Summer City Flood Prevention Program (夏期都市水害防止プログラム Kaki Toshi Suigai Bōshi Puroguramu?) is a large-scale disaster prevention program conducted in Academy City in order to test underground passageways' effectiveness during a flood.
Apparently only used in places that has underground streets and passageways like in School District 7, though it also takes place in the entire city and can includes some above-ground roads, the program has the underground deliberately flooded for a time by guiding river water into them after passing it through water purification equipment in order to test the underground's drainage equipment and emergency shutters. This, however, essentially turns all the city's shortcuts into flowing pools. The program apparently allows for people to swim in the pools.
The only known time this program took place was in the summer of the previous year of the story timeline, the same one where Kamijou Touma and Shokuhou Misaki finally told their names to one another.
- Shinyaku Toaru Majutsu no Index Light Novel Volume 11 Chapter 1 Part 4