Application of Coal Ash to Postmine Land for Prevention of Soil Erosion in Coal Mine in Indonesia: Utilization of Fly Ash and Bottom Ash

Table 4

Risk assessment of soil erosion in Indonesia.

Class	Surface soil loss (cm/year)
Very high	>4.8
High	1.8–4.8
Moderate	0.9–1.8
Low	0.15–0.9
Very low	<0.15