Streamflow response of a small forested catchment on different time scales

Abstract

The hydrological response of a catchment to rainfall on different time scales is result of a complex system involving a range of physical processes which may operate simultaneously and have different spatial and temporal influences. This paper presents the analysis of streamflow response of a small humid-temperate catchment (Aixola, 4.8 km<sup>2</sup>) in the Basque Country on different time scales and discusses the role of the controlling factors. Firstly, daily time series analysis was used to establish a hypothesis on the general functioning of the catchment through the relationship between precipitation and discharge on an annual and multi-annual scale (2003–2008). Second, rainfall-runoff relationships and relationships among several hydrological variables, including catchment antecedent conditions, were explored at the event scale (222 events) to check and improve the hypothesis. Finally, the evolution of electrical conductivity (EC) during some of the monitored storm events (28 events) was examined to identify the time-origin of waters. Quick response of the catchment to almost all the rainfall events as well as a considerable regulation capacity was deduced from the correlation and spectral analyses. These results agree with runoff event scale data analysis; however the event analysis revealed the non-linearity of the system, as antecedent conditions play a significant role in this catchment. Further, analysis at the event scale made possible to clarify factors controlling (precipitation, precipitation intensity and initial discharge) the different aspects of the runoff response (runoff coefficient and discharge increase) for this catchment. Finally, the evolution of EC of the waters enabled the time origin (event or pre-event waters) of the quickflow to be established; specifically, the conductivity showed that pre-event waters usually represent a high percentage of the total discharge during runoff peaks. The importance of soil waters in the catchment is being studied more deeply

Near‐surface water fluxes and their controls in a sloping heterogeneously layered volcanic soil beneath a supra‐wet tropical montane cloud forest (NW Costa Rica)

“…In addition, such observations allow determination of the degree of connectivity between hillslope processes and catchment runoff response (Loritz et al, 2017; McGuire & McDonnell, 2010; Spence et al, 2010; Uchida et al, 2006; Wienhöfer & Zehe, 2014). Reflecting the complex interactions between the numerous factors and processes governing soil moisture dynamics, the relationship between soil moisture content and stormflow amount is usually non‐linear (Penna et al, 2015; Zabaleta & Antigüedad, 2013; Zehe & Blöschl, 2004). In addition, this relationship often exhibits threshold‐type behaviour (Crow et al, 2018; Detty & McGuire, 2010; Fu et al, 2013; Graham et al, 2010; Tromp‐van Meerveld & McDonnell, 2006b; Zhang et al, 2019).…”