ABSTRACT
This chapter explains the channel networks developed by groundwater sapping in fine-grained sediments: analogs to some Martian valleys. The linear, areal, angular and topologically related parameters of Martian channel networks are closely aligned with patterns developed by surface runoff or those developed by groundwater sapping processes. The threshold of erosion of fine-grained sediments subjected to emergent groundwater flow is more complicated than the threshold of motion of flat-lying sediments beneath a fluid flow because of the added effects of the groundwater flow and, often, because of appreciable surface gradient. Ultimately we plan to develop a three-dimensional computer simulation model that should simulate networks similar to those created in the three-dimensional experiments and illustrate the mechanics of groundwater capture. Finally, neither the laboratory sapping networks nor, presumably, the suspected Martian analogs have approached a steady-state morphology. The chapter discusses simulation of sapping channel networks, schematic drawing of the three-dimensional experimental sapping chamber and mechanics of sapping of fine-grained sediments.
