Soil Types and Erosion Problems on Guilford College's Campus

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Soil Types and Erosion Problems on Guilford College's Campus Powered By Docstoc
					A GIS analysis of soil erosion potential on the Guilford College campus
      Abigail D. Blodgett and Angela M. Moore. Environmental Studies, Guilford College
                    North Carolina Academy of Sciences March 19, 2005
                                                                                 Introduction                                                                                                                                                                                         Erosion Observed on the Guilford College Campus
            Soil erosion is a serious environmental problem. It can cause degraded soil quality and decrease the productivity of the land. Also, excessive erosion can increase sediment
 pollution in streams and waterways. This can decrease water quality, make it a less suitable habitat for species living in the water, and increase the cost to maintain waterways.
            The purpose of this study is to determine if some areas on the Guilford College campus are more susceptible to erosion than other areas. Based on the characteristics of the land,                                          Where There is Visible Erosion on Campus                                                                      Amount of Mitigation at Each Site
 there may be more erosion in some areas than in others. Erosion will already be accelerated in some areas on campus due to current heavy construction, particularly around the Milner parking
 with the construction of 5 new dormitories and a community center. The Revised Universal Soil Loss Equation is used in this study to estimate the annual soil loss in tons per acre.                      There are 46 spots on the main part of
                                                                                                                                                                                                     campus where erosion is occurring. Signs of
                                                                                                                                                                                                     erosion that were looked for include a lack of                                                                                                                                                    The majority of erosion
                                                                                                                                                                                                     vegetation, an unnatural buildup of sediments,                                                                                                                                              points on campus, 28 out of the
                                                                                      Procedure                                                                                                      and gullies created by runoff during storms.                                                                                                                                                46, are not being mitigated at all.
                                                                                                                                                                                                           The majority of these points are located on                                                                                                                                           There are 16 points that are being
                                                                                                                                                                                                                                                                                                (to stream)
To evaluate the properties of soils found on Guilford College’s campus, a base map of the college was created using GIS Arc Map, version 9.0. Maps for water, streams, colleges, topography,        the Coronaco-Urban land complex (CuB). This                                                                                                                                                 slightly mitigated. This means
and buildings were obtained from the city of Greensboro, North Carolina. A map of soils in Guilford County was obtained from the National Cooperative Soil Survey.                                   soil type is on the most highly elevated part of                                                                                                                                            that there is a little hay thrown
                                                                                                                                                                                                     campus, and the rest of campus surrounding this                                                                                                                                             down on the area or some pebbles.
To evaluate the potential for erosion based on the properties of the soils on campus, a map was created using the National Cooperative Soil Survey data.                                            area down-cuts towards the stream and the lake.                                                                                                                                             There are only 2 points that are
                                                                                                                                                                                                     This means that the sediments lost from the                                                                                                                                                 being fully mitigated. This means
The next step was to estimate the amount of soil loss on campus. The Revised Universal Soil Loss Equation (RUSLE) was used to determine if certain areas of campus are more susceptible             majority of the points of erosion on campus are                                                                                                                                             that there is a substantial amount
to erosion than others. The K, R, C, and P factors were found through outside resources. The C factor values were added as a new column in the attribute table of the land use layer, the K factor   polluting the stream and the lake. A small amount                                                                                                                                           of pebbles on the area. Also, the 3
values were added to the attribute table of the soils layer, and then the layers were both converted to raster to set up for the RUSLE calculation. The LS factor was determined manually. Maps      of points are also located on the Coronaca clay                                                                                                                                             major areas of erosion near the
were created to show the K, C, and LS factors since they differ throughout the campus. The LS factor was determined using a raster data set with the raster calculator found in the Spatial          loam (CrC) soil type where the apartments are,                                                                                                                                              lake depicted by the RUSLE
Analyst tools. First, the slope of the area in degrees raster data was added in to the base map. Then, that data was used to find flow accumulation, and the flow accumulation was then used to      and the Madison clay loam (McD2) soil type                                                                                                                                                  findings as well as the findings
find the LS values. Finally, the RUSLE equation was solved by multiplying the 5 coefficients together in the raster calculator.                                                                      around the lake. The only difference between a                                                                                                                                              from the field observations are
                                                                                                                                                                                                     Coronaca soil and a Madison soil that affects                                                                                                                                               barely being mitigated.
