Effects of climate anomalies on warm-season low flows in Switzerland

Floriancic, Marius; Berghuijs, Wouter; Jonas, Tobias; Kirchner, James W.; Molnár, Péter

doi:10.5194/hess-24-5423-2020

Cited by 18 publications

(20 citation statements)

References 59 publications

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“…This suggests that reservoirs will typically have a small influence on the seasonal timing of annual minimum flows across our study sites, although they may affect the magnitude of those flows. This finding is consistent with previous studies which determined that low‐flow timing is more strongly controlled by climate than by human activities in US and Swiss catchments (Ferrazzi et al., 2019; Floriancic et al., 2020; Sadri et al., 2016). We caution the reader that this analysis is not comprehensive as it was only done for 33 catchments where we had information on the timing of dam construction.…”

Section: Resultssupporting

confidence: 93%

Seasonality and Drivers of Low Flows Across Europe and the United States

Floriancic

Berghuijs

Molnár

et al. 2021

Water Resources Research

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Low river flows can negatively impact society and the riverine environment. Thus, it is useful to predict their seasonal timing and reveal their main drivers. The typical timing of low flows varies between regions, yet systematic overviews across Europe and the United States are rare.Here, we identify regional patterns of the seasonal timing of annual minimum flows, and the consistency of that timing, across 1860 European and US catchments. Catchments where low flows typically occur during late summer or winter tend to have more consistent low-flow timings.We compare the timing of annual low flows with that of potential climatic drivers. Low flows in 89% of the European and 86% of the US catchments exhibit statistically significant (p<0.05) overlap in timing with at least one potential climatic driver. In most catchments, low flows tend to occur during the warm season, reflecting a period of high potential evapotranspiration exceeding precipitation. In the higher-elevation European Alps, Scandinavia, the Rocky Mountains, and the Upper Midwest and Plains states, low flows mostly occur during winter as a result of freezing temperatures which inhibit snowmelt. Binomial statistics also enabled us to statistically exclude individual climatic drivers for certain regions. The regional patterns of timings and drivers of low flows across Europe and the contiguous US can inform low-flow management, provide context for the evolution of low flows under climate change, and point to processes that require attention in future low-flow research.

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Section: Resultssupporting

confidence: 93%

Seasonality and Drivers of Low Flows Across Europe and the United States

Floriancic

Berghuijs

Molnár

et al. 2021

Water Resources Research

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“…Considering extreme hydrometeorological conditions like droughts, there may be elevation dependence in potential response. Examples from the midlatitudes show a mixed picture but overall indicate an increasing importance of precipitation and evapotranspiration anomalies below roughly 2,000 m a.s.l., shifting toward snow accumulation processes at higher elevations (Bales et al., 2018; Floriancic et al., 2020; Gilbert & Maxwell, 2018). However, analysis on the 2003 Alpine drought event highlighted the importance of enhanced evapotranspiration fluxes in forested areas above 1,000 m a.s.l.…”

Section: Impacts and Implications Of Changing Elevation‐dependent Cli...mentioning

