A regional analysis of the impact of dams on water temperature in medium-size rivers in eastern Canada

2016 ◽  
Vol 73 (12) ◽  
pp. 1885-1897 ◽  
Author(s):  
Audrey Maheu ◽  
André St-Hilaire ◽  
Daniel Caissie ◽  
Nassir El-Jabi ◽  
Guillaume Bourque ◽  
...  
Keyword(s):  
Water Temperature ◽  
Thermal Regime ◽  
Regional Scale ◽  
Regional Analysis ◽  
Annual Runoff ◽  
Rate Of Change ◽  
Medium Size ◽  
Regulated Rivers ◽  
Eastern Canada ◽  
The Impact

Various studies have helped gain a better understanding of the thermal impacts of dams on a site-specific basis, but very few studies have compared the thermal impacts of varying types of dams within the same region. In this study, we conducted a regional-scale assessment of the impacts of dams on the thermal regime of 13 medium-size rivers in eastern Canada. The objectives of this study were to identify features of the thermal regime of rivers that are predominantly impacted by dams and to compare the impacts associated with different types of regulation (run-of-river, storage, peaking). The thermal regime of regulated and unregulated rivers was characterized using 15 metrics that described the magnitude, frequency, duration, timing, and rate of change of water temperature. Results indicate that storage and peaking dams impounding at least 10% of the median annual runoff generally (i) reduced the magnitude of water temperature variation at seasonal, daily, and subdaily timescales and (ii) increased the monthly mean water temperature in September. This regional assessment offers important insight regarding a generalized pattern of thermal alteration by dams, and this information could be used to guide biological monitoring efforts in regulated rivers.

scholarly journals Modeling impacts of highly regulated inflow on thermal regime and water age in a shallow reservoir

2013 ◽  
Vol 15 (4) ◽  
pp. 1312-1325 ◽  
Author(s):  
Binbin Wu ◽  
Guoqiang Wang ◽  
Changming Liu ◽  
Zongxue Xu
Keyword(s):  
Water Temperature ◽  
Thermal Regime ◽  
Northern China ◽  
Transport Processes ◽  
Water Age ◽  
Shallow Reservoir ◽  
Thermal Effluent ◽  
Negative Effect ◽  
The Impact ◽  
Shallow Reservoirs

Thermal regime and transport of dissolved pollutants, strongly related to water quality and algae bloom in reservoirs, may be quantized by indicators of water temperature and water age, respectively, and these indicators are more spatially and temporally variant in shallow reservoirs. Here, a two-dimensional model was used for studying characteristics of the indicators in Douhe Reservoir, based on data of the year 2008. Douhe Reservoir is a typical shallow reservoir in Northern China, characterized by highly regulated inflow and thermal effluent. The impacts of the regulated inflow on reservoir thermal regime and water age were then analyzed through numerical experiments. The results show that the effects of inflow are associated with the flow circulations induced by inflow, thermal effluent, and wind. The most efficient inflows for alleviating thermal pollution and improving water exchange are 32.5 and 19.5 m3/s, respectively. A positive logarithmic correlation is found between water temperature and water age under the impact of inflow, while thermal effluent and wind have a slightly negative effect on the correlation. These findings provide useful information for better understanding the complex hydrodynamic and mass transport processes in a shallow reservoir.

scholarly journals Comparison of a deterministic and statistical approach for the prediction of thermal indices in regulated and unregulated river reaches: case study of the Fourchue River (Québec, Canada)

2020 ◽  
Vol 55 (4) ◽  
pp. 394-408
Author(s):  
Laurie Beaupré ◽  
André St-Hilaire ◽  
Anik Daigle ◽  
Normand Bergeron
Keyword(s):  
Statistical Model ◽  
Water Temperature ◽  
Thermal Regime ◽  
Anthropogenic Impacts ◽  
Stressful Events ◽  
Fish Distribution ◽  
Management Tool ◽  
Thermal Indices ◽  
The Impact ◽  
Mean Square Errors

