scholarly journals Is the future of large shallow lakes blue-green? Comparing the response of a catchment-lake model chain to climate predictions

2017 ◽  
Vol 141 (2) ◽  
pp. 347-361 ◽  
Author(s):  
Fabien Cremona ◽  
Sirje Vilbaste ◽  
Raoul-Marie Couture ◽  
Peeter Nõges ◽  
Tiina Nõges
Keyword(s):  
Shallow Lakes ◽  
Lake Model ◽  
The Future ◽  
Model Chain

scholarly journals Climate impact on floods: changes in high flows in Sweden in the past and the future (1911–2100)

2015 ◽  
Vol 19 (2) ◽  
pp. 771-784 ◽  
Author(s):  
B. Arheimer ◽  
G. Lindström
Keyword(s):  
Climate Impact ◽  
Complex Model ◽  
Snow Accumulation ◽  
Past Century ◽  
Intense Rainfall ◽  
The South ◽  
The Past ◽  
The Future ◽  
High Flows ◽  
Model Chain

Abstract. There is an ongoing discussion whether floods occur more frequently today than in the past, and whether they will increase in number and magnitude in the future. To explore this issue in Sweden, we merged observed time series for the past century from 69 gauging sites throughout the country (450 000 km2) with high-resolution dynamic model projections of the upcoming century. The results show that the changes in annual maximum daily flows in Sweden oscillate between dry and wet periods but exhibit no significant trend over the past 100 years. Temperature was found to be the strongest climate driver of changes in river high flows, which are related primarily to snowmelt in Sweden. Annual daily high flows may decrease by on average −1% per decade in the future, mainly due to lower peaks from snowmelt in the spring (−2% per decade) as a result of higher temperatures and a shorter snow season. In contrast, autumn flows may increase by +3% per decade due to more intense rainfall. This indicates a shift in flood-generating processes in the future, with greater influence of rain-fed floods. Changes in climate may have a more significant impact on some specific rivers than on the average for the whole country. Our results suggest that the temporal pattern in future daily high flow in some catchments will shift in time, with spring floods in the northern–central part of Sweden occurring about 1 month earlier than today. High flows in the southern part of the country may become more frequent. Moreover, the current boundary between snow-driven floods in northern–central Sweden and rain-driven floods in the south may move toward higher latitudes due to less snow accumulation in the south and at low altitudes. The findings also indicate a tendency in observations toward the modeled projections for timing of daily high flows over the last 25 years. Uncertainties related to both the observed data and the complex model chain of climate impact assessments in hydrology are discussed.

scholarly journals Dynamics and Economics of Shallow Lakes: A Survey

2021 ◽  
Vol 13 (24) ◽  
pp. 13763
Author(s):  
Dmitry Gromov ◽  
Thorsten Upmann
Keyword(s):  
Linear Model ◽  
Shallow Lakes ◽  
Shallow Lake ◽  
Regime Shift ◽  
Multiple Steady States ◽  
Typical Representative ◽  
Lake Model ◽  
Ecological Problems ◽  
Multiple Domains ◽  
Substantial Interest

We provide an overview of the results devoted to the analysis of the dynamics and economics of shallow lakes, spanning the period from 1999 until now. A shallow lake serves as a typical representative of an ecological system subject to (possibly irreversible) regime shifts. The dynamics of a shallow lake are described by a non-linear model with multiple steady states and multiple domains of attraction and is thus suitable to model the evolution of an ecosystem featuring both resilience within a domain of stability and an abrupt regime shift outside of it. Beyond this, the shallow lake model can also be viewed as a metaphor for many other ecological problems. Due to the broad applicability of this model, there is substantial interest in the management of shallow lakes and both their optimal regulation and competitive usage.

