The fact that persistent spatial organization in catchments exists inspired many scientists to speculate whether this is a manifestation of self-reinforcing co-development due to an underlying organizing principle. Spatial organization of catchments manifests through different fingerprints and affects different processes:
- Hillslope scale spatial organization of soil types manifests in a typical arrangement of soil types along the topographic gradient. This is of key importance for overland flow, sediment yields, water availability for evaporation and temporal stability of soil moisture patterns.
- Spatially organized variability at the pedon scale (within a soil type) is reflected in a spatial correlation of soil hydraulic properties, which translates into spatially correlated storage and recharge.
- Soils and unconsolidated rock are veined with connected networks of preferential flow paths either created by biota (worms, rodents, roots) or by abiotic processes (shrinkage cracks, pipes, rills). Activated preferential flow networks allow for high mass flows even at small driving gradients and thus dominate export and redistribution of water and matter across many scales.
The rationale of this Chapman conference is thus to foster the development of a holistic framework to explore and understand how spatial organization controls complex behavior of intermediate scale catchments with the emphasis set on short and long term catchment flows of water and energy. Here, “holistic” means to harmonize the triad of observation, theory/explanation and prediction.