Abstract Water temperature is an important factor modifying fish distribution patterns and community abundance in streams, and this is especially true for salmonids. Knowing that dams often modify the thermal regime of rivers, understanding these changes is of crucial importance for fish habitat management. This study aims to improve knowledge about the impact of dams on the thermal regime of rivers during the summer season and to assess the relative efficiency of two modelling tools used to predict water temperature downstream of dams. A deterministic model (Stream Network Temperature (SNTEMP)) and a statistical model based on a canonical correlation analysis were calibrated on the Fourchue River (St-Alexandre-de-Kamouraska, Québec, Canada) upstream and downstream of a reservoir. SNTEMP was used to simulate mean water temperature time series using meteorological inputs and discharge. The statistical model was used to directly estimate thermal indices (descriptive statistics of the thermal regime). The two models were compared based on their efficiency to estimate thermal indices such as mean and maximum monthly water temperatures and other parameters of importance in the understanding of the distribution and growth of ichthyofauna. Water temperature was monitored at 18 locations in the Fourchue River during the summers of 2011 and 12 locations in 2012 to describe the thermal regime and calibrate the models. The statistical model achieved better results than SNTEMP in estimating most of the thermal indices, especially the mean and maximum daily ranges with root mean square errors of 4.1 and 4.9 °C, respectively, for SNTEMP as compared to 0.5 and 1.1 °C for the leave-one-out validation and 0.6 and 1.4 °C for the split-sample mode for the statistical model. The better performance of the statistical model for metrics related to thermally stressful events for fish makes it more appealing as a management tool for water resources and fisheries managers. However, SNTEMP should be considered when the objective is to investigate the impact of climate change, reservoir operations or other anthropogenic impacts.

Understanding the Thermal Regime of Rivers Influenced by Small and Medium Size Dams in Eastern Canada

2016 ◽  
Vol 32 (10) ◽  
pp. 2032-2044 ◽  
Author(s):  
A. Maheu ◽  
A. St-Hilaire ◽  
D. Caissie ◽  
N. El-Jabi
Keyword(s):  
Thermal Regime ◽  
Medium Size ◽  
Eastern Canada

scholarly journals The Impact of a Hemispheric Circulation Regime on Fall Precipitation over North America

2010 ◽  
Vol 11 (5) ◽  
pp. 1182-1189 ◽  
Author(s):  
David Small ◽  
Shafiqul Islam ◽  
Mathew Barlow
Keyword(s):  
North America ◽  
Regional Scale ◽  
Circulation Pattern ◽  
Precipitation Variability ◽  
Eastern Canada ◽  
The North ◽  
Quarter Wavelength ◽  
Leading Mode ◽  
Precipitation Anomalies ◽  
The Impact

Abstract While there is growing evidence that the main contribution to trends in U.S. precipitation occurs during fall, most studies of seasonal precipitation have focused on winter or summer. Here, the leading mode of fall precipitation variability over North America is isolated from multiple data sources and connected to a hemispheric-scale circulation pattern. Over North America, the leading mode of fall precipitation variability in both station-based and satellite-blended data is a tripole that links fall precipitation anomalies in southern Alaska, the central United States, and eastern Canada. This mode is part of a larger pattern of alternating wet and dry anomalies stretching from the western Pacific to the North Atlantic. Dynamically, the precipitation anomalies are closely associated with changes to regional-scale moisture transport that are, in turn, linked to two independently identified hemispheric-scale wave patterns that are one-quarter wavelength out of phase (i.e., in quadrature) and resemble the circumglobal teleconnection.

Control of karst areas on space-time dynamics of floods, by combining annual and event-based analyses

2020 ◽  
Author(s):  
Martin Le Mesnil ◽  
Jean-Baptiste Charlier ◽  
Roger Moussa ◽  
Yvan Caballero ◽  
Nathalie Dörfliger
Keyword(s):  
Regional Scale ◽  
Flood Event ◽  
Medium Size ◽  
Water Budgets ◽  
Karst Areas ◽  
Rainfall Patterns ◽  
Annual Water ◽  
Flood Dynamics ◽  
The Impact ◽  
Regional Rainfall

