scholarly journals Future changes in annual, seasonal and monthly runoff signatures in contrasting Alpine catchments in Austria

2021 ◽  
Vol 25 (6) ◽  
pp. 3429-3453
Author(s):  
Sarah Hanus ◽  
Markus Hrachowitz ◽  
Harry Zekollari ◽  
Gerrit Schoups ◽  
Miren Vizcaino ◽  
...  
Keyword(s):  
Climate Change ◽  
High Elevation ◽  
Climate Projections ◽  
Annual Maximum ◽  
Ice Dynamics ◽  
Pronounced Increase ◽  
Monthly Runoff ◽  
Alpine Catchments ◽  
Maximum Flows ◽  
Hydrological Regimes

Abstract. Hydrological regimes of alpine catchments are expected to be strongly affected by climate change, mostly due to their dependence on snow and ice dynamics. While seasonal changes have been studied extensively, studies on changes in the timing and magnitude of annual extremes remain rare. This study investigates the effects of climate change on runoff patterns in six contrasting Alpine catchments in Austria using a process-based, semi-distributed hydrological model and projections from 14 regional and global climate model combinations for two representative concentration pathways, namely RCP4.5 and RCP8.5. The study catchments represent a spectrum of different hydrological regimes, from pluvial–nival to nivo-glacial, as well as distinct topographies and land forms, characterizing different elevation zones across the eastern Alps to provide a comprehensive picture of future runoff changes. The climate projections are used to model river runoff in 2071–2100, which are then compared to the 1981–2010 reference period for all study catchments. Changes in the timing and magnitude of annual maximum and minimum flows, as well as in monthly runoff and snowmelt, are quantified and analyzed. Our results indicate a substantial shift to earlier occurrences in annual maximum flows by 9 to 31 d and an extension of the potential flood season by 1 to 3 months for high-elevation catchments. For low-elevation catchments, changes in the timing of annual maximum flows are less pronounced. Magnitudes of annual maximum flows are likely to increase by 2 %–18 % under RCP4.5, while no clear changes are projected for four catchments under RCP8.5. The latter is caused by a pronounced increase in evaporation and decrease in snowmelt contributions, which offset increases in precipitation. In the future, minimum annual runoff will occur 13–31 d earlier in the winter months for high-elevation catchments, whereas for low-elevation catchments a shift from winter to autumn by about 15–100 d is projected, with generally larger changes for RCP8.5. While all catchments show an increase in mean magnitude of minimum flows by 7–30% under RCP4.5, this is only the case for four catchments under RCP8.5. Our results suggest a relationship between the elevation of catchments and changes in the timing of annual maximum and minimum flows. For the magnitude of the extreme flows, a relationship is found between catchment elevation and annual minimum flows, whereas this relationship is lacking between elevation and annual maximum flow.

scholarly journals Timing and magnitude of future annual runoff extremes in contrasting Alpine catchments in Austria

2021 ◽  
Author(s):  
Sarah Hanus ◽  
Markus Hrachowitz ◽  
Harry Zekollari ◽  
Gerrit Schoups ◽  
Miren Vizcaino ◽  
...  
Keyword(s):  
Climate Change ◽  
High Elevation ◽  
Annual Runoff ◽  
Snow Melt ◽  
Annual Maximum ◽  
Ice Dynamics ◽  
Rcp 8.5 ◽  
Alpine Catchments ◽  
Maximum Flows ◽  
Hydrological Regimes

