| On peak | At foot of mountain-upstream | Difference |
Chibas mountains | 0.2 | 0.3 | −0.1 |
Ahagar Mountains | 0.15 | 0.24 | −0.09 |
Gebel Mara | 0.37 | 0.5 | −0.13 |
Assir mountains | 0.1 | 0.4 | −0.3 |