_:b1217227 . _:b1217227 . _:b1217227 . _:b1217227 "A narrow and shallow incision into soil resulting from erosion by overland flow that has been focused into a thin thread by soil surface roughness. Rilling, the process of rill formation, is common on agricultural land and unvegetated ground."^^ . _:b1217227 "Wikipedia:Rill"^^ .