What is a heat map in GIS and how is it used to identify risk hotspots?

• A. A heat map displays exact point locations without aggregation.
• B. A heat map shows intensity of a variable across space, highlighting concentrations of risk factors to prioritize mitigation and resource allocation.
• C. A heat map is the same as a pie chart of land use categories.
• D. A heat map cannot be used to identify hotspots of risk.

Answer: (B)

A heat map in GIS visualizes how intensely a variable varies across space, using color to show where risk factors are concentrated. By converting point data or raster values into a continuous surface, a smoothing or density method (like kernel density) creates a map where brighter or warmer colors indicate higher risk values and cooler colors indicate lower values. This visualization makes hotspots—areas where risk factors cluster—easy to spot, so you can prioritize mitigation efforts and allocate resources where they’ll have the most impact. It’s a way of turning scattered data into a map of urgency rather than showing exact locations; you can use a single risk indicator or combine factors into a composite score. Keep in mind that choices in the method and color scale affect how hotspots appear, and the map abstracts exact figures in favor of relative intensity.