Using springs to study groundwater flow and active geologic processes

Springs water provides a unique opportunity to study a range of subsurface processes in regions with few boreholes or wells. However, because springs integrate the signal of geological and hydrological processes over large sp atial areas and long periods of time, they are an indirect source of inform ation. This review illustrates a variety of techniques and approaches that are used to interpret measurements of isotopic tracers, water chemistry, di scharge, and temperature. As an example, a set of springs in the Oregon Cas cades is considered. By using tracers, temperature, and discharge measureme nts, it is possible to determine the mean-residence time of water, infer th e spatial pattern and extent of groundwater flow, estimate basin-scale hydr aulic properties, calculate the regional hear flow, and quantify the rate o f magmatic intrusion beneath the volcanic are.