The last was to determine how much and where soil erosion was actually occurring on campus. To do this, I used a Magellan Meridian Gold GPS unit to mark the points of erosion on                   erosion is that a Madison soil is on a somewhat                                                                                                                                                   According to this data,
campus. These waypoints were then loaded into the base map as a new layer in order to evaluate their location in relation to the type of soil at each point. I then added additional columns into    steeper slope (National Cooperative soil Survey                                                                                                                                             erosion is not being addressed as
the attributes table for the waypoints to show amount of mitigation at each site and the causes of erosion. Three maps were created from this data.                                                  1977).                                                                                                                                                                                      much as it should by the grounds
                                                                                                                                                                                                            There is a major correlation between the                                                                                                                                             staff. Since the soil lost is being
                                                                                                                                                                                                     outcome of the RUSLE equation and the erosion                                                                                                                                               transported into the stream, the
                                                                                                         Types of Soils on Campus                                                                    that is currently visible on campus. The 3 most                                                                                                                                             lake, and ultimately most of the
                          Greensboro, NC                                                                                                                                                             prominent lines of erosion on campus are on the                                                                                                                                             water bodies in Guilford County,
                                                                                                                                                                                                                                                                                                                                                                                                 controlling erosion should be
                                                                                                                                                                                                     edge of the athletic field, just as predicted by the
                                                                                                                                                                                                     RUSLE equation (see Annual Soil Loss on                                                                                                                                                     more of a concern to the college.
                                                                                               The meadows                                                                                           Campus Measured in Tons per Acre). These 3
                                                                                               are mostly                                                                                            major problem areas are contributing greatly
                                                                                               MhC2. This                                                                                            towards excessive sediment pollution in the lake.
                                                                                               soil has a low
                                                                                               potential for
                                                                                               urban uses
                                                                                               because of its
                                                                                               slope,                                                                                                                                                                    Causes of Erosion
                                                                                               and high mica                                                                                                                                                                                                            Runoff creates
                                                                                                                                                                                                                                                                                                                                                            Recommendations and Conclusions
                                                                                               content                                                                                                                                                                                                                  erosion when there
                                                                                               (National                                                                                             Lack of vegetation                                                                                                 is a period of                    Modeling general erosion trends with GIS is relatively straight-forward and can
                                                                                               Cooperative                                                                                           can be humanly                                                                                                     rainfall. When it                 be conducted with publicly available spatial data.
                                                                                               Soil Survey                                                                                           induced, a result of                                                                                               rains, the storm
                                                                                               1977).                                                                                                over grazing or                                                                                                    drain here empties                Using GIS to implement the RUSLE equation for general soil erosion
                                                                                                                                                                                                     foraging, or a
                      Potential for Erosion                                                                                                                                                          natural occurrence.
                                                                                                                                                                                                                                                                                                                        runoff, causing
                                                                                                                                                                                                                                                                                                                                                          effectively predicted some specific areas of significant erosion on campus, that
                                                                                                                                                                                                                                                                                                                                                          matched well with field observations.

                                                                                                                                                                                                                                                                                                                                                          Based on this study, this methodology appears to provide a good screening tool
                                                                                                                                                                                                      Heavy pedestrian
                          The majority of the soils on campus are classified as being                                                                                                                                                                                                                                                                     to identify locations with likely soil erosion problems.
                                                                                                                                                                                                      traffic removes
                         moderately eroded, so land use restrictions should be
                                                                                               The main part                                                                                          vegetation so there
                         considered. Methods to control erosion should always be                                                                                                                                                                                                                                                                          There are various practices that could be implement to control erosion more
                                                                                               of campus is                                                                                           is an increased
                         applied to construction sites on campus especially. If the                                                                                                                                                                                                                                                                       effectively on campus:
                                                                                               mostly CuB,                                                                                            amount of erosion
                         potential for erosion of these soils was ignored, it would                                                                                                                                                                                                                                                                            First of all, erosion mitigation should always occur when there is
                                                                                               an urban land                                                                                          because soil is
                         result in a significant amount of sediment pollution into the                                                                                                                                                                                                                                                                         construction. Some methods to do this are temporary sediment basins, cover
                                                                                               complex.                                                                                               exposed.
                         stream and the lake on campus, and ultimately all of the                                                                                                                                                                                                                                                                              areas that have a lack of vegetation with hay, cover sediment piles with
                         water bodies in Guilford County.                                                                                                                                                                                                                                                                   Erosion is also                    tarps, and vegetate the area as soon as possible.
