Riverine thermal regimes are an important but overlooked component of environmental flows. Dams and other human activities can strongly modify the natural thermal regime of rivers by altering water temperatures, often decreasing temperatures downstream. Five key challenges to incorporating thermal regimes into environmental flow assessments are: 1) improving understanding of natural thermal variability, 2) quantifying the degree dams alter thermal regimes, 3) relating thermal changes to ecological impacts, 4) developing thermal criteria, and 5) implementing management strategies to restore thermal conditions.
Modelling climate change impacts on nutrients and primary production in coast...Marco Pesce
There is high confidence that the anthropogenic increase of atmospheric greenhouse gases (GHGs) is causing modifications in the Earth's climate. Coastal waterbodies such as estuaries, bays and lagoons are among those most affected by the ongoing changes in climate. Being located at the land-sea interface, such waterbodies are subjected to the combined changes in the physical-chemical processes of atmosphere, upstream land and coastal waters. Particularly, climate change is expected to alter phytoplankton communities by changing their environmental drivers (especially climate-related), thus exacerbating the symptoms of eutrophication events, such as hypoxia, harmful algal blooms (HAB) and loss of habitat. A better understanding of the links between climate related drivers and phytoplankton is therefore necessary for projecting climate change impacts on aquatic ecosystems. Here we present the case study of the Zero river basin in Italy, one of the main contributors of freshwater and nutrient to the salt-marsh Palude di Cona, a coastal water body belonging to the lagoon of Venice. To project the impacts of climate change on freshwater inputs, nutrient loadings and their effects on the phytoplankton community of the receiving waterbody, we formulated and applied an integrated modelling approach made of: climate simulations derived by coupling a General Circulation Model (GCM) and a Regional Climate Model (RCM) under alternative emission scenarios, the hydrological model Soil and Water Assessment Tool (SWAT) and the ecological model AQUATOX. Climate projections point out an increase of precipitations in the winter period and a decrease in the summer months, while temperature shows a significant increase over the whole year. Water discharge and nutrient loads simulated by SWAT show a tendency to increase (decrease) in the winter (summer) period. AQUATOX projects changes in the concentration of nutrients in the salt-marsh Palude di Cona, and variations in the biomass and species of the phytoplankton community.
A B S T R A C T
Urban stormwater lakes in cold regions are ice-covered for substantial parts of the winter. It has long been considered that the ice-covered period is the “dormant season,” during which ecological processes are inactive. However, little is known about this period due to the historical focus on the open-water season. Recent pioneering research on ice-covered natural lakes has suggested that some critical ecological processes play out on the ice. The objective of this study was to investigate the active processes in ice-covered stormwater lakes. Data collected during a two-year field measurement program at a stormwater lake located in Edmonton, Alberta, Canada were analyzed. The lake was covered by ice from November to mid-April of the following year. The mean value of chlorophyll-a during the ice-covered period was 22.09% of the mean value for the open-water season, suggesting that primary productivity under ice can be important. Nitrogen and phosphorus were remarkably higher during the ice-covered period, while dissolved organic carbon showed little seasonal variation. Under ice-covered conditions, the total phosphorus was the major nutrient controlling the ratio of total nitrogen to total phosphorus, and a significant positive correlation existed between total phosphorus and chlorophyll-a when the ratio was smaller than 10. The results provide preliminary evidence of the critical nutrient processes in the Stormwater Lake during the ice-covered period.
DSD-INT 2019 DANUBIUS-RI the Scientific Agenda-BradleyDeltares
Presentation by Chris Bradley (University of Birmingham, United Kingdom), at the DANUBIUS Modelling Workshop, during Delft Software Days - Edition 2019. Friday, 8 November 2019, Delft.
Today Water, Climate & Energy is related to every
aspect of human life: social equity, ecosystem & economic
sustainability. Water is used to generate energy; energy is used to
provide water. Water, energy and climate are inextricably linked,
which is of great concern and increasing importance for future.
