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 Future changes in hydrological extremes of a Mediterranean catchment: what can we say in an uncertainty context?

2020 ◽  
Author(s):  
Lila Collet ◽  
Thibault Lemaitre-Basset ◽  
Guillaume Thirel ◽  
Juraj Parajka ◽  
Guillaume Evin ◽  
...  
Keyword(s):  
Climate Change ◽  
Uncertainty Analysis ◽  
Climate Change Impact ◽  
Climate Projections ◽  
Total Uncertainty ◽  
River Catchment ◽  
Low Flows ◽  
Hydrological Extremes ◽  
Hydrological Hazards ◽  
Change Impact

<p><span>The Mediterranean region is a hot spot for climate change impact on the water cycle where water resources are anticipated to decrease and hydrological extremes to intensify while population and water use conflicts growth would keep rising. However, the analysis of the uncertainty related to hydrological projections is generally poorly quantified and difficult to translate to decision-makers. In this study, an in-depth analysis of projections and uncertainties for extreme high- and low-flows was performed. Climatic projections derived from a recent downscaling method over France (Adamont, Verfaillie et al., 2017) were used, and hydrological projections were produced on the Hérault River catchment based on two different Radiative Concentration Pathways (RCPs), five global and regional climate model (GCM/RCM) couples, three hydrological models (HMs), and twenty-nine calibration schemes (Lemaitre-Basset et al., sub). This ensemble was analysed with the QUALYPSO approach (Evin et al., 2019) that allows transient uncertainty analysis of ensembles derived from incomplete GCM/RCM matrix. The quasi-ergodic analysis of variance (QE-ANOVA) used in QUALYPSO evaluates the contribution of each impact modelling step to the total uncertainty. For high-flows, GCMs and RCPs contribute the most to the total uncertainty at the short and long lead-time, respectively. For low-flows, HMs structure and calibration period are the most important sources of uncertainty across 2006-2100. While high-flow projections show a significant mean increase of 30% by 2085 compared to the historical period (confidence intervals: [-1%; +64%]), low-flows would slightly decrease (-7%) by 2085, but with a higher uncertainty (confidence interval: [-24%; +13%]). The time horizons for which a change (e.g. -50, -20, -10, …, +10, +20, +50%) in high- and low-flows intensity becomes robust (i.e. when more than 66% of the ensemble is above/below a given threshold) were also assessed. This provides strong messages to water managers of the Hérault River catchment who can then anticipate the time needed to prepare and adapt to climate change impacts for extreme hydrological hazards.</span></p><p>References:</p><p>Evin, G., Hingray, B., Blanchet, J., Eckert, N., Morin, S., & Verfaillie, D. (2019). Partitioning Uncertainty Components of an Incomplete Ensemble of Climate Projections Using Data Augmentation. JOURNAL OF CLIMATE, 32, 18. https://doi.org/10.1175/JCLI-D-18-0606.1</p><p>Lemaitre-Basset, T., Collet, L., Thirel, G., Parajka, J., Evin, G., Hingray, B. (submitted) Climate change impact and uncertainty analysis on hydrological extremes in a Mediterranean catchment. Hydrological Sciences Journal</p><p>Verfaillie, D., Déqué, M., Morin, S., & Lafaysse, M. (2017). The method ADAMONT v1.0 for statistical adjustment of climate projections applicable to energy balance land surface models. Geoscientific Model Development, 10(11), 4257–4283. https://doi.org/10.5194/gmd-10-4257-2017</p>

scholarly journals Climate change impact and uncertainty analysis on hydrological extremes in a French Mediterranean catchment

2021 ◽  
pp. 1-16
Author(s):  
Thibault Lemaitre-Basset ◽  
Lila Collet ◽  
Guillaume Thirel ◽  
Juraj Parajka ◽  
Guillaume Evin ◽  
...  
Keyword(s):  
Climate Change ◽  
Uncertainty Analysis ◽  
Climate Change Impact ◽  
Hydrological Extremes ◽  
Change Impact

scholarly journals Climate change impact on river flow extremes in the Upper Blue Nile River basin

2018 ◽  
Vol 10 (4) ◽  
pp. 759-781 ◽  
Author(s):  
Hadush K. Meresa ◽  
Mulusew T. Gatachew
Keyword(s):  
Climate Change ◽  
River Basin ◽  
Climate Change Impact ◽  
River Flow ◽  
Nile River ◽  
Hydrological Models ◽  
Hydrological Extremes ◽  
Dry Spell ◽  
Change Impact ◽  
Blue Nile River Basin

Abstract This paper aims to study climate change impact on the hydrological extremes and projected precipitation extremes in far future (2071–2100) period in the Upper Blue Nile River basin (UBNRB). The changes in precipitation extremes were derived from the most recent AFROCORDEX climate data base projection scenarios compared to the reference period (1971–2000). The climate change impacts on the hydrological extremes were evaluated using three conceptual hydrological models: GR4 J, HBV, and HMETS; and two objective functions: NSE and LogNSE. These hydrological models are calibrated and validated in the periods 1971–2000 and 2001–2010, respectively. The results indicate that the wet/dry spell will significantly decrease/increase due to climate change in some sites of the region, while in others, there is increase/decrease in wet/dry spell but not significantly, respectively. The extreme river flow will be less attenuated and more variable in terms of magnitude, and more irregular in terms of seasonal occurrence than at present. Low flows are projected to increase most prominently for lowland sites, due to the combined effects of projected decreases in Belg and Bega precipitation, and projected increases in evapotranspiration that will reduce residual soil moisture in Bega and Belg seasons.

scholarly journals Evidence of climate change impact on stream low flow from the tropical mountain rainforest watershed in Hainan Island, China

2016 ◽  
Vol 8 (2) ◽  
pp. 293-302 ◽  
Author(s):  
Zhang Zhou ◽  
Ying Ouyang ◽  
Zhijun Qiu ◽  
Guangyi Zhou ◽  
Mingxian Lin ◽  
...  
Keyword(s):  
Climate Change ◽  
Air Temperature ◽  
Climate Change Impact ◽  
Water Resource Management ◽  
Hainan Island ◽  
Low Flow ◽  
Annual Rainfall ◽  
Time Increment ◽  
Low Flows ◽  
Change Impact

Stream low flow estimates are central to assessing climate change impact, water resource management, and ecosystem restoration. This study investigated the impacts of climate change upon stream low flows from a rainforest watershed in Jianfengling (JFL) Mountain, Hainan Island, China, using the low flow selection method as well as the frequency and probability analysis technique. Results showed that low flow at this watershed over a period of 18 years (1990–2007) was 0.58 m3/s and its recurrence probability and recurrence interval were, respectively, 99% and 1.01 years for low flow with a 60-day duration. Low flow rate decreased linearly both as time increment elapsed (R2 = 0.62, p < 0.01) and as air temperature rose (R2 = 0.60, p < 0.05), whereas the recurrence intervals of low flow were shorter (or occurred more frequently) as time increment elapsed. In contrast, no correlation existed between annual rainfall and low flow for this watershed, indicating that rainfall was not a factor influencing stream low flows. Since there were little to no anthropogenic activities rather than air temperature rise over time at this watershed, we attributed the decreased rate and frequent occurrence of low flow to the warming air temperature as time elapsed.

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.

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