Projecting thermal stratification and hypolimnetic oxygen conditions by coupling paleolimnological and 1D lake model approaches

2021 ◽  
Author(s):  
Jean-Philippe Jenny ◽  
Olivia Itier ◽  
Victor Frossard ◽  
David Etienne ◽  
Jean Guillard
Keyword(s):  
Climate Change ◽  
Thermal Regime ◽  
Thermal Stratification ◽  
Climatic Factors ◽  
Climate Data ◽  
The Past ◽  
Lake Model ◽  
Hypolimnetic Oxygen ◽  
The Future ◽  
Oxygen Conditions

<p>Climate change raises many questions about the future of lakes’ thermal regime and hypolimnetic oxygen conditions. One dimensional models have been widely implemented over that last years <sup>1–3</sup>, but most of these models are calibrated against very few years of limnological records, potentially limiting the robustness in long-term reconstructions and preventing inclusion of future scenarios. To analysis the variability and the effects of climate change on thermal regime and oxygen conditions of deep hard-water lakes, we relayed on paleolimnological records and 1D thermal lake model calibrated against time series of limnological data collected by the French Observatoire des LAcs (OLA). Continuous sediment records on four peri-alpine lakes (Lake Geneva, Lake Annecy, Lake Bourget and Lake Aiguebelette) were analysed using micro-XRF Mn-Fe ratio as proxy to infer near-annual trends of oxygen conditions for the past 300 years<sup>4</sup>. Past hypoxia dynamics were further inferred from varved records preserved in sediment cores<sup>5</sup>. General Lake Model (GLM), i.e. a 1-D modelling tool, has been constrained by climate data derived from meteorological observations and CMIP6 simulations in order to reconstruct and forcast stratification regims for the next century. Our paleolimnological results show that fluctuations in hypoxic volumes since the 1950s were great and that these fluctuations were essentially driven by climatic factors, legitimating the use of thermal model approaches for future projections of hypolimnetic oxygen conditions. In this line, thermal regime simulations based on GLM forecast an intensification in thermal stratification and an increase in volumes of water warmer than 9°C over the period 1850-2100 with potential consequence for hypolimnetic oxygen conditions and ecological habitats. Coupling model and paleolimnological approaches seem a promising way to examine the evolution of lakes in the past, and to realistically anticipate the future of lakes for the next decades.</p>

scholarly journals Hydrological impacts of climate change on small ungauged catchments-results from a GCM-RCM-hydrologic model chain

2019 ◽  
Author(s):  
Aynalem T. Tsegaw ◽  
Marie Pontoppidan ◽  
Erle Kristvik ◽  
Knut Alfredsen ◽  
Tone M. Muthanna
Keyword(s):  
Climate Change ◽  
High Resolution ◽  
Hydrological Model ◽  
Flow Patterns ◽  
Reference Period ◽  
Future Period ◽  
The Future ◽  
The Mean ◽  
Model Chain ◽  
Impacts Of Climate Change

Abstract. Climate change is one of the greatest threats to the World's environment. In Norway, the change will strongly affect the pattern, frequency and magnitudes of stream flows. However, it is highly challenging to quantify to what extent it will affect flow patterns and floods from small ungauged rural catchments due to unavailability or inadequacy of hydro-meteorological data for the calibration of hydrological models and tailoring methods to a small-scale level. To provide meaningful climate impact studies at small catchments, it is therefore beneficial to use high spatial and temporal resolution climate projections as input to a high-resolution hydrological model. Here we use such a model chain to assess the impacts of climate change on flow patterns and frequency of floods in small ungauged rural catchments in western Norway using a new high-resolution regional climate projection, with improved performance with regards to the precipitation distribution, and the regionalized hydrological model (Distance Distribution Dynamics) between the reference period (1981–2011) and a future period (2071–2100). The FDCs of all study catchments show there will be more wetter periods in the future than the reference period. The results also show that in the future period, the mean annual flow increases by 16.5 % to 33.3 %, and there will be an increase in the mean autumn, mean winter and mean spring flows ranging from 4.3 % to 256.3 %. The mean summer flow decreases by 7.2 % to 35.2 %. The mean annual maximum floods increase by 28.9 % to 38.3 %, and floods of 2 to 200 years return periods increase by 16.1 % to 42.7 %. The findings of this study could be of practical use to regional decision-makers if considered alongside other previous and future findings.

scholarly journals Assessment of climate change and prospective analysis on shallow lakes. Las Encadenadas del Oeste watershed, Buenos Aires - Argentina

