Evaluation of Net-free Erosion Control Blankets

Abstract

Erosion control blankets (ECBs) protect soil from being detached and transported by raindrops and subsequential overland runoff while assisting in vegetation growth. ECBs have several characteristics, for example, thickness, mass per unit area, tensile strength, elongation, water absorption, etc. However, the impact of these characteristics on the performance in mitigating erosion has yet to be well understood. To better understand the interactions of ECB properties with the detachment and transport of sediment, field tests were conducted at the Erosion Control Research and Training Center at the University of Illinois Urbana-Champaign. Various ECBs, including net-free ECBs and bionet ECBs, were tested on a 3H:1V hillslope under a 30-minute simulated rainfall event (2 in./hr). The soil used on the testing plot was silty clay loam. To investigate ECB effectiveness, total runoff volume, runoff start/end time, peak runoff rate, and sediment yield were monitored during each test. The results showed that water absorption played a big role in enhancing the performance of ECBs. The materials absorbed a large amount of water at the beginning and then acted as a wet film to cover the hillslope, reducing soil erosion by the overland flow when the soil was saturated. This wet film continued to reduce soil detachment, although it probably did not help with runoff reduction after saturation. Among the blankets tested, Profile F4 Netless was the most degradable and lightest one. North American Green DS75 had the most cost efficiency with $0.4 /sq. yd. There was no big difference in the installation method.