| Value |
Category |
| 1 |
By sewers |
| 2 |
Protected canal |
| 3 |
Opened canal |
| 4 |
Swallow-hole |
| 5 |
River |
| 6 |
Hole |
| 7 |
Nature |
| 8 |
Other |
Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.