A suite of groundwater models have
been developed for the shallow riparian environment along the Rio Grande in
New Mexico to support analysis of restoration options and river management strategies.1
Five fine-mesh, three-dimensional riparian zone groundwater models (riparian
models) were developed for the Rio Grande in central New Mexico spanning approximately
120 river miles. Each of the four-layer models has a uniform grid, with grid
cells measuring 250 feet x 125 feet. The five models represent physical processes
relevant to assessing shallow groundwater conditions, exchanges between surface
water and shallow groundwater within the floodplain of the Rio Grande, and interaction
between shallow and deep groundwater systems. Modeled interactions include seepage
from the river, interception of shallow groundwater by drains, recharge to shallow
groundwater from flooded overbank areas, and water depletions due to open water
evaporation and riparian evapotranspiration, implemented using the RIP-ET package.
Riparian evapotranspiration rates are variable, depending on the existing mapped
vegetation classifications in the riparian zone. The models have been used to
evaluate the relationship of shallow riparian groundwater conditions to variations
in (a) regional groundwater conditions, (b) flood magnitude and duration, and
(c) vegetation type and coverage. The simulations conducted illustrate the dynamic
nature of riparian zone behavior.