John Walton Fall, 2010. Grows over shallow water table areas High amount of evapotranspiration Water balance component Q out of reach = Q into.

John WaltonFall, 2010

Salt cedar polygons.kmz

• Grows over shallow water table areas

• High amount of evapotranspiration

• Water balance component

• Qout of reach =

• Qinto reach + Groundwater inputs + Surface runoff

• -evaporation – transpiration - human use

• Solve water balance for groundwater input

• Assume steady state system where groundwater recharge equals discharge

• Take measured surface water flows and diversions• Estimate ET from Salt Cedar/Mesquite/cane

bosque area• Divide groundwater input by drainage basin area

to obtain large scale groundwater recharge rates• Answer: ~ 1 cm/year

•  The potential difference between electrodes placed in the ground is measured. When an electric current is passed between two electrodes placed outside the measurement electrodes a potential difference is created.

• Deeper penetration of the electrical field occurs as the electrodes are spaced further apart. 

• Interpretation of this data can be complex in some cases