Hydrology is vital to human civilisations as well as to natural ecosystems, yet it has only emerged as a distinct scientific discipline during the last 50 years or so. This book reviews the development of modern hydrology primarily through the experiences of the multidisciplinary team of scientists and engineers at Wallingford, near Oxford, who have been at the forefront of many of the developments in UK hydrological research. These topics include: • The development of basic understanding through  the collection of data with specialised instrumentation in experimental basins • The study of extreme flows – both floods and droughts • The role moisture in the soil • Studies of the processes controlling  evaporation • Water resource studies • Modelling and prediction of the extremes of flow improved • Understanding of water quality issues • A widening recognition of the importance of an ecosystem approach  • Meeting the challenges of climate change, • Data handling • Future developments in hydrology and the pressures which generate them. Readership: hydrologists in both academia and a wide range of applied fields such as civil engineering, meteorology, geography and physics, as well as advanced students in earth science, environmental science and physical geography programmes worldwide.