Flood Location Mapping for a Series of Rain Events

During the summer of 2014 the Village of La Grange, IL experienced multiple high intensity rain events that exceeded the capacity of the village’s sewer system, resulting in flooded basements, streets, and rear yards.   On August 22nd, 2014, approximately 4.24 inches of rain fell over the area in a short amount of time.  In this and several other heavy rain events in June, water flowed overland and pooled in depression areas, resulting in water entering houses through window wells and other low openings. This event caused numerous basement backups throughout the village, of which the Public Works Department received hundreds of reports of flooding and damage as a result.  To help the department get a better picture of the extent of the flooding, they asked the village’s Geographic Information Systems (GIS) department to map all the locations where a flooding call was reported to see if there were any patterns that could be determined.

As a new member of the GIS Consortium, the village’s Public Works Director called upon GIS to map out the addresses provided by the callers in order to distinguish where concentrations of various types of flooding occurred. The GIS department took the address and flooding type list provided by Public Works and mapped these addresses against the address database in La Grange. This plotted out the points on a map and the points were symbolized according to the flooding type. The maps were used as tools to best deploy resources and understand areas of focus and concern.