Peter German (GS) first raised the issue of how preferential flow in soils due to preferential flow in a famous paper with Keith Beven (GS) in 1982, Macropores flow in soils. A benchmark paper from which uncountable studies followed. Now retired, he wrote a book entitled "Preferential flow: Stokes approach to infiltration and drainage".
Stokesian flows are those that happens when all acceleration is dissipated, so the subtitle is not very informative on the content. More detailed comments will arrive when I will have read it. For now you can get it by clicking on the Figure.