Impact of Intensive Production Forestry on Water Quality

• Assessing the impacts of forest cutting, site preparation, and intensive silvicultural treatments on storm runoff, water yield, water chemistry, vegetation development, and soul properties.

• Assessing the effects of herbicide releases applications and fertilization in forest streams.

• Assessing downstream impacts of upstream practices.

• Comparing the impacts of current watershed treatments to those conducted at the sites 20 years ago.

 

   TexIS (Texas Intensive Silviculture Study) Bulk Density Evaluation

    The objective of this project is to evaluate changes in soil organic carbon due to afforestation of marginal farmland in east Texas.  In order to effectively monitor changes in SOC over the duration of the afforestation project, a baseline for SOC was needed.  In order to understand the spatial distribution of SOC before tree planting on the farmlands used in the project, baseline SOC values were displayed using GIS technology.

    A two ha sampling grid system was overlaid on aerial photographs of the properties.  GPS coordinates for the plot centers where determined in the GIS laboratory and located in the field using a GPS unit.  A steel post was set at each plot center.  Two soil samples, one 1m north and the other 1m south of the plot center, were extracted using a push probe to a depth of 40 cm at each point.  Each sample was dried at 70^oC, ground to pass a 2mm sieve, and analyzed for carbon and nitrogen content on a Leco C/N analyzer.

    The GIS carbon model provided evidence of anthropogenic influences on SOC on these properties, probably due to manure spreading from the dairy operations.  The soil mapping units from the soil survey were not effective predictors of variation of SOC, probably again due to anthropogenic influences.  Total nitrogen concentrations are usually strongly correlated to SOC.  The Nitrogen models indicated that the relationship holds on these study sites.

    The accuracy of two popular GPS receivers, the Trimble GeoExplorer 3 and the Trimble Pro XRS that were chosen for their common use and wide range in purchase price, are evaluated for use in natural resource applications.  With the increased popularity of GPS involved with natural resource management activities in recent years, and the wide range in purchase price of current units, it is imperative that the users understand the ability of each unit to accurately identify the true horizontal and vertical location of a surface feature.  It is the objective of this project to assess the accuracy of the two most popular GPS units used by natural resource professionals by comparing the distance between GPS derived points and their corresponding surveyed points on a time continuum (e.g. number of received satellite signals per surface feature location), to ascertain the relative efficiency of each receiver.

    Once their relative accuracy has been identified, natural resource managers will be able to save time and money by assessing the relative efficiency of each receiver based on a particular managers mapping, location identification and navigational needs by analyzing the cost and time involved to identify the true horizontal and vertical location of a surface feature.

    The goal of the project was to assess the spatial and seasonal variation of the most significant floods, maximum magnitudes, and flood-area relations in the conterminous U.S.  This was done by using:

• 843 U.S. floods with return periods greater than 100 years occurred prior to 1995 were obtained from a USGS flood Summary report (Perry et al., 2001).

• 26 extraordinary floods were obtained from studies by Rodier and Roche (1984) and Costa (1987).

• It yielded 869 most significant floods, 578 were in the eastern and 291 were in the western U.S.

• The size of watershed areas in four category groups and % number of watersheds in each group were no significant differences between the East and West.

• The maximum floods delineated by envelope curves showed no difference among the East, West and the East and West combined, and were slightly greater than those estimated by Costa (1987).

• The East had the mean of the floods 11% higher and mean K coefficient significantly greater than the West, but it had a smaller number of floods with K>5 than the West (72 or 4% vs. 30 or10%).

• Of the six regions, the potential for producing severe floods seems to be greater in the S. Plains and Southeast regions and less in the Mt/N. Plains and Cornbelt/Lakes States regions.

• Floods occurring in the S. Plains, especially in the south-central Texas along the Balcones Escarpment, are potentially higher than any other regions in the conterminous U.S.

• Extreme floods can occur in any season of the year, but certain seasons may have greater potential than others due to geographical locations.

• In the Pacific Coast where marine climates dominate, more the 3/4 of the most significant floods occurred in late winter and early spring (December-February).

• In the continental dominated climate Mt/N. Plains region, 2/3 of the floods occurred in late spring and early summer (May-July), however the impact of the Gulf of Mexico causes the summer 6 months (May-Oct) in the S. Plains to account for more than 90% of the floods.

• In the East, more than 50% of the floods occurred in June-August for the two northern regions and March and April for the southern region.

• Due to the great variation of the floods and a small sample size, the developed Q-A models in arid regions were less accurate than those for humid regions.

    A user-created trail is any non-system path created by the passage of visitors, in our case commercial pack stock, which is discernible and would not likely recover within one year.  The commercial Pack Stations identified the trails that they use and/or used in the past that are greater than 0.25 miles.  Field work was then done to locate these trails and classify sections of the trail as being; an incision, trail widening, having vegetation and sod damage, trail dividing into multiple trails, water diverted onto the trail, or the section is in fine order.  A Trimble GeoXT GPS devise was used to log each section as a line feature.  Each section is then evaluated on its overall and potential condition being that 1 is that the general impacts are light to 3 being that serious resource problems are imminent and immediate attention is required.  Point data was also collected with the GPS to indicate specific problems found on the route being; a stream crossing, vegetation and sod damage, spring and seep crossing, and/or headcuts and nickpoints associated with the trail.  Each point had an overall condition factor as identified above.

    The primary goals of this project were to:

• Inventory non-system trails that commercial pack stock have requested authorization to use.

• Establish a baseline of conditions or characteristics for the user-trails.

• Prevent the creation of additional user-created trails and limit the impacts associated with existing user-created trails.

• Emphasize managing or eliminating user-trails that route to locations the system trail already extends to.

    Once a complete evaluation is done on the trails, the trail will be either approved for usage or not approved and commercial stock will no longer be able to travel that route.

Costa, J. E., 1987. A comparison of the largest rainfall-runoff floods in the United States with those of the People's Republic of china and the World. Jour. Hydrology 96(1987): 101-105.

 

Perry, C. A., B. N. Aldridge, and H. C. Ross, 2001. Summary of Significant Floods in the United States, Puerto Rico, and the Virgin Islands, 1970 through 1989. USGS Water Supply Paper 2502. 598 pp.