Global primary energy demand is projected to increase by just
over 50% between now and 2030, which can be met by more
prod., consuming water & other natural resources, adopting
better technologies and also encouraging changes in energy use
pattern. Water withdrawals are predicted to increase by 50% by
2025 in developing countries and 18% in developed countries.
The worst fallouts of the climate change are shrinking of water
resources. Climate change acts as an amplifier of the already
intense competition over water & energy sources.
Solving the interlinked challenges of water, energy & climate in
a sustainable manner is one of the fundamental goals of the
present generation. To achieve this, related research and
knowledge should be expanded and discussed with in technical
circles. Technology, innovation a sense of shared responsibility
and political will are factors that bring real solutions to keep pace
with increasing needs. Resolving growing issues will require
better and integrated policy frameworks & political engagement
for all stakeholders within and across water sheds. Leadership
from all parts of society is must for change to happen.
The influence of climate change on water quality, soil moisture and fires in ...Nicolas Racedo
Three research papers on the influence of climate change on water quality, soil moisture and fires in the CEI "San Ignacio" - Fundacion Cruzada Patagonica (an agro-technical high school).
Papers were presented at the GLE 2008, organized by the Globe program (www.globe.gov) in Cape Town, South Africa.
Modelling climate change impacts on nutrients and primary production in coast...Marco Pesce
There is high confidence that the anthropogenic increase of atmospheric greenhouse gases (GHGs) is causing modifications in the Earth's climate. Coastal waterbodies such as estuaries, bays and lagoons are among those most affected by the ongoing changes in climate. Being located at the land-sea interface, such waterbodies are subjected to the combined changes in the physical-chemical processes of atmosphere, upstream land and coastal waters. Particularly, climate change is expected to alter phytoplankton communities by changing their environmental drivers (especially climate-related), thus exacerbating the symptoms of eutrophication events, such as hypoxia, harmful algal blooms (HAB) and loss of habitat. A better understanding of the links between climate related drivers and phytoplankton is therefore necessary for projecting climate change impacts on aquatic ecosystems. Here we present the case study of the Zero river basin in Italy, one of the main contributors of freshwater and nutrient to the salt-marsh Palude di Cona, a coastal water body belonging to the lagoon of Venice. To project the impacts of climate change on freshwater inputs, nutrient loadings and their effects on the phytoplankton community of the receiving waterbody, we formulated and applied an integrated modelling approach made of: climate simulations derived by coupling a General Circulation Model (GCM) and a Regional Climate Model (RCM) under alternative emission scenarios, the hydrological model Soil and Water Assessment Tool (SWAT) and the ecological model AQUATOX. Climate projections point out an increase of precipitations in the winter period and a decrease in the summer months, while temperature shows a significant increase over the whole year. Water discharge and nutrient loads simulated by SWAT show a tendency to increase (decrease) in the winter (summer) period. AQUATOX projects changes in the concentration of nutrients in the salt-marsh Palude di Cona, and variations in the biomass and species of the phytoplankton community.
A B S T R A C T
Urban stormwater lakes in cold regions are ice-covered for substantial parts of the winter. It has long been considered that the ice-covered period is the “dormant season,” during which ecological processes are inactive. However, little is known about this period due to the historical focus on the open-water season. Recent pioneering research on ice-covered natural lakes has suggested that some critical ecological processes play out on the ice. The objective of this study was to investigate the active processes in ice-covered stormwater lakes. Data collected during a two-year field measurement program at a stormwater lake located in Edmonton, Alberta, Canada were analyzed. The lake was covered by ice from November to mid-April of the following year. The mean value of chlorophyll-a during the ice-covered period was 22.09% of the mean value for the open-water season, suggesting that primary productivity under ice can be important. Nitrogen and phosphorus were remarkably higher during the ice-covered period, while dissolved organic carbon showed little seasonal variation. Under ice-covered conditions, the total phosphorus was the major nutrient controlling the ratio of total nitrogen to total phosphorus, and a significant positive correlation existed between total phosphorus and chlorophyll-a when the ratio was smaller than 10. The results provide preliminary evidence of the critical nutrient processes in the Stormwater Lake during the ice-covered period.
