Geography Reference
In-Depth Information
Table 8. Modified values of the parameter W (percolation rate)
Groundwater Recharge (mm/year)
Percolation Rate (W)
>400
0.75
300-400
1
200-300
1.25
100-200
1.5
50-100
1.75
25-50
2
≤25
2.25
6.3.9. COP Method
The COP method of groundwater vulnerability assessment is mainly
developed for the carbonate (karst) aquifers. This method provides assessment
of intrinsic vulnerability of the aquifers based on three factors: flow
C
oncentration,
O
verlying layers and
P
recipitation.
According to European approach (Daly et al., 2002; Goldscheider and
Popescu, 2004), the basic concept of this method is to assess the natural
groundwater protection (O factor), which is determined by the properties of
overlying soils and the unsaturated zone.
The method also aimed at estimating how the groundwater protection can
be modified by the infiltration process (i.e., diffuse or concentrated) defined by
C factor and the climatic conditions (e.g., precipitation) defined by P factor
(Kouli et al., 2008).
Furthermore, the COP method establishes detailed guidelines, standard
tables and formulae for vulnerability assessment and selects suitable variables,
parameters and factors to be used according to the European Approach (Daly
et al., 2002; Zwahlen, 2004).
The method can have wide acceptance in most countries of the world as
the geoenvironmental data required by the method is easily available with
some fieldwork but no extensive input from GIS is needed.
Moreover, the method is applicable in different climatic conditions and
different types of carbonate aquifers, e.g. diffuse and conduit flow systems.
These flexibilities associated with the COP method make the method more
practical and useful for planners and decision makers framing and
implementing suitable schemes of groundwater protection.
The COP method, comprising of the three factors to evaluate the intrinsic
vulnerability of a groundwater resource, is expressed by the following formula
(Daly et al., 2002):
