The efficiency function of detention reservoirs in urban drainage systems

Abstract

Detention reservoirs in urban drainage systems are provided for reducing the peak flows downstream of the reservoir. The flow reduction is due to the storage volume of the reservoir in which the incoming flow is temporarily stored. The relationship between the peak reduction ratio (the peak outflow discharge to the peak inflow discharge) and the relative storage ratio (maximum volume stored in the reservoir to the volume of the inflow hydrograph) is evaluated in this study. This relationship, named the efficiency function, is derived by a numerical solution of the dimensionless routing equation. Using the three‐parameter gamma distribution to represent the inflow to the reservoir, the efficiency functions can be expressed by simple linear equations. Each equation depends on a single parameter whose value is determined by the reservoir configuration (depth‐storage relationship) and the type of the outlet device (e.g., spillway or culvert). The implementation of the efficiency function is most suitable for the preliminary design stage where a large number of alternative designs can be easily tested without performing the conventional routing procedure.

Graphical estimation of detention pond volume for rainfall of short duration

“…10 displays the dimensionless storage volumes comparison between this study, TR-55 (SCS 1986), Kessler andDiskin (1991), andSWCB (2002). TR-55 underestimates the storage volume compared with other methods.…”

“…SCS also developed a approximate detention basin routing for rainfall types I, IA, II, and III. Kessler and Diskin (1991) adopted the dimensionless gamma distribution function as the inflow hydrograph and developed the graphic relationship between S f /V f and O p /I p for spillway and culvert outlets. They also built two efficiency functions as follows:…”

“…(a) Inflow hydrographs: Five inflow hydrographs, triangular inflow hydrograph (Basha 1995), trapezoidal inflow hydrograph (Donahue and McCuen 1981;Burton 1980;Guo 1999), dimensionless inflow hydrograph (Mockus 1957;Akan 1989;Akan 1990;Akan 1994), instantaneous unit hydrograph (IUH) (Kessler and Diskin 1991;McEnore 1992), characteristic curves (HEC 1980) and hydrograph procedure (Urban 2001;Guo 2004), have been used. Among these, triangular inflow hydrograph can specifically represent the relationship between peak inflow and recession time for short duration (Hong et al 2006).…”

The methods of evaluating storage volume for single-chamber reservoir in urban catchments

“… triangular (Abt and Grig 1978, Basha 1995, Gomez et al 2001, Hong 2008,  trapezoidal (Burton 1980, Aron and Kibler 1990, Guo 1999, Hong et al 2006, Graber 2009, Froehlich 2009),  defi ned by gamma probability density function (Kessler and Diskin 1991, McEnroe 1992, Akan and Houghtalen 2003,  curvilinear (Q = f(t) in the SCS method (Akan 1990) Banasik et al 2014) confi rms that the hydrograph of outfl ow from a small catchment, i.e. with the surface of up to 200 ha, caused by a short-term intensive rainfall can be defi ned using a triangle, a power function or the gamma distribution.…”

Reservoir attenuation of floods from ungauged basins

“…Currently, direct computational techniques, without the aid of graphs are more acceptable. Numerical methods, such as the Runge-Kutta algorithm (Chow et al, 1988;Kessler & Diskin, 1991;Bedient & Huber, 1992) and the iterative trapezoidal integration algorithm (Fread, 1993), are used to generate the outflow hydrograph in each time interval. However, both hydraulic and hydrological routing methods require the upstream inflow hydrograph of the reservoir.…”