Observations of the subglacial hydrological system reveal a richness of responses that are thought to reflect variations in the water supply, morphology, and connectivity of the system. To contribute insight into the physical controls that result in qualitative variations in system response, a lumped-element formalism is developed and used to simulate the behavior of simple hydraulic circuits. The circuit elements for an idealized subglacial water system differ from those used to analyze conventional hydraulic flows, but the motivation is similar: lumped systems are governed by ordinary differential equations, whereas continuous systems are governed by partial differential equations. The accompanying examples illustrate the capture property of R¿thlisberger channels, the concept of morphological switching, the role of water storage geometry in contributing to system nonlinearity, and the effects of seasonal variations in storage capacity and hydraulic resistance. ¿ American Geophysical Union 1996