Structuring and processing information using GIS

In the previous section Starting IMS, the existing megasite-specific information was organized and used for the preliminary description of the main contamination sources, transport pathways and receptors, leading to the development of a conceptual model and the delineation of the Risk Management Zone (RMZ) for the megasite. In the present step, a detailed megasite characterization is performed, to construct a more elaborated basis for estimating current and future risks on a megasite scale (see figure below). The results are stored in a database and presented in the form of maps (by using GIS software tools), to give a detailed overview of the megasite, as well as to support the further risk assessment.

The information concerns the following:

• contamination sources
  • on the basis of preselected priority contaminants
  • on the basis of existing and new data, and data intra/extrapolation procedures leading to regional maps
• receptors at risk
  • groundwater, surface water, and land use related receptors
  • the functional use of the receptors.
• pathways between sources and receptors, and parameters that may influence the risks for (emissions to) the receptors:
  • groundwater: parameters for hydrogeological, geochemical and natural attenuation (NA) processes in aquifers,
  • surface water resources: parameters for the NA at the groundwater-surface water interface (NAI), upstream emissions and emissions other than from soil and groundwater (i.e. wastewater discharges), sediment as source of contaminants,
  • air: parameters of wind characteristics, erosion, precipitation and volatilisation.
    
    
    
    

Output

The output is the GIS database and maps of the megasite that present elaborated characteristics of:

• the contaminant sources,
• the receptors and their functional use (and related quality criteria),
• the pathways and process parameters (NA and NAI).