More thoughts on Erosion

I have found more pictures I took after the floods of 2004One shows even more damage than I saw in the others.It was taken with the telephoto

.

.

This picture shows the subsoil which is like marble size balls. When they become wet they are very greasy and slippery and during excessive rainfall they simply roll down the slope taking the top soil and grass with them..

.




.




.

.

This pic shows the root system of two African grasses, on the left and far right, Eragrostis curvula and centre Themeda triandra, root development is down two feet showing the tremedous ability to hold the soil together. The roots are very tough and fibrous.

This picture shows the poor root growth of ryegrass growing on a hillside.Some very weak roots do go down deeper but they are so weak and non fibrous that they cannot hold the soil.