scholarly journals Sensitivity to climate change of the thermal structure and ice cover regime of three hydropower reservoirs

2014 ◽  
Vol 510 ◽  
pp. 208-227 ◽  
Author(s):  
Solomon Gebre ◽  
Thibault Boissy ◽  
Knut Alfredsen
Keyword(s):  
Climate Change ◽  
Thermal Structure ◽  
Ice Cover ◽  
Hydropower Reservoirs

Wintertime growth in Atlantic salmon under changing climate: the importance of ice cover for individual growth dynamics

2021 ◽  
Author(s):  
Laura Härkönen ◽  
Pauliina Louhi ◽  
Riina Huusko ◽  
Ari Huusko
Keyword(s):  
Climate Change ◽  
Atlantic Salmon ◽  
Growth Rates ◽  
Growth Dynamics ◽  
Ice Cover ◽  
Individual Growth ◽  
Late Winter ◽  
Dynamic Nature ◽  
Individual Level ◽  
Growth Variation

Understanding the dynamic nature of individual growth in stream-dwelling salmonids may help forecast consequences of climate change on northern fish populations. Here, we performed an experimental capture-mark-recapture study in Atlantic salmon to quantify factors influencing wintertime growth variation among juveniles under different scenarios for ice cover reduction. We applied multiple imputation to simulate missing size observations for unrecaptured fish, and to account for individual-level variation in growth rates. The salmon parr exhibited substantial body length shrinkage in early winter, suppressed growth through mid-winter, and increasing growth rates in late winter and particularly in spring. Unexpectedly, the presence of ice cover had no direct effects on wintertime growth. Instead, our results implied increasing energetic costs with reducing ice cover: individuals exposed to absent or shortened ice-covered period gained mass at a lowered rate in spring whereas the present, long ice-covered period was followed by rapid growth. This study emphasizes natural resilience of Atlantic salmon to wintertime environmental variation which may help the species to cope with the reductions in ice cover duration due to climate change.

Arctic sea ice cover in connection with climate change

2015 ◽  
Vol 51 (9) ◽  
pp. 889-902 ◽  
Author(s):  
G. V. Alekseev ◽  
E. I. Aleksandrov ◽  
N. I. Glok ◽  
N. E. Ivanov ◽  
V. M. Smolyanitsky ◽  
...  
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Ice Cover ◽  
Arctic Sea Ice ◽  
Arctic Sea

Dissolved oxygen stratification and response to thermal structure and long-term climate change in a large and deep subtropical reservoir (Lake Qiandaohu, China)

2015 ◽  
Vol 75 ◽  
pp. 249-258 ◽  
Author(s):  
Yunlin Zhang ◽  
Zhixu Wu ◽  
Mingliang Liu ◽  
Jianbo He ◽  
Kun Shi ◽  
...  
Keyword(s):  
Climate Change ◽  
Dissolved Oxygen ◽  
Thermal Structure

Antarctic marine primary production, biogeochemical carbon cycles and climatic change

1992 ◽  
Vol 338 (1285) ◽  
pp. 289-297 ◽  
Keyword(s):  
Climate Change ◽  
Southern Ocean ◽  
Primary Production ◽  
Climatic Change ◽  
Carbon Fixation ◽  
Algal Growth ◽  
Ice Cover ◽  
Phytoplankton Production ◽  
Numerical Predictions ◽  
Model Predictions

In the Southern Ocean, inorganic macronutrients are very rarely depleted by phytoplankton growth. This has led to speculation on possible additional CO 2 drawdown in this region. However, the effects of climate change can only be predicted once the role of environmental and biotic factors limiting phytoplankton carbon fixation are understood. It is clear that the Southern Ocean is heterogeneous, and no single factor controls prim ary production overall. Ice cover and vertical mixing influence algal growth rates by m odulating radiance flux. Micronutrients, especially iron, may limit growth in some areas. Primary production is also suppressed by high removal rates of algal biomass. Grazing by zooplankton is the major factor determining magnitude and quality of vertical particle flux. Several of the physical controls on phytoplankton production are sensitive to climate change. Although it is impossible to make numerical predictions of future change on the basis of our present knowledge, qualitative assessments can be put forward on the basis of model predictions of climate change and known factors controlling prim ary production. Changes in water temperature and in windinduced mixing are likely to be slight and have little effect. Model predictions of changes in sea-ice cover vary widely, making prediction of biogeochemical effects impossible. Even if climatic change induces increased nutrient uptake, there are several reasons to suspect that carbon sequestration will be ineffective in comparison with continuing anthropogenic CO 2 emission.

River ice breakup processes: recent advances and future directions

2007 ◽  
Vol 34 (6) ◽  
pp. 703-716 ◽  
Author(s):  
Spyros Beltaos
Keyword(s):  
Climate Change ◽  
Effective Means ◽  
Climate Change Impacts ◽  
Ice Cover ◽  
Aquatic Life ◽  
Ice Jams ◽  
Ice Jam ◽  
Ice Breakup ◽  
Extreme Flood ◽  
Mitigation Methods

The breakup of the winter ice cover is a brief but seminal event in the regime of northern rivers, and in the life cycle of river and basin ecosystems. Breakup ice jams can cause extreme flood events, with major impacts on riverside communities, aquatic life, infrastructure, navigation, and hydropower generation. Related concerns are underscored by the issue of climate change and the faster warming that is predicted for northern parts of the globe. Advances in knowledge of breakup processes and related topics, achieved over the past 15 years or so, are outlined. They pertain to breakup initiation and ice-jam formation, ice-jam properties and numerical modelling of ice jams, waves generated by ice-jam releases, forecasting and mitigation methods, sediment transport, ecological aspects, and climate-change impacts. Major knowledge gaps are associated with the dynamic interaction of moving ice with the flow and with the stationary ice cover. Increasing computing capacity and remote sensing sophistication are expected to provide effective means for bridging these gaps. Key words: climate, ecology, forecasting, ice jam, modelling, onset, sediment, wave.

