Spring 2017

Mentor: Dr. Jonathan Phillips

Stream Channel Responses to Increased Nonpoint Source Pollution: A Spatial Analysis of Red River Gorge Watershed

Introduction

Throughout the state, the Kentucky Division of Water has recognized several watersheds in need of urgent restoration (Figure 1). This status is a result of at least one nonpoint source pollution such as urban runoff, failed septic systems, agriculture, and surface mining. Among this list is the Red River Gorge Watershed, covering ~148 mi^2. Within the drainage area, pathogens introduced by illegal dumping, loss of streamside vegetation, erosion, and runoff from towns, fields, surface mines, and mills threaten public health. KDOW has attributed the poor water quality to sources of increased sedimentation, impairing the aquatic habitat of local headwater tributaries. This project aims to define probable cause of increased sedimentation to unregulated outdoor regulation and other regional land uses as a function of the regional geology. Evident in Figure 2 and Figure 3, most portions of USFS designated trails lie on the more resistant upper Mississippian and Pennsylvanian formations. In Figure 4, however, the trails lying among seemingly resistant strata are actually lying amid a very expansive region characterized by risk of landslides and slope instability. Figure 5 illustrates the regional surface gradient, supporting the risk of slope failures as well as showing the range of elevation the trails actually occupy.  In Figure 2, concentrations of barren land and forested regions provide evidence for trail popularity, land use, and stream channel responses to increased sedimentation sources. Where the park is largely accessible, there will be increased impacts of downstream aquatic habitat impairment, sediment production, runoff, and bank destabilization. 

Methods

Assembling data of varying file types, sizes, and projections required performing different functions available in ArcGIS 10.1 including georeferencing, selecting by attribute, projection transformations, spatial joins, and extracting by mask. Using the slope function under spatial analyst tools was required to derive slope values for the DEM raster dataset. The statistics function was utilized to obtain stream and trail mileages within each sub-watershed.

Struggles to adequately represent the necessary data originated in the difficulties to locate applicable data online. Once the represented data was downloaded, problems georeferencing certain images and complications overlaying various files arose. Ultimately, it was determined that the desired overlays would only provide statistical data for different features present in their respective watersheds, information that is often considered inherently obtuse when investigating fragile ecological relationships. The affinity of one feature to another could be made with probable cause due to geographic distribution of spatial characteristics. Failure to georeference a pertinent Red River Gorge Forest Service Map prohibited the creation of a park boundary polygon, as well as a shapefile representing roads throughout the region. A Red River Gorge Geological Area map boundary would have added an appreciable reference to the region and spatial relationships in question; however, references to the land cover, geology, and USFS designated trails provides us with the opportunity to draw the same conclusions.

Data for the various representations of hydrology originated from sources including the Kentucky Geological Survey’s Geospatial Data Library, Kentucky Division of Geographic Information (KDOGI), Kentucky Division of Water, Kentucky Energy and Environment Cabinet, and the National Hydrologic Dataset provided by the USGS. These provided figures for the illustration of Kentucky River Basins, Major Rivers of Kentucky, Priority Watersheds, Stream Hydrology by County, and Hydrologic Units for Sub-Watersheds. Pertaining to the geographic units, the Kentucky state polygon was sourced from KDOGI and the Menifee-Powell-Wolfe County boundaries were collected from the KGS. The surface data by which many of the relationships have been based on originate from a host of sources involving a Simplified Geology of Kentucky file by KGS, 10 Meter DEM Elevation Service of Kentucky by USGS, Land Cover by the USGS and MRLC consortium, and designated trails provided by a USFS forest service map.

Discussion

Concentration of barren land are in proximity to Tunnel Ridge Road along popular and accessible trails, specifically the initial stretch of the Gray’s Arch Trail, around the junction of Auxier Ridge and Courthouse Rock Trails as well as ~200 ft. below this ridge-top section accompanying an upstream portion of a Red River headwater branch (Fish Trap Branch). Portions of barren land are also exposed on the gentle low gradient hillside immediately north of Nada Tunnel, a particularly sinuous part of the Ky 77 Scenic Byway [roads not illustrated]. A patch of barren land is also recognizable along the Rush Ridge Trail, specifically at a scenic viewpoint [trail names not illustrated]. Excessive foot traffic and visitor occupancy at these sites merely erodes the top surface of the ridge-line trails of resistant sandstone by disengaging ridge-top vegetation, allowing for any barren landscape exposure to be limited to the confined spatial extents of increased activity. High levels of recreational tourists in the region begin to increase sedimentation processes when the trails come in direct contact or close proximity to streams and regions of high grade topography. Though not as common within park boundaries [park boundary not illustrated], appearances of the pasture/hay land classification described by grass dominated vegetation, tends to lie adjacent to roads and alongside streams. Proximity and clustering of vegetation along streams could simply represent floodplain extent; however, it’s worth noting that just as the Red River leaves Menifee County and flows west into Powell County, the sinuosity of the channel increases abruptly along with the grassy vegetation occurrences. This is most likely occurring in response to a simultaneous drop in elevation, forest type, and geological unit transgression. Higher degrees of sinuosity are a function of greater volumes of sediment storage. Major accumulation of the grass-vegetated land increases with distance radiating from Red River Gorge boundary [boundary inferred in difference in Land Cover and is even more concentrated in regions that are more densely populated. This could be explained by an increase in neighborhoods, or similarly an increase in residential lawns.

Given by the land cover map, evergreen forest occupancy is constricted to the Clifty Wilderness region of the Red River Gorge Geological Area among the Clifty Creek and Swift Camp Creek Sub-watersheds. While it is safe to assume that increased human disturbance within a forested region would account for more degraded water qualities, the swift camp creek region of the gorge is least accessible and least popular. This is probably why the evergreens have remained populated there. However, the swift camp creek watershed also has the highest levels of pollutants. This can be attributed to city of Campton [not represented] that lies just southeast of the watershed. There, increased runoff and failed sewage systems have been identified as the prime contributors to the impaired water quality.