DSD-INT 2019 DANUBIUS-RI the Scientific Agenda-BradleyDeltares
Presentation by Chris Bradley (University of Birmingham, United Kingdom), at the DANUBIUS Modelling Workshop, during Delft Software Days - Edition 2019. Friday, 8 November 2019, Delft.
Today Water, Climate & Energy is related to every
aspect of human life: social equity, ecosystem & economic
sustainability. Water is used to generate energy; energy is used to
provide water. Water, energy and climate are inextricably linked,
which is of great concern and increasing importance for future.
Global primary energy demand is projected to increase by just
over 50% between now and 2030, which can be met by more
prod., consuming water & other natural resources, adopting
better technologies and also encouraging changes in energy use
pattern. Water withdrawals are predicted to increase by 50% by
2025 in developing countries and 18% in developed countries.
The worst fallouts of the climate change are shrinking of water
resources. Climate change acts as an amplifier of the already
intense competition over water & energy sources.
Solving the interlinked challenges of water, energy & climate in
a sustainable manner is one of the fundamental goals of the
present generation. To achieve this, related research and
knowledge should be expanded and discussed with in technical
circles. Technology, innovation a sense of shared responsibility
and political will are factors that bring real solutions to keep pace
with increasing needs. Resolving growing issues will require
better and integrated policy frameworks & political engagement
for all stakeholders within and across water sheds. Leadership
from all parts of society is must for change to happen.
The influence of climate change on water quality, soil moisture and fires in ...Nicolas Racedo
Three research papers on the influence of climate change on water quality, soil moisture and fires in the CEI "San Ignacio" - Fundacion Cruzada Patagonica (an agro-technical high school).
Papers were presented at the GLE 2008, organized by the Globe program (www.globe.gov) in Cape Town, South Africa.
GIS based spatial distribution of Temperature and Chlorophyll-a along Kalpakk...IJERA Editor
This paper briefly describes the status of Temperature and Chlorophyll-a trend in Kalpakkam Coast, discusses its ecological and temperature impacts recommending measures to achieve long term sustainability using advanced tools like Geographic Information System (GIS). Present study reveals the monthly spatial distribution of Temperature and Chlorophyll-a at Kalpakkam. Transect based in-situ Temperature and Chlorophyll-a collected at 200m, 500m and 1 km distance into the sea was interpolated using the Inverse Distance Weightage (IDW) method in ARC GIS. Data revealed the extent of spatial distribution of thermal effluent in Kalpakkam. It could be found that temperature range of 26.2 – 31.9°C provided substantial Chlorophyll-a concentration between 0.8 – 2.9 mg/m3 for surface and bottom waters. Further, increase of Chlorophyll-a levels did not lead to higher productivity. Combined temperature and chlorophyll a showed little synergistic effects. It is concluded that the effect of thermal discharge from the power plant into the receiving water body is quite localized and productivity of the coastal waters are not affected. From the results obtained, the spatial data has been found to be useful in determining zones of safe use of seawater and to understand the extent of relationship between the relatable parameters.
impactos del cambio climatico en ecosistemas costerosXin San
Anthropogenically induced global climate change has profound implications for marine
ecosystems and the economic and social systems that depend upon them. The
relationship between temperature and individual performance is reasonably well
understood, and much climate-related research has focused on potential shifts in
distribution and abundance driven directly by temperature. However, recent work has
revealed that both abiotic changes and biological responses in the ocean will be
substantially more complex. For example, changes in ocean chemistry may be more
important than changes in temperature for the performance and survival of many
organisms. Ocean circulation, which drives larval transport, will also change, with
important consequences for population dynamics. Furthermore, climatic impacts on one
or a few leverage species may result in sweeping community-level changes. Finally,
synergistic effects between climate and other anthropogenic variables, particularly fishing
pressure, will likely exacerbate climate-induced changes. Efforts to manage and conserve
living marine systems in the face of climate change will require improvements to the
existing predictive framework. Key directions for future research include identifying key
demographic transitions that influence population dynamics, predicting changes in the
community-level impacts of ecologically dominant species, incorporating populations
ability to evolve (adapt), and understanding the scales over which climate will change and
living systems will respond.
