Estimating Groundwater Fluxes across Interfaces

Water is the most important substance on Earth. While not a mineral itself, water rules the mineral kingdom since interaction with water is fundamental to all geological processes. And water can even slip into the mineral kingdom by freezing into ice. Water occurs in the hydrologic cycle as soil water, groundwater and surface water. We also find water vapor in the atmosphere and frozen water in ice sheets and glaciers. The interactions among the various water reservoirs are receiving increased attention recently as researchers investigate fluxes of water across the interfaces between reservoirs. Groundwater/surface water interaction has long been a topic of interest among hydrologists. Much attention has been given to both the theory and measurement of groundwater fluxes to and from surface water bodies, yet there are still many difficulties in obtaining accurate estimates of the spatial and temporal distribution of these fluxes, including fluxes to and from rivers and streams, reservoirs and lakes, wetlands, and the ocean. Similarly, there are no standard procedures for measuring recharge to the groundwater system from precipitation. Recharge/discharge estimates are of interest at many different scales and for many different purposes. These fluxes affect physical, chemical and biological processes in the subsurface. Furthermore, basin scale biogeochemical cycles are determined in part by recharge/discharge patterns and the physiology of vegetation is strongly linked to recharge/discharge zones. Inflow of groundwater to surface water bodies carries nutrients important to biological communities. Recent work at the groundwater-stream interface (the hyporheic zone) and at the groundwater/lake interface has demonstrated that most of the chemical transformation occurs within a few inches of the interface. Improved measurements of groundwater fluxes and associated biogeochemical processes within these interfaces are needed. Understanding the spatial and temporal distribution of recharge is a basic prerequisite for effective groundwater resource management and modeling and is one of the keys to economic development in rapidly expanding urban, Estimating Groundwater Fluxes across Interfaces Featured Faculty Research