| Vulnerability class | 
        Surface    of area of particular clas-ses of    vulnerability [km2] | 
        Practical    specification of vulnerability classes (developed on the basis    of Foster et.al. 2002) | 
      
      
        | DRASTICindex | 
        CD    index | 
        NV    index | 
      
      
        | Avery low | 
        <1 | 
        <1 | 
        <1 | 
        Practically no    vulnerability of groundwater to contamina-tion | 
      
      
        | B low | 
        13 | 
        2 | 
        426 | 
        Vulnerability    of groundwater to conservative contamina-tion in their    constant effect. | 
      
      
        | C medium | 
        324 | 
        247 | 
        136 | 
        Vulnerability    of groundwater to some contamination,mainly    conservative in conditions of their constant effect. | 
      
      
        | D moderately-high | 
        229 | 
        340 | 
        57 | 
        Vulnerability    of groundwater to some contamination, but only in    conditions of their constant effect. | 
      
      
        | E high | 
        53 | 
        30 | 
        <1 | 
        Vulnerability    of groundwater to a lot of contamination and fast activity    of contamination in many situations. | 
      
      
        | F very high | 
        <1 | 
        <1 | 
        <1 | 
        Vulnerability    of groundwater to a lot of contamination and fast activity    of contamination in most situations. |