Abstract.

This monograph discusses the mechanics of Meandering Rivers with the help of the mathematical and modeling tools built up in the previous monograph of the same Authors (monograph 1 of the present series). After introducing the reader to the ubiquitous character of meandering streams, we discuss the hydrodynamics of curved channels with fixed beds and banks. Next, we extend the analysis to account for the mobile character of the bed and show that it gives rise to the alternate sequence of riffles and pools that characterize river meanders. Allowing for the erodible character of the river banks then allows to build up a rational theory of meander formation able to explain most of the features observed in nature: meander growth, migration, skewing, multiple loops, cutoffs and meander belts.

The Lower Mississippi River, extending from Cairo, Illinois to the Gulf of Mexico, annually transports approximately 170 million tonnes of sediment. Historically, the quantity and calibre of sediment derived from catchment erosion have been affected by changes in land-use and management. For example, soil erosion increased during the 19th and early 20th centuries due to settlement by Europeans and this may have elevated catchment sediment supply to the Mississippi River, while more recently the supply of sediment from tributaries is known to have decreased markedly as a result of river engineering and management. Specifically, the construction of large dams as part of the Mississippi River and Tributaries (MR & T) Project has trapped sediment that would otherwise have been supplied to the Mississippi, particularly by the Missouri River. Marked changes have also occurred in the extent of eroding bankline along the Mississippi and these must have reduced the input of sediment derived from this source. For example, during the last three decades, a sustained construction program of bank revetments and dikes has produced a stable alignment. Given these trends in sediment supply from catchment, tributary and bank sources, it is not surprising that most studies of sediment movement report a large decrease in measured sediment loads at selected monitoring stations along the Mississippi River over the last 50 years (Kesel, 1988; Dardeau and Causey, 1990). However, a case can be made that the bed material load must have increased since the 1940s. This argument is based on analysis of morphological changes observed along the river that have led to an overall increase in slope and available stream power, coupled with the fact that bed material sizes along the river have remained almost constant.

The proceedings of the 4th Symposium on River, Coastal and Estuarine Morphodynamics offers the latest research results concerning quantitative modelling of the interaction of water and sediment and the shapes this interaction makes in rivers, watersheds, estuaries, the coast, the continental shelf and the deep sea. Morphodynamics is the study of the evolution of landscape and seascape features, from small scale to large.

Around the world, many people live, work and recreate in river, estuarine and coastal areas, systems which are also important wildlife habitats. It is imperative to understand the physics of such systems. A key element here is morphodynamics: the mutual interaction and adjustment of landform topography and fluid dynamics involving the motion of sed

Coastal, estuarine, fluvial and submarine morphodynamics encompass some of the leading processes shaping our planet. They stem mainly, but not only, from the interaction of water in motion and movable sediment boundaries, resulting in morphological changes produced by erosion, transport and deposition of sediments that generate a variety of landsca