We are generating an extensive set of field based observations within the Minnesota River Basin. All data is undergoing quality assurance analysis and will be made available at the end of the project through a data repository.
Biogeochemistry. We have collected water samples for chemical analysis from over 200 locations throughout the basin. Samples have been collected over the past three years at various times of the open water season. Sampling events have been designed to capture variability over time as well as variability derived from land use or contributing area throughout subnetworks. This data is informing our understanding of the role of land features and season in both generating and providing resistance to unwanted change. We are also collecting data to quantify rates of biogeochemical processes. To this end we measure denitrification potential, water column light decay, discharge and stable isotopes at select sites.
Food web structure. We are collecting measurements of macro-invertebrate distribution dynamics and stable isotope content of tissue to determine food web structure.
Paleochannel geometry. Paleochannels, preserved on terraces via meander cutoffs during an incisional period, record the channel geometry and thus discharge throughout a river’s history. We measured paleochannel geometry on terraces throughout the Le Sueur River in south-central Minnesota, to track how channel geometry has changed throughout the last 13,400 years. Five paleochannels were identified on terraces along the Le Sueur River from 1m-resolution lidar data. Ground Penetrating Radar (GPR) was used to obtain a subsurface image across paleomeanders to estimate the geometry of paleochannels. OSL samples were collected from overbank deposits to determine the time of channel abandonment. Paleodischarge coupled with depositional ages provide a history of flow conditions on the Le Sueur River.
Dynamic bluff erosion. We have collected bathymetry, velocity, discharge, water surface elevation and grain size distribution data at two actively eroding bluff sites. We established a Structure from Motion (SfM) photogrammetry platform in April 2013 to take daily photographs of the bluffs for calculations of geomorphic change. Photos from the first 16 months of observation have indicated a total of 18 significant erosion events. In May 2015 we installed 20 additional trail cameras that will take daily photographs of bluffs distributed throughout the Le Sueur, Blue Earth and Watonwan rivers.
Channel bathymetry. Beginning in summer 2013 and continuing in summer 2015 we are mapping extensive areas of the Minnesota River and Le Sueur River channel beds using an Acoustic Doppler Current Profiler coupled with a real-time-kinematic GPS system. We have developed a system that allows our rtkGPS to tie into the Minnesota Department of Transportation Continuously Operating Reference Station Network, using a CDMA-enabled cell phone. This allows us to get real-time corrections for GPS locations with precision of 2-3 cm. All of this instrumentation is loaded on a 17’ cataraft with an outboard motor and data is assimilated on a laptop or tablet computer. As of summer 2015, we have mapped a total of 110 km of the mainstem Minnesota River. Right: Figure explaining the process of collecting channel bathymetry on the Minnesota River.
Bluff and ravine inventories. As part of a sediment budget effort in the Blue Earth, Watonwan, and Le Sueur Rivers, we have mapped and characterized major ravines and near-channel bluffs. The data can be downloaded here.
Ravine monitoring. ISCO and Sigma Hach samplers were installed at the mouth of 3 ravines and in the upper channel along 2 ravines. All samplers measured water level and collected water samples during storms. All samples were analyzed for total suspended solids. In addition, area-velocity meters at 4 sites allowed for discharge calculations.