2021 ◽  
Author(s):  
Caroline Tengroth ◽  
Alejandra Mabel Geraldi
Keyword(s):  
Climate Change ◽  
Shallow Lakes ◽  
Shallow Lake ◽  
Minimum Temperature ◽  
Water Levels ◽  
Lake Area ◽  
Temperature And Precipitation ◽  
The Future ◽  
Climate Station ◽  
Basin Area

The earth’s ecosystem is fragile, and sometimes even small changes in the climate can have impacts on the environment and society. Changes in temperature and precipitation can cause numerous feedbacks that effect the ecosystem of the whole Earth. Many studies hold that the temperature will rise in some places, while other areas will experience a cooling in annual mean temperatures. The study area is famous for its many ponds. These ecosystems will be both physically, biologically, and chemically affected by climate change and its feedbacks. Las Encadenadas del Oeste consists of seven shallow lakes (Epecuen, La Paraguaya, Venado, Del Monte, Cochico, Alsina, and Inchauspe) of various depths and sizes is a closed river basin system aligned in an east-west direction. The objectives of this work are to demonstrate the change in shallow lake size over a period of 20 years and to relate these changes to temperature and precipitation over the basin area for the same period. It is also intended to examine future temperature and precipitation scenarios in the study area. Maximum and minimum temperature data and precipitation data was retrieved from a climate station in Carhue. A multiple regression analysis was performed and five models and the shallow lake area were compared. The water levels in the shallow lakes will continue to fluctuate in the future as precipitation and temperature varies. Temperatures will increase quickly in the area; and around a 3 ºC change is expected before 2099. Only small variations in the temperatures have previously caused the lake to change in size. Precipitation patterns show a high variation, but the change is very small. Minimum temperature, which is already the most significant factor according to the statistical analysis, will in the future be an even more important factor if changes occur.

International determination of the total motion of the pole

1961 ◽  
Vol 13 ◽  
pp. 29-41
Author(s):  
Wm. Markowitz
Keyword(s):  
Secular Motion ◽  
The Future

A symposium on the future of the International Latitude Service (I. L. S.) is to be held in Helsinki in July 1960. My report for the symposium consists of two parts. Part I, denoded (Mk I) was published [1] earlier in 1960 under the title “Latitude and Longitude, and the Secular Motion of the Pole”. Part II is the present paper, denoded (Mk II).

Status of the Lick Proper Motion Program

1978 ◽  
Vol 48 ◽  
pp. 387-388
Author(s):  
A. R. Klemola
Keyword(s):  
Proper Motion ◽  
The Future

Second-epoch photographs have now been obtained for nearly 850 of the 1246 fields of the proper motion program with centers at declination -20° and northwards. For the sky at 0° and northward only 130 fields remain to be taken in the next year or two. The 270 southern fields with centers at -5° to -20° remain for the future.

Some Structural Features of Metaphase Chromosomes of Mice and Men

1967 ◽  
Vol 25 ◽  
pp. 190-191
Author(s):  
Godfrey C. Hoskins ◽  
Betty B. Hoskins
Keyword(s):  
Electron Microscopy ◽  
Electron Micrographs ◽  
Structural Features ◽  
Metaphase Chromosomes ◽  
The Future ◽  
Of Mice And Men ◽  
Mouse Cells ◽  
Human And Mouse

Metaphase chromosomes from human and mouse cells in vitro are isolated by micrurgy, fixed, and placed on grids for electron microscopy. Interpretations of electron micrographs by current methods indicate the following structural features.Chromosomal spindle fibrils about 200Å thick form fascicles about 600Å thick, wrapped by dense spiraling fibrils (DSF) less than 100Å thick as they near the kinomere. Such a fascicle joins the future daughter kinomere of each metaphase chromatid with those of adjacent non-homologous chromatids to either side. Thus, four fascicles (SF, 1-4) attach to each metaphase kinomere (K). It is thought that fascicles extend from the kinomere poleward, fray out to let chromosomal fibrils act as traction fibrils against polar fibrils, then regroup to join the adjacent kinomere.

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