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Catchments consist of distinct landforms that affect the storage and release of subsurface water. Certain landforms may be the main contributors to streamflow during extended dry periods, and these may vary for different catchments in a given region. We present a unique dataset from snapshot field campaigns during low‐flow conditions in 11 catchments across Switzerland to illustrate this. The catchments differed in size (10 to 110 km2), varied from predominantly agricultural lowlands to Alpine areas, and covered a range of physical characteristics. During each snapshot campaign, we jointly measured streamflow and collected water samples for the analysis of major ions and stable water isotopes. For every sampling location (basin), we determined several landscape characteristics from national geo‐datasets, including drainage area, elevation, slope, flowpath length, dominant land use, and geological and geomorphological characteristics, such as the lithology and fraction of quaternary deposits. The results demonstrate very large spatial variability in specific low‐flow discharge and water chemistry: Neighboring sampling locations could differ significantly in their specific discharge, isotopic composition, and ion concentrations, indicating that different sources contribute to streamflow during extended dry periods. However, none of the landscape characteristics that we analysed could explain the spatial variability in specific discharge or streamwater chemistry in multiple catchments. This suggests that local features determine the spatial differences in discharge and water chemistry during low‐flow conditions and that this variability cannot be assessed a priori from available geodata and statistical relations to landscape characteristics. The results furthermore suggest that measurements at the catchment outlet during low‐flow conditions do not reflect the heterogeneity of the different source areas in the catchment that contribute to streamflow.

Section: Limitations Of the Low-flow Snapshot Campaigns And Future mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Spatial variability in specific discharge and streamwater chemistry during low flows: Results from snapshot sampling campaigns in eleven Swiss catchments

Floriancic

Fischer

Molnár

et al. 2019

“…To study water quality at this scale, a so-called 'snapshot' or synoptic water quality sampling scheme should be applied. Most snapshot studies have been performed under stable base-flow conditions Webb, 1975, 1978;Grayson et al, 1997;Thornton and Dise, 1998;Gburek and Folmar, 1999;Salvia et al, 1999;Buck et al, 2004, Van der Perk et al, 2007 but rarely under different hydrological conditions (Thornton and Dise, 1998). Probably, it is often not feasible to collect synoptic monitoring or sampling data because of the vast size of the study area.…”

Section: Introductionmentioning

confidence: 99%

Spatio‐temporal patterns of nutrient concentrations and export in a north‐eastern European lowland catchment

Mourad

Perk

2009

Abstract:In 2002-2004 we undertook six sampling campaigns during representative hydrological stages in a 901 km 2 Estonian lowland catchment to quantify the spatial and seasonal variability of in-stream dissolved inorganic nitrogen (DIN) and dissolved reactive phosphorus (DRP) concentrations and to identify the influence of land cover and landscape structure. Using a synoptic approach we mapped concentrations in all stream orders. Using linear regression, the relations between the share of agricultural land and log-transformed in-stream concentrations were explored. Both the share of agricultural land in the entire 'area of influence' upstream from a sampling location, as well as the share in a 150-m buffer around the stream were used as linear regression input variables. Log-transformed DIN and DRP concentration variability was highest for lower order streams, while it averaged out in higher order streams during all seasons. Between-season variation in export can mainly be attributed to discharge variation. In extremely dry periods, there are no significant relations between land cover/structure and in-stream ln(DIN) concentrations and only weak relations for ln(DRP) concentrations. In other seasons, the share of agricultural land in the upstream area can explain concentrations in higher order streams better than in lower order streams. The prediction of ln(DIN) concentrations in lower order streams can be improved by using the share of agricultural land in a 150-m buffer as an input variable. This indicates that hydrological connectivity must be taken into account for lower order streams, while land cover shares are enough to explain concentrations for higher order streams.

Spatiotemporal variability of water quality and stable water isotopes in intensively managed prairie watersheds

Untereiner

Ali

Stadnyk

2015

Abstract:Low-relief and highly engineered prairie landscapes present many challenges for water quality modelling. Limited investigation has been carried out to determine whether drains, canals and diversions (artificial waterways) impact water quality relative to natural or naturalized systems or to assess the value of stable water isotopes as predictor variables for specific water quality metrics. The goal of this paper is to investigate the spatiotemporal variability of water chemistry in a typical prairie watershed by (1) comparing water quality and stable water isotopic ratios between naturalized and artificial waterways; (2) evaluating the relationships between topographic and land use characteristics, water quality and stable water isotopic ratios; and (3) expressing and predicting PO 4 concentrations as a function of stable water isotopic ratios. Focus was on the 2509 km 2 mostly agricultural Seine River Watershed located in southern Manitoba, Canada. Twenty-four sampling sites located along naturalized river reaches, drains and diversions were visited once a week from May to June 2013. Surface water samples were collected and tested for physical water quality parameters and PO 4 concentrations, δ 2 H and δ 18O. Kruskal-Wallis tests show no significant differences in water chemistry among waterway types, while strong correlations were found between physical water quality parameters, PO 4 concentrations, isotopic ratios and watershed characteristics. PO 4 concentrations were successfully predicted from isotopic ratios using linear regression models. These results bear significant importance for the mostly ungauged prairie watersheds, thanks to the relative ease and lower cost of measuring stable water isotopic ratios in comparison to nutrient concentrations.