Dean Paron (of Minnesota Department of Natural Resources), presented at the Adapting Forested Watersheds to Climate Change Workshop, at The Waters, Minocqua, WI on March 15-16, 2017. The workshop was hosted by the Northern Institute of Applied Climate Science (NIACS), USDA Climate Hubs, and the Wisconsin Initiative on Climate Change Impacts (WICCI).
TMDL For Temperature in Ken’s Lake, Utah Prepa.docxherthalearmont
TMDL
For Temperature in
Ken’s Lake, Utah
Prepared by
Utah Department of Environmental Quality/Division of Water Quality
Michael D. Allred
Project Manager
Harry Lewis Judd
Project Supervisor
2
Utah Department of Environmental Quality
Division of Water Quality
TMDL Section
Waterbody ID
Ken’s Lake
Location
San Juan County, Utah
HUC # 14030005
Pollutants of Concern
Temperature
Impaired Beneficial Uses
Class 3A: Protected for cold water species of
game fish and other cold water aquatic life,
including the necessary aquatic organisms in
their food chain.
Loading Assessment
Temperature impairment is a result of natural
causes. The energy input is a direct result of
heating by the sun.
Defined Targets/Endpoints
Petition for delisting based on analysis.
Implementation Strategy
Incorporate site-specific standard for
temperature as per target/endpoint description.
This document is identified as a TMDL for Ken’s Lake and is officially submitted
to the U.S. EPA to act upon and approve as a TMDL.
3
I. Introduction
Ken’s Lake is an off-stream reservoir at the foot of the west slopes of the La Sal Mountains in
southeastern Utah. The impoundment is approximately 10 miles south of Moab (see Figure 1) and is
part of the Mill Creek Watershed. The valley is a long graben, where the underlying rocks have
dropped below the surrounding terrain. It is an arid redrock desert. Water is brought into the lake via
the Sheley Diversion Tunnel from Mill Creek. The Grand County Water Conservancy District initiated
development of Ken’s Lake in 1979. The lake was developed to serve the agricultural irrigation needs
of residents of Moab’s Spanish Valley. The reservoir includes a dam that is 95 feet high and 4,050 feet
long. Nearly 900,000 cubic yards of earth were needed to complete the dam, which is designed to ho ld
2,610 acre-feet of water. The reservoir has a surface area of 35 hectares/86 acres, is 2,690 feet long,
1,400 feet wide and has a maximum depth of 70 feet.
The sole perennial inflow to Ken’s Lake is the canal from the Sheley Diversion. Outflow is to a
pressurized irrigation system, which provides water to irrigated acreage in Spanish Valley. Vegetation
in the surrounding area is sparse and predominantly shrub and grassland.
Figure 1 - Mill Creek Watershed
The reservoir contains populations of largemouth bass, green sunfish, channel catfish, brown trout, and
rainbow trout. These species provide a valuable recreation resource for residents and visitors of the
Moab area. Approximately 11,000 catchable-size rainbow trout are stocked annually by UDWR. The
Utah Division of Wildlife Resources feels that this water is appropriately designated as a coldwater
trout fishery, but is managed as such on a seasonal rather than year-round basis. UDWR recognizes
4
that summer water temperatures are too high for stocked fish to survive y ...
