Regional daily baseflow prediction

Abstract

Abstract:The purposes of this study are to identify the bias of applying the analysis of a log-log plot of baseflow and to derive an equation to describe successive regional mean baseflow. The function dQ/dt D a Q b has been used to describe baseflow in many studies that obtain the values of a and b from the log-log plot. According to analysis in this study, the value of 1 can be assigned to b in two boundary conditions, but the parameter a is proved to be related to the depth of water table and starting time of recession and thus different values of a may be found for different recession events. This paper points out that no single regression line can be obtained by plotting all baseflow data on a log-log diagram. Instead, there should be parallel lines, and each for a recession event. It implies that no single set of parameters a and b can be applied to predict baseflow. Thus, a new equation describing the relationship between three successive mean baseflows was derived in this study. The bias in the analysis of the log-log plot and the ability of the derived equation to predict baseflow were verified for five watersheds in Taiwan. Results indicate that the formula of mean baseflow prediction can provide reasonable estimates of flows with a leading time of 6 days. Furthermore, stream flows of the Tonkawa creek watershed in USA were used to verify that using average flows can result in better predictions than using instantaneous flows.

Assessment of extreme drought and human interference on baseflow of the Yangtze River

“…A common way to identify the groundwater infiltrations to stream is linked to the baseflow, which is defined as the net flow from groundwater storage to a stream (Singh, 1968). Baseflow has been used as an approximation of groundwater discharge and play an important role in water resources management (Szilagyi et al, 2003;Tung et al, 2004). Many investigations on baseflow characteristics, such as baseflow estimation (Singh, 1968;Reilly and Kroll, 2003), baseflow prediction (Tung et al, 2004), and impacted factors on the baseflow (Wittenberg, 2003;Kirk et al, 2008), have been used in some rivers.…”

“…Baseflow has been used as an approximation of groundwater discharge and play an important role in water resources management (Szilagyi et al, 2003;Tung et al, 2004). Many investigations on baseflow characteristics, such as baseflow estimation (Singh, 1968;Reilly and Kroll, 2003), baseflow prediction (Tung et al, 2004), and impacted factors on the baseflow (Wittenberg, 2003;Kirk et al, 2008), have been used in some rivers. The changes of baseflow in response to human activities and climate changes have also been studied (Cooper et al, 1995;Wittenberg, 2003;Kirk et al, 2008).…”

Reply to comment on ‘C.‐P. Tung, N.‐M. Hong, C.‐H. Chen, and Y.‐C. Tan. 2004. Regional daily baseflow prediction. Hydrological Processes 18: 2147–2164’

“…For the case b D 3/2, the average discharge over a time interval t can be shown as Equation (A1) (see Equation (15) in Tung et al, 2004):…”

“…The recession analysis uses a log-log plot with time-averaged flows to estimate interception and slope of the Equation (1). Tung et al (2004) found that coefficient a is not always a constant. Instead, the coefficients are functions of initial water tables and the start time of a recession event.…”

Comment on ‘C.‐P. Tung, N.‐M. Hong, C.‐H. Chen and Y.‐C. Tan, Regional daily baseflow prediction. Hydrological Processes, 18(2004) 2147–2164’

“…Tung et al (2004) point out a practical issue, which is the error introduced by using time-averaged values of discharge. The issue, however, is probably not serious for many practical applications and the error can be made negligible by using time intervals that are appropriate to the time rate of change in discharge.…”