Soil Movement in West VirginiaWatersheds

A GIS

Assessment

Greg HamonsDr. Michael StragerDr. 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

Oven Dry and Burn Pour off and discard

Place in water

(Mostly Mineral)

Manually separate predominantly mineral from

predominantly organic

Mineral associated with predominantly organic fraction

Apply average percent to predominantly organic fraction weight

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

Mineral associated with predominantly mineral fraction

Total Sediment

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,

Land-cover, 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

Spatial Analysis Toolbar

Slope Grid

Raster Calculator

Moisture Index

HydrologyTools

Flow Direction

Flow Accumulation

Stream Networks

Digital Elevation Map (DEM) 3-MeterResolution

DistanceGrids

Aspect Grid

Curvature

Inputs --- Tools ---

Output Grids ---

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

21.58º Followed by: Moisture- +3.62 (Range -4.3 – 7.6) Aspect- 141º

– 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