scholarly journals Future changes in Mekong River hydrology: impact of climate change and reservoir operation on discharge

2012 ◽  
Vol 9 (5) ◽  
pp. 6569-6614 ◽  
Author(s):  
H. Lauri ◽  
H. de Moel ◽  
P. J. Ward ◽  
T. A. Räsänen ◽  
M. Keskinen ◽  
...  
Keyword(s):  
Climate Change ◽  
Reservoir Operation ◽  
General Circulation ◽  
General Circulation Models ◽  
Dry Season ◽  
Mekong River ◽  
Cumulative Impacts ◽  
Cumulative Impact ◽  
Impacts Of Climate Change ◽  
Hydropower Reservoirs

Abstract. The transboundary Mekong River is facing two on-going changes that are estimated to significantly impact its hydrology and the characteristics of its exceptional flood pulse. The rapid economic development of the riparian countries has led to massive plans for hydropower construction, and the projected climate change is expected to alter the monsoon patterns and increase temperature in the basin. The aim of this study is to assess the cumulative impact of these factors on the hydrology of the Mekong within next 20–30 yr. We downscaled output of five General Circulation Models (GCMs) that were found to perform well in the Mekong region. For the simulation of reservoir operation, we used an optimisation approach to estimate the operation of multiple reservoirs, including both existing and planned hydropower reservoirs. For hydrological assessment, we used a distributed hydrological model, VMod, with a grid resolution of 5 km × 5 km. In terms of climate change's impact to hydrology, we found a high variation in the discharge results depending on which of the GCMs is used as input. The simulated change in discharge at Kratie (Cambodia) between the baseline (1982–1992) and projected time period (2032–2042) ranges from −11% to +15% for the wet season and −10% to +13% for the dry season. Our analysis also shows that the changes in discharge due to planned reservoir operations are clearly larger than those simulated due to climate change: 25–160% higher dry season flows and 5–24% lower flood peaks in Kratie. The projected cumulative impacts follow rather closely the reservoir operation impacts, with an envelope around them induced by the different GCMs. Our results thus indicate that within the coming 20–30 yr, the operation of planned hydropower reservoirs is likely to have a larger impact on the Mekong hydrograph than the impacts of climate change, particularly during the dry season. On the other hand, climate change will increase the uncertainty of the estimated hydropower impacts. Consequently, both dam planners and dam operators should pay better attention to the cumulative impacts of climate change and reservoir operation to the aquatic ecosystems, including the multibillion-dollar Mekong fisheries.

scholarly journals Projection of the Climate Change Effects on the Vertical Thermal Structure of Juam Reservoir

2014 ◽  
Vol 30 (5) ◽  
pp. 491-502 ◽  
Author(s):  
Sung Wan Yoon ◽  
Gwan Yeong Park ◽  
Se Woong Chung ◽  
Boo Sik Kang
Keyword(s):  
Climate Change ◽  
Thermal Structure ◽  
Climate Change Effects

scholarly journals Wave Climate Associated With Changing Water Level and Ice Cover in Lake Michigan

2021 ◽  
Vol 8 ◽  
Author(s):  
Chenfu Huang ◽  
Longhuan Zhu ◽  
Gangfeng Ma ◽  
Guy A. Meadows ◽  
Pengfei Xue
Keyword(s):  
Climate Change ◽  
Water Level ◽  
Lake Michigan ◽  
Linear Trend ◽  
Ice Cover ◽  
Wave Climate ◽  
Water Levels ◽  
Regional Warming ◽  
Model Simulations

Detailed knowledge of wave climate change is essential for understanding coastal geomorphological processes, ecosystem resilience, the design of offshore and coastal engineering structures and aquaculture systems. In Lake Michigan, the in-situ wave observations suitable for long-term analysis are limited to two offshore MetOcean buoys. Since this distribution is inadequate to fully represent spatial patterns of wave climate across the lake, a series of high-resolution SWAN model simulations were performed for the analysis of long-term wave climate change for the entirety of Lake Michigan from 1979 to 2020. Model results were validated against observations from two offshore buoys and 16 coastal buoys. Linear regression analysis of significant wave height (Hs) (mean, 90th percentile, and 99th percentile) across the entire lake using this 42-year simulation suggests that there is no simple linear trend of long-term changes of Hs for the majority (>90%) of the lake. To address the inadequacy of linear trend analysis used in previous studies, a 10-year trailing moving mean was applied to the Hs statistics to remove seasonal and annual variability, focusing on identifying long-term wave climate change. Model results reveal the regime shifts of Hs that correspond to long-term lake water level changes. Specifically, downward trends of Hs were found in the decade of 1990–2000; low Hs during 2000–2010 coincident with low lake levels; and upward trends of Hs were found during 2010–2020 along with rising water levels. The coherent pattern between the wave climate and the water level was hypothesized to result from changing storm frequency and intensity crossing the lake basin, which influences both waves (instantly through increased wind stress on the surface) and water levels (following, with a lag through precipitation and runoff). Hence, recent water level increases and wave growth were likely associated with increased storminess observed in the Great Lakes. With regional warming, the decrease in ice cover in Lake Michigan (particularly in the northernmost region of the lake) favored the wave growth in the winter due to increased surface wind stress, wind fetch, and wave transmission. Model simulations suggest that the basin-wide Hs can increase significantly during the winter season with projected regional warming and associated decreases in winter ice cover. The recent increases in wave height and water level, along with warming climate and ice reduction, may yield increasing coastal damages such as accelerating coastal erosion.

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