Flood generation: process patterns from the raindrop to the ocean

[摘要] This article reviews river flood generation processes andflow paths across space scales. The scale steps include the pore, profile,hillslope, catchment, regional and continental scales, representing a scalerange of a total of 10 orders of magnitude. Although the processes differbetween the scales, there are notable similarities. At all scales, there aremedia patterns that control the flow of water and are themselves influencedby the flow of water. The processes are therefore not spatially random (asin thermodynamics) but organized, and preferential flow is the rule ratherthan the exception. Hydrological connectivity, i.e. the presence of coherentflow paths, is an essential characteristic at all scales. There are similarcontrols on water flow and thus on flood generation at all scales butwith different relative magnitudes. Processes at lower scales affect floodgeneration at larger scales, not simply as a multiple repetition of pore-scale processes but through interactions which cause emergent behaviour ofprocess patterns. For this reason, when modelling these processes, the scaletransitions need to be simplified in a way that reflects the relevantstructures (e.g. connectivity) and boundary conditions (e.g. groundwatertable) at each scale. In conclusion, it is argued that upscaling as the meremultiple application of small-scale process descriptions will not capturethe larger-scale patterns of flood generation. Instead, there is a need tolearn from observed patterns of flood generation processes at all spatialscales.

[学科分类] 妇产科学