Project Overview

In GDEX, we will estimate daily rates of D, drainage from the rooting zone, in both vegetated and bare sand plots. Hydrologic monitoring of the vadose (unsaturated) zone and water table beneath the plots will show both the quantity and timing of groundwater recharge as upland vegetation is lost and recovers. The time lag between drought impacts on upland grasslands and corresponding shifts in the water table sustaining interdunal wetlands is critical to both H1 and H4. This hydrologic coupling of uplands to ground water is still poorly understood, and will be addressed by:

1. The hydrologic component of GDEX,
2. Ongoing hydrologic research at GSL and Jumbo Valley Fen, and
3. Modeling of water fluxes between the root zone and water table (or interdunal wetlands) in the unsaturated zone using standard software (HYDRUS-1 and HYDRUS-2) and permeability data for the Sand Hills.
   
   

In the work plan that follows, we emphasize three major components of our study:

1. Reconstructing Sand Hills climate and dynamics during the late Holocene;
2. A new grassland destabilization experiment (GDEX); and
3. Mesoscale climate modeling.

Our measurements of ET and hydrology in interdunal valleys at GSL, hydrologic research at Jumbo Valley Fen, and theoretical modeling of Sand Hills hydrology are ongoing. Although not discussed in detail below, they are also important to the broader research effort.