Multiscale Trend Analysis of River Basin Dynamics

Storm runoff hydrographs are the signature of a basin's dynamics to a given precipitation forcing. As such, their study across basins and over a range of scales offers the opportunity to detect and quantify nonlinearities and scaling laws in river basin dynamics. Manual extraction of hydrograph characteristics (e.g., time to peak, relaxation time and peak magnitude) however, is tedious and has prevented extensive regional analyses of such observations for the purpose of scaling and regionalization. In this paper, (1) we propose a new methodology, called multiscale trend analysis (MTA) for the automatic and reliable extraction of hydrograph characteristics from hourly or finer scale streamflow series, and (2) we report the results of a regional multiscaling analysis of hydrologic response characteristics from 31 stations for drainage areas ranging from 10 to 10⁴ km² over the Kansas/Oklahoma region. Our results suggest the presence of statistical multiscaling in hydrologic response characteristics and a change of scaling regimes at a scale of approximately 700 km². We relate this scale to the scale at which channel morphometry properties, fluvial regimes, and statistical properties of floods also change and highlight the interconnection of physical processes and statistical laws in river basin dynamics.