In New England, patterns of glacial deposition strongly influence wetland occurrence and function. Wetlands overlying permeable deposits may be associated with important aquifers where they can produce slight modifications in water quality and head distribution within the aquifer. Impacts to wetlands undoubtedly will affect the functions, but the precise nature of the effect is difficult to predict. The difficulty is especially true of incremental impacts to wetlands, which may, for example, produce a change in streamflow disproportionate to wetland area in the drainage basin (i.e., a non-linear effect). Additional research is needed before hydrologic function can be reliably correlated with physical properties of wetlands and landscapes. A model is proposed to structure future research and explore relationships between hydrologic function and physical properties of wetlands and landscapes. The model considers: nature of the underlying deposits (geologic type), location in the drainage basin (topographic position), relationship to the principal zone of saturation (hydrologic position), and hydrologic character of the organic deposit. (Copyright (c) 1988 Springer Verlag.)