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.