Abstract. Hydrological regimes of alpine catchments are expected to be strongly affected by climate change mostly due to their dependence on snow and ice dynamics. While seasonal changes have been studied extensively, studies on changes in the timing and magnitude of annual extremes remain rare. This study investigates the effects of climate change on runoff patterns in six contrasting alpine catchments in Austria using a process-based semi-distributed hydrological model and projections from 14 regional climate and global climate model combinations for RCP 4.5 and RCP 8.5. The study catchments represent a spectrum of different hydrological regimes, from pluvial-nival to nivo-glacial, as well as distinct topographies and land forms, characterizing different elevation zones across the Eastern Alps to provide a comprehensive picture of future runoff changes. The climate projections are used to model river runoff in 2071–2100, which are then compared to the 1981–2010 reference period for all study catchments. Changes in timing and magnitude of annual maximum and minimum flows as well as in monthly runoff and snow melt are quantified and analyzed. Our results indicate a substantial shift to earlier occurrences in annual maximum flows by 9 to 31 days and an extension of the potential flood season by one to three months for high-elevation catchments. For low-elevation catchments, changes in timing of annual maximum flows are less pronounced. Magnitudes of annual maximum flows are likely to increase by 2–18 % under RCP 4.5, while no clear changes are projected for four catchments under RCP 8.5. The latter is caused by a pronounced increase in evaporation and decrease in snow melt contributions which offset increases in precipitation. Minimum annual runoff occur 13–31 days earlier in the winter months for high-elevation catchments, whereas for low-elevation catchments a shift from winter to autumn by about 15–100 days is projected. While all catchments show an increase in mean magnitude of minimum flows by 7–30 % under RCP 4.5, this is only the case for four catchments under RCP 8.5. Our results suggest a relationship between the elevation of catchments and changes in timing of annual maximum and minimum flows. For the magnitude of the extreme flows, a relationship is found between catchment elevation and annual minimum flows, whereas this relationship is lacking between elevation and annual maximum flow.

Timing and magnitude of runoff in Austrian mountain catchments in a warming climate

2021 ◽  
Author(s):  
Sarah Hanus ◽  
Harry Zekollari ◽  
Gerrit Schoups ◽  
Roland Kaitna ◽  
Markus Hrachowitz
Keyword(s):  
Climate Change ◽  
High Elevation ◽  
Climate Projections ◽  
Distributed Hydrological Model ◽  
Annual Maximum ◽  
Lower Elevation ◽  
Comprehensive Picture ◽  
Rcp 8.5 ◽  
Alpine Catchments ◽  
Maximum Flows

<p>Hydrological regimes of alpine catchments are expected to be strongly influenced by climate change due to their dependence on snow dynamics. While seasonal changes have been studied extensively, studies on changes in the timing and magnitude of annual extremes remain rare. This study investigates the effects of climate change on runoff patterns in six alpine catchments in Austria by using a topography-driven semi-distributed hydrological model and 14 climate projections for RCP 4.5 and RCP 8.5. The study catchments represent a range of alpine catchments, from pluvial-nival to nivo-glacial, as the study focuses on providing a comprehensive picture of future runoff changes on catchments at different altitudes. Simulations of 1981-2010 are compared to projections of 2071-2100 by examining changes in timing and magnitude of annual maximum and minimum flows as well as monthly discharges.</p><p>Our results indicate a substantial shift to earlier occurrences in annual maximum flows by 9 to 31 days on average and an extension of the potential flood season by 1 to 3 months for high elevation catchments. For lower elevation catchments, changes in timing of annual maximum flows are less pronounced. Magnitudes of annual maximum flows are likely to increase, with four catchments exhibiting larger increases under RCP 4.5 compared to RCP 8.5. The timing of minimum annual discharges shifts to earlier in the winter months for high elevation catchments, whereas for lower elevation catchments a shift from winter to autumn is observed. While all catchments show an increase in mean magnitude of minimum flows under RCP 4.5, this is not the case for two low elevation catchments under RCP 8.5.</p><p>Our results suggest a relationship between the altitude of catchments and changes in timing of annual maximum and minimum flows and magnitude of low flows, whereas no relationship between altitude and magnitude of annual maximum flows could be distinguished.</p>

scholarly journals Climate change and its impacts on river discharge in two climate regions in China

2015 ◽  
Vol 19 (11) ◽  
pp. 4609-4618 ◽  
Author(s):  
H. Xu ◽  
Y. Luo
Keyword(s):  
Climate Change ◽  
River Discharge ◽  
Climate Change Impacts ◽  
High Flow ◽  
Global Climate Models ◽  
Assessment Tools ◽  
Low Flow ◽  
Climate Projections ◽  
Seasonal Temperature ◽  
Pronounced Increase

