Exploring streamflow response to effective rainfall across event magnitude scale

Abstract

Abstract:Sets of flow events from four catchments were selected in order to study how dynamics in the conversion of effective rainfall into streamflow depends on the event size. The approach taken was to optimize parameters of a linear delay function and effective rainfall series concurrently from precipitation-streamflow data without imposing a functional form of the precipitation filter a priori. The delay function is an instantaneous unit hydrograph (IUH) having a mathematical form of the two-parameter gamma distribution. Results from two small research catchments (0Ð18 and 0Ð63 km 2 ) with sub-daily data suggest a clear relationship between the event magnitude and response dynamics. The effect of the sampling frequency of data was addressed by gradually increasing aggregation interval of rainfall and flow data and repeating the optimization for each aggregated dataset. IUHs for different data aggregation intervals (for a single event) tended to be similar unless the aggregation changed the locations of data peaks. IUHs identified in larger catchments (58 and 1235 km 2 ) also showed variability through events; however, no systematic event magnitude dependence, as was visible in the small research catchments, was detected. Finally, the dependency detected in the small catchments was exploited in a rainfall-runoff model, where the scale parameter of the gamma distribution was linearly related to the effective rainfall intensity. Prediction of peak flows improved when the event dependency was taken into account.

A measure of watershed nonlinearity: interpreting a variable instantaneous unit hydrograph model on two vastly different sized watersheds

“…2, a family of four 3-hour unit hydrographs derived from flood records, in which as the flood peak discharge increases from a low of 3200 c. The work of Minshall (1960) has been cited by many studies as a classical case of nonlinear watershed response, some of which were cited previously by Ding (1974). Since then, other studies citing Minshall's work include Overton and Meadows (1976), Chen and Singh (1986), Singh (1988), Robinson et al (1995), Lee and Yen (2000), Cranmer et al (2001), Sivapalan et al (2002), Kokkonen et al (2004), and Paik and Kumar (2004). By contrast, the work of Childs (1958) has rarely been cited, Ashfag and Webster (2000) being a notable exception.…”

Recession curve estimation for storm event separations

“…The method by which effective rainfall becomes storm runoff is a problem that has stimulated much research in hydrology (Kokkonen et al, 2004). In the literature there are multiple methods that are used to calculate the effective rainfall.…”

The variation of discharge entering the Niger Delta system, 1951–2000, and estimates of change under global warming

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