Application of mathematical modelling methods in the protection of groundwater environment

Application of mathematical modelling methods…
35 
practically impossible. Hence, most presently existing models consider, for practi-
cal reasons (hardware, time of calculations etc.), only selected problems.
POSSIBILITIES OF APPLICATION OF NUMERICAL MODELS
Application of models of pollutant transport and flow in ground waters pertain 
mainly to the assessment of the effect of local sources, both spatial and point, of 
pollution and to outlining buffer zones of water intakes and protected areas.
Local point sources of pollution are mainly dumping sites and surface and un-
derground reservoir constructions. Application of mathematical modelling methods 
enables to estimate their potential effect on surrounding area in terms of: range of 
impact and concentration of substances in water and soil. It is also possible to pre-
dict temporal changes of these values. In the case of reservoir constructions it is 
also possible to simulate their damage and possible environmental consequences 
for soil-water habitat.
As for dispersed sources of pollution, mathematical modelling methods are 
applicable mainly in croplands. Plant protective chemicals may exert significant 
impact on the quality of ground and surface water resources. To estimate the 
amount of substances polluting the groundwater system it is necessary to recognise 
their transport and transformation in the plant-soil-water system. Mathematical 
modelling enables to determine interactions among various processes with the con-
sideration of the effect of land use, water management and farming activities.
Dispersion models of groundwater cycling which solve together the dispersion 
(migration and interaction of substances with environment) and movement (filtra-
tion) equations may be used to define buffer zone around intakes of these waters 
(M
ACIOSZCZYK
et al
., 1993). For regional systems, due to complicated and often 
heterogeneous hydrogeologic conditions, the equations might be hard to solve. The 
reasons include numerical problems and mainly poor understanding of the systems 
as to spatial and nonlinear parameter distribution and spatial and temporal distribu-
tion of edge conditions. For simplicity, three dimensional modelling is reduced in 
these applications to plane or to quasi spatial modelling (
Ś
LESICKA
, 2007).
MATHEMATICAL MODELLING AND GEOGRAPHIC INFORMATION 
SYSTEMS (GIS) 
Significant, though indirect application of mathematical modelling is its use 
for the enlargement of information gathered in the process of recognition and as-
sessment of conditions that prevail in soil-water environment. Results of model-
ling, if appropriately presented, could be an important element of decision support 
in environmental management.

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36 
M. 
Ś
LESICKI
In the projects of protection of soil-water environment there is a need to com-
bine and process large amount of information from various disciplines to estimate 
parameters of phenomena and to determine the range and time table of necessary 
undertakings. GIS might be a powerful tool in environmental management. Prop-
erly configured GIS might be an effective part of the decision support system by 
combining visualisation tools with databases. Data in tabular and graphic forms 
may be used to perform spatial analysis and to select the best scenarios.
GIS and computer aided design and drafting systems (CADD) might be com-
bined with models of three dimensional flow and transport of pollutants in ground 
waters forming a complex decision supporting system intended to manage the pro-
jects of soil and groundwater protection.
GIS is a useful tool to combine tabular data on pollutants (“what”) with spatial 
characteristics (“where”) with the consideration of temporal changes (“when”). In 
combined use of three dimensional CADD programmes and three dimensional 
models of ground waters, GIS is an indispensable tool for collecting and analysing 
data on environmental status. Combined consideration of past and predicted data 
enables to consider time as the fourth dimension by creating animated sequences.
The main task of decision support system is to enable the user performing 
„experiments” with a model and studying the effect of undertaken decisions on 
modelled object in order to select desired scenarios. To make such a system for en-
vironmental protection of ground waters one should:
−
integrate hydrologic models with CADD and GIS programmes,
−
combine three dimensional hydrologic models with CADD programme,
−
perform three dimensional spatial analysis with GIS,
−
use animation techniques to present temporal changes (forth dimension).
In the decision support system, GIS plays crucial role for hydrogeological and 
hydrological applications since it enables both data management and their three 
dimensional visualisation. GIS is a set of spatial operators that allows combining 
spatial databases with geographic information. Models of GIS databases have 
a complex character since they must include data and relations both graphic (map) 
and tabular (attributes). GIS allows the user to combine tabular information (in 
a form of calculation sheet or database) with graphic objects in a map or CADD 
graph. The user may combine and process that information to solve problems like:
−
determination of the usefulness of various objects for study,
−
identification of ground and geologic formations in which ground waters may be 
especially sensitive to pollution,
−
analysis of the risk of surface and subsurface water pollution in the vicinity of 
croplands or waste dumping sites.
GIS enables integration of data in effective way with a possibility of various 
approach to browsing and analysing these data. Information contained in tabular 
database may be available through a map or a map can be created based on infor-

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Application of mathematical modelling methods…
37 
mation from tabular database. The map may be made based on data of polluted ar-
eas with the distinction of types and extent of pollution.
Fourth dimension describing temporal changes is added to the model by inte-
gration with the programme of computer animation. Graphic and tabular output 
describes only the status of the system in a given moment. Incorporation of mo-
mentary results into an animated sequence usually gives clearer illustration of pol-
lutant dispersion and results of undertaken protective measures. Properties of three 
dimensional graph processing (change of the observation angle, size reduction or 
enlargement, creation perspective views etc.) available in CADD programme en-
able their use in the technology of creating animated sequences.
Integration of described components allows for circumventing their individual 
limitations and includes processes presented in Fig. 1.
Fig. 1. General scheme of the decision support system 
Combined use of three dimensional models of inflow and transport of pollut-
ants in ground waters and GIS programmes has been recently the most intensively 
Input 
¾
Base 
map 
¾
Data on grounds 
¾
Samples from drilling 
¾
Geological 
data 
¾
Data on pollutants 
¾
Meteorological 
data 
¾
Hydraulic 
data 
¾
Hydrogeological 
data 
¾
Operational 
data