Abstract. Understanding the heterogeneity of climate change and its impacts on annual and seasonal discharge and the difference between median flow and extreme flow in different climate regions is of utmost importance to successful water management. To quantify the spatial and temporal heterogeneity of climate change impacts on hydrological processes, this study simulated river discharge in the River Huangfuchuan in semi-arid northern China and in the River Xiangxi in humid southern China. The study assessed the uncertainty in projected discharge for three time periods (2020s, 2050s and 2080s) using seven equally weighted GCMs (global climate models) for the SRES (Special Reports on Emissions Scenarios) A1B scenario. Climate projections that were applied to semi-distributed hydrological models (Soil Water Assessment Tools, SWAT) in both catchments showed trends toward warmer and wetter conditions, particularly for the River Huangfuchuan. Results based on seven GCMs' projections indicated changes from −1.1 to 8.6 °C and 0.3 to 7.0 °C in seasonal temperature and changes from −29 to 139 % and −32 to 85 % in seasonal precipitation in the rivers Huangfuchuan and Xiangxi, respectively. The largest increases in temperature and precipitation in both catchments were projected in the spring and winter seasons. The main projected hydrologic impact was a more pronounced increase in annual discharge in the River Huangfuchuan than in the River Xiangxi. Most of the GCMs projected increased discharge in all seasons, especially in spring, although the magnitude of these increases varied between GCMs. The peak flows were projected to appear earlier than usual in the River Huangfuchuan and later than usual in the River Xiangxi, while the GCMs were fairly consistent in projecting increased extreme flows in both catchments with varying magnitude compared to median flows. For the River Huangfuchuan in the 2080s, median flow changed from −2 to 304 %, compared to a −1 to 145 % change in high flow (Q05 exceedance threshold). For the River Xiangxi, low flow (Q95 exceedance threshold) changed from −1 to 77 % and high flow changed from −1 to 62 %, while median flow changed from −4 to 23 %. The uncertainty analysis provided an improved understanding of future hydrologic behavior in the watershed. Furthermore, this study indicated that the uncertainty constrained by GCMs was critical and should always be considered in analysis of climate change impacts and adaptation.

Uncertainty in hydrological modelling of climate change impacts in four Norwegian catchments

2011 ◽  
Vol 42 (6) ◽  
pp. 457-471 ◽  
Author(s):  
Deborah Lawrence ◽  
Ingjerd Haddeland
Keyword(s):  
Climate Change ◽  
Parameter Uncertainty ◽  
Hydrological Model ◽  
Climate Model ◽  
Annual Maximum ◽  
Climate Scenarios ◽  
Local Conditions ◽  
Practical Applications ◽  
Maximum Flows ◽  
Hydrological Parameter

Projections for the hydrological impacts of climate change are necessarily reliant on a chain of models for which numerous alternative models and approaches are available. Many of these alternatives produce dissimilar results which can undermine their use in practical applications due to these differences. A methodology for developing climate change impact projections and for representing the range of model outcomes is demonstrated based on the application of a hydrological model with input data from six regional climate scenarios, which have been further adjusted to match local conditions. Multiple best-fit hydrological model parameter sets are also used so that hydrological parameter uncertainty is included in the analysis. The methodology is applied to consider projected changes in the average annual maximum daily mean runoff in four catchments (Flaksvatn, Viksvatn, Masi and Nybergsund) which are characterised by regional differences in seasonal flow regimes. For catchments where rainfall makes the predominant contribution to annual maximum flows, hydrological parameter uncertainty is significant relative to other uncertainty sources. Parameter uncertainty is less important in catchments where spring snowmelt dominates the generation of maximum flows. In this case, differences between climate scenarios and methods for adjusting climate model output to local conditions dominate uncertainty.

scholarly journals Future runoff regime changes and their time of emergence for 93 catchments in Switzerland

