Soil Movement in West Virginia Watersheds A GIS

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Soil Movement in

West Virginia

Watersheds

A GIS

Assessment

Greg Hamons

Dr. Michael Strager

Dr. Jingxin Wang

A little about me….

Native West Virginian

Pocahontas County

B.S. in Forest Resource Management

Seeking M.S. Forestry

Very interested in Forestry and GIS Analysis!

Issue

Sedimentation

Soil movement can cause lots of damage especially when its moving into water resources.

Pollution of streams, Raise flood levels, Raise stream temperatures, Degrade site/stream quality and Productivity, and reduce navigational abilities.

Sediment created from Silvicultural

Operations is the issue at hand.

Project Description

Problems:

Soil Movement, specifically sedimentation, is very detrimental to streams and forested sites.

Pollution to Water Resources

Site Degradation-Both Environmentally and Aesthetically

Habitat and Productivity Loss-Both Onsite and Downstream

Assess Best Management Practices (BMP) Functionality

GOAL: FIND SIGNIFICANT SOIL MOVEMENT

CONTRIBUTORS and IDENTIFY DIFFERENCES

BETWEEN WATERSHEDS

Project: Study Area

Two Watersheds located in Tucker County, WV

Both Similar in

Geologic and

Physical Makeup.

Slopes

Elevations

Land-cover etc…

Project Description

Study designed to evaluate soil movement and it’s relation to logging.

Two Watersheds (Control and Treatment)

Silt-fence Installed around all Streams

Material Removed Once a Year

Extensive Mapping Procedures

Classification/Regression Trees to Model and/or Predict Sedimentation

Silt-fence Installation

Data Collection and Recording

Total Oven-Dry

Material

Burn sub-samples, calculate average percent mineral (Mostly Organic)

Apply average percent to predominantly organic fraction weight

Mineral associated with predominantly organic fraction

Manually separate predominantly mineral from predominantly organic

Place in water

(Mostly Mineral)

Oven Dry and Burn Pour off and discard

Total Sediment

Mineral associated with predominantly mineral fraction

Methods

Use GIS to identify Landscape elements in each watershed that contribute to soil movement. (i.e.

Disturbance, Moisture, Slope, Soil Types, etc…)

Calculations: Derived From Digital Elevation Map

Slope, Aspect, Flow Direction, Flow Accumulation, Moisture

Index, Distance Grids (from road, from stream, etc.), Soils,

Landcover, etc…

Many Variables!

Analysis Performed Using Various Extensions of the

ESRI ArcMap 9.1 GIS program. As well as the newly developed

3-Meter DEM

and Aerial Photography from the WV GIS Tech-center.

Statistical Method-Classification Trees

R Statistical Package

Digital Elevation Map (DEM) 3-Meter

Resolution

Spatial Analysis Toolbar

Slope Grid Distance

Grids

Curvature

Aspect Grid

Raster Calculator

Moisture Index

Inputs --Tools ---

Output Grids ---

Hydrology

Tools

Flow Direction

Flow

Accumulation

Stream Networks

Sediment a function of…

Sediment Reaching Silt-fence=

F (Slope, Distance From Silt-fence, Distance

From Disturbance, Distance From Slope

Breaks, Moisture, Aspect, Accumulation, Soil

Type, Vegetation, Land-use, )

Very Dynamic Subject

Ecological Land Units (ELU)

Moisture Index

This index assumes that the relative moisture in a particular area (in this case a grid cell) primarily depends on two factors;

How much water is flowing into the area and how fast the water can flow out of the area.

Ln [(catchment area + 1) / (slope + 1)]

The created index is a relative one so the numbers don’t represent any type of units.

Higher Positive Numbers are Wetter

Lower Negative Numbers are Drier

Strager (2006)

Analyses Performed

Also:

Classification Tree Modeling Technique

Statistical Analyses (S-plus and R Statistics Systems)

Future Analyses

Stream Loading-Sediment

Refining of Classification Tree Modeling

Key to possibly modeling the soil movement or sedimentation

Results

According to the Statistical Modeling: R

Slope is the most important variable

21.58

º

Followed by:

Moisture- +3.62 (Range -4.3

– 7.6)

Aspect- 141

º

– Combined Grids Using Raster Calculator

Model Refinement to Include more Variables

Coming Soon!

Conclusions

3-Meter DEM much higher accuracy!

1:4800 scale aerial photography gives great visual representation!

Leads to more thorough analysis.

Detailed 3-D Representation.

Hydrology Tools Very Influential

Upon Completion of Analyses:

Identify Contributors to Soil Movement

Order there level of Importance

Assess current Best Management Practices (BMP)

Model/Predict Soil Loss

Thank You

Any

Questions?

References

(Grayson et al. 1992; Mitasova 1996; Moore, I. D. et al. 1988; Boer et al. 1996, O’Loughlin 1986, Parker 1982)

Strager 2006

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