The Groundwater Characterization Project's objectives are to fully describe the groundwater hydrology of the Reservation, the interactions between groundwater and surface water, and to integrate this information into management tools, including a numerical model, monitoring plan, and resource protection policies and ordinances. This project is an ongoing study. The numerical models will be updated as new data is incorporated since the data acquisition will be continuous. Some of our data sources include: stream flow; precipitation; monitoring well water level; mass well water level; and vegetation cover.
Stream (Flume) Data
Four flumes are located on the Reservation, 3 in perennial creeks and 1 in an intermittent creek. These flumes record water level and discharge information on these creeks. The flume locations are sampled for conventional water parameters.
Monitoring Wells
Six (6) monitoring wells are regularly sampled for water level. Each well taps a different aquifer giving us information about water quantity, an important factor in the GW model.
Water Level Monitors
Two (2) surface water level monitors are located in Reservation wetlands. Since the wetland's water surface is the groundwater table's representation on land, the water level of the wetland is important to our GW model.
Precipitation
Precipitation is the most important factor in the GW model. All the water that recharges the Reservation's aquifers comes from rainfall. The Swinomish Weather Station records precipitation near the Swinoimsh Casino.
Vegetation Cover
Vegetation cover is another important factor which determines the amount of rainfall that reaches the ground as well as how much water is lost through evapotranspiration. We are producing GIS maps of vegetation coverage from aerial photos of the Reservation.
Vegetation Mapping
The Swinomish Geographic Information Services (GIS) and Water Resources Program worked on verifying vegetation points on the Reservation. The vegetation points were determined by NASA from the NASA spectral thematic mapper areal data. The point were determined by wavelength analysis.
Our job was to ground truth these points to make sure that the analysis determined the correct vegetation type. The types were broken into 7 different catagories ranging from dense conifers, deciduous, shrubs, grassland, and bare earth. Over 450 points were sent to us for verification. Only a subset of the points was ground truthed since a majority of the points were determined to be correct based on location and known history.
This data was sent back to NASA and a completed upland and tideland vegetation map will be produced. The map will have a resolution of 5m for the uplands and 1m for the tidelands. This map will fill two critical holes in our data. First, this map will be the completion of the eelgrass vegetation map that was started in 2000. The upland data (which was a last minute add on) will help us complete the refinement of our recharge rate to the Reservation aquifers (a Groundwater Project).
Subsurface Borings
Subsurface borings involve the drilling of wells but not installation of wells. The drilling gives us information about the aquifers in areas not well understood. Samples of the aquifer materials are taken and analysed for aquifer characteristics.