Geography Reference
In-Depth Information
Thus, the overlay and index methods are particularly suitable for use with
geographic information systems (Tilahun and Merkel, 2010). An overlay and
index method, being a multicriteria model, aggregates different hydrological/
hydrogeological factors that control the movement of pollutants from the
ground surface to underlying aquifer.
A GIS-based overlay and index method combines factors controlling
pollutant migration according to certain multi-criterion rule and computes
resulting value of vulnerability index for different spatial locations.
A general methodology for applying groundwater vulnerability methods in
GIS framework is shown in Figure 6.
Geological and
Hydrogeological Data
Existing Maps
Remote Sensing Data
Geographical Information System (GIS) Framework
Data Digitization
Creation of Thematic Layers by Spatial Analyses
Assigning Ratings to Different Features of Each Thematic Layer
Assigning Relative Weights to Different Thematic Layers
Converting Vector Maps to Raster-Based Maps
GIS-Based Computations According to Vulnerability Method
Groundwater
Vulnerability Map
Figure 6. General GIS-based methodology for groundwater vulnerability study.
