Contour Stone Lines slow down runoff, increase water infiltration, and sediment is captured behind these semi-permeable barriers, improving production. A perennial grass can supplement the lines where stone is scarce. Suited to low slopes, high runoff and hand labour. This technique is readily adopted by resource-poor farmers and can lead to a harvest even in years with low and erratic rainfall.
Similar to a sieve, the willows allow water to flow through but trap the sediment back. Within a year, these structures can trap up to 10cm of sediment. Over time, this increases as the willows become more established and more sediment can be kept back. After 20 to 30 years, the vegetation will have complete cover and sediment erosion is almost completely stopped.