Erosion problems from different aspects

Sammanfattning 4 papers: (1) Kjellman, W: Unorthodox thoughts on filter criteria; (2) Hedar, PA: Filters as protection against erosion; (3) Andersson, S: Stability of armour layer of uniform stones in running water; (4) Söderblom, R: Some laboratory experiments on the dispersion and erosion of clay materials.