exclusive. The goal of data collection should be to provide decisionmakers with answers—what are the problems in a watershed, what are the causes of the problems, and what actions might lessen the problems (see Box 4.1).

The term information as used here connotes interpretation, synthesis, and communication of data. Knowledge connotes the translation of data, information, and ideas into explanations. Thus, explanations may be limited at the root by basic data. For instance, historical data for watersheds are often limited in coverage, of unreliable accuracy, or require significant assembly and interpretation (Trimble and Cooke, 1991). The usefulness of data, information, and knowledge is often limited because they are not offered to decisionmakers in forms that are appropriate.

Traditionally, scientific questions concentrated on understanding specific processes and research was designed to provide focused data collection. For example, research to understand runoff processes required the collection of physical data to quantify such things as precipitation and soil characteristics. Current research efforts tend to be broader in scope and are directed toward integrating our understanding of specific processes. to address problems at the watershed scale. As a result, data collection efforts now are more diffuse and include economic, social, and perceptual data.

There is a long tradition of collecting data in selected ''experimental" watersheds, and these have provided the setting for the development of our current understanding of physical and biological watershed processes. Experimental watersheds that were initially instrumented to quantify hydrologic processes have become a valuable cornerstone on which to build integrated research programs addressing hydrologic, climatic, biotic, biotic, and social factors, and their interactions. Until now, most experimental watersheds have been at sites where human influence is minimal. New experimented sites are needed in locations where social and biophysical systems interact significantly, and the addition of the Baltimore and Phoenix regions to the national Long-Term Ecological Research (LTER) program of the National Science Foundation is an important step. Current research to integrate multidisciplinary projects will build on the detailed data collection and process studies conducted at experimental watersheds. It is the strength of many of these watersheds that long-term data collection efforts can be used to quantify the year-to-year variability in natural processes, thus improving the scientific defensibility of interpretations based on the collected data.

Figure 4.1 summarizes active experimental watersheds in the United States (NRC, 1997). Most research watersheds receive support through the U.S. Forest