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8. Applications of Groundwater Quality Models
8.1.2 Groundwater Pollution of Saturated Loose Aquifers
A significant amount of work has been done to predict groundwater pollution in saturated loose aquifers with advection-dispersion models and there
have been some successful cases. In these cases, the study procedure mentioned above are generally adopted. The following is abrief introduction of
two case studies. For more case studies, refer to Van der Heijde et al. (1985).
The Study of Groundwater Pollution in an Alluvial Aquifer in
the Rocky Mountains of Colorado
This is a successful example of using the hydrodynamic dispersion model on
a regional scale. The calculated results were provided by Konikow (1977) of
the USGS. In this study, an advection-dispersion model was calibrated by
observation data of over 30 years.
From 1943 to 1956, industrial was te water containing a high concentration
of so me chloride compound was disposed of in unlined ponds at a munitions
factory. The was te water percolated from the ponds into the alluvial aquifers,
and then spread out over several square miles, causing serious harm to the
crops. Starting from 1956, the was te water has been disposed ofin a reservoir
lined with bitumen, and clean water has been injected into the original ponds
to displace the polluted groundwater. As a result, the groundwater pollution
has now been reduced in that region.
The following are some advantages of establishing an advection-dispersion
model for the region:
1. The geological and hydrogeological conditions in the region are weH
known.
2. There is sufficient long-term observation data of water quality for model
calibration.
3. There are historical records of waste water treatment in the munitions
factory. Chloride can be regarded as a conservative tracer. Both adsorption and chemical reactions need not be considered.
In the first phase of the study, all available data was collected and analyzed. The data from about 200 wells, including observation wells, test wells,
irrigation wells and domestic wells, was analyzed. Four maps were prepared
from the data to show the elevations of the bedrock, the levels of water tables,
the thickness of alluvial deposits, and the distribution of transmissivities.
These maps illustrated that the alluvial deposit was an aquifer system which
was inclined, discontinuous, and heterogeneous, with different groundwater
flow directions.
In the second phase, a mathematical model of two-dimensional steady flow
was developed to estimate the rech arge of the aquifer and to compute the
distribution of groundwater velocities. During the calibration of the flow
model, it was interesting to find out that there were areas where some alluvial
8. Applications of Groundwater Quality Models
8.1.2 Groundwater Pollution of Saturated Loose Aquifers
A significant amount of work has been done to predict groundwater pollution in saturated loose aquifers with advection-dispersion models and there
have been some successful cases. In these cases, the study procedure mentioned above are generally adopted. The following is abrief introduction of
two case studies. For more case studies, refer to Van der Heijde et al. (1985).
The Study of Groundwater Pollution in an Alluvial Aquifer in
the Rocky Mountains of Colorado
This is a successful example of using the hydrodynamic dispersion model on
a regional scale. The calculated results were provided by Konikow (1977) of
the USGS. In this study, an advection-dispersion model was calibrated by
observation data of over 30 years.
From 1943 to 1956, industrial was te water containing a high concentration
of so me chloride compound was disposed of in unlined ponds at a munitions
factory. The was te water percolated from the ponds into the alluvial aquifers,
and then spread out over several square miles, causing serious harm to the
crops. Starting from 1956, the was te water has been disposed ofin a reservoir
lined with bitumen, and clean water has been injected into the original ponds
to displace the polluted groundwater. As a result, the groundwater pollution
has now been reduced in that region.
The following are some advantages of establishing an advection-dispersion
model for the region:
1. The geological and hydrogeological conditions in the region are weH
known.
2. There is sufficient long-term observation data of water quality for model
calibration.
3. There are historical records of waste water treatment in the munitions
factory. Chloride can be regarded as a conservative tracer. Both adsorption and chemical reactions need not be considered.
In the first phase of the study, all available data was collected and analyzed. The data from about 200 wells, including observation wells, test wells,
irrigation wells and domestic wells, was analyzed. Four maps were prepared
from the data to show the elevations of the bedrock, the levels of water tables,
the thickness of alluvial deposits, and the distribution of transmissivities.
These maps illustrated that the alluvial deposit was an aquifer system which
was inclined, discontinuous, and heterogeneous, with different groundwater
flow directions.
In the second phase, a mathematical model of two-dimensional steady flow
was developed to estimate the rech arge of the aquifer and to compute the
distribution of groundwater velocities. During the calibration of the flow
model, it was interesting to find out that there were areas where some alluvial