LUMPED-ELEMENT ANALYSIS OF SUBGLACIAL HYDRAULIC CIRCUITS

Observations of the subglacial hydrological system reveal a richness o f responses that are thought to reflect variations in the water supply , morphology, and connectivity of the system. To contribute insight in to the physical controls that result in qualitative variations in syst em response, a lumped-element formalism is developed and used to simul ate the behavior of simple hydraulic circuits. The circuit elements fo r an idealized subglacial water system differ from those used to analy ze conventional hydraulic flows, but the motivation is similar: lumped systems are governed by ordinary differential equations, whereas cont inuous systems are governed by partial differential equations. The acc ompanying examples illustrate the capture property of Rothlisberger ch annels, the concept of morphological switching, the role of water stor age geometry in contributing to system nonlinearity, and the effects o f seasonal variations in storage capacity and hydraulic resistance.