<p>The study of flood risks requires a better understanding of the hydrological response of catchments, by identifying the drivers responsible for their variability, such as seasonal and regional rainfall patterns, initial catchment conditions and geology. Many catchments are not conservative, mainly due to Interbasin Groundwater Flows (IGF), that limits the application of traditional water balances methods on a regional scale. The role of karst areas on IGF is highly suspected to promote particular hydrological processes that change the annual water budgets as well as flood event dynamics.</p><p>The aim of our work is to assess the impact of IGF in karst and non-karst catchments of medium size (100-500 km²), on annual water budgets and flood dynamics. To this end, we developed a two-step methodology, applied on 120 elementary catchment in France, for which daily rainfall and runoff time series of several decades were available.</p><p>First, the traditional annual water budget method of L’vovich was adapted to non-conservative catchments, including an explicit term of IGF, as well as hydrograph decomposition. Results show that IGF occurrence is linked to the presence of karst areas, and that it affects both flood and baseflow components, sometimes in a very significant way. Second, a flood event analysis was conducted using a hydrograph characterization, including the analysis of lateral losses and gains on reaches delimited by 2 stations. The variability of these parameters was then studied as a function of seasonal and regional rainfall patterns, initial catchment conditions, and geology. Results show that geology (with the presence of karst areas) affect all parameters (flood shape and lateral exchanges), while rainfall pattern and initial catchment conditions mainly influence the flood dynamics.</p><p>Globally, our results show that, in addition to classical drivers (rainfall & initial catchment conditions), the spatial variability of flood pattern and dynamics is highly influenced by geology and notably karst areas. This study brings ways to improve the efficiency of hydrological models, by including IGF as a specific process. Results are also interesting in terms of extension to ungauged basins, as IGF occurrence is linked to the occurrence of karst areas.</p>

The signal of climate changes over the last two millennia in the Gulf of St. Lawrence, eastern Canada

2021 ◽  
pp. 1-16
Author(s):  
Xiner Wu ◽  
Anne de Vernal ◽  
Bianca Fréchette ◽  
Matthias Moros ◽  
Kerstin Perner
Keyword(s):  
Climate Changes ◽  
Regional Scale ◽  
Ice Age ◽  
Eastern Canada ◽  
Air Masses ◽  
The Past ◽  
Wind Regimes ◽  
Natural Climate ◽  
The Last Two Millennia ◽  
The Impact

Abstract Climate changes over the past two millennia in the central part of the Gulf of St. Lawrence are documented in this paper with the aim of determining and understanding the natural climate variability and the impact of anthropogenic forcing at a regional scale. The palynological content (dinocysts, pollen, and spores) of the composite marine sediment core MSM46-03 collected in the Laurentian Channel was used to reconstruct oceanographic and climatic changes with a multidecadal temporal resolution. Sea-surface conditions, including summer salinity and temperature, sea-ice cover, and primary productivity, were reconstructed from dinocyst assemblages. Results revealed a remarkable cooling trend of about 4°C after 1230 cal yr BP (720 CE) and a culmination with a cold pulse dated to 170–40 cal yr BP (1780–1910 CE), which likely corresponds to the regional signal of the Little Ice Age. This cold interval was followed by a rapid warming of about 3°C. In the pollen assemblages, the decrease of Pinus abundance over the past 1700 yr suggests changes in wind regimes, likely resulting from increased southerly incursions of cold and dry Arctic air masses into southeastern Canada.

Impact of changing rainfall conditions on surface and groundwater resources in an experimental watershed in Greece

2013 ◽  
Vol 12 (2) ◽  
pp. 119-125
Keyword(s):  
Groundwater Resources ◽  
Annual Runoff ◽  
Annual Rainfall ◽  
Rainfall Regime ◽  
Winter Rainfall ◽  
Rainfall Depth ◽  
Rainfall Volume ◽  
The Mean ◽  
Groundwater Reserves ◽  
The Impact

The present study concerns the impact of a change in the rainfall regime on surface and groundwater resources in an experimental watershed. The research is conducted in a gauged mountainous watershed (15.18 km2) that is located on the eastern side of Penteli Mountain, in the prefecture of Attica, Greece and the study period concerns the years from 2003 to 2008. The decrease in the annual rainfall depth during the last two hydrological years 2006-2007, 2007-2008 is 10% and 35%, respectively, in relation to the average of the previous years. In addition, the monthly distribution of rainfall is characterized by a distinct decrease in winter rainfall volume. The field measurements show that this change in rainfall conditions has a direct impact on the surface runoff of the watershed, as well as on the groundwater reserves. The mean annual runoff in the last two hydrological years has decreased by 56% and 75% in relation to the average of the previous years. Moreover, the groundwater level follows a declining trend and has dropped significantly in the last two years.