2020 ◽  
Author(s):  
Regula Muelchi ◽  
Ole Rössler ◽  
Jan Schwanbeck ◽  
Rolf Weingartner ◽  
Olivia Martius
Keyword(s):  
Climate Change ◽  
Strong Influence ◽  
Climate Model ◽  
High Elevation ◽  
Snow Accumulation ◽  
Seasonal Patterns ◽  
Climate Projections ◽  
Local Climate ◽  
Runoff Change ◽  
Runoff Changes

Abstract. Assessments of climate change impacts on runoff regimes are essential for adaptation and mitigation planning. Changing runoff regimes and thus changing seasonal patterns of water availability have strong influence on various sectors such as agriculture, energy production or fishery. In this study, we use the most up to date local climate projections for Switzerland (CH2018) that were downscaled with a post-processing method (quantile mapping). This enables detailed information on changes in runoff regimes and their time of emergence for 93 rivers in Switzerland under three emission pathways RCP2.6, RCP4.5, and RCP8.5. Changes in seasonal patterns are projected with increasing winter runoff and decreasing summer and autumn runoff. Spring runoff is projected to increase in high elevation catchments and to decrease in lower lying catchments. Despite strong increases in winter and partly in spring, the yearly mean runoff is projected to decrease in most catchments. Results show a strong elevation dependence for the signal and magnitude of change. Compared to lower lying catchments, runoff changes in high elevation catchments (above 1500 masl) are larger in winter, spring, and summer due to the strong influence of reduced snow accumulation and earlier snow melt as well as glacier melt. Under RCP8.5 (RCP2.6) and for catchments with mean altitude below 1500 masl, average relative runoff change in winter is +27 % (+5 %), in spring −5 % (−6 %), in summer −31 % (−4 %), in autumn −21 % (−6 %), and −8 % (−4 %) throughout the year. For catchments with mean elevation above 1500 masl, runoff changes on average by +77 % (+24 %) in winter, by +28 % (+16 %) in spring, by −41 % (−9 %) in summer, by −15 % (−4 %) in autumn, and by −9 % (−0.6 %) in the yearly mean. The changes and the climate model agreement on the signal of change increase with increasing global mean temperatures or stronger emission scenarios. This amplification highlights the importance of climate change mitigation. Under RCP8.5, early times of emergence in winter (before 2065; period 2036–2065) and summer (before 2065) were found for catchments with mean altitudes above 1500 masl. Significant changes in catchments below 1500 masl emerge later in the century. However, not all catchments show a time of emergence in all seasons and in some catchments the detected significant changes are not persistent over time.

A 15,000 year record of vegetation and climate change from a treeline lake in the Rocky Mountains, Wyoming, USA

The Holocene ◽  
2011 ◽  
Vol 22 (7) ◽  
pp. 739-748 ◽  
Author(s):  
Scott Mensing ◽  
John Korfmacher ◽  
Thomas Minckley ◽  
Robert Musselman
Keyword(s):  
Climate Change ◽  
Rocky Mountains ◽  
Vegetation Change ◽  
Climatic Variability ◽  
High Elevation ◽  
Sagebrush Steppe ◽  
Climate Projections ◽  
Upward Movement ◽  
Regional Patterns ◽  
Vegetation And Climate

Future climate projections predict warming at high elevations that will impact treeline species, but complex topographic relief in mountains complicates ecologic response, and we have a limited number of long-term studies examining vegetation change related to climate. In this study, pollen and conifer stomata were analyzed from a 2.3 m sediment core extending to 15,330 cal. yr BP recovered from a treeline lake in the Rocky Mountains of Wyoming. Both pollen and stomata record a sequence of vegetation and climate change similar in most respects to other regional studies, with sagebrush steppe and lowered treeline during the Late Pleistocene, rapid upward movement of treeline beginning about 11,500 cal. yr BP, treeline above modern between ~9000 and 6000 cal. yr BP, and then moving downslope ~5000 cal. yr BP, reaching modern limits by ~3000 cal. yr BP. Between 6000 and 5000 cal. yr BP sediments become increasingly organic and sedimentation rates increase. We interpret this as evidence for lower lake levels during an extended dry period with warmer summer temperatures and treeline advance. The complex topography of the Rocky Mountains makes it challenging to identify regional patterns associated with short term climatic variability, but our results contribute to gaining a better understanding of past ecologic responses at high elevation sites.

