Methods of Groundwater Vulnerability and Protectability Assessment - Groundwater Vulnerability: Chernobyl Nuclear Disaster - page 3

Another example of the zoning method combined with modern GIS tech-
nology is the development of a regional groundwater vulnerability map of
Scotland (in scale 1:100,000) by Ball et al . [2004] in the framework of the
SNIFFER project. They performed the initial data analysis by overlaying
maps of soil and vadose zone thickness, lithology and permeability, character
of aquifer occurrence, hydraulic conductivity, porosity, and fracturing degree
of rocks. As a result they classified the study area into seven characteristic
types of hydrogeological conditions determined by most frequently occurring
lithological sections of vadoze zone and character of groundwater occurrence:
(1) highly permeable alluvium-delluvium deposits (drift), (2) exposed hard
fractured rocks, (3) hard fractured rocks covered by soil layer, (4) hard frac-
tured rocks covered by drift layer, (5) fractured open rocks with double
porosity, (6) fractured rocks covered by soil layer, and (7) fractured rocks
covered by drift layer. According to these types, seven scenarios of ground-
water vulnerability categorization have been developed which include 199
different vulnerability codes (possible combinations of gradations for thick-
ness and hydraulic conductivity of layers for the above seven section types).
In the study area of Scotland, only 46 of these 199 gradations occur. The
resulting map of groundwater vulnerability is obtained after the GIS zoning
procedure according to the above seven types of groundwater occurrence. The
authors conclude that the majority of the studied area of Scotland has
maximum or very high groundwater vulnerability because of wide occurrence
of highly fractured weathered hard rocks, often uncovered or covered by thin
layers of soil and highly permeable drift.
The hydrogeological zoning method is able to provide broad-scale regional
groundwater vulnerability maps, including modern GIS-based maps with high
resolution which use large volumes of data of hydrogeological, geological,
climatic, relief, and other characteristics. An assessment system and gradations
developed using this method in most cases are targeted only to the assessment
area for which it was developed, and they cannot be used without special
adaptation for groundwater vulnerability assessments of other areas.
1.2. index Methods
The necessity of fast and effective assessments of the groundwater pollution
risks related with increasing requirements of municipal services of water supply,
farms, environment protection agencies, etc., in the United States, France, Italy,
Germany, and other countries, starting from the 1980s, stimulated the development
of different index-type and rating-type assessment systems of groundwater con-
tamination risks, groundwater vulnerability and protectability based on simple
algorithms of unification (summation, generalization) of parameters, and factors
characterizing the hydrogeological conditions and protection ability of the