Catchment areas for towns/cities, shopping centres/commercial activities using urban gravity models such as the Huff Model.
The figure on this page is the catchment area for the Sandton City shopping centre in Johannesburg.
Size of the shopping centre and distance to possible consumers were used to determine the attractiveness of the centre.
The probability of consumers visiting the centre was calculated and mapped. Darker red represents a higher probability.
The same methodology can be used to identify catchment areas for rural towns.