Methods of Groundwater Vulnerability and Protectability Assessment - Groundwater Vulnerability: Chernobyl Nuclear Disaster - page 9

The protective capacity is assessed by score tables accounting for lithology,
effective capacity, granulometry, fracturing, and karst. The detailed score tables
are given in the COST-620 Project report [ Zwahlen , 2004].
The final gradations of groundwater vulnerability PI index are as follows:
PI = 4-5 (very low vulnerability), 3-4 (low), 2-3 (average), 1-2 (high), and 0-1
(maximum). In fact, this index gives the groundwater protectability rather than
vulnerability, as it increases with the decrease in vulnerability (increase in protect-
ability) of the assessed groundwater.
The PI method is used in the “European approach” to groundwater vulnera-
bility assessment of karstic areas [ Daly et al ., 2002] developed during the European
Community (EC) COST-620 Project. In the result of this project, the COP method
was designed based on three main indicators: (1) concentration of flow, (2) over-
lying layers, and (3) precipitation regime. The first of these indicators ( C and O )
correspond to the I and P indicators, respectively, of the PI method described
above, and the third one ( P ) is a climatic indicator accounting for the annual atmo-
spheric precipitation, frequency, duration, and intensity of precipitation events
[ Zwahlen , 2004].
The modified European approach was developed by Shestopalov et al . [2009]
in Ukraine (called by authors “the Mountain Crimea approach”) for assessment
of karst groundwater vulnerability. In this approach the COP method was adapted
and modified for specific conditions of the area of Ai-Petri karst massif in moun-
tainous Crimea representing the main recharge area of the regional groundwater
system. The modification of the European approach includes accounting for the
special properties of the epikarst and concentration of the underground runoff by
karst caves. The GIS-based resulting map of assessed groundwater vulnerability in
the PI method scale is obtained for the research area.
From the above consideration, it can be concluded that the common fea-
ture of the index-rating methods is in a significant degree “judgmental”
approach to the definition of rating scores and scales for main factors and
indicators of groundwater vulnerability.

1.3. Parametric Methods

The most known system of groundwater protectability assessment standardized
in the former USSR was developed by Goldberg [1983, 1987], who determined the
groundwater protectability to be the state of overlaying of an aquifer by deposits,
first of all low-permeable ones, which prevent the penetration of contaminants
from the land surface into groundwater. According to his representation, the
groundwater's protectability depends on a number of factors which can be classified
into three main groups, natural, technogenic, and physicochemical, as follows:
1.

Natural Factors Presence of low-permeable deposits in the vertical section;
depth to groundwater table; thickness, lithology, and permeability properties
of rocks (first low-permeable) overlying the aquifer; capacity (sorption)