scholarly journals The Effects of Climate Change on Seasonal Snowpack and the Hydrology of the Northeastern and Upper Midwest United States

2016 ◽  
Vol 29 (18) ◽  
pp. 6527-6541 ◽  
Author(s):  
Eleonora M. C. Demaria ◽  
Joshua K. Roundy ◽  
Sungwook Wi ◽  
Richard N. Palmer
Keyword(s):  
Climate Change ◽  
United States ◽  
Snow Cover ◽  
Climate Models ◽  
Snow Water Equivalent ◽  
High Elevation ◽  
Early Spring ◽  
Climate Projections ◽  
Upper Midwest ◽  
Midwest United States

Abstract The potential effects of climate change on the snowpack of the northeastern and upper Midwest United States are assessed using statistically downscaled climate projections from an ensemble of 10 climate models and a macroscale hydrological model. Climate simulations for the region indicate warmer-than-normal temperatures and wetter conditions for the snow season (November–April) during the twenty-first century. However, despite projected increases in seasonal precipitation, statistically significant negative trends in snow water equivalent (SWE) are found for the region. Snow cover is likely to migrate northward in the future as a result of warmer-than-present air temperatures, with higher loss rates in northern latitudes and at high elevation. Decreases in future (2041–95) snow cover in early spring will likely affect the timing of maximum spring peak streamflow, with earlier peaks predicted in more than 80% of the 124 basins studied.

scholarly journals A large-sample investigation into uncertain climate change impacts on high flows across Great Britain

2021 ◽  
Author(s):  
Rosanna Lane ◽  
Gemma Coxon ◽  
Jim Freer ◽  
Jan Seibert ◽  
Thorsten Wagener
Keyword(s):  
Climate Change ◽  
Great Britain ◽  
Climate Change Impacts ◽  
Heavy Precipitation ◽  
Hydrological Modelling ◽  
Climate Projections ◽  
Annual Maximum ◽  
Parameter Uncertainties ◽  
High Flows ◽  
The Impact

Abstract. Climate change may significantly increase flood risk across Great Britain (GB), but there are large uncertainties in both future climatic changes and how these propagate into changing river flows. Here, the impact of climate change on the magnitude and frequency of high flows is modelled for 346 larger (> 144 km2) catchments across GB using the latest UK Climate Projections (UKCP18) and the DECIPHeR hydrological modelling framework. This study provides the first spatially consistent GB projections including both climate ensembles and hydrological model parameter uncertainties. Generally, results indicated an increase in the magnitude and frequency of high flows (Q10, Q1 and annual maximum) along the west coast of GB in the future (2050–2075), with increases in annual maximum flows of up to 65 % for west Scotland. In contrast, median flows (Q50) were projected to decrease across GB. All flow projections contained large uncertainties, and while the RCMs were the largest source of uncertainty overall, hydrological modelling uncertainties were considerable in east and south-east England. Regional variation in flow projections were found to relate to i) differences in climatic change and ii) catchment conditions during the baseline period as characterised by the runoff coefficient (mean discharge divided by mean precipitation). Importantly, increased heavy-precipitation events (defined by an increase in 99th percentile precipitation) did not always result in increased flood flows for catchments with low runoff coefficients, highlighting the varying factors leading to changes in high flows. These results provide a national overview of climate change impacts on high flows across GB, which will inform climate change adaptation, while also highlighting the need to account for uncertainty sources when modelling climate change impact on high flows.

scholarly journals Climate Change Impact on the Magnitude and Timing of Hydrological Extremes Across Great Britain

