A special workshop on scale problems in hydrology was held at Princeton University, Princeton, New Jersey, during October 31-November 3, 1984. This workshop was the second in a series on this general topic. The proceedings of the first workshop, held in Caracas, Venezuela, in January 1982, appeared in the Journal of Hydrology (Volume 65:1/3, 1983). This book contains the papers presented at the second workshop. The scale problems in hydrology and other geophysical sciences stem from the recognition that the mathematical relationships describing a physical phenomenon are mostly scale dependent in the sense that different relationships manifest at different space-time scales. The broad scientific problem then is to identify and for mulate suitable relationships at the scales of practical interest, test them experimen tally and seek consistent analytical connections between these relationships and those known at other scales. For example, the current hydrologic theories of evaporation, infiltration, subsurface water transport and water sediment transport overland and in channels etc. derive mostly from laboratory experiments and therefore generally apply at "small" space-time scales. A rigorous extrapolation of these theories to large spatial and temporal basin scales, as mandated by practical considerations, appears very difficult. Consequently, analytical formulations of suitable hydrologic theories at basin wide space-time scales and their experimental verification is currently being perceived to be an exciting and challenging area of scientific research in hydrology. In order to successfully meet these challenges in the future, this series of workshops was initiated.

Sealing up in Hydrology using Remote Sensing Edited by J. B. Stewart Institute of Hydrology, UK E. T. Engman NASA Goddard Space Flight Center, USA R. A. Feddes Wageningen Agricultural University, The Netherlands Y. Kerr Centre d’Etudes Spatiales de la Biosphere, France The most pressing modern environmental problems are considered to affect the entire globe. For example, climate change, deforestation and desertification are all happening on such a large scale that they may affect the sustainability of man’s future. What is needed to address this question quantitatively are more reliable data on large scale land use and land-use change, and their impacts on water resources and climate. The catch is that we are never going to be able to measure directly key hydrological and meteorological variables at enough points on the ground to give adequate description of the large areas (regions and continents) for which information is required. The only way to get this is via large scale modelling and the development of remote sensing techniques. This book brings together the presentations made at a recent workshop by experts, who met to consider the problems of scaling up from local to global spatial scales and from the instantaneous satellite measurements to daily or longer time scales. The authors’ collective views represent the state of the art of their science as seen by an active international remote sensing community, and ground and planetary-based measurement scientists and modellers. The front cover illustration is reproduced courtesy of N. Fey

This book offers a comprehensive overview of the challenges in hydrological modeling. Hydrology, on both a local and global scale, has undergone dramatic changes, largely due to variations in climate, population growth and the associated land-use and land-cover changes. Written by experts in the field, the book provides decision-makers with a better understanding of the science, impacts, and consequences of these climate and land-use changes on hydrology. Further, offering insights into how the changing behavior of hydrological processes, related uncertainties and their evolution affect the modeling process, it is of interest for all researchers and practitioners using hydrological modeling.

There is a growing need for appropriate models which address the management of land and water resources and ecosystems at large space and time scales. Theories of non-linear hydrological processes must be extrapolated to large-scale, three-dimensional natural systems such as drainage basins, flood plains and wetlands. This book reports on recent progress in research on scale issues in hydrological modelling. It brings together 27 papers from two special issues of the journal Hydrological Processes. The book makes a significant contribution towards developing research strategies for linking model parameterisations across a range of temporal and spatial scales. The papers selected for this book reflect the tremendous advances which have been made in research into scale issues in hydrological modelling during the last ten years.