scholarly journals Effects of decreasing acid deposition and climate change on acid extremes in an upland stream

2007 ◽  
Vol 4 (5) ◽  
pp. 2901-2944 ◽  
Author(s):  
C. D. Evans ◽  
B. Reynolds ◽  
C. Hinton ◽  
S. Hughes ◽  
D. Norris ◽  
...  
Keyword(s):  
Climate Change ◽  
Acid Deposition ◽  
Base Cation ◽  
High Flow ◽  
Sea Salt ◽  
Chemical Recovery ◽  
Organic Soils ◽  
Mean Flow ◽  
Acid Episodes

Abstract. This study assesses the major chemical processes leading to acid extremes in a small, moorland stream in mid-Wales, UK, which has been monitored since 1979. Results suggest that base cation (mainly calcium) dilution, the "sea-salt effect", and elevated nitrate pulses, are the major causes of seasonal/episodic minima in acid neutralising capacity (ANC), and that the relative importance of these drivers has remained approximately constant during 25 years of decreasing acid deposition and associated long-term chemical recovery. Many of the chemical variations causing short-term reductions in stream acidity, particularly base cation dilution and organic acid increases, are closely related to changes in water-flowpath and therefore to stream discharge. Changes in the observed pH-discharge relationship over time indicate that high-flow pH has increased more rapidly than mean-flow pH, and therefore that episodes have decreased in magnitude since 1980. However a two-box application of the dynamic model MAGIC, whilst reproducing this trend, suggests that it will not persist in the long term, with mean ANC continuing to increase until 2100, but the ANC of the upper soil (the source of relatively acid water during high-flow episodes) stabilising close to zero beyond 2030. With climate change predicted to lead to an increase in maximum flows in the latter half of the century, high-flow related acid episodes may actually become more rather than less severe in the long term, although the model suggests that this effect may be small. Two other predicted climatic changes could also detrimentally impact on acid episodes: increased severity of winter "sea-salt" episodes due to higher wind speeds during winter storms; and larger sulphate pulses due to oxidation of reduced sulphur held in organic soils, during more extreme summer droughts. At the Gwy, the near-coastal location and relatively small extent of peat soils suggest that sea-salt episodes may have the greatest influence.

scholarly journals Effects of decreasing acid deposition and climate change on acid extremes in an upland stream

2008 ◽  
Vol 12 (2) ◽  
pp. 337-351 ◽  
Author(s):  
C. D. Evans ◽  
B. Reynolds ◽  
C. Hinton ◽  
S. Hughes ◽  
D. Norris ◽  
...  
Keyword(s):  
Climate Change ◽  
Acid Deposition ◽  
Base Cation ◽  
High Flow ◽  
Sea Salt ◽  
Chemical Recovery ◽  
Organic Soils ◽  
Mean Flow ◽  
Acid Episodes

Abstract. This study assesses the major chemical processes leading to acid extremes in a small, moorland stream in mid-Wales, UK, which has been monitored since 1979. Results suggest that base cation (mainly calcium) dilution, the "sea-salt effect", and elevated nitrate pulses, are the major causes of seasonal/episodic minima in acid neutralising capacity (ANC), and that the relative importance of these drivers has remained approximately constant during 25 years of decreasing acid deposition and associated long-term chemical recovery. Many of the chemical variations causing short-term reductions in stream acidity, particularly base cation dilution and organic acid increases, are closely related to changes in water-flowpath and therefore to stream discharge. Changes in the observed pH-discharge relationship over time indicate that high-flow pH has increased more rapidly than mean-flow pH, and therefore that episodes have decreased in magnitude since 1980. However a two-box application of the dynamic model MAGIC, whilst reproducing this trend, suggests that it will not persist in the long term, with mean ANC continuing to increase until 2100, but the ANC of the upper soil (the source of relatively acid water during high-flow episodes) stabilising close to zero beyond 2030. With climate change predicted to lead to an increase in maximum flows in the latter half of the century, high-flow related acid episodes may actually become more rather than less severe in the long term, although the model suggests that this effect may be small. Two other predicted climatic changes could also detrimentally impact on acid episodes: increased severity of winter "sea-salt" episodes due to higher wind speeds during winter storms; and larger sulphate pulses due to oxidation of reduced sulphur held in organic soils, during more extreme summer droughts. At the Gwy, the near-coastal location and relatively small extent of peat soils suggest that sea-salt episodes may have the greatest influence.

scholarly journals Investigation of Low- and High-Flow Characteristics of Karst Catchments under Climate Change

Water ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 925 ◽  
Author(s):  
Klaudija Sapač ◽  
Anže Medved ◽  
Simon Rusjan ◽  
Nejc Bezak
Keyword(s):  
Climate Change ◽  
Flow Characteristics ◽  
High Flow ◽  
Flood Frequency Analysis ◽  
Mean Flow ◽  
Large Variability ◽  
Precipitation Decrease ◽  
Karst Areas ◽  
The Future ◽  
The Impact

It is not clear how projected climate change will impact the hydrological functioning of complex catchments that have significant karst characteristics. Therefore, in this paper we focused on the investigation of the low- and high-flow characteristics of the karst Ljubljanica River catchment. One smaller (51 km2) and one larger (1135 km2) catchment were selected in order to investigate the projected climate change impact on the hydrological conditions. For the investigation of the hydrological situation in the future, we used a lumped conceptual hydrological model. The model was calibrated using past measured daily data. Using the calibrated model, we investigated the impact of five different climate models outputs for the moderately optimistic scenario (RCP4.5). We investigated the situation in next 30-years periods: 2011–2040, 2041–2070, and 2071–2100. Several low and high-flow indices were calculated and compared. The results indicate that a summer precipitation decrease (i.e., 2011–2070) could lead to lower low-flow values for the investigated areas, which could increase the vulnerability of karst areas. Thus, additional focus should be given to water resource management in karst areas. On the other hand, mean flow could increase in the future. The same also applies for the high-flows where flood frequency analysis results indicate that a climate adaptation factor could be used for the hydrotechnical engineering design. However, differences among investigated models are large and show large variability among investigated cases.

scholarly journals Climate change as a confounding factor in reversibility of acidification: RAIN and CLIMEX projects

2001 ◽  
Vol 5 (3) ◽  
pp. 477-486 ◽  
Author(s):  
R. F. Wright ◽  
A. Jenkins
Keyword(s):  
Climate Change ◽  
Acid Deposition ◽  
Forest Canopy ◽  
Inorganic Nitrogen ◽  
Sea Salt ◽  
Related Factors ◽  
Run Off ◽  
Acid Neutralising Capacity ◽  
Sulphate Deposition ◽  
Recovery From Acidification

Abstract. The RAIN and CLIMEX experiments at Risdalsheia, southernmost Norway, together cover 17 years (1984-2000) of whole-catchment manipulation of acid deposition and climate. A 1200 m2 roof placed over the forest canopy at KIM catchment excluded about 80% of ambient acid deposition; clean rain was sprinkled under the roof. A climate change treatment (3.7°C increase in air temperature and increase in air carbon dioxide concentrations to 560 ppmv) was superimposed on the clean rain treatment for four years (1995-1998). Sea-salt inputs and temperature are climate-related factors that influence water chemistry and can confound long-term trends caused by changes in deposition of sulphur and nitrogen. The RAIN and CLIMEX experiments at Risdalsheia provided direct experimental data that allow quantitative assessment of these factors. Run-off chemistry responded rapidly to the decreased acid deposition. Sulphate concentrations decreased by 50% within three years; nitrate and ammonium concentrations decreased to new steady-state levels within the first year. Acid neutralising capacity increased and hydrogen ion and inorganic aluminium decreased. Similar recovery from acidification was also observed at the reference catchment, ROLF, in response to the general 50% reduction in sulphate deposition over southern Norway in the late 1980s and 1990s. Variations in sea-salt deposition caused large variations in run-off chemistry at the reference catchment ROLF and the year-to-year noise in acid neutralising capacity was as large as the overall trend over the period. These variations were absent at KIM catchment because the sea-salt inputs were held constant over the entire 17 years of the clean rain treatment. The climate change experiment at KIM catchment resulted in increased leaching of inorganic nitrogen, probably due to increased mineralisation and nitrification rates in the soils. Keywords: acid deposition, global change, water, soil, catchment, experiment, Norway.

scholarly journals Developing hydrological and reservoir models under deep uncertainty of climate change: robustness of water supply reservoir

2019 ◽  
Vol 19 (8) ◽  
pp. 2222-2230
Author(s):  
Daniel Marton ◽  
Kateřina Knoppová
Keyword(s):  
Climate Change ◽  
Storage Capacity ◽  
Management Strategies ◽  
Simulation Models ◽  
Mean Flow ◽  
Deep Uncertainty ◽  
Reservoir Storage ◽  
Reservoir Performance ◽  
Climate Change Uncertainty

Abstract Adaptation of water resources to climate change, drought management strategies, and hydrological and reservoir modelling have become serious issues in the context of climate change uncertainty. The aim of this paper is to introduce methods and tools for hydrological analysis and robust reservoir performance evaluation in this time of deep uncertainty. Newly developed lumped water balance and reservoir simulation models will be used to perform hydrological analysis, and a robust reservoir storage capacity reliability assessment will also be conducted. The hydrological data in relation to climate change will be constructed using two climatological datasets created by statistical downscaling tools LARS WG and ENSEMBLE Downscaling Portal. The hydrological analysis and the temporal reliability of the assessment of reservoir storage capacity and robustness in the context of climate change uncertainty will be presented as a case study of the Vir I reservoir and the Svratka River basin in the Czech Republic, in central Europe. The resulting models show a decrease in long-term mean flow, ranging from 6% to 32%, and in reservoir outflow from 1.5% to 26%, depending on the timescale, downscaling tools and emission scenarios.

scholarly journals The decreasing importance of acidification episodes with recovery from acidification: an analysis of the 30-year record from Birkenes, Norway

2008 ◽  
Vol 12 (2) ◽  
pp. 353-362 ◽  
Author(s):  
R. F. Wright
Keyword(s):  
High Flow ◽  
Chemical Recovery ◽  
Empirical Relationships ◽  
Streamwater Chemistry ◽  
Recovery From Acidification ◽  
Acid Episodes

Abstract. The 30-year record 1975–2004 of weekly samples of streamwater chemistry from Birkenes, Norway, shows 106 acid episodes below the threshold of ANC−50 µeq l−1. The frequency, severity and duration of episodes have diminished since about 1990 due to chemical recovery following reduced deposition of sulphur. In particular SO4-driven episodes in the first runoff following drought have become less intense and less frequent, whereas episodes driven by climate (wind, high flow) continue. The data show significant empirical relationships between strength of the driver, degree of chemical recovery, and severity of ANC depression.

scholarly journals The browning and re-browning of lakes: Divergent lake-water organic carbon trends linked to acid deposition and climate change

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Carsten Meyer-Jacob ◽  
Neal Michelutti ◽  
Andrew M. Paterson ◽  
Brian F. Cumming ◽  
Wendel (Bill) Keller ◽  
...  
Keyword(s):  
Climate Change ◽  
Organic Carbon ◽  
Acid Deposition ◽  
Lake Water ◽  
Spectroscopic Techniques ◽  
Central Canada ◽  
Atmospheric Acid Deposition ◽  
Aquatic Productivity ◽  
Productivity Potential

Abstract Dissolved organic carbon (DOC) concentrations and water colour are increasing in many inland waters across northern Europe and northeastern North America. This inland-water “browning” has profound physical, chemical and biological repercussions for aquatic ecosystems affecting water quality, biological community structures and aquatic productivity. Potential drivers of this “browning” trend are complex and include reductions in atmospheric acid deposition, changes in land use/cover, increased nitrogen deposition and climate change. However, because of the overlapping impacts of these stressors, their relative contributions to DOC dynamics remain unclear, and without appropriate long-term monitoring data, it has not been possible to determine whether the ongoing “browning” is unprecedented or simply a “re-browning” to pre-industrial DOC levels. Here, we demonstrate the long-term impacts of acid deposition and climate change on lake-water DOC concentrations in low and high acid-deposition areas using infrared spectroscopic techniques on ~200-year-long lake-sediment records from central Canada. We show that acid deposition suppressed naturally higher DOC concentrations during the 20th century, but that a “re-browning” of lakes is now occurring with emissions reductions in formerly high deposition areas. In contrast, in low deposition areas, climate change is forcing lakes towards new ecological states, as lake-water DOC concentrations now often exceed pre-industrial levels.

scholarly journals The decreasing importance of acidification episodes with recovery from acidification: an analysis of the 30-year record from Birkenes, Norway

2007 ◽  
Vol 4 (5) ◽  
pp. 2945-2973 ◽  
Author(s):  
R. F. Wright
Keyword(s):  
High Flow ◽  
Chemical Recovery ◽  
Empirical Relationships ◽  
Streamwater Chemistry ◽  
Recovery From Acidification ◽  
Acid Episodes

Abstract. The 30-year record 1975–2004 of weekly samples of streamwater chemistry from Birkenes, Norway, shows 106 acid episodes below the threshold of ANC –50 μeq l−1. The frequency, severity and duration of episodes have diminished since about 1990 due to chemical recovery following reduced deposition of sulphur. In particular SO4-driven episodes in the first runoff following drought have become less intense and less frequent, whereas episodes driven by climate (wind, high flow) continue. The data show significant empirical relationships between strength of the driver, degree of chemical recovery, and severity of ANC depression.

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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