Regularity-based functional streamflow disaggregation: 2. Extended demonstration

Within the scope of a program to empirically assess the pathways across large river systems of substances from diffuse sources, a method has been proposed and demonstrated in part 1 of blind functional streamflow disaggregation (FSD). It yields fast, transient, and (s) low conceptual, parallel component flows. We apply the technique here to German and Austrian gauging stations from watersheds of the Elbe and Danube basins, covering geomorphologic conditions from lowlands to alpine. Potential relations to the classical concept of river runoff composition (base flow, interflow, and overland flow) are evaluated by contrasting FSD analyses with direct rainfall-runoff syntheses using the distributed models Large Area Runoff Simulation Model (LARSIM), Soil and Water Assessment Tool (SWAT), and Soil and Water Integrated Model (SWIM). The material is supplemented in part by another empirical technique, Differentielle Ganglinien-Analyse (DIFGA), and by the Hydrologiska Byrans Vattenbalansavdelning (HBV) model in a lumped mode. Blind FSD in its shortcut version turns out to be competitive in general with the simulations consulted. A moderately higher surface and subsurface flow diversification, however, like the one borne in a greedy'' FSD process, is indicated. We shed a glance in passing at further useful applications, from supporting hydrologic modeling to tracing climatic signatures in internal changes of the terrestrial hydrologic cycle.