Influence of Weft Density on Runoff Erosion Control Performance of Rolled Erosion Control Systems

Rolled erosion control systems (RECSs) used in erosion control application mitigates runoff erosion through micro-barriers created by cross-laid weft yarns of RECS. Increase in number of cross-laid weft yarns (weft density) of RECSs is expected to improve its performance, so coir and jute RECSs with different weft density were prepared and evaluated for erosion control performance and germination performance. Runoff erosion test was performed in a bench-scale setup designed based on ASTM D 7101 standard, at zero and soil infiltration condition (with and without soil), at three different slope angles of 15°, 30°, and 45°. Whereas, germination test was performed using earthen pots and wheat seeds, based on ASTM D 7322 standard. Increased weft density resulted in improved performance of jute RECSs at all slope angles and infiltration condition, due to increased storage volume and better drapability. But the performance of coarser yarn count coir RECSs reduced at higher slope angle, due to increased flexural rigidity. In germination test, increase in weft density of finer yarn RECSs resulted in improved total rooting and percentage of vegetation, due to lower flexural rigidity and higher moisture holding. Whereas in coarser yarn RECSs, increase in weft density resulted in decreased total rooting and percentage of vegetation. It was also observed that the jute RECSs facilitates faster initial growth and highest total rooting as compared to coir RECSs due to finer and soft jute fibers that facilitate easy vegetation growth and better moisture-holding capacity.