THE INTERACTION BETWEEN GROUNDWATER AND SURFACE WATER: FROM TOM WINTER'S MODELS TO THE REAL WORLD

During the late 1970s and early 1980s, Tom Winter used state-of-the-art numerical models to simulate groundwater flow and exchange at the interface between groundwater and surface water in a wide range of hypothetical settings. Results from those models greatly advanced hydrological thinking at the sediment-water interface and generated new concepts regarding exchange between groundwater and surface water. Tom often was met with the question, “But have you ever seen this in the real world?” Thus began a campaign to collect field data in a broad range of climatic and geologic settings to determine whether modeled results were realistic. After several decades of field research conducted by numerous investigators, most of the processes indicated by Tom’s early modeling efforts have now been documented. Many of the concepts that were thought to be unrealistic or modeling anomalies have been shown to be common. From transient flow reversals to migration of stagnation points to loss of water from the center of a sinkhole lake, examples are presented that demonstrate the evolution from hypothetical result to generally recognized hydrological configuration. Tom’s iterative approach of model-based hypothesis followed by field work commonly generated new and improved hypotheses, leading to one of Tom’s often-repeated quips, “You need to study a place for a while before you even begin to ask the right questions."