Multiscale hydrologic remote sensing perspectives and applications

Water connects physical, geochemical, and ecological processes with varying scales. During the last few decades, the scientific community has realized that obtaining abetter understanding of two major complex issues across different scales in hydrologic cycle demands more research efforts. They include (1) how climate change impact could interrupt the hydrologic cycle and endanger the structure, function, and services provided by aquatic ecosystem; and (2) how hydrologic observatories may be adequately configured to overcome barriers when collecting necessary feedbacks within the constrained hydrologic systems with respect to multiple scales. The need to collect those positive or negative feedbacks thus actuates more actions to enhance fundamental understanding of the complex interactions within and among natural and human systems. With this movement, concerns about the availability and quality of water to sustain life and to fuel economies motivate deepened research in hydrologic remote sensing that can accommodate an all-inclusive capability of sensing, monitoring, modeling, and decision making to mitigate the natural and human-induced stresses on the environment. This leads to the rapid development of integrated hydrologic observatories with synergistic functionality that may be brought in to fit various purposes of water-related scientific studies across space and time scales. Hence, this book addresses work that has been conducted throughout the world over the past decade, such as 1. What are the local, watershed, and regional differences in soil moisture and evapotranspiration when using different measurement methods and models at different scales? 2. What are the potential impacts of coastal bathymetry associated with geomorphology, and how do these current and wave fields affect coastal areas? 3. How can the effects of land surface temperature, vegetation cover, evapotranspiration, and precipitation be collectively integrated to conduct ecohydrologic and drought assessment at urban regions with the aid of ground-based, airborne, and spaceborne remote sensing images? 4. How can the scenarios of global warming potential and the remote sensing products of snow water equivalent be fitted into the hydrologic modeling to address the changing flood and drought conditions in a watershed? 5. How can the images collected by different satellites be fused, synthesized, and integrated to promote the overall accuracy of predictions of hydrologic components in the hydrologic cycle at the global scale? 6. How well may the GRACE satellite exhibit with regard to showing an allinclusive viewpoint to reveal the changes of total water storage in the hydrologic cycle? 7. With global evapotranspiration, soil moisture, and precipitation all available at the global scale, can GRACE outputs be smoothly translated into the corresponding hydrologic components coherently? 8. How can the extent and function of relevant satellite remote sensing images be incorporated and concatenated as an integral part of drought and forest fire monitoring systems? On this foundation, many new techniques and methods developed for spaceborne, airborne, and ground-based measurements, mathematical modeling, and remote sensing image processing tools have been collectively presented across five distinctive topical areas in this book. The book will be a useful source of reference for undergraduate and graduate students and working professionals who are involved in the study of global change, hydrologic science, meteorology, climatology, biology, ecology, and agricultural and forest sciences. It will also be beneficial to scientists in related research fields, as well as professors, policy makers, and the general public. As the editor of this book, I wish to express my great appreciation for the contributions of many individuals who helped write, coedit, proofread, and review these book chapters. I am indebted to the 64 authors and coauthors within the scientific community who have shared their expertise and contributed much time and effort in the preparation of the book chapters. I also wish to give credit to the numerous funding agencies promoting the scientific research in hydrologic remote sensing, leading to the generation of invaluable findings presented in this book. I acknowledge the management and editorial assistance of Irma Shagla and Kari Budyk. The special efforts of many individuals including Dr. Hong Yang (coeditor), Dr. Chung-Lin Shie, Dr. Pat J.-F. Yeh, and Huei-Wen Liu are appreciated.