Tall Grass Prairie Hydrological Monitoring Project
BACKGROUND
The Tall Grass Prairie Natural Area in south-eastern Manitoba is one of the only remaining tall-grass prairie remnants left in North America, and the largest in Canada. This rare habitat type supports dozens of tall-grass prairie species that are, in turn, dependent on the grasslands, savannahs, wet prairies, and sedge meadow wetlands of this endangered landscape.
The Tall Grass Prairie Preserve (TGPP) was created to secure and restore this important landscape, and the key ecological processes that sustain it, and to conserve the many rare plants, insects and animals that live there.
In 2010, the Nature Conservancy of Canada (NCC) initiated a multi-year hydrological monitoring study in the Tall Grass Prairie Natural Area. NCC's goal was to study near-surface groundwater patterns in the vicinity of suspected hydrological impairments. Basic knowledge about near-surface hydrology is needed so as to inform science-based wetland ecosystem conservation and recovery actions. This project is expected to improve wetland health by informing land management designed to maintain and promote natural hydrological processes.
Ten monitoring wells were installed in 2010 in the vicinity of five suspected hydrological impairments. In the same year, four water level loggers were installed and produced a comprehensive set up synchronized measures, while the remaining wells were manually monitored and information was much less comprehensive. Subsequently, data loggers were installed in 2011 at all 10 monitoring wells for the remainder of the project, which allowed for a more thorough analysis.
RESULTS
Results from the study indicate that there is some degress of impairment of the near-surface hydrological regime at three monitoring locations. At these locations, marked differences are evident beween the paired wells with regards to timing and depth to groundwater as well as seasonal patterns.
For example, one of the sites shows water levels that are higher on the east side of the berm than that on the west side (Figure 1).
The pattern also suggests that the east side has a greater deal of water storage, and the west side is much flashier with water levels rising and falling quickly. The hydrological disruption at this site caused by the ditch and berm is especially evident with slower drainage of water on the east compared to the west in both late June and late October (Figure 1). A fourth location shows no impairment, as water levels and patterns are very similar between wells. Due to unforeseen circumstances, data could not be analyzed for the fifth location.
FIGURE 1: 2012 water levels at one monitoring location in Manitoba's Tall Grass Prairie Preserve
WHAT'S NEXT
NCC has further plans to incorporate vegetative monitoring data into the study, in order to relate hydrological information to biodiversity trends, including populations of the endangered Western Prairie Fringed Orchid. Analyses will additionally include climate data obtained from weather station records.
Future plans also include a project that, if funded, would enable NCC to collect more information on local hydrology in order to effectively implement wetland conservation actions. Through this project, NCC intends to map local watershed and hydrological patterns; identify key restoration sites to improve local water quality and biodiversity (emphasis on species at risk); and using an experimental approach, restore hydrology at a known site using tools such as tile drainage to determine if this type of mechanism can be used to effectively improve water flow while maintaining existing road and agricultural infrastructure.
PARTNERS: Manitoba Conservation & Water Stewardship, Dr. Phil Gerla (University of North Dakota), and Manitoba Tall Grass Prairie Preserve
