The authors of this book have been approached by consulting engineers: "You know about remote sensing and thus you can obtain hydrological information where no data exist, even without ground measurements, so that I can design the required capacity of a drinking water supply reservoir in a developing country. " On the other hand, the authors have been told: "Remote sensing is not of much use since it is still impossible to estimate ground water resources or surface water flows from remote sensing data. " The major aim of this book is to correct such unjustified illusions as well as...