                                                                                                                                                                                                     Construction                                                                                                           caused by                          To control erosion where there is a lack of vegetation, the grounds staff
                                                                                                   There are 13 types of soils on Guilford College’s Campus. There are 3                                                                                                                                                                                       should focus on keeping grass and/or basic plants all areas on campus.
                                                                                                                                                                                                     highly disturbs                                                                                                        runoff in these
                                                                                                sandy loams, 3 sandy clay loams, 4 clay loams, and 2 urban land                                                                                                                                                                                                The area on campus that is a source of erosion should be covered with
                                                                                                                                                                                                     soils by moving,                                                                                                       pictures. These
                                                                                                complexes.                                                                                                                                                                                                                                                     tarps if the school uses the leaves and the wood from these piles. If they
                                                                                                                                                                                                     uplifting, and                                                                                                         piles of soil
                                                                                                   The soil boundaries were created by estimation with the use of aerial                                                                                                                                                                                       aren’t used, then the piles should be dispersed throughout the woods.
                                                                                                                                                                                                     piling the soils so                                                                                                    were made by
                                                                                                photos, and then verification on the ground by soil scientists (Soil Survey                                                                                                                                                                                    Steep slopes should be prevented and leveled out.
                                                                                                                                                                                                     that more erosion                                                                                                      the grounds
                                                                                                Division Staff 1993).
                                                                                                                                                                                                     occurs with runoff                                                                                                     staff.
                                                                                                                                                                                                     and wind.                                                                                                                                            In addition to these simple methods for erosion control, the points of erosion
                                                                                                                                                                                                                                                                                                                                                          marked in this study should not be ignored after they are tended to by these
                                                                                                                                                                                                                                                                                                                        A source means that               controls. Since the campus is always changing, especially recently, it is crucial
                                                                                                                                                                                                                                                                                                                        there is a pile of                that these points are checked up on a least once a month to make sure that these
                                                   Estimated Annual Soil Loss Using RUSLE                                                                                                                                                                                                                               sediments that will
                                                                                                                                                                                                                                                                                                                        be eroded by rain or
                                                                                                                                                                                                                                                                                                                                                          controls are working and still existent.

                                                                                                                                                                                                                                                                                                                        wind. This source is               Also, there should be a future studies to collect field observations of erosion
                                                                                                                                                                                                                                                                                                                        a pile of leaves and              occurring in the woods to compare to the outcome of the RUSLE equation as well
                                       The Revised Universal Annual Soil Loss Equation (RUSLE)                                                                                                                                                                                                                          a pile of lumber on               as to measure sediment concentration in the streams and in the lake overtime to
  RUSLE is a general equation that provides                                                                                                                                                                                                                                                                             the edge of the                   determine the effect of any mitigation efforts.
  the basis for most assessment of soil erosion.                                                                               A= average annual soil loss in tons per acre                                                                                                                                             woods.
  It calculates the expected annual potential                                                                                  K= soil-erodibility factor                                                                                                                                                                                                 Overall, permanent erosion controls need to be implemented on campus in
  soil loss per acre based on rainfall pattern,                       A = K * R * C * LS * P                                   R= rainfall erosion index                                                                                                                                                                                                  addition to the temporary controls that generally already exist. Vegetating more
  soil composition, vegetative cover, slope and                                                                                C= crop management or plant cover factor                                                                                                                                                                                   areas on campus would be the easiest permanent erosion control. Also, there
  conservation practices. It is empirical, or                                                                                  LS= slope geometry, based on steepness and length                                                                                                                                                                          should existing steep slopes, especially near the lake, should be leveled out and
  based on observations, rather than                                                                                           P=conservation practice factors                                                                                                                                                                                            future ones should be prevented.
  theoretical.                                                                                                                                                                                       The Slope Geometry (LS Factor)                                                     The Annual Soil Loss on Campus Measured in
                                                                                                                                                                                                                                                    The LS factor is determined                         Tons Per Acre
                                                                                                                The Plant Cover Factor (C Factor)                                                                                                   by slope length and
                                                                                                                                                                                                                                                                                                                     The other 2 coefficient not
           The Soil Erodibility Factor (K Factor)                                                                                                                                                                                                   steepness in relation to the
                                                                                                                                                                                                                                                                                                                     picture are the rainfall
                                                                                                                                                        The C factor reflects the type of                                                           potential for erosion. The
                                                                                                                                                                                                                                                                                                                     erosion index (R factor)              Special acknowledgements towards Richard Farris for helping to identify soil types
                                                         The K factor values were                                                                       land cover in relation to the                                                               LS factor of each 5 ft by 5 ft
                                                                                                                                                                                                                                                                                                                     and the conservation                  for ground-truthing the county soil data and to Chris Freeman with the Greensboro
                                                         obtained from the Guilford                                                                     amount of rainfall interception.                                                            cell in this raster data set is
                                                                                                                                                                                                                                                                                                                     practice factors (the P               GIS office for providing the raster data to compute the LS factor.
