In human geography, a catchment area is the area from which a city, service or institution attracts a population that uses its services. For example, a school catchment area is the geographic area from which students are eligible to attend a local school.
Contents
Governments and community service organizations often define catchment areas for planning purposes and public safety such as ensuring universal access to services like fire departments, police departments, ambulance bases and hospitals.
Creation
Catchment areas are generally established and modified by local governments. These boundaries can be modeled using geographic information systems (GIS). There can be large variability in the services provided within different catchments in the same area depending upon how and when those catchments were established. They are usually contiguous but can overlap when they describe competing services.
Defining
Catchments can be defined based upon a number of factors including distance to the facility, actual travel time to the facility, geographic boundaries or population within the catchment. In a distance based catchment, the area serviced will often depend on the number of visits expected to that institution by each individual. For example, it may be more acceptable to have a larger catchment for a hospital where any one individual will have few annual visits in comparison to a school where visits will be daily and hence desired distance would be closer. When a facility’s capacity can only service a certain volume, the catchment may be used to limit a population’s ability to access services outside of that area. For example, children may be unable to enroll in a school outside of their catchment to prevent the school's services being exceeded.