GEOG M107 Lecture Notes - Lecture 10: Rill, Tillage
Document Summary
Expensive: only used where specific need exists. Cropping and tillage less expensive and less obtrusive. Not effective on sandy areas, stony land, or shallow soils. 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 back slopes stabilized by vegetation or stones. Carry soil uphill once stones in place. Graded (gradient- means slope) terrace: graded channel that collects runoff and slowly leads it to vegetated area or prepared outlet. Reduces rill and gully erosion, but soil deposited in terrace channels. Level terrace: built with level channel that holds water behind ridge until absorbed by soil. Steep-backslope terrace: on relatively steep land, flat front slope with steep backslope supported by permanent grass cover. Contour bunds: small versions of graded terraces, built by hand in developing countries, placed at narrow intervals.