                                                         County Soil Survey. The part                                                                   The woods on campus have the                                                                determined not only by the
                                                                                                                                                        lowest C factor at 0.003. This is                                                           slope within each cell, but                                      factor). The R factor for
                                                         of campus that is the most
                                                                                                                                                        because there is a canopy                                                                   from the cell around it at a                                     Greensboro is 225
                                                         developed has a soil
                                                         erodibility factor 0f 0.24. The                                                                preventing a large percentage of                                                            higher elevation. The                                            (Randolph 2004). The P
                                                                                                                                                                                                                                                                                                                     factor is 1 because there are
                                                         majority of the woods and the                                                                  rainfall from contributing to                                                               equation used to determine
                                                                                                                                                        erosion. The open fields have a                                                             the LS factor reflects                                           no conservation practices
                                                         area around the lake has a soil                                                                                                                                                                                                                                                                  National Cooperative Soil Survey. 1977. Soil Survey of Guilford County, North
                                                                                                                                                        slightly higher C factor, 0.004,                                                            variated topography.                                             on campus.
                                                         erodibility factor of 0.28. A                                                                                                                                                                                                                                                                    Carolina.
                                                                                                                                                        because there is less of a canopy.                                                          On campus, the areas with                                        The areas on campus with
                                                         small section of the woods
                                                                                                                                                        The developed part of campus                                                                the highest LS values are                                        the highest annual soil loss
                                                         and part of the meadows has a                                                                                                                                                                                                                                                                    Randolph, John. 2004. Environmental Land Use Planning and Management. Island
                                                                                                                                                        was classified as suburban with a                                                           directly west and along the                                      is on the edge of the
                                                         soil erodibility factor is 0.32.                                                                                                                                                                                                                                                                 Press, Washington D. C.
                                                                                                                                                        C factor value of 0.01 because                                                              stream in the woods and                                          athletic fields. This is
                                                         This means that the soils
                                                                                                                                                        there is less vegetation due to the                                                         surrounding the lake. This                                       because of the high C
                                                         covering the developed part                                                                                                                                                                                                                                                                      Soil Survey Division Staff. 1993. Soil Survey Manual. Soil Conservation Service.
                                                                                                                                                        presence of impermeable                                                                     mean that the sediments                                          factor value that the athletic
                                                         of campus are less susceptible                                                                                                                                                                                                                                                                   U.S. Department of Agriculture Handbook 18.
                                                                                                                                                        surfaces and human intervention.                                                            from the main part of                                            fields have. This result is
                                                         to erosion than the rest of
                                                                                                                                                        The athletic fields on campus                                                               campus flow downhill                                             especially problematic with
                                                         campus that is less disturbed.                                                                                                                                                                                                                                                                   Yang, D. S. Kanae, T. Oki, T. Koikel, & T. Musiake. 2003. Global potential soil
                                                                                                                                                        were classified as golf courses                                                             towards the stream in the                                        the field near the lake
                                                         This is because the soils on                                                                                                                                                                                                                                                                     erosion with reference to land use and climate change. Hydrological Processes, 17
                                                                                                                                                        with the highest C factor value of                                                          woods and the lake. This is                                      because there is a steep
                                                         the developed part of campus                                                                                                                                                                                                                                                                     (14): 2913-2928.
                                                         have a higher percentage of                                                                    ).2 because there isn’t any plants                                                          problematic because this                                         slope with sediment
                                                                                                                                                        besides grass and is highly                                                                 means that there is a certain                                    buildup on the edge that is
                                                         clay, which highly resistant to
                                                                                                                                                        altered by frequent mowing and                                                              degree of sediment pollution                                     closest to the lake (see
                                                         detachment from runoff
                                                                                                                                                        fertilizer. (Yang 2003).                                                                    occurring in the stream and                                      Causes of Erosion
                                                         (National Cooperative Soil
                                                                                                                                                                                                                                                    the lake.                                                        pictures).
                                                         Survey 1977).