Dongas, Erosion, & Ecosystem Health

image


Donga is Afrikaans for a gully created by erosion. I cannot explain why this word is the prefect descriptor for these naturally occurring phenomenon, but it must be something to do with the emotive accompaniment verbalized in “donga.” In the word donga I feel the earth beneath giving away, cracking open, and washing down. Dongas are more frequently found in areas of rural homesteads, agriculture, or grazing, but still appear in the mountains and still represent the same symptom: the earth is out of balance here.

There is a connection to land in South Africa I have experienced no where else. Humans have a long history on this land, somehow at some point they may have fused. Every time I walked over a donga, my mind recalled a few lines from “Cry, the Beloved Country” by Paton.

“The great red hills stand desolate, and the earth has torn away like flesh. The lightning flashes over them, the clouds pour down upon them, the dead streams come to life, full of the red blood of the earth. Down in the valleys women scratch the soil that is left and the maize hardly reaches the height of a man. They are valleys of old men and women, of mothers and children. The men are away, the young men and girls are away. The soil cannot keep them any more.”

Erosion is a large issue in South Africa,where there is an estimated 300-400 million tons of land lost annually to erosion and costs an estimated R 2 billion (including costs for filtering sediment from dam water). South Africa’s neighbor Lesotho is estimated to have no more arable land available by 2040, and many other countries experience other serious threats. Erosion is a naturally occurring process where sediment is moved from one location by water or air to another location, but us (as humanity) have frequently accelerated and unbalanced this process. Agriculture, horticulture, developments, and poor land management all disrupt the natural movement of water across the land. And high sediment run-off leads to sedimentation of waterways (impacting the water quality and habitat) and loss of healthy topsoil which is valuable to natural environments and agriculture.

donga erosion fynbos

Naturally occurring disruptions can also accelerate erosion, like wild fires. This deep donga may have started after a burn of all the vegetation that typically held the top soil in place. Walking up the bank of this donga was difficult as the soil quality was so poor and sandy, but you may see that the natural flora is recovering and will help slow the removal of topsoil. In the top photo you can see the plants at the water’s edge, which in time will continue to place deeper roots, grow larger and slow the movement of water and debris through the donga. This too will heal, as all things eventually return to balance, it is just a matter of time.