How tourism industry agglomeration improves tourism economic efficiency?

2021 ◽  
pp. 135481662110091
Author(s):  
Zhoufei Li ◽  
Huiyue Liu
Keyword(s):  
Positive Impact ◽  
Regional Analysis ◽  
Tourism Industry ◽  
Scale Efficiency ◽  
Eastern Region ◽  
Location Quotient ◽  
Industry Agglomeration ◽  
Central Regions ◽  
National Perspective ◽  
The Impact

The agglomeration of the tourism industry has important effects on its efficiency. This article used panel data on the Chinese provincial tourism industry for the 2011–2016 period, applied the location quotient index and three-stage data envelopment analysis method to, respectively, measure the degree of agglomeration and efficiency, and explained the impact of agglomeration on tourism efficiency. The empirical results of this study indicate the following. (1) China’s tourism industry shows a trend towards agglomeration, revealing gradient differences where the highest degree of agglomeration is in the eastern region, followed by the western and central regions. (2) After eliminating random and environmental factors, the adjusted efficiencies are lower than the unadjusted efficiencies. The average overall tourism efficiency is higher in the eastern region than in the central and western regions. (3) From the national perspective, industrial agglomeration can significantly improve the overall efficiency (TE), pure technical efficiency (PTE), and scale efficiency of the tourism industry. (4) Based on regional analysis, the agglomeration of the eastern tourism industry can significantly enhance its TE and PTE. Agglomeration for the western area has a significant positive impact on PTE. There is no significant relationship between agglomeration and efficiency in the central region.

Exploring the impact of introducing a physical model into statistical methods on the evaluation of regional scale debris flow susceptibility

2021 ◽  
Vol 106 (1) ◽  
pp. 881-912
Author(s):  
Jingbo Sun ◽  
Shengwu Qin ◽  
Shuangshuang Qiao ◽  
Yang Chen ◽  
Gang Su ◽  
...  
Keyword(s):  
Debris Flow ◽  
Physical Model ◽  
Statistical Methods ◽  
Regional Scale ◽  
The Impact ◽  
Debris Flow Susceptibility

Static grid carbon factors – Can we do better?

2021 ◽  
pp. 014362442199196
Author(s):  
Jamie Risner ◽  
Anna Sutherland
Keyword(s):  
Carbon Emissions ◽  
Regional Analysis ◽  
Electricity Consumption ◽  
Carbon Intensity ◽  
External Temperature ◽  
Building Regulations ◽  
Calculation Methodology ◽  
Alternative Methodology ◽  
The Uk ◽  
The Impact

The average carbon intensity (gCO2e/kWh) of electricity provided by the UK National Grid is decreasing and becoming more time variable. This paper reviews the impact on energy calculations of using various levels of data resolution (half hourly, daily, monthly and annual) and of moving to region specific data. This analysis is in two parts, one focused on the potential impact on Part L assessments and the other on reported carbon emissions for existing buildings. Analysis demonstrated that an increase in calculated emissions of up to 12% is possible when using an emissions calculation methodology employing higher resolution grid carbon intensity data. Regional analysis indicated an even larger calculation discrepancy, with some regions annual emissions increasing by a factor of ten as compared to other regions. This paper proposes a path forward for the industry to improve the accuracy of analysis by using better data sources. The proposed change in calculation methodology is analogous to moving from using an annual average external temperature to using a CIBSE weather profile for a specific city or using a future weather file. Practical application: This paper aims to quantify the inaccuracy of a calculation methodology in common use in the industry and key to building regulations (specifically Building Regulations Part L – Conservation of Fuel and Power) – translating electricity consumption into carbon emissions. It proposes an alternative methodology which improves the accuracy of the calculation based on improved data inputs.

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