| Value | Category | Cases | |
|---|---|---|---|
| 1 | Sump(modern pit) | 117 |
2.9%
|
| 2 | Open hole | 110 |
2.8%
|
| 3 | Gutter | 80 |
2%
|
| 4 | In nature | 3631 |
91.5%
|
| 5 | Other | 30 |
0.8%
|