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A Groundwater - Surface Water Interface
Modeling
the interactions between surface water systems and the groundwater table
has always been a challenging problem.
Although a few models are available that address this issue for
single ponds, until now, modeling groundwater interactions with interconnected ponds
and other complex drainage systems has not been possible inside a single
computer program. The new PercPackTM
plug-in
for ICPR now makes this a routine analysis.
For
example, consider the 3-pond system shown in the schematic below.
Ponds 1, 2 and 3 each receive runoff from upland areas. Ponds 1 and
2 are connected to Pond 3 via pipes and Pond 3 is connected to a surface
outlet with a weir. Flow rates through the pipes and across the weir
depend directly on the stages in each of the ponds and at the surface
outlet. Stages in the ponds, in turn, depend on flows through the pipes and
weir. In other words, they are all hydraulically dependent on one
another. ICPR has always handled these types of complex surface
systems with relative ease.
Now
let's complicate things a little more. Assume that the weir is set
well above the pipes such that a considerable amount of the surface runoff
is "trapped" in the ponds below the weir and the only way to
recover the storage is through percolation. Percolation rates depend not
only on soil properties below the ponds and water levels in the pond, but
also on the location of the water table below and adjacent to the
ponds.
This becomes an incredibly complex problem because the water
table is not static and it will mound as water percolates from the ponds,
thereby reducing percolation. Percolation rates affect the water table and
the water table affects the percolation rates. It's similar to a
time-variable tailwater condition on a pipe or weir.
The
PercPackTM
plug-in for ICPR allows you to connect each of the ponds to a "groundwater
sink" (designated as "Soil Column" in the above sketch)
with a "Percolation Link". These links work similar to other
links in ICPR in the sense that they move water from one node to another
node based on water levels at the nodes and specific properties of the
links. The data
form for
a percolation link includes information on the soils, the surficial aquifer, and the
pond and computational geometry.
Given this information, ICPR solves the
surface and groundwater systems simultaneously, accounting fully for the
interactions between both systems including groundwater
mounding below and
adjacent to ponds.
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PercPackTM
Now
Available!!
Download
an Order Form
for the latest pricing and options.
PercPackTM
is an optional add-on to ICPR. You must already have the Windows
version of ICPR or purchase it separately. Ordering information will
be available at the time of release.
Fully
Integrated
Groundwater
- Surface Water
Model
PercPackTM
plugs directly into ICPR, fully
integrating the groundwater algorithms with the surface water algorithms.
Consequently,
there is no need for tedious iterations with separate groundwater models
and programs. PercPackTM
is implemented in the form of three new link types, each accessed directly
from the ICPR Routing menu.
Typical
Applications
Green-Ampt
Rainfall
Excess Method
The
Green-Ampt
method has also been
added as an option to the traditional curve number method for both the SCS
Unit Hydrograph and the Santa Barbara Urban Hydrograph methods. A soil
storage recovery procedure is included in the algorithms making it
possible to perform multi-event and long term simulations.
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