Monday, February 04, 2013, 12:00PM - 1:00PM
Colorado School of Mines
Full title: "Looking into the black box of stream-riparian groundwater exchange: Exploring catchment controls on flowpaths during baseflow recession"
Abstract: Stream-groundwater interactions are critical to ecosystem structure, function, and water quality in many streams. In this work, we explore hyporheic exchange (connectivity between streams and near-stream aquifers) in two steep, narrow headwater catchments at the H. J. Andrews (HJA) Watershed in Oregon.
Traditional characterization of hyporheic exchange relies upon solute tracer studies and a spatially sparse set of observations in streams and shallow monitoring wells. We demonstrate the use of electrical resistivity (ER) methods to image hyporheic exchange in both two and three-dimensions, and identify flowpaths at different temporal scales of stream connectivity. These data are an improvement over traditional methods, which would otherwise provide only reach-averaged values, or single observations in space. Temporal moments of solute and ER data are used to compress trends into descriptive statistics and identify the distribution of dominant solute transport processes (e.g., transient storage dominated, advection dominated) in the subsurface.
Bio: Singha’s research contributes to understanding of hydrologic processes by integrating geophysical techniques, hydrologic tools, and mathematical simulation, allowing the development of improved predictive models. Her theoretical work concentrates on quantifying the “geophysical footprint,” or the impact of spatially and temporally varying measurement physics, on using geophysical data to constrain the operation of parameters controlling fluid flow and solute transport in a variety of settings. She explores processes associated with fluid flow and contaminant transport in porous media and fractured rock as well as groundwater-surface-water interactions. She has also collaborated on a variety of projects in related areas, including linking water quality degradation and human behavior, imaging moisture dynamics in desert ecosystems, exploring changes in infiltration after fire, and quantifying kinetics of iron reduction given electrical measurements.
Free and open to the public