EROSION AND STABILITY OF A MINE SOIL

Mine soils developed from mine spoils commonly have a wide range of pa rticle size. The slopes of old spoil piles usually are marked by gulli es due to years of uncontrolled erosion. These characteristics raise q uestions about applicability of available theories and models for esti mating runoff and erosion. An investigation was made to determine whet her available erosion models can work for mine soils and can account f or gully erosion. The investigation at an abandoned surface mine consi sted of measurement of soil and sediment properties, measurement of ru noff and erosion, observations of armor by rock fragments on gully flo or, and calculations with available theories of sediment transport and slope stability. The results at this site suggest that (1) prediction s with the ANSWERS model have about the same accuracy as those made fo r agricultural lands; (2) armor provided by rock fragments are tempora ry as they are periodically removed by debris flows; (3) detachment by rainfall impact is the primary cause of erosion on short steep slopes ; and (4) a simplified method can be used for estimating erosion on su ch slopes.