar Concave Concave LP Convex Convex NA Planar Planar Concave Instream Geomorphic Units I. Intro → Geomorphic Units & Process-Form Associations II. Classification & Field Identification III. Your Book (River Styles) I. Sculpted, Erosional Bedrock & Boulder GUs II. Mid-Channel, Depositional GUs III. Bank-Attached, Depositional GUs IV. Sculpted, Erosional Fine-Grained GUs V. Unit & Compound GUs VI. Forced GUs IV. Continuum of GUs V. Fluvial Taxonomy GUs (Topographically Defined) I. Tier 1 – Stage II. Tier 2 – Shape / Form III. Tier 3 – Attributed VI. GUT (Geomorphic Unit Toolkit) Tier 3 • Get to those names: • e.g., Pools, Riffles, Point Bars, Runs From: Wheaton et al. (2015) – Geomorphology; DOI: 10.1016/j.geomorph.2015.07.010 Tier 3 - Morphology • d Wheaton et al. (2015) DOI: 10.1016/j.geomorph.2015.07.010 Wheaton et al. (2015) Key Attribute Definitions DOI: 10.1016/j.geomorph.2015.07.010 A Bunch of Horrible (but useful) Tables • Lists the values of Key Attributes (from Table 6) to help you discriminate units • Definition is based on Tiers 1 & 2 plus these discriminating attributes • Also provide other “known as” or commonly confused with. 36 of 68 Fluvial Geomorphic Units are In-Channel Wheaton et al. (2015) • DOI: 10.1016/j.geomorph.2015.07.010 Convexities - Bars Concavities (Pools) & Planar Wheaton et al. (2015) Filtering Through Taxonomy DOI: 10.1016/j.geomorph.2015.07.010 Active Tier 1: In-Channel Floodplain Terrace Fan Hillslope Total: Tier 1 Count 1 1 1 1 1 5 Tier 2 Count 3 3 3 3 3 15 Tier 3: ∟Concavities 12 12 1 1 1 27 ∟Convexities 18 5 0 3 1 27 ∟Planar 6 5 2 0 1 14 Tier 3 Subtotal: 36 22 3 4 3 68 • Prior to Tiers… could be one of 68 n = 68 • @ Tier 1, knowing I’m in channel, one of 36 n = 36 • @ Tier 2, knowing I’m a concavity, one of 12 n = 12 • @ Tier 3, knowing I’m forced by___, one of ___ Back to that Riffle Tier 1 Tier 2 Tier 3 Stage Height Shape/Type Specific Morphology Key Attributes to Differentiate Specific Morphologies GU Forcing Low Flow Relative GU Orientation GU Position Low Flow Water Roughness Surface Slope Also Known As Similar to or Confused With In-Channel ∟ Convexity (e.g. bar) Similar to other bars but found in disconnected side channels or ∟ Backwater Bar Grade Control Varies Varies Side Channel Varies Slackwater deposit secondary channels Bank-Attached or Similar to other bars, but in much ∟ Boulder Bar Flow Width Varies Streamwise Mid-Channel Varies Boulder Berm higher gradient systems. An amalgamation of multiple unit bars and other bar types (complex ∟ Compound Bar Varies Varies Varies Varies Varies Bar complex history) Expansion bar, except in response Radial DS & to gradient drop from tributary to ∟ Confluence Bar Grade Control Varies Streamwise Bank-Attached Varies NA mainstem. Planform & Flow Width Point bar, but no longer bank- ∟ Diagonal Bar Expansion Varies Diagonal Mid-Channel Varies Mid-Channel Bar attached (separated by chute) Planform, SE, and/or Flow Bank-Attached or ∟ Eddy Bar Width Constriction Varies Streamwise Mid-Channel Varies Separation Bar Transverse bar, but in response to slope lowering, and does not span ∟ Expansion Bar Flow Width Varies Transverse Mid-Channel Varies NA channel Bank-Attached or ∟ Forced Bar Varies Varies Streamwise Mid-Channel Varies NA Eddy Bar Riffle, but forced by channel spanning structural element buried ∟ Forced Riffle Channel Spanning SE Moderate (< 1) Transverse Channel Spanning Shallow NA in bed Point bars, but can be in bends with By Planform or By Flow lower curvature or channels with ∟ Lateral Bar Width Varies Streamwise Bank-Attached Varies Alternate Bar lower sinuosity or straight Similar to other mid-channel bars but distinctive in DS tear-dropped ∟ Lobate Bar Grade Control Varies Radial DS Mid-Channel Varies Mid-Channel Bar shape and avalanche faces Similar to other mid-channel bars but distinctive in elongated streamwise orientation and ∟ Longitudinal Bar Flow Width Varies Moderate (< 1) Mid-Channel Varies Mid-Channel Bar upstream convexity at bar head Alternate bars, but in bends with ∟ Point Bar Planform forced Varies Streamwise Bank-Attached Varies Bank-Attached Bar higher curvature Eddy Bar, but occurs DS of both flow separation and reattachment ∟ Reattachment Bar Varies Varies Streamwise Bank-Attached Varies NA point Forced by SE and Flow Scroll bar or levee; generally ∟ Ridge Separation Varies Streamwise Bank-Attached Varies NA straighter, more linear feature ∟ Riffle Flow Width Expansion Moderate (< 1) Transverse Channel Spanning Moderate Transverse Bar Sometimes confused with runs Planform & Flow Width Ridge, but positioned on point bar ∟ Scroll Bar Expansion Varies Streamwise Bank-Attached Varies NA and generally curved The fundamental building block of all ∟ Unit Bar Flow Width Expansion Varies Varies Varies Varies NA bars Wheaton et al. (2015) DOI: 10.1016/j.geomorph.2015.07.010 TIER 3 - MORPHOLOGY • d Key Tier 3 Attributes: Types Description Occurs when a non-uniform hydraulic flow pattern creates a flow environment conducive to forcing the formation, GU Forcing maintenance or accentuation of a geomorphic unit. ∟Not Forced The GU forms on its own (e.g. free bars) ∟By Structural Element Forcing can be caused by structural elements (e.g. large woody debris causing a plunge pool or an eddy bar) ∟By Geomorphic Unit Forcing can be caused by another geomorphic unit (e.g. a pool can be forced by a bar) ∟By Planform Forcing can be induced by sinuosity (e.g. flow separation on inside bends leading to point bars) Forcing is often associated with flow width expansion for depositional units and flow with constriction for erosional units ∟By Flow Width GU Orientation The orientation is defined by the longest axis of the geomorphic unit and relative to dominant flow direction.