9726535 Wondzell This award supports a three year collaborative research project between Professor Steven Wondzell of Oregon State University and Professor Futoshi Nakamura of Hokkaido University in Japan. The researchers will be exploring the influence of natural processes and human modifications of river channels on stream-groundwater interactions in the hyporheic zone of mountain streams. The overall objective is to learn about controls on the extent of the hyporheic zone and associated biological and geochemical processes in mountain watersheds. The researchers are interested in constraints on vertical and lateral exchange flows of surface and groundwater and how exchange flows may be limited by controls on flow path direction and flow rate. Their general approach is to combine: (1) field studies of existing natural and managed sites; (2) before/after observations at sites altered by natural processes or experimental manipulations of flood control structures; and (3) modeling to draw general conclusions about types and magnitudes of effects of various constraining factors. This project brings together the efforts of two laboratories that have complimentary expertise, research capabilities and equipment. Streams at the Andrews Experimental Forest in Oregon range from relatively pristine to moderately impacted. They offer the opportunity to study the natural dynamics of forest-stream interactions and their influence on surface-and subsurface exchange flows. Stream networks in Japan are highly modified relative to streams in the Pacific Northwest. Thus, the Japanese streams provide an important contrast to the pristine streams in Oregon. Research results will include further refinements of the conceptual framework for riparian ecosystems as well as specific findings relevant to the mountain streams under study. Through the exchange of ideas and technology, this project will broaden our base of basic knowledge and promote international understand ing and cooperation. ***
