Erosion, Sediment, and Land Conservation
Domain scope
This domain tests erosion processes, soil loss prediction, sediment delivery, and conservation practices used to control erosion and protect receiving waters.
Core rules and concepts
- Erosion involves detachment, transport, and deposition. RUSLE predicts sheet and rill erosion, not gully erosion.
- RUSLE: A = R × K × LS × C × P, where R is rainfall erosivity, K is soil erodibility, LS is slope length and steepness, C is cover management, and P is support practice.
- C and P are dimensionless and reduce soil loss when correctly managed.
- Sediment delivery ratio relates eroded soil to sediment reaching a water body; deposition and buffers reduce delivery.
- BMPs include silt fence, sediment basins, vegetative buffers, contour farming, terracing, and no-till.
Worked example
R = 200, K = 0.3, LS = 2, C = 0.2, P = 0.5. A = 200 × 0.3 × 2 × 0.2 × 0.5 = 12 t/acre/yr. Reducing C to 0.05 through continuous cover would lower predicted loss to 3 t/acre/yr.
Traps that cost marks
Using RUSLE for gully erosion; mixing metric and US customary units; forgetting that C and P are dimensionless; and assuming all eroded sediment reaches surface water.