Station Research

The Western Carolina Hydrologic Research Station (WCHRS) is located on the campus of Western Carolina University in Cullowhee, North Carolina. The natural setting of the station and the land use history, is typical of much of the Southern Appalachians, specifically in western North Carolina.

Map of Western Carolina Hydrological Research Station

  

The research station is located within the Cullowhee Creek watershed and includes part of the Long Branch watershed and the entire Gribble Gap headwaters basin.

The groundwater studies are focused at stream reaches in three different geomorphic zones: Gribble Gap Creek (0.44 km 2a colluvial reach, flows into Long Branch (4.39 km 2an alluvial-colluvial reach, which flows into Cullowhee Creek (62 km 2) an alluvial reach.

The research station is equipped with about 45 groundwater wells, 3 rain gage sites, 9 soil moisture sites on 3 slopes, 6 stream gages, and one sampling lysimeter. For more information on locations and equipment, explore the Research Station Facilities.

What is studied at the station?

There are three primary scientific research objectives for the site:

  1. Determine how the interaction of groundwater and stream water vary with their geomorphic (aka landscape) setting. Fundamental to this question is the underlying hypothesis that the geomorphic setting of streams is predictive of hydrologic processes, including the interaction of groundwater and stream water (Walsh et al. 2010; Hiatt et al. 2011). This is important to understanding the quantity of water resources as well as the quality in both streams and groundwater.
  2. Document where and when recharge of groundwater occurs in the watershed, especially as it relates to different bedrock and soil types, landscapes, and land covers.
  3. Understand the influence of historic land uses and ongoing changes in land cover today on water resources and quality. Though the focus of research is on questions related to watershed hydrology, interdisciplinary questions, especially related to ecosystems, are also studied. Most of the specific questions studied are relevant to regional problems. A goal of the studies is to provide improved scientific understanding to guide sound environmental management.

Subject Matter

Specific areas of Research

Below you'll find details and figures on specific areas of the research performed at the WCHRS.

GROUNDWATER

Most groundwater wells in the WCHRS are located near streams, so water tables are generally shallow (<2 m). Seasonally, the groundwater table is lowest in the early fall and highest in spring. (Lord et al. 2012)

SEE FIGURE 2

Sediment types are different in the three reaches, reflective of the geomorphic processes that formed the landscape. The hydraulic conductivity (aka permeability) of the sediments ranges from 9x10 -6 cm s -1 to 6x10 -4 cm s -1. Though there is no statistically significant difference in the average hydraulic conductivity between the three reaches, the Gribble Gap (GG) site has less variability in hydraulic conductivity than Cullowhee Creek (CC) and Long Branch (LB). (Hiatt et al. 2011)

SEE FIGURE 3

GROUNDWATER AND STREAMS

The relationship of groundwater to streams in the WCHRS varies substantially from the headwaters, where it is most complex, to the downstream Cullowhee Creek floodplain. Along Cullowhee Creek, the groundwater flows towards the (gaining) stream during all the seasons. In the Gribble Gap headwaters, stream reaches alternate between gaining and losing over short distances; the relationship also varies seasonally. At the Long Branch site, the stream is gaining and receives most groundwater input through the fan deposits that abut the southern channel bank. (Ferri et al. 2013)

SEE FIGURE 4

WATER CHEMISTRY

Most of the monitoring and studies at the WCHRS have focused on physical aspects of hydrology. However, some preliminary work on water chemistry has been completed to understand basic water chemical patterns, how hydrogen and oxygen isotope traits of vary with water types in the station and to understand the influence of present-day land use. In general, the water chemistry is similar throughout the station with a few outliers. There is most chemical variability in the headwaters, Gribble Gap. Also, reflective of the groundwater interaction with stream water, the groundwater (GW) pH is most similar to stream water (SW) at Cullowhee Creek and least similar at Gribble Gap. (Lord et al., 2012)

SEE FIGURE 5 & 6

WATER QUALITY AND LAND USE

As indicated above, few studies of been completed to directly evaluate the effects of current land use on water quality. However, a preliminary research project, carried out in a course, Geol 305 Soils & Hydrology, by Dunlap, Freeman, Howard, and Wood (2014, WCU, unpublished) showed perennial streams that drain developed campus property have significantly higher conductivity values than Cullowhee Creek and other tributaries that drain the minimally developed land. Their data are based on sampling Cullowhee Creek, and tributaries, up and downstream at six sites during baseflow and stormflow conditions during spring 2014.

SEE FIGURE 7

WHEN DOES GROUNDWATER RECHARGE OCCUR?

The southern Appalachians receive abundant rainfall; Cullowhee typically receives 127 to 140 cm of rainfall each year. In spite of this and the generally low-density population, droughts do cause groundwater wells to go dry, leaving residents without a water supply.

Learning more about where and when groundwater recharge happens in the region is important to support the high population growth rates as well as sustaining streams. Most groundwater recharge occurs during the periods of the fall and winter months when active vegetation isn't using much of the fresh rainwater in the soil for growth. Even during the winter months, not all rain results in groundwater recharge.

A preliminary study in the Long Branch and Gribble Gap watersheds showed that some rains likely prompt groundwater recharge (see A in Figure 8), but that a 5 mm rainfall in November did not likely result in groundwater recharge (see B in Figure 8) (Ferri, 2014, unpublished geology senior thesis, WCU)

SEE FIGURE 8

Real-Time Data

WCHRS Students at a local stream

  

WCHRS is a part of a state-wide NCDEQ Groudwater Study. Data from two groundwater wells on the campus of Western Carolina University is periodically collected and you can visualize and download that data here. We also have a gauge on Long Branch that we are hoping to get online soon. 

NASA's Integrated Precipitation Hydrology Experiment (IPHEX) also has paired tipping bucket rain gages set on the roof of WCU's Health and Human Science Building.  This site is adjacent to our sites at Gribble Gap and Long Branch.  These data are here and are listed in the table as 'WCU' (Gauge Number: NASA0028).

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