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8. Applications of Groundwater Quality Models
d. Determining the maximum permissible drawdown or the maximum permissible pumpage in order to prevent poor quality water from entering
the supply aquifers;
e. Prescribing the quality standards for both artificial recharge water and
waste water to be drained;
f. Providing the quantitative basis for water resources management and
pollution remediation;
2. Field Survey
The objective of field survey is to collect field data concerning geology,
hydrology and environment, which include the geometric shape and boundary conditions, lithology and heterogeneity, recharge and extraction, relationships between surface water and groundwater, historical and present
states of pollution, range and intensity of pollution sources, and so forth.
Field surveys can provide a basis for model selection.
3. Model Selection
The selection of a model depends on the results of field survey and accuracy
requirements of the problem. A variety of water quality models and their
selection criteria have been introduced in Section 7.1. If a distributed parameter water quality model is chosen, we have to construct a conceptual model
and judge what parameters can be estimated by field surveys and what
parameters should be estimated by field tests.
4. Field Tests
If sufficient historical data is not available, then pumping tests and tracer
injection tests are needed at the si te for determining the unknown parameters or calibrating the conceptual model. Based on the data of the field
survey and the requirements of model calibration, an experiment design
should be made. During the tests, the changes of water levels are observed
and water sampIes are analyzed to obtain the concentrations of the chemical
components that we are interested in. If multi-Iayer or three-dimensional
water quality models are used, it is necessary to take water sampIes at different depths in order to obtain the changes of concentration with depth.
5. Programming and Data Compiling
Analyses of nearly all practical groundwater quality problems depend on the
use of numerical methods. Therefore, it is necessary to prepare some suitable
programs. According to the conditions of practical problems and the performance of the computers, hydrologists may select a ready-made program.
Before using the program, data should be prepared according to the requirements ofthe program. For instance, the following input data are required for
two-dimensional advection-dispersion models:
8. Applications of Groundwater Quality Models
d. Determining the maximum permissible drawdown or the maximum permissible pumpage in order to prevent poor quality water from entering
the supply aquifers;
e. Prescribing the quality standards for both artificial recharge water and
waste water to be drained;
f. Providing the quantitative basis for water resources management and
pollution remediation;
2. Field Survey
The objective of field survey is to collect field data concerning geology,
hydrology and environment, which include the geometric shape and boundary conditions, lithology and heterogeneity, recharge and extraction, relationships between surface water and groundwater, historical and present
states of pollution, range and intensity of pollution sources, and so forth.
Field surveys can provide a basis for model selection.
3. Model Selection
The selection of a model depends on the results of field survey and accuracy
requirements of the problem. A variety of water quality models and their
selection criteria have been introduced in Section 7.1. If a distributed parameter water quality model is chosen, we have to construct a conceptual model
and judge what parameters can be estimated by field surveys and what
parameters should be estimated by field tests.
4. Field Tests
If sufficient historical data is not available, then pumping tests and tracer
injection tests are needed at the si te for determining the unknown parameters or calibrating the conceptual model. Based on the data of the field
survey and the requirements of model calibration, an experiment design
should be made. During the tests, the changes of water levels are observed
and water sampIes are analyzed to obtain the concentrations of the chemical
components that we are interested in. If multi-Iayer or three-dimensional
water quality models are used, it is necessary to take water sampIes at different depths in order to obtain the changes of concentration with depth.
5. Programming and Data Compiling
Analyses of nearly all practical groundwater quality problems depend on the
use of numerical methods. Therefore, it is necessary to prepare some suitable
programs. According to the conditions of practical problems and the performance of the computers, hydrologists may select a ready-made program.
Before using the program, data should be prepared according to the requirements ofthe program. For instance, the following input data are required for
two-dimensional advection-dispersion models: