Modelling the impacts of climate change on upland catchments in southwest Scotland using MIKE SHE and the UKCP09 probabilistic projections

2012 ◽  
Vol 43 (4) ◽  
pp. 507-530 ◽  
Author(s):  
J. R. Thompson
Keyword(s):  
Potential Evapotranspiration ◽  
Hydrological Models ◽  
Water Acidification ◽  
Surface Water Acidification ◽  
Emissions Scenarios ◽  
Winter Flooding ◽  
Extreme Probability ◽  
Annual Discharge ◽  
Upland Catchments ◽  
Impacts Of Climate Change

Hydrological models of three upland sub-catchments of Loch Dee, southwest Scotland, are calibrated and validated against observed discharge. Perturbed precipitation and potential evapotranspiration (PET) are generated from UKCIP09 projections for Low, Medium and High emissions scenarios for the 2050s and 2080s for probability levels between 10 and 90%. Annual and monthly PET increases for all scenarios. Central estimates of increases in annual PET are up to 10.7 (2050s) and 15.8% (2080s). Precipitation becomes more seasonal, increasing in winter and decreasing in summer for all but the extreme probability levels. Annual precipitation declines for the lowest (up to 30%) probability levels and increases thereafter (up to 5.8% for the 2050s and 10.3% for the 2080s at the 50% level). Changes in discharge are driven by those for precipitation. Although there is uncertainty in changes in annual discharge, most scenarios increase winter discharges (2050s: up to 24.2%; 2080s: up to 50.9% at the 50% level) and reduce summer flows (2050s: up to 34.2%, 2080s: up to 48.7% at the 50% level). Potential impacts include enhanced winter flooding and lower summer reservoir levels with implications for hydropower. Greater seasonality in discharge may impact fisheries and ongoing recovery from surface water acidification.

scholarly journals Climate change impacts on the hydrologic regime of a Canadian river: comparing uncertainties arising from climate natural variability and lumped hydrological model structures

2013 ◽  
Vol 10 (11) ◽  
pp. 14189-14227 ◽  
Author(s):  
G. Seiller ◽  
F. Anctil
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Hydrological Model ◽  
Potential Evapotranspiration ◽  
Natural Variability ◽  
Hydrological Models ◽  
Natural Climate Variability ◽  
Natural Climate ◽  
Model Structures ◽  
Impacts Of Climate Change

Abstract. Diagnosing the impacts of climate change on water resources is a difficult task pertaining to the uncertainties arising from the different modeling steps. Lumped hydrological model structures contribute to this uncertainty as well as the natural climate variability, illustrated by several members from the same Global Circulation Model. In this paper, the hydroclimatic modeling chain consist of twenty-four potential evapotranspiration formulations, twenty lumped conceptual hydrological models, and seven snowmelt modules. These structures are applied on a natural Canadian sub-catchment to address related uncertainties and compare them to the natural variability as depicted by five climatic members. Uncertainties are commented on the observation period and on simulated and projected climates. They rely on interannual hydrographs and hydrological indicators analysis. Results show that the natural climate variability is the major source of uncertainty, followed by the potential evapotranspiration formulations and hydrological models. The selected snowmelt modules, however, do not contribute much to the uncertainty. The analysis also illustrates that the streamflow simulation over the current climate period is already conditioned by tools' selection, propagating this uncertainty on reference and future projection, while climatic members add over it. These findings demonstrate the importance of opting for several climatic members to encompass the important uncertainty related to the climate natural variability, but also of selecting multiple modeling tools to provide a trustworthy diagnosis of the impacts of climate change on water resources.

scholarly journals Climate change impacts on the hydrologic regime of a Canadian river: comparing uncertainties arising from climate natural variability and lumped hydrological model structures

2014 ◽  
Vol 18 (6) ◽  
pp. 2033-2047 ◽  
Author(s):  
G. Seiller ◽  
F. Anctil
Keyword(s):  
Climate Change ◽  
Water Resources ◽  
Climate Variability ◽  
Hydrological Model ◽  
Potential Evapotranspiration ◽  
Hydrological Models ◽  
Natural Climate Variability ◽  
Natural Climate ◽  
Model Structures ◽  
Impacts Of Climate Change

Abstract. Diagnosing the impacts of climate change on water resources is a difficult task pertaining to the uncertainties arising from the different modelling steps. Lumped hydrological model structures contribute to this uncertainty as well as the natural climate variability, illustrated by several members from the same Global Circulation Model. In this paper, the hydroclimatic modelling chain consists of twenty-four potential evapotranspiration formulations, twenty lumped conceptual hydrological models, and seven snowmelt modules. These structures are applied on a natural Canadian sub-catchment to address related uncertainties and compare them to the natural internal variability of simulated climate system as depicted by five climatic members. Uncertainty in simulated streamflow under current and projected climates is assessed. They rely on interannual hydrographs and hydrological indicators analysis. Results show that natural climate variability is the major source of uncertainty, followed by potential evapotranspiration formulations and hydrological models. The selected snowmelt modules, however, do not contribute much to the uncertainty. The analysis also illustrates that the streamflow simulation over the current climate period is already conditioned by the tools' selection. This uncertainty is propagated to reference simulations and future projections, amplified by climatic members. These findings demonstrate the importance of opting for several climatic members to encompass the important uncertainty related to the climate natural variability, but also of selecting multiple modelling tools to provide a trustworthy diagnosis of the impacts of climate change on water resources.

Mapping the relative risk of surface water acidification based on cumulative acid deposition over the past 25 years in Japan

2016 ◽  
Vol 21 (3) ◽  
pp. 115-124 ◽  
Author(s):  
Naoyuki Yamashita ◽  
Hiroyuki Sase ◽  
Tsuyoshi Ohizumi ◽  
Junichi Kurokawa ◽  
Toshimasa Ohara ◽  
...  
Keyword(s):  
Relative Risk ◽  
Surface Water ◽  
Acid Deposition ◽  
Water Acidification ◽  
The Past ◽  
Surface Water Acidification

Establishing past environmental conditions and tracking long-term environmental change in the Canadian Maritime provinces using lake sediments

2013 ◽  
Vol 21 (1) ◽  
pp. 15-27 ◽  
Author(s):  
Jennifer B. Korosi ◽  
Brian K. Ginn ◽  
Brian F. Cumming ◽  
John P. Smol
Keyword(s):  
Nova Scotia ◽  
Surface Water ◽  
Environmental Change ◽  
New Brunswick ◽  
Water Acidification ◽  
Maritime Provinces ◽  
Freshwater Resources ◽  
Anthropogenic Stressors ◽  
Surface Water Acidification

Freshwater lakes in the Canadian Maritime provinces have been detrimentally influenced by multiple, often synergistic, anthropogenically-sourced environmental stressors. These include surface-water acidification (and a subsequent decrease in calcium loading to lakes); increased nutrient inputs; watershed development; invasive species; and climate change. While detailed studies of these stressors are often hindered by a lack of predisturbance monitoring information; in many cases, these missing data can be determined using paleolimnological techniques, along with inferences on the full extent of environmental change (and natural variability), the timing of changes, and linkages to probable causes for change. As freshwater resources are important for fisheries, agriculture, municipal drinking water, and recreational activities, among others, understanding long-term ecological changes in response to anthropogenic stressors is critical. To assess the impacts of the major water-quality issues facing freshwater resources in this ecologically significant region, a large number of paleolimnological studies have recently been conducted in Nova Scotia and southern New Brunswick. These studies showed that several lakes in southwestern Nova Scotia, especially those in Kejimkujik National Park, have undergone surface-water acidification (mean decline of 0.5 pH units) in response to local-source SO2 emissions and the long-range transport of airborne pollutants. There has been no measureable chemical or biological recovery since emission restrictions were enacted. Lakewater calcium (Ca) decline, a recently recognized environmental stressor that is inextricably linked to acidification, has negatively affected the keystone zooplankter Daphnia in at least two lakes in Nova Scotia (and likely more), with critical implications for aquatic food webs. A consistent pattern of increasing planktonic diatoms and scaled chrysophytes was observed in lakes across Nova Scotia and New Brunswick, suggesting that the strength and duration of lake thermal stratification has increased since pre-industrial times in response to warming temperatures (∼1.5 °C since 1870). These include three lakes near Bridgewater, Nova Scotia, that are among the last known habitat for critically endangered Atlantic whitefish (Coregonus huntsmani). Overall, these studies suggest that aquatic ecosystems in the Maritime Provinces are being affected by multiple anthropogenic stressors and paleolimnology can be effective for inferring the ecological implications of these stressors.

A simple approach to mimic the effect of active vegetation in hydrological models to better estimate hydrological variables under climate change

2021 ◽  
Author(s):  
Thedini Asali Peiris ◽  
Petra Döll
Keyword(s):  
Climate Change ◽  
Land Surface ◽  
Climate Models ◽  
Potential Evapotranspiration ◽  
Global Climate ◽  
Global Climate Models ◽  
Hydrological Models ◽  
Net Radiation ◽  
Ensemble Mean ◽  
The Impact

<p>Unlike global climate models, hydrological models cannot simulate the feedbacks among atmospheric processes, vegetation, water, and energy exchange at the land surface. This severely limits their ability to quantify the impact of climate change and the concurrent increase of atmospheric CO<sub>2</sub> concentrations on evapotranspiration and thus runoff. Hydrological models generally calculate actual evapotranspiration as a fraction of potential evapotranspiration (PET), which is computed as a function of temperature and net radiation and sometimes of humidity and wind speed. Almost no hydrological model takes into account that PET changes because the vegetation responds to changing CO<sub>2</sub> and climate. This active vegetation response consists of three components. With higher CO<sub>2</sub> concentrations, 1) plant stomata close, reducing transpiration (physiological effect) and 2) plants may grow better, with more leaves, increasing transpiration (structural effect), while 3) climatic changes lead to changes in plants growth and even biome shifts, changing evapotranspiration. Global climate models, which include dynamic vegetation models, simulate all these processes, albeit with a high uncertainty, and take into account the feedbacks to the atmosphere.</p><p>Milly and Dunne (2016) (MD) found that in the case of RCP8.5 the change of PET (computed using the Penman-Monteith equation) between 1981- 2000 and 2081-2100 is much higher than the change of non-water-stressed evapotranspiration (NWSET) computed by an ensemble of global climate models. This overestimation is partially due to the neglect of active vegetation response and partially due to the neglected feedbacks between the atmosphere and the land surface.</p><p>The objective of this paper is to present a simple approach for hydrological models that enables them to mimic the effect of active vegetation on potential evapotranspiration under climate change, thus improving computation of freshwater-related climate change hazards by hydrological models. MD proposed an alternative approach to estimate changes in PET for impact studies that is only a function of the changes in energy and not of temperature and achieves a good fit to the ensemble mean change of evapotranspiration computed by the ensemble of global climate models in months and grid cells without water stress. We developed an implementation of the MD idea for hydrological models using the Priestley-Taylor equation (PET-PT) to estimate PET as a function of net radiation and temperature. With PET-PT, an increasing temperature trend leads to strong increases in PET. Our proposed methodology (PET-MD) helps to remove this effect, retaining the impact of temperature on PET but not on long-term PET change.</p><p>We implemented the PET-MD approach in the global hydrological model WaterGAP2.2d. and computed daily time series of PET between 1981 and 2099 using bias-adjusted climate data of four global climate models for RCP 8.5. We evaluated, computed PET-PT and PET-MD at the grid cell level and globally, comparing also to the results of the Milly-Dunne study. The global analysis suggests that the application of PET-MD reduces the PET change until the end of this century from 3.341 mm/day according to PET-PT to 3.087 mm/day (ensemble mean over the four global climate models).</p><p>Milly, P.C.D., Dunne K.A. (2016). DOI:10.1038/nclimate3046.</p>

Comparison between dynamic and static sensitivity analysis approaches for impact assessment of different potential evapotranspiration methods on hydrological models performance

2021 ◽  
Author(s):  
Rodric Mérimé Nonki ◽  
André Lenouo ◽  
Christopher J. Lennard ◽  
Raphael M. Tshimanga ◽  
Clément Tchawoua
Keyword(s):  
Sensitivity Analysis ◽  
Impact Assessment ◽  
Hydrological Modeling ◽  
Potential Evapotranspiration ◽  
Model Performance ◽  
Estimation Methods ◽  
Model Parameters ◽  
Hydrological Models ◽  
Sensitivity Approach ◽  
Static Sensitivity

AbstractPotential Evapotranspiration (PET) plays a crucial role in water management, including irrigation systems design and management. It is an essential input to hydrological models. Direct measurement of PET is difficult, time-consuming and costly, therefore a number of different methods are used to compute this variable. This study compares the two sensitivity analysis approaches generally used for PET impact assessment on hydrological model performance. We conducted the study in the Upper Benue River Basin (UBRB) located in northern Cameroon using two lumped-conceptual rainfall-runoff models and nineteen PET estimation methods. A Monte-Carlo procedure was implemented to calibrate the hydrological models for each PET input while considering similar objective functions. Although there were notable differences between PET estimation methods, the hydrological models performance was satisfactory for each PET input in the calibration and validation periods. The optimized model parameters were significantly affected by the PET-inputs, especially the parameter responsible to transform PET into actual ET. The hydrological models performance was insensitive to the PET input using a dynamic sensitivity approach, while he was significantly affected using a static sensitivity approach. This means that the over-or under-estimation of PET is compensated by the model parameters during the model recalibration. The model performance was insensitive to the rescaling PET input for both dynamic and static sensitivities approaches. These results demonstrate that the effect of PET input to model performance is necessarily dependent on the sensitivity analysis approach used and suggest that the dynamic approach is more effective for hydrological modeling perspectives.

The Surface Water Acidification Project (SWAP) Palaeolimnology Programme

1990 ◽  
Vol 327 (1240) ◽  
pp. 227-232 ◽  
Keyword(s):  
Surface Water ◽  
High Resolution ◽  
Lake Sediment ◽  
Water Acidification ◽  
Diatom Analysis ◽  
Atmospheric Contamination ◽  
Surface Water Acidification ◽  
History Of ◽  
Study Sites ◽  
Water Acidity

Improvements in techniques of lake-sediment analysis over the last two decades have enabled palaeolimnologists to reconstruct changes in water acidity and atmospheric contamination with high resolution. In the Surface Water Acidification Project (SWAP) Palaeolimnology Programme these techniques have been used to trace the history of a range of specially selected study sites and to evaluate alternative causes for lake acidification. At the same time further improvements in some of the techniques, especially diatom analysis, have been made.

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