Isochrones of travel time and distribution of flood storage from a tracer study on a small watershed

Abstract

In the practical application of many methods of flood hydrograph synthesis it is necessary to space isochrones of travel time over the watershed or to allocate the distribution of storage. The available evidence for guiding this procedure is reviewed, but most information applies to large stream systems and to flows lower than the flood discharges of interest. Times of travel data from tracing of flood runoff on a small watershed have been compared with the evidence from large streams. Average velocities were found to increase slightly in a downstream direction through the watershed, despite decreasing slope. This increase conforms with published hydraulic geometry relationships. Five geomorphological parameters have been tested as methods for spacing isochrones. Field inspection to determine mean depths, and possibly roughness, at bank‐full stages should lead to greatest accuracy, but simple parameters based on stream length also gave good results.

HYPERstream: a multi-scale framework for streamflow routing in large-scale hydrological model

“…Equation (1) is consistent with the general conceptual framework used to derive the WFIUH by rescaling the geomorphological width function through a suitable constant velocity Mesa and Mifflin, 1986;Gupta and Mesa, 1988;Rodríguez-Iturbe and Rinaldo, 1997). We note that the assumption of constant channel velocity is supported by experimental measurements, especially for high flow conditions (see, e.g., Pilgrim, 1976Pilgrim, , 1977. Additionally, stream hydrodynamic dispersion is neglected, owing to its small to negligible effect on the hydrological response, which has been demonstrated to be dominated by geomorphological dispersion already embedded into the rescaled width function (Rinaldo et al, 1991(Rinaldo et al, , 1995Rodríguez-Iturbe and Rinaldo, 1997).…”

Analytical modeling of the hydrologic response under moving rainstorms: Storm–catchment interaction and resonance

“…We assume that every point (x, y) has a corresponding value of travel time s(x, y) of water particles moving from (x, y) to the catchment outlet. Thus, the time-invariant travel time distribution fully describes the hydrologic response of the basin to an instantaneous input of uniform rainfall ; this approach has been broadly employed in previous works (Dooge, 1973) and has an experimental basis on the observations of Pilgrim (1976) (Pilgrim, 1976(Pilgrim, , 1977. Based on this assumption, the contribution to runoff hydrograph of p in the neighborhood dxdy and in the time interval dt 0 is given by…”

A review of the synthetic unit hydrograph: from the empirical UH to advanced geomorphological methods

“…The exponential holding time mechanism assumption is not physically justified and has been criticized by Gupta and Waymire (1983), Kirshen and Bras (1983) and Rinaldo et al (1991). According to Pilgrim (1977), the velocity at any moment of a given storm may be assumed to be the same throughout the whole drainage basin; however, in practice, it changes during the storm and hence the GIUH changes. The velocity also changes from one storm to another.…”