ABSTRACT
The sediment budget concept represents a means of expressing the principle of conservation of mass or mass balance that characterizes the operation of erosion, transport, and deposition processes within the environment. The concept can be applied to a range of spatially defined environmental systems, including drainage basins, beaches, dunefields, lakes, and glaciers, and to smaller subsystems within these, such as a slope, an alluvial fan or a channel reach within a drainage basin. The mass balance equation for a given system or subsystem takes the form:
Output ¼ Input D Storage
Sediment budgets can be established at different spatial and temporal scales, ranging, for example, from a global representation of land erosion and land-ocean sediment transfer involving annual fluxes, to the evolution of a sand or gravel bar within a river channel during an individual event. Their potential value lies in two main applications. First, they can provide a conceptual framework for developing an improved understanding of the interaction of erosion, transport, and deposition processes, by quantifying the fluxes involved and demonstrating the importance of sinks or stores. Second, they can provide a useful management tool for assessing changes resulting from human activities, and for informing the design of sediment management and control strategies and the prediction of the likely impact of future environmental change. From a water science perspective, it is appropriate to emphasize the sediment budgets of drainage basins and this entry will focus on this aspect. Some workers interpret the term ‘‘sediment’’ to embrace both particulate (or clastic) and dissolved material (or solutes), but here attention will be limited to clastic material or sediment sensu stricto. This contribution will briefly review the development of sediment budget studies, provide examples of sediment budgets developed for particular drainage basins, and discuss their implications and practical application, and finally outline the problems associated with establishing reliable
catchment sediment budgets and thus using the sediment budget as a management tool.
