Piezometric response in zones of a watershed with lateral preferential flow as a first‐order control on subsurface flow

Abstract

Abstract:Characterizing zones of a watershed based on the water table is used to understand and predict internal watershed processes. In watersheds dominated by lateral preferential flow, the water table response typically shows a distinct hydraulically limited pattern. This response is characterized by a capping of the rising water table when the lateral preferential flow features are activated and subsurface flow still increases. We expected that this response would be related to the contributing area since nearby hillslope excavations showed that the development of preferential flow network was positively correlated with the contributing area. The watershed was stratified into three predetermined zones and installed 25 piezometers to measure the water table dynamics. The objectives were (1) to characterize the water table-runoff relationship, (2) to prove preferential flow by observable characteristics and (3) to test the feasibility of identifying areas within a watershed that are dominated by lateral preferential flow. Watershed zones were not well defined and there was no strong relationship between the hydraulically limited response and observable watershed characteristics. Although zones might still be useful for grouping the hillslope processes, the piezometric response may not be an appropriate indicator for mapping the watershed into areas with runoff dominated by lateral preferential flow.

Spatio-temporal variability of piezometric response on two steep alpine hillslopes

“…The hydro-meteorological variables used in this study were continuously monitored from 25 June to 20 October 2008, 2009 and 2010. The total cumulative precipitation was 506, 351 and 412 mm for 2008and 2010, respectively. The 20-year average precipitation (1992 for the area for the same period was 503 mm: this reveals that 2009 and 2010 were relatively dry years, whereas 2008 was very close to the average long-term precipitation.…”

“…Transient groundwater response at the hillslope scale often shows a marked spatio‐temporal variability (Montgomery et al ., ; Anderson et al ., ; Haught and van Meerveld, ; Bachmair and Weiler, , ; Dhakal and Sullivan, ), nonlinearities and threshold effects (Tromp‐van Meerveld and McDonnell, , ; Detty and McGuire , ; Penna et al ., ), making it difficult to identify its dominant controls. Surface and bedrock topography, soil depth, soil properties and distance upslope were identified as the most important physical characteristics affecting the spatio‐temporal variability of shallow groundwater response (Freer et al ., ; Detty and McGuire, ; Bachmair and Weiler, ; Dhakal and Sullivan, ).…”

Linking Spatial Patterns of Groundwater Table Dynamics and Streamflow Generation Processes in a Small Developed Catchment

“…Similar to references [15,51], correlation analysis on a daily basis between the 20 piezometers measured automatically are performed for the hydrological year 2012-2013, to further characterize the groundwater head level relations. Additional correlation analyses between the discharge at sites 13 and 18 and the groundwater head levels at each piezometer are calculated to investigate groundwater level response to streamflow.…”

Field-Based Observation of Hydrological Processes

“…Rates of pipe flow are largely determined by their diameter, and it has been recognized that there are certain precipitation thresholds that must be exceeded before pipe flow will dominate the subsurface flow (Weiler and McDonnell, 2007). We are still lacking the knowledge to address these pipe flow issues; however, there have been several attempts to perform more sophisticated tracer-based and hydrometric studies (Anderson et al 2009a(Anderson et al , 2009bAnderson et al, 2010) or to use other approaches to understand the flow pathways along the soil bedrock interface (Graham, 2009). We are still lacking the knowledge to address these pipe flow issues; however, there have been several attempts to perform more sophisticated tracer-based and hydrometric studies (Anderson et al 2009a(Anderson et al , 2009bAnderson et al, 2010) or to use other approaches to understand the flow pathways along the soil bedrock interface (Graham, 2009).…”