confidence: 99%

Climate Changes and Their Elevational Patterns in the Mountains of the World

Pepin

Arnone

Gobiet

et al. 2022

Reviews of Geophysics

260

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Quantifying rates of climate change in mountain regions is of considerable interest, not least because mountains are viewed as climate “hotspots” where change can anticipate or amplify what is occurring elsewhere. Accelerating mountain climate change has extensive environmental impacts, including depletion of snow/ice reserves, critical for the world's water supply. Whilst the concept of elevation‐dependent warming (EDW), whereby warming rates are stratified by elevation, is widely accepted, no consistent EDW profile at the global scale has been identified. Past assessments have also neglected elevation‐dependent changes in precipitation. In this comprehensive analysis, both in situ station temperature and precipitation data from mountain regions, and global gridded data sets (observations, reanalyses, and model hindcasts) are employed to examine the elevation dependency of temperature and precipitation changes since 1900. In situ observations in paired studies (using adjacent stations) show a tendency toward enhanced warming at higher elevations. However, when all mountain/lowland studies are pooled into two groups, no systematic difference in high versus low elevation group warming rates is found. Precipitation changes based on station data are inconsistent with no systematic contrast between mountain and lowland precipitation trends. Gridded data sets (CRU, GISTEMP, GPCC, ERA5, and CMIP5) show increased warming rates at higher elevations in some regions, but on a global scale there is no universal amplification of warming in mountains. Increases in mountain precipitation are weaker than for low elevations worldwide, meaning reduced elevation‐dependency of precipitation, especially in midlatitudes. Agreement on elevation‐dependent changes between gridded data sets is weak for temperature but stronger for precipitation.

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“…This occurs because as shown in this study, model structures do not correlate with such properties (high p ‐values). Although they play a role in controlling storage and baseflow released for low flows, landscape have secondary impact on causing low flows (Floriancic et al, 2020). The high correlation between climate characteristics and the structural framework supports the notion that if model structures depend on hydrological characteristics, climate is the dominant control (Smakhtin, 2001).…”

Section: Discussionmentioning

confidence: 99%

“…It also corrects Leong and Yokoo (2019b) suggestions that all perennial catchments or ephemeral catchments should have the same model structure, respectively, which is not the case as discovered here. A possible explanation of non-correlation of topographic indices is due to the limited ability of such indices to control low flows where evapotranspiration is the dominant control (Floriancic et al, 2020;Western et al, 1999). The elimination or minimizing of non-correlating surface indices (e.g., area and elev_mean) as shown in this framework, could benefit its transferable capabilities, as such indices are quite unsuitable for determining catchment similarities at larger spatial scales (Beven et al, 2021).…”

Section: Reproduction Of Fdcmentioning

confidence: 99%

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A multiple hydrograph separation technique for identifying hydrological model structures and an interpretation of dominant process controls on flow duration curves

Leong

Yokoo

2022

Hydrological Processes

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There has been significant progress made towards understanding the process controls that govern the shapes of flow duration curves (FDC). However, the transferability of the knowledge gained to large spatial scales is still lacking, partly due to the fixed representation of the model structures representing the unobserved underground layer. In the context of improving large scale applicability/transferability of FDC studies: (1) we propose a novel approach to transform/restructure the representation of the subsurface component in hydrological models to be flexible and adaptable in any environment and (2) provide a thorough interpretation of the dominant processes that impact the shape of FDCs. The flexible structure is designed from a series of multiple connected linear reservoirs that are developed from a unique multiple hydrograph separation procedure, to estimate the number of distinct hydrological processes at play. The main results are: (1) wet catchments have more complex model structures (more reservoirs) than arid catchments; indicating that subsurface processes are potentially more present in wet catchments than in drier ones. Dry catchments have more near surface occurring processes, thus have less complex model structures. However, more complexity is potentially required within the internal reservoirs of dry catchments. (2) The strength of interference in the intermediate reservoirs in controlling the dominant processes towards the bottom determined the shape of FDCs, and this increased with aridity. The novel finding is that a model structure can be determined by the catchment's ability to generate flows as well as the strength of low flow persistence. Hence, we propose a conceptual framework for the development of flexible model structures based on the shapes of FDCs. The transformation of models to be flexible in this research, should contribute to studies that seek the transferability of models over large spatial scales.

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Effects of climate anomalies on warm-season low flows in Switzerland

Cited by 18 publications

References 59 publications

Seasonality and Drivers of Low Flows Across Europe and the United States

Seasonality and Drivers of Low Flows Across Europe and the United States

Climate Changes and Their Elevational Patterns in the Mountains of the World

A multiple hydrograph separation technique for identifying hydrological model structures and an interpretation of dominant process controls on flow duration curves

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