Historical Analysis of Disturbance Zones on Finley Creek, Southwest Missouri<br />Derek J. Martin a and Robert T. Pavlowskybc<br />aResearch Specialist, Ozarks Environmental and Water Resources Institute, Missouri State University<br />bDirector, Ozarks Environmental and Water Resources Institute, Missouri State University<br />cProfessor of physical geography, Department of Geography, Geology and Planning, Missouri State University<br />This project applies geographic information systems (GIS) and the use of historical aerial photograph analysis to quantify channel change and assess watershed- and reach-scale relationships among channel disturbance zones, riparian vegetation, bank erosion, and gravel bar distribution along Finley Creek, southwest Missouri. Historical aerial photograph coverage of the main stem of Finley Creek was acquired for the years 1955, 1979, and 2005. Channel bank lines, gravel bars, and riparian land cover were digitized from each of the georectified photographs and overlaid in a GIS in order to identify disturbance zones. Disturbance zones were organized into one of four types: (i) extension, (ii) translation, (iii) chute cutoff, or (iv) megabar. Spatial analyses were performed to examine possible controlling factors of disturbance type development and evolution such as tributary and sub-watershed inputs, valley characteristics, channel confinement, and landuse/landcover. Initial investigations suggest that tributary drainage area and land use as well as valley characteristics exert a strong influence on disturbance reach development, whereas riparian land cover appears to have a negligible effect. This finding may result from the “internal” forcing effect that excess gravel bar deposition has on the channel bank erosion that is independent of bank resistance offered by vegetation. <br />Results and Conclusions<br />Study Area<br />Abstract<br />Classification<br />Finley Creek Watershed Characteristics<br />Mega-bar Formation<br />Kansas City<br />Chute Cutoff<br />Extension<br />Translation<br />St. Louis<br />Geology<br />Topography<br />Tulsa<br />N<br />Research Objectives<br />Landuse<br /><ul><li>Identify and classify disturbance zones on mainstem of Finley Creek
Investigate possible controlling factors of disturbance zone/type development
Interpret disturbance formation/evolution within the context of Ozarks physiography</li></ul>What’s a Disturbance Zone?<br />Extension<br />Translation<br />Chute Cutoff<br />Megabar Formation<br />median mig rate of .97m/yr<br />median mig rate of 2.23 m/yr<br />median length of 43.0 m<br />median channel displacement of 41.0m<br /><ul><li>An area where excessive erosion or deposition has taken place, often resulting in extreme changes in channel pattern (Jacobson, 1995)</li></ul>Disturbance Zones in Ozark Streams<br />Methodology<br />Landcover Influence<br />Aerial Photograph Acquisition<br />2006<br />1955<br />1955<br />1979<br />2006<br />3. Data Analysis<br />Dist Zone Determination<br />1. Historical Aerial Photograph Analysis<br />Maximum RMS error of 3.0<br />From Jacobson, 1995<br />Dist Zone Classificaton<br />Ozarks stream disturbance zone as described by Oscar H. Hershey - 1895<br />Photo Acquisition<br />Watershed Variables<br />Aerial Photograph-Derived Data<br />Photo Rectification<br />Sinuostiy<br />Disturbance Zone Identification<br />Error Analysis<br />Migration Rates<br />“…generally a narrow tract of river swamp deposit spreads to a few times the width of the stream, and changes about from side to side as it is displaced by the river approaching the bluffs”<br />Centerline buffer based on maximum photo rectification test point error<br />Some literature suggests that channel migration (disturbance) occurs more frequently in areas dominated by grass as opposed to trees. However, within the Finley River, riparian landcover appears to play no role in the development of disturbance areas. There was no difference between stable and disturbance zones when comparing them with the dominant landcover. <br />Drainage Area<br />Active Channel Width<br />2. Data Extraction/Compilation<br />Confinement Ratio<br />Riparian Landcover Analysis<br />Valley Confinement Influence<br />Valley Width<br />Channel Centerlines<br />Centerline Buffer for Error Compensation<br />Centerline Buffer for Riparian Landcover <br />Gravel Bars<br />Riparian Landcover<br />Channel Pattern Classification<br />Soils<br />DEM-Derived Data<br />DEM<br />Brice, 1975<br />In order to understand the history and behavior of disturbance zones in Finley Creek , they must first be identified and classified. Disturbance zone classifications have been adapted from the following chronology of channel pattern classifications.<br />Watershed Delineation<br />Slope Derivation<br />Rotation<br />Translation<br />10m DEM<br />Nanson and Hickin, 1983<br />Schumm, 1981<br />A t-test (α = .05) confirms that disturbance zones tend to form in areas with higher confinement ratios than stable zones.<br />Although dramatic changes in channel form have taken place at many disturbance areas, sinuosity has remained relatively stable.<br />Lobing and Compound Growth<br />Extension<br />Meander Classification<br />Slope<br />Stream Network<br />Sub-watershed Delineation<br />Continued Research<br />Stream Profile<br />Straight: <1.05<br />Sinuous: 1.05 ~ 1.25<br />Meandering: >1.25<br />Continued research will focus on factors affecting the development of each specific type of disturbance zone such as specific characteristics of valley confinement , contributing drainage area, and gravel accumulations.<br />Confining Valley Features<br />
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