GEOG M107 Chapter Notes - Chapter 10: Soil Conservation, Subsoil, Rill
Document Summary
Expensive: only used where specific need exists (where erosive effects of water/wind are most concentrated) Cropping and tillage less expensive and less obtrusive. To control runoff water and erosion from roadways and other building projects. To restrain nature"s rampaging waters and strong winds. Not effective on sandy areas, stony land, or shallow soils (over bedrock or fine-textured, impermeable subsoils) Impractical on fields with complex topography and steep slopes. Bench terrace: built where supply of good, level, agricultural land limited but population demands cultivation. Nearly vertical backslopes stabilized by vegetation or stones. Carry soil uphill once stones in place. Graded terrace: graded (sloped) channel that intercepts/collects runoff and slowly leads it to vegetated area (pastures/woods) or prepared outlet (waterways) Reduces erosion more than runoff, because of shortened slope length, slow runoff velocity, and trapped sediments. Reduces rill and gully erosion, but local sheet erosion may occur (but most of the sediment is deposited in the terrace channels)
