Evaluating the Relative Importance of Shallow Subsurface Flow in a Prairie Landscape

Water Resources Research

Spence

et al. 2021

Self Cite

Studies examining hydrologic response to climatic inputs at hillslope and small catchment scales have shown highly nonlinear runoff behavior (Beven et al., 1988; McDonnell et al., 2007; Sivapalan, 2006; Sivapalan et al., 2002). While these studies have greatly advanced our understanding of runoff generation processes, the "uniqueness of place" (Beven, 2000) inherent to isolated studies has resulted in limited transferability of some findings, making generalization across sites difficult (McDonnell et al., 2007; Scaife & Band, 2017; Sivapalan, 2006). The difficulty in generalizing some process conceptualizations has motivated a shift in focus toward emergent properties, that is, properties that cannot be predicted from individual landscape components but reflect landscape heterogeneity and process complexity (Lehmann et al., 2007; McDonnell et al., 2007). Thresholds in runoff response are one of these properties and are generally defined as critical moments in time or points in space at which runoff behavior rapidly changes (Ali et al., 2013; Phillips, 2006). For critical moments in time, thresholds are typically defined as values of one or multiple meteorological factors that trigger a nonlinear change in hydrologic response characteristics. Thresholds are assessed through the evaluation of scatter plots that compare hydrologic response metrics (y-axis) to meteorological factors (x-axis). To date, threshold-related research has mostly taken place on hillslopes and catchments in temperate or humid environments (e.g.,

Section: Study Sitesmentioning

confidence: 99%

Evaluating the Ubiquity of Thresholds in Rainfall‐Runoff Response Across Contrasting Environments

Ross

Water Resources Research

Spence

et al. 2021

Self Cite

“…The selected sites vary in drainage area, climate regime, topography, land cover, and subsurface properties. Each site has been the subject of substantial hydrologic research and has been described in detail by others (e.g., Ali & Roy, 2010b;McKee & Druliner, 1998;Oswald et al, 2011;Ross, Ali, Bansah, & Laing, 2017;Tromp-van Meerveld, James, McDonnell, & Peters, 2008;Western & Grayson, 1998;Woods et al, 2013). Site characteristics, including drainage area, physiographic variables (i.e., relief, mean slope, and standard deviation of slope), and long-term climate variables (i.e., mean annual values of temperature, potential evapotranspiration, and total precipitation) were derived from available meteorological and elevation data.…”

Section: Introductionmentioning

confidence: 99%

Comparison of event‐specific rainfall–runoff responses and their controls in contrasting geographic areas

Ross

Spence

et al. 2019

Hydrological Processes

Self Cite

Numerous studies have examined the event‐specific hydrologic response of hillslopes and catchments to rainfall. Knowledge gaps, however, remain regarding the relative influence of different meteorological factors on hydrologic response, the predictability of hydrologic response from site characteristics, or even the best metrics to use to effectively capture the temporal variability of hydrologic response. This study aimed to address those knowledge gaps by focusing on 21 sites with contrasting climate, topography, geology, soil properties, and land cover. High‐frequency rainfall and discharge records were analysed, resulting in the delineation of over 1,600 rainfall–runoff events, which were described using a suite of hydrologic response metrics and meteorological factors. Univariate and multivariate statistical techniques were then applied to synthesize the information conveyed by the computed metrics and factors, notably measures of central tendency and variability, variation partitioning, partial correlations, and principal component analysis. Results showed that some response magnitude metrics generally reported in the literature (e.g., runoff ratio and area‐normalized peak discharge) did not vary significantly among sites. The temporal variability in site‐specific hydrologic response was often attributable to the joint influence of storage‐driven (e.g., total event rainfall and antecedent precipitation) and intensity‐driven (e.g., rainfall intensity and antecedent potential evapotranspiration) meteorological factors. Mean annual temperature and potential evapotranspiration at a given site appeared to be good predictors of hydrologic response timing (e.g., response lag and lag to peak). Response timing metrics, particularly those associated with response initiation, were also identified as the metrics most critical for capturing intrasite response variability. This study therefore contributes to the growing knowledge on event‐specific hydrologic response by highlighting the importance of response timing metrics and intensity‐driven meteorological factors, which are infrequently discussed in the literature. As few correlations were found between physiographic variables and response metrics, more data‐driven studies are recommended to further our understanding of landscape–hydrology interactions.

“…Medium‐intensity to high‐intensity rainfall events in late spring may have yielded a faster tile activation by raising the water table to or above the tile position or by satisfying the water storage potential of the soil profile. During medium‐intensity rainfall events, runoff may have begun as HOF but then changed to SOF when the water table rose to the ground level (Ross et al, ). High‐intensity, short‐duration summer thunderstorms likely triggered tiles by providing enough water for infiltration and vertical percolation.…”

Section: Discussionmentioning

confidence: 99%

“…Notably, the presence of frozen ground may impede infiltration, increasing the potential for HOF (Gray et al, ) and decreasing the potential for TF in spring. Under summer and fall conditions, threshold runoff responses to rainfall characteristics and AMC have been shown in the Canadian Prairies (Ross, Ali, Bansah, & Laing, ; Shook, Pomeroy, & van der Kamp, ), but it is unclear if and how tile drainage may modify these relationships.…”

Section: Introductionmentioning

confidence: 99%

Hydroclimatic controls on runoff activation in an artificially drained, near‐level vertisolic clay landscape in a Prairie climate

Kokulan

Macrae

et al. 2018

Hydrological Processes

Water quality problems are frequently influenced by hydrological processes, particularly in landscapes in which land drainage has been modified. The expansion of agricultural tile drainage in the Northern Great Plains of North America is occurring, yet is controversial due to persistent water quality problems such as eutrophication. Runoff-generating mechanisms inNorth American tile-drained landscapes in vertisolic soils have not been investigated but are important for understanding the impacts of tile drainage on water quantity and quality. This study evaluated the role of climate drivers on the activation of overland (OF) and tile (TF) flow and groundwater flow responses (GWT) on tile-drained and nontile-drained farm fields in Southern Manitoba, Canada. The response times of different flow paths (OF, TF, and GWT)were compared for 23 hydrological events (April-September 2015, 2016) to infer dominant runoff generation processes. Runoff responses (all pathways) were more rapid following higher intensity rainfall. Subsurface responses were hastened by wetter antecedent conditions in spring and delayed by the seasonal soil-ice layer. The activation of OF did not differ between the tiled and nontiled fields, suggesting that tile drains do little to reduce the occurrence of OF in this landscape. Rapid vertical preferential flow into tiles via preferential flow pathways was uncommon at our site, and the soil profile instead wet up from the top down. These conclusions have implications for the expansion of tile drainage and the impact of such an expansion on hydrological and biogeochemical processes in agricultural landscapes.