In accordance with the original EF approach, the WSF here is
calculated by multiplying the yearly water demand (m3/year) for
each type by the WSF index [m2/m3]. The WSF index represents the
area necessary to capture a cubic meter of available water in the
regional water supply hinterland in [m2/m3]. The result is the WSF
[m2/a] which reveals how much of the regional water supply area
or “catchment” is necessary to supply water on an annual basis.
A WSF matrix with regional estimates will be provided in the case
study. In line with the conceptual provisions of land use classifications,
we can then calculate the WSF land need indices based on
regional data for a particular region. The lists in Tables 1 and 2 are
samples of the possible land uses that may be included. The actual
land use break-downs and classification will depend on the local or
regional land use patterns and data available.