Mechanical Structures and Engineering Techniques

Abstract

Mechanical or engineering structures are designed to control runoff and soil erosion in fields where biological control practices alone are insufficient to reduce soil erosion to permissible levels. Because construction of engineering structures involves soil disturbance, change in landscape features, and some removal of land from production, biological practices such as residue mulching, no-till, reduced tillage, cover crops, riparian buffers, and grass filter strips must be the first choice for controlling soil erosion. Biological measures are also less expensive than engineering structures. Vegetative cover moderates erosion in a natural and ecological manner. Plants interact with the soil beneath in a mutual relationship while reducing soil erosion. Their roots increase soil shear strength and water infiltration and reduce detachment of soil particles. The canopy cover intercepts and changes the erosive raindrops into non-erosive streams of water throughfall. Dense stands retard runoff velocity and increase the infiltration opportunity time, thereby reducing runoff.