IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 4 - HYDRO-ENVIRONMENT : Skewness of Travel Time Distribution
Skewness of Travel Time Distribution
Author : Joo-Cheol Kim and Kwansue Jung
Positively skewed shape is one of the most common features imprinted in hydrologic nd response function such as unit hydrograph. Following the previous approaches to the 2 moment of rd GIUH the 3 moment of travel time distribution at the basin?s outlet is analytically formulated in the framework of width function-based GIUH theory with the Inverse Gaussian distribution. For the illustrative purpose it is applied to 5 subbasins of the Bocheong creek watershed in Korea. Due to the lack of the appropriate information about the hydrodynamic conditions of the subbasins of interest their approximate ranges presented by D?odorici and Rigon (2003) are used as the reference values. The total rd 3 moment of travel time distribution can be largely divided into two distinctive contributions each of which comes from the variance of hydrologic response caused by dispersion mechanisms, the variance-borne contribution, and the skewness of rescaled width function by kinematic interaction between hillslope and channel under the assumption of pure advection, the geomorphologic-kinematic contribution, respectively. It is noted that the ratio between hillslope and channel network celerity affects rd the geomorphologic-kinematic contribution to the 3 moment of travel time distribution. The alteration of rd rd the celerity ratio up to 100 produces the drastic change of the 3 moment. Especially the sign of the 3 moment for two subbasins, whose width function is negatively skewed, changes from negative to positive at the celerity ratio about 5 to 20. This is consistent with suggestion of Botter and Rinaldo (2003). To sum up the difference of velocity between hillslope and channel network is the main factor to shape the skewness of hydrologic response. The relative role of the variance-borne and geomorphologic-kinematic contribution to the gross skewness of hydrologic response needs to be further investigated in associated with the site specific hydrodynamic conditions.
File Size : 467,090 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Date Published : 18/07/2016
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