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Articolo
pubblicato sulla rivista Environmental Monitoring And
Assessment 2002, n. 79, pp 57-74.
A
PROBABILISTIC METHODOLOGY TO ASSESS THE RISK OF GROUNDWATER
QUALITY DEGRADATION
Autori:
G. PASSARELLA1,
M. VURRO1,
V. D’AGOSTINO2,
G. GIULIANO3
and M. J. BARCELONA4
1
Water Research
Institute, CNR, V. le De Blasio, Bari, Italy;
2 Tecnopolis
CSATA s.p.Casamassima, Valenzano, Bari, Italy;
3
Water
Research Institute, CNR, Via Reno, Rome, Italy;
4
Department
of Civil and Environmental Engineering, University of Michigan, Ann
Arbor, Michigan, U.S.A.
Abstract
An
approach to assess the risk
of
groundwater quality degradation with regard to fixed standards, based
on Disjunctive Kriging (DK)
is presented. The DK
allows
one to evaluate the Conditional Probability (CP) of overriding a given
threshold of concentration of a pollutant at a given time, and at a
generic point in a considered groundwater system. The result of such
investigation over the considered area can be plotted in form of maps
of spatial
risk.
By repeating this analysis at different times, several spatial
risk maps
will be produced, one for each considered time. By means of
non-parametric statistics, the temporal trend of the CPs can be
evaluated at every point of the considered area. The trend
index,
assessed by means of a sort of classification of the trend values
obtained as described above, can be superimposed on the most recent
values of the spatial
risk (i.e.:
the most recent values of probability). Consequently a classification
of the risk of groundwater quality degradation results with which to
weigh both the spatial distribution and the temporal behaviour of the
probability to exceed a given standard threshold. The methodology has
been applied to values of nitrate concentration sampled in the
monitoring well network of the Modena plain, northern Italy.
This
area is characterised by intensive agricultural exploitation and hog
breeding along with industrial and civil developments. The influence
of agriculture on groundwater results in a high nitrate pollution that
limits its use for potable purposes.
Per ulteriori informazioni
Vito D'Agostino
tel. 0804670235
e-mail: v.dagostino@tno.it
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