2021 ◽  
Vol 3 ◽  
Author(s):  
Rosanna A. Lane ◽  
Alison L. Kay
Keyword(s):  
Climate Change ◽  
Great Britain ◽  
Return Period ◽  
Climate Change Impact ◽  
Annual Maximum ◽  
Low Flows ◽  
Hydrological Extremes ◽  
Change Impact ◽  
High Flows ◽  
Maximum Flows

Climate change could intensify hydrological extremes, changing not just the magnitude but also the timing of flood and drought events. Understanding these potential future changes to hydrological extremes at the national level is critical to guide policy decisions and ensure adequate adaptation measures are put in place. Here, climate change impact on the magnitude and timing of extreme flows is modelled across Great Britain (GB), using an ensemble of climate data from the latest UK Climate Projections product (UKCP18) and a national grid-based hydrological model. All ensemble members show large reductions in low flows, of around −90 to −25% for 10-year return period low flows by 2050–2080. The direction of change for high flows is uncertain, but increases in 10-year return period high flows of over 9% are possible across most of the country. Simultaneous worsening of both extremes (i.e., a reduction in low flows combined with an increase in high flows) are projected in the west. Changes to flow timing are also projected; with mostly earlier annual maximum flows across Scotland, later annual maximum flows across England and Wales, and later low flows across GB. However, these changes are generally not statistically significant due to the high interannual variability of annual maximum/minimum flow timing. These results highlight the need for adaptation strategies that can cope with a wide range of future changes in hydrological extremes, and consider changes in the timing as well as magnitude.

scholarly journals Climate change and its impacts on river discharge in two climate regions in China

2015 ◽  
Vol 12 (7) ◽  
pp. 7099-7126
Author(s):  
H. Xu ◽  
Y. Luo
Keyword(s):  
Climate Change ◽  
River Discharge ◽  
Climate Change Impacts ◽  
High Flow ◽  
Assessment Tools ◽  
Low Flow ◽  
Climate Projections ◽  
Seasonal Temperature ◽  
Mean Flow ◽  
Pronounced Increase

Abstract. Understanding the heterogeneity of climate change and its impacts on annual and seasonal discharge, and the difference between mean flow and extreme flow in different climate regions is of utmost importance to successful water management. To quantify the spatial and temporal heterogeneity of climate change impacts on hydrological processes, this study simulated river discharge in the River Huangfuchuan in semi-arid northern China and the River Xiangxi in humid southern China. We assessed the uncertainty in projected discharge for three time periods (2020s, 2050s and 2080s) using seven equally weighted GCMs for the SRES A1B scenario. Climate projections that were applied to semi-distributed hydrological models Soil Water Assessment Tools (SWAT) in both catchments showed trends toward warmer and wetter conditions, particularly for the River Huangfuchuan. Results based on seven GCMs' projections indicated −1.1 to 8.6 and 0.3 to 7.0 °C changes in seasonal temperature and −29 to 139 and −32 to 85 % changes in seasonal precipitation in River Huangfuchuan and River Xiangxi, respectively. The largest increases in temperature and precipitation in both catchments were projected in the spring and winter seasons. The main projected hydrologic impact was a more pronounced increase in annual discharge in the River Huangfuchuan than in the River Xiangxi. Most of the GCMs projected increased discharge in all seasons, especially in spring, although the magnitude of these increases varied between GCMs. Peak flows was projected to appear earlier than usual in River Huangfuchuan and later than usual in River Xiangxi. While the GCMs were fairly consistent in projecting increased extreme flows in both catchments, the increases were of varying magnitude compared to mean flows. For River Huangfuchuan in the 2080s, median flow changed from −2 to 304 %, compared to a −1 to 145 % change in high flow (Q05 exceedence threshold). For River Xiangxi, low flow (Q95 exceedence threshold) changed from −1 to 77 % and high flow changed from −1 to 62 %, while mean flow changed from −4 to 23 %. The uncertainty analysis provided an improved understanding of future hydrologic behavior in the watershed. Furthermore, this study indicated that the uncertainty constrained by GCMs was critical and should always be considered in analysis of climate change impacts and adaptation.

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