Design, Construction and Evaluation of Narrow Base Terraces

Abstract

NARROW base terraces were introduced in the Corn-belt in 1977. Their profile has been changed from cut on the uphill side to cut on the downhill side. By 1983, 322 narrow base terrace systems totaling 375 km were installed in 10 counties in northern Iowa (SCS, 1983) and have also been installed in Illinois, Minnesota, Missouri and Nebraska. Practices used to design, construct, and maintain narrow base terrace systems are presented and discussed. Construction costs are presented and compared to the cost of other types of terrace systems. The main advantage of the narrow base terrace systems are lower cost of construction, less soil movement, improved farmability and increased safety. The main disadvantage is that 9% or more of the land area is taken out of production. They also need more attention during construction and additional attention and maintenance is required after construction to reduce the possibility of failure.