Landscape controls on spatiotemporal discharge variability in a boreal catchment

Abstract

Improving the understanding of how stream flow dynamics are influenced by landscape characteristics, such as soils, vegetation and terrain, is a central endeavor of catchment hydrology. Here we investigate how spatial variability in stream flow is related to landscape characteristics using specific discharge time series from 14 partly nested subcatchments in the Krycklan basin (0.12 – 68 km2). Multivariate principal component analyses combined with univariate analyses showed that while variability in landscape characteristics and specific discharge were strongly related, the spatial patterns varied with season and wetness conditions. During spring snowmelt and at the annual scale, specific discharge was positively related to the sum of wetland and lake area. During summer, when flows are lowest, specific discharge was negatively related to catchment tree volume, but positively related to deeper sediment deposits and catchment area. The results indicate how more densely forested areas on till soils become relatively drier during summer months, while wet areas and deeper sediment soils maintain a higher summer base flow. Annual and seasonal differences in specific discharge can therefore be explained to a large extent by expected variability in evapotranspiration fluxes and snow accumulation. These analyses provide an organizing principle for how specific discharge varies spatially across the boreal landscape, and how this variation is manifested for different wetness conditions, seasons and time scales.

Using isotopes to constrain water flux and age estimates in snow-influenced catchments using the STARR (Spatially distributed Tracer-Aided Rainfall–Runoff) model

“…We used temporally constant lapse rates, but they may vary in different seasons, latitudes, and orographic influences (Stone and Carlson, 1979;Sevruk and Mieglitz, 2002). Altitude effects are negligible for the gently sloping Krycklan site (Karlsen et al, 2016).…”

Topography significantly influencing low flows in snow-dominated watersheds

“…Studies of watershed topography on hydrological processes often include topics such as specific discharge (Karlsen et al, 2016), spatial baseflow distribution (Shope, 2016), transit time (McGuire et al, 2005;McGuire and McDonnell, 2006), and hydrological connectivity (Jencso and McGlynn, 2011). These studies were often based on a short period of data (< 5 years), limiting our ability to draw general conclusions on how topography affects hydrological processes.…”

Topography significantly influencing low flows in snow-dominated watersheds

“…Our study identified that TWI and wetland area were not significantly related to flow variables, indicating that these factors had a limited role in the selected flow variables in our region. This may be because the watersheds in this area need 265 to overcome a soil moisture storage threshold prior to releasing water (Karlsen et al, 2016). In summary, our 5 selected TIs significantly represent low flow characteristics of the watersheds in the southern interior of British Columbia, Canada, which is characterized by a snow-dominated hydrological regime.…”

“…Studies of watershed topography on hydrological processes often include topics such as specific discharge (Karlsen et al, 2016), spatial baseflow distribution (Shope, 2016), transit time (McGuire and McDonnell, 2006;McGuire et al, 2005), and hydrological connectivity (Jencso and McGlynn, 2011). 65…”

“…As far as we know, no studies have quantified topographic controls on various flow magnitudes. Nevertheless, the relationship between topography and the mean transit time (McGuire and McDonnell, 2006), temporal specific discharge (Karlsen et al, 2016), and hydrological connectivity (Jencso and McGlynn, 2011) have been investigated. It is no doubt that topography is one 230 of the major contributors to hydrological variations (Price, 2011;Smakhtin, 2001).…”