It was not until the 20thcentury that many geomorphologists began to integrate the work of hydraulic engineers and hydrologists with geomorphic concepts in fluvial systems. Statistical manipulations and concepts aided greatly in the development of ideas on the relation of the magnitude and frequency of hydrologic events on the fluvial system. Also arising primarily as a result of the statistical outlook was the approach where characteristics of the river and its basin were looked upon as random variables in a population. Different approaches, whether old or new, are tools used to aid in better understanding the morphology of the earth's surface features and the processes by which a river works to create and modify the form of the land. The papers in this volume, originally published in 1973, reflect these approaches but more than that they unify and integrate the results of research with basic concepts and principles of fluvial morphology and process.