Hillslope hydrology and wetland response of two small zero‐order boreal catchments on the Precambrian Shield

Abstract

Abstract:Two Precambrian Shield zero-order catchments were monitored from January 2003 to July 2004 to characterize their hydrological and biogeochemical characteristics prior to a forest management experiment. Hydrometric observations were used to examine temporal trends in hillslope-wetland connectivity and the hillslope runoff processes that control wetland event response. The hillslope groundwater flux from the longer transect (E1) was continuous throughout the study period. Groundwater fluxes from a shorter and steeper hillslope (E0) were intermittent during the study period. Large depression storage elements (termed micro-basins) located on the upper hillslope of the E1 catchment appeared to be at least partly responsible for the observed rapid wetland runoff responses. These micro-basins were hydrologically connected to a downslope wetland by a subsurface channel of glacial cobbles that functioned as a macropore channel during episodic runoff events. The runoff response from the hilltop micro-basins is controlled by antecedent water table position and water is quickly piped to the wetland fringe through the cobble channel during high water table conditions. During periods of low water table position, seepage along the bedrock-soil interface from the hilltop micro-basin and other hillslopes maintained hillslope-wetland connectivity. The micro-basins create a dynamic variable source-area runoff system where the contributing area expands downslope during episodic runoff events. The micro-basins occupied 30% of the E1 catchment and are a common feature on the Precambrian Shield.

On the Sensitivity of Hillslope Runoff and Channel Transmission Losses in Arid Piedmont Slopes

“…The hydrologic connectivity between upland hillslopes and downstream channels has been the subject of broad interest in many climatic settings (e.g., Frisbee et al, 2007;Gutiérrez-Jurado et al, 2007;Jencso et al, 2009;Lin et al, 2006;Puigdefabregas et al, 1998;Sidle et al, 2000). In comparison to more humid areas, the interaction between hillslopes and channels is more limited in arid and semiarid climates (Osborn & Renard, 1970;Yair & Lavee, 1985).…”

Groundwater dynamics in a till hillslope: flow directions, gradients and delay

“…Despite the potential changes in flow directions, most studies in hillslope hydrology have been performed using wells along transects (McGlynn et al , 1999; Ferone and Devito, 2004; Bradley et al , 2007; Frisbee et al , 2007; Jencso et al , 2009). If flow directions vary significantly over time this variation might have important implications.…”

Use of soil moisture dynamics and patterns at different spatio-temporal scales for the investigation of subsurface flow processes

“…Kienzler and Naef, 2007;Meyles et al, 2003;McNamara et al, 2005;Frisbee et al, 2007;Germann and Zimmermann, 2005;Zhou et al, 2002;Hino et al, 1988) or for the investigation of the effects of changes in land use or management on hydrological processes Starr and Timlin, 2004). See also Robinson et al (2008) and Vereecken et al (2008) for comprehensive reviews on measurement techniques and the value of soil moisture data, respectively.…”

“…In most studies soil moisture was measured either with high spatial or with high temporal resolution, thus producing either spatial soil moisture patterns (Bardossy and Lehmann, 1998;Brocca et al, 2007;Meyles et al, 2003;Williams et al, 2003;Western et al, 2004;Rezzoug et al, 2005;Nyberg, 1996) or information on the dynamics (e.g. McNamara et al, 2005;Starr and Timlin, 2004;Frisbee et al, 2007). A combination of both can only be achieved with either a large number of probes measuring continuously such as in Starr and Timlin (2004) and Taumer et al (2006) or with geophysical methods such as described for example in Zhou et al (2001), were electric resistivity tomography was used to investigate soil moisture dynamics on a 3.5×3.5 m plot at hourly resolution.…”