New method to calculate the dynamic factor–flow velocity in Geomorphologic instantaneous unit hydrograph

Abstract

The determination of characteristic flow velocity is a hydrodynamic problem needs to be solved in the application of geomorphologic instantaneous unit hydrograph (GIUH) for runoff simulation in areas with no or limited data. In this study, 120 watersheds are collected to construct a regression model; 85 of these basins are used for regression analysis, and the 35 remaining basins are utilized to verify the feasibility of the constructed model. Random forest algorithm is applied to screen out important geomorphologic factors from the 16 extracted factors that may affect flow velocity. Multivariate regression is used to establish the numerical relationship between velocity and the selected factors. Sensitivity analysis of each adopted factor in the constructed model is conducted using the LH-OAT method. The rationality and feasibility of the regression model are validated by comparing the flow velocity calculation with a previous approach, which is also calculated based on geomorphological parameters. Subsequently, the runoff simulation based on the GIUH model is evaluated using the proposed technique. Results demonstrate that the proposed formula possesses high fitting accuracy and can be easily used to calculate flow velocity and generate GIUH.

The Influence of Two Different Time of Concentration Equations on the GIUH-based Flood Hydrograph Estimates of Keduang and Temon Sub-Watersheds, Indonesia

“…The dynamic parameter velocity of the watershed can be calculated using the combination of the time of concentration (tc) equation and the velocity (V) equations. Many empirical equations may be utilized to determine the time of concentration-time [1,5,23]. The time of concentration equations according to Kirpich and Ventura is shown in equations ( 7) and ( 8), respectively.…”

“…There are many formulas for Tc that utilize the first approach including Kirpich and Ventura. The Kirpich time of concentration is more widely used than that of Ventura due to basin size considerations [1,[3][4][5] because of the Kirpich equation is more suitable for relatively small catchment areas (0.004-0.453 km 2 ). The Ventura time of concentration was developed for rural basins in Italy; however, it is considered suitable for application in tropical climates and relatively large catchment areas.…”

Mitigation of Scour Failure Risk of a River Bridge Located in an Ungauged Basin

“…( 4)-( 6). There are various approaches for estimation of the v value that considers watershed characteristics and excess rainfall depths (Chen et al, 2019;Ghumman et al, 2017;Gupta, Waymire, & Wang, 1980, Hosseini, Mahjouri, & Riahi, 2016Rodriguez-Iturbe, Gonzalez-Sanabria, & Bras, 1982;Sahoo et al, 2006). Sahoo et al (2006) proposed a stepfunction relationship between excess rainfall intensity and flow velocity.…”

“…Hosseini et al (2016) adopted the main channel length and watershed slope, while Ghumman et al (2017) considered the excess rainfall, drainage area and kinematic wave parameter of the channel to estimate the expected peak velocity. On the other hand, Chen et al (2019) proposed a new method to estimate the dynamic-factor peak velocity considering the extraction of geomorphologic characteristics of the watershed using random forest technique. In most of the similar studies, the peak velocity was calculated as 2.0-2.5 m/s, so in this study the peak velocity was taken as 2.5 m/s, as recommended by Kumar et al (2007).…”

The Event-specific Geomorphological Instantaneous Unit Hydrograph (E-GIUH): The basin hydrological response characteristic of a flood event

“…GIUH applications often rely on a unique set of parameters in order to calibrate the model (e.g. (Boudhraâ et al, 2018;Chen et al, 2019;Choi et al, 2011;Moussa, 1997;Yao et al, 2014), thereby suggesting that a single representative GIUH can be associated with a catchment. However, several studies have highlighted the influence on the catchment response of: i) the rain spatial distribution (Emmanuel et al, 2017;Goni et al, 2019;Olivera and Maidment, 1999;Zoccatelli et al, 2010), and ii) the rain event magnitude (Rodriguez et al, 2005;Saco and Kumar, 2002b).…”