Answer:
Accelerated erosion or change in cover tend to persist and grow over time because the continuous erosion of the channel further escalate the rate of erosion by further widening of the channel unless there is a human intervention to stop this. Once the vegetative cover of a soil is altered, it leaves room for erosion (the degree of the erosion depends on the degree of loss or gain of vegetative cover). In a bad case where there is a loss of vegetative covering of the soil, erosion sets in, washing away the top soil and reducing the cover vegetation even more. These two activities are those type of activities that grows over time once they are activated.