This proposal will advance integrative hydrologic science through the development of a hydrologic information system that can be implemented at universities throughout the United States. It involves collaboration between hydrologic scientists from the Consortium of Universities for the Advancement of Hydrologic Science, Inc (CUAHSI) and computer scientists from the San Diego Supercomputer Center, and supports a larger strategy at NSF to develop cyberinfrastructure to advance interdisciplinary study of environmental systems. The CUAHSI Hydrologic Information System will be built around a hydrologic data model that synthesizes data from diverse sources describing the water environment, and will support knowledge discovery through its own analysis and visualization tools and links to external modeling and software systems. The Hydrologic Information System will be built as a network so that data sources from many geographic locations can be automatically harvested and imbedded within a common data framework at the user's location. In this project, a prototype system will be developed with the San Diego Supercomputer Center as the hub, and the experience thus gained used to define a request for proposals for a CUAHSI Center for Hydrologic Information which will be responsible for the long-term maintenance and support of this system. Integrative hydrologic science will be addressed through a series of CUAHSI science driver questions posed first for a hydrologic observatory planning study of the Neuse River Basin, whose data will be synthesized into the CUAHSI hydrologic data model as a prototype Digital Watershed. Similar Digital Watersheds will be constructed using later CUAHSI planning studies for hydrologic observatories elsewhere in the nation, thus providing a comprehensive information base for comparative studies across different hydrologic regimes. These datasets will be made freely available through an internet interface, and the hydrologic data model will also be provided to hydrologic scientists who want to develop Digital Watersheds at other locations. The intellectual merit of this project is that it harnesses information technology to support hydrologic science by building around a data model that has a coherent intellectual structure and synthesizes data from many disciplines. It will enable the tracing of water movement and transport of constituents vertically between atmosphere, surface water and groundwater, and horizontally through the landscape from watersheds and aquifers to streams, rivers, estuaries and bays. It will integrate data across scales of space and time. This will enable the testing of hypotheses about the interfaces between hydrologic processes in a manner and scale that is rarely attempted now. The results of these studies will be published in journal articles and as a series of CUAHSI monographs. The prototype hydrologic information system developed in this project will be of significant value in itself for hydrologic science research and also as a guide to the future long-term implementation of CUAHSI hydrologic information systems. The broader impacts of this project include its networking of hydrologic scientists at many universities who will jointly be contributing and receiving hydrologic information. The CUAHSI hydrologic information system and its accompanying datasets will be developed in the public domain and available to the professional hydrology community and to educators at all levels. As educational exercises using this information are developed by CUAHSI scientists, they will be shared with the broader community through such facilities as the Digital Library for Earth System Education (DLESE
