Historical Analysis of Disturbance Zones on Finley Creek, Southwest MissouriDerek J. Martin a and Robert T. Pavlowskybc
aResearch Specialist, Ozarks Environmental and Water Resources Institute, Missouri State UniversitybDirector, Ozarks Environmental and Water Resources Institute, Missouri State University
cProfessor of physical geography, Department of Geography, Geology and Planning, Missouri State University
Results and Conclusions
Channel Pattern Classification
Translation Rotation
Extension
Lobing and Compound
Growth
Nanson and Hickin, 1983Schumm, 1981
Brice, 1975
Straight: <1.05Sinuous: 1.05 ~ 1.25Meandering: >1.25
Meander Classification
Research Objectives
•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
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.
1955 2006
What’s a Disturbance Zone?
• An area where excessive erosion or deposition has taken place, often resulting in extreme changes in channel pattern (Jacobson, 1995)
From Jacobson, 1995
Disturbance Zones in Ozark Streams
“…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”
Ozarks stream disturbance zone as described by Oscar H. Hershey - 1895
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.
Classification
R² = 0.0843
R² = 0.0936
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100
% G
rass
Co
ver
Distance Downstream (km)
% Grass Cover
Dist Stable
R² = 0.1015
R² = 0.1481
40
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100
% F
ore
st C
ove
r
Distance Downstream (km)
% Forest Cover
Dist Stable
R² = 0.0139
R² = 0.0762
0
5
10
15
20
25
30
0 10 20 30 40 50 60 70 80 90 100
% G
rave
l Co
ver
Distance Downstream (km)
%Gravel/Other
Dist Stable
0
100
200
300
400
500
600
700
800
0 10 20 30 40 50 60 70 80 90
Val
ley
Wid
th (
m)
Downstream Distance (km)
Downstream Location of Disturbance AreasChute Cutoff
Translation
Extension
Mega-Bar
.16 Dist per Km .90 Dist per Km .80 Dist per Km
ExtensionTranslationChute CutoffMegabar Formation
median mig rate of .97m/yrmedian mig rate of 2.23 m/yrmedian length of 43.0 mmedian channel displacement of 41.0m
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.
Landcover Influence
Valley Confinement Influence
Study Area
Finley Creek Watershed Characteristics
St. Louis
Kansas City
Tulsa
Geology
Topography
LanduseN
Chute Cutoff Extension TranslationMega-bar Formation
Methodology
2. Data Extraction/Compilation
Channel Centerlines
Centerline Buffer for Error Compensation
Centerline Buffer for Riparian Landcover
Gravel Bars
Riparian Landcover
Soils
DEM
Watershed Delineation
Slope Derivation
3. Data Analysis
Dist Zone Determination
Dist Zone Classificaton
Watershed Variables
Sinuostiy
Migration Rates
Drainage Area
Active Channel Width
Valley Width
Confinement Ratio
1. Historical Aerial Photograph Analysis
Photo Rectification
Error Analysis
Photo Acquisition
10m DEM
Slope
Confining Valley Features
Stream Network
Stream Profile
Sub-watershed Delineation
DEM-Derived Data
1955 1979 2006
Aerial Photograph Acquisition
Maximum RMS error of 3.0
Aerial Photograph-Derived Data
Disturbance Zone Identification
Riparian Landcover Analysis
Centerline buffer based on maximum photo rectification test point error
0
5
10
15
20
25
30
35
40
20 30 40 50 60 70 80 90
Co
nfi
nem
ent R
atio
(W
v/W
c)
Downstream Distance
Confinement Ratios
Disturbance
Stable
A t-test (α = .05) confirms that disturbance zones tend to form in areas with higher confinement ratios than stable zones.
Although dramatic changes in channel form have taken place at many disturbance areas, sinuosity has remained relatively stable.
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1955 1979 2006
Sin
uo
sity
Upper
Middle
Lower
Abstract
Continued Research
Continued research will focus on factors affecting the development of each specific type of disturbance zone such as specificcharacteristics of valley confinement , contributing drainage area, and gravel accumulations.
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