Get an international perspective on the latest issues relating to spatial analysis, accuracy in the location and special representation of data and real world features, and emerging standards for digital spatial methods and applications. Twelve peer-reviewed papers cover: Accuracy and Uncertainty in Spatial Data and Analysis • Application of krieging and other geostatistical techniques • Fractal analysis for spatial applications • Difficulty in defining the level of accuracy for environmental and hydrologic data • Spatial variability, uncertainty, and risk for use in decision support systems • Use and application of global positioning systems (GPS) Modeling and Spatial Analysis of Environmental and Hydrologic Systems in Spatial Data Environments • Spatial techniques to model environmental systems • Development of object models for hydrologic systems. • Development of a flood warning system for watersheds in Spain • Modeling the distribution of soil moisture with remote sensing and geographic information systems (GIS) • Data integration with GIS as a management tool for decision support • Efforts to model surface soil moisture from satellite microwave observations • Use of response units to assess erosion processes in semiarid areas in southern Africa Standardization and Standard Digital Data Sets • Methods, descriptions, and digital data products, such as the watershed boundary standards for the U.S. • Status of standards in use by the U.S. government related to GIS data • Role of other organizations in the development of standards for GIS • Development of standard merged products of satellite imagery and elevation data for natural resource mapping in Canada • Development of a series of standard digital databases, in which U.S. Geological Survey has been particularly active This publication is based on a symposium sponsored by ASTM International in cooperation with the International Commission on Remote Sensing of the International Association of Hydrologic Sciences, the Canada Centre for Remote Sensing, the U. S. Geological Survey, and the U.S. Bureau of Reclamation.