Recession analysis revisited: impacts of climate on parameter estimation

Abstract

Abstract. Recession analysis is a classical method in hydrology to assess watersheds' hydrological properties by means of the receding limb of a hydrograph, frequently expressed as the rate of change in discharge (-dQ/dt) against discharge (Q). This relationship is often assumed to take the form of a power law -dQ/dt=aQb, where a and b are recession parameters. Recent studies have highlighted major differences in the estimation of the recession parameters depending on the method, casting doubt on our ability to properly evaluate and compare hydrological properties across watersheds based on recession analysis of -dQ/dt vs. Q. This study shows that estimation based on collective recessions as an average watershed response is strongly affected by the distributions of event inter-arrival time, magnitudes, and antecedent conditions, implying that the resulting recession parameters do not represent watershed properties as much as they represent the climate. The main outcome from this work highlights that proper evaluation of watershed properties is only ensured by considering independent individual recession events. While average properties can be assessed by considering the average (or median) values of a and b, their variabilities provide critical insight into the sensitivity of a watershed to the initial conditions involved prior to each recharge event.

Including Regional Knowledge Improves Baseflow Signature Predictions in Large Sample Hydrology

“…Recession analysis has been used extensively to quantify the drainage behavior of catchments (Brutsaert & Nieber, 1977; Jachens et al, 2020; Tashie et al, 2020; Roques et al, 2017). It is often assumed that the relationship between the rate of change of streamflow and streamflow follows a power law.…”

“… where α and β m are parameters that can be obtained by fitting Equation to recession data. There are numerous methodological choices that can impact the resulting parameter values (e.g., Dralle et al, 2017; Jachens et al, 2020; Stoelzle et al, 2013). We extract recession segments that are strictly decreasing ( ), remove the first day, and only keep recession segments of 5 days or longer (Jachens et al, 2020).…”

“…There are numerous methodological choices that can impact the resulting parameter values (e.g., Dralle et al, 2017; Jachens et al, 2020; Stoelzle et al, 2013). We extract recession segments that are strictly decreasing ( ), remove the first day, and only keep recession segments of 5 days or longer (Jachens et al, 2020). We calculate the derivative by using the exponential time stepping scheme proposed by Roques et al (2017).…”

Streamflow Recession Analysis Using Water Height

“…When considering drought resilience, comparing b values for high and low flows can be used to identify a change in hydraulic regime and using b values at low flows to indicate a watershed's sensitivity to climate change. Where b increases as Q decreases, streamflow becomes more stable, or sustained, at low flows and may indicate watersheds that are less sensitive to drought (Berghuijs et al, 2016; Jachens et al, 2020). In this case, b values are larger at low flows than at high flows.…”

“…As noted, observations reveal large variability in recession behavior, including cases where b is larger at lower Q than at higher Q (e.g., Clark et al, 2009; Mutzner et al, 2013; Rupp & Selker, 2006a), inconsistent the aforementioned hydraulic theory. Recent studies have suggested that such cases are common (Jachens et al, 2020; Tashie et al, 2020). In contrast, if b decreases as Q decreases, this indicates that streamflow is more stable, or sustained, at high flows while streamflow declines at a faster rate at low flows.…”