Effect of Temperature on Stream Fish Energetics and Tolerance to Increasing U...Marylou Moore
ABSTRACT
Urban development threatens stream systems throughout the world and has been shown to correspond with predictable changes in fish assemblage attributes. These shifts in fish communities suggests that there may be species specific differences in tolerance to altered environmental conditions related to urbanization. Over the last three decades, a great amount of literature has focused on the development of community-level metrics for assessing biotic integrity of fishes within flowing waters. While these efforts have spawned a great deal of information on community and guild-level responses by stream fishes, it is unknown how individual species’ evolutionary adaptation and physiological acclimation correspond to their ability to tolerate drastic environmental change. This study investigated temperature-dependent responses of metabolism and thermal sensitivity in redbreast sunfish (Lepomis auritus) collected from sites representative of the lowest and highest degree of urban land use throughout the Etowah Watershed, Georgia. Standard metabolic rate (SMR) was shown to be significantly lower in fish drawn from the urban stream at both experimental temperatures (20 °C and 25 °C). Additionally, the urban population had a significantly higher metabolic scope at 25 °C than the non-urban population. These findings support the hypothesis that intraspecific differences in thermal tolerance may exist at localized scales within a small watershed. This study also provides the first known reports of the metabolic rate and aerobic scope of L. auritus.
Behavioral responses to annual temperature variationalter th.docxtaitcandie
Behavioral responses to annual temperature variation
alter the dominant energy pathway, growth, and
condition of a cold-water predator
Matthew M. Guzzoa,1, Paul J. Blanchfielda,b, and Michael D. Renniea,c,d
aDepartment of Biological Sciences, University of Manitoba, Winnipeg, MB R3T 2N2, Canada; bFreshwater Institute, Fisheries and Oceans Canada, Winnipeg,
MB R3T 2N6, Canada; cDepartment of Biology, Lakehead University, Thunder Bay, ON P7B 5E1, Canada; and dIISD Experimental Lakes Area Inc., Winnipeg,
MB R3B 0T4, Canada
Edited by Mary E. Power, University of California, Berkeley, CA, and approved July 11, 2017 (received for review February 17, 2017)
There is a pressing need to understand how ecosystems will
respond to climate change. To date, no long-term empirical studies
have confirmed that fish populations exhibit adaptive foraging
behavior in response to temperature variation and the potential
implications this has on fitness. Here, we use an unparalleled 11-y
acoustic telemetry, stable isotope, and mark–recapture dataset to
test if a population of lake trout (Salvelinus namaycush), a cold-
water stenotherm, adjusted its use of habitat and energy sources
in response to annual variations in lake temperatures during the
open-water season and how these changes translated to the
growth and condition of individual fish. We found that climate
influenced access to littoral regions in spring (data from teleme-
try), which in turn influenced energy acquisition (data from iso-
topes), and growth (mark–recapture data). In more stressful years,
those with shorter springs and longer summers, lake trout had
reduced access to littoral habitat and assimilated less littoral en-
ergy, resulting in reduced growth and condition. Annual variation
in prey abundance influenced lake trout foraging tactics (i.e., the
balance of the number and duration of forays) but not the overall
time spent in littoral regions. Lake trout greatly reduced their
use of littoral habitat and occupied deep pelagic waters during
the summer. Together, our results provide clear evidence that
climate-mediated behavior can influence the dominant energy
pathways of top predators, with implications ranging from indi-
vidual fitness to food web stability.
food web | climate change | habitat coupling | lake trout |
north-temperate lake
There is growing urgency to understand how ecosystems areresponding to climate change (1, 2). Recent work, using
latitudinal gradients as proxies to warming, has argued that the
behavioral responses of mobile top predators to changing tem-
peratures can drive fundamental shifts in aquatic food webs by
altering the coupling of major energy pathways (3, 4). Although
this work is intriguing, no one has yet examined long-term em-
pirical data that have explicitly tested if populations of top
predators can shift their foraging behavior in response to annual
changes in temperature or has evaluated what implications this
might have for individual fitness. Tempor.
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
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Objective:
Prepare a presentation or a paper using research, basic comparative analysis, data organization and application of economic information. You will make an informed assessment of an economic climate outside of the United States to accomplish an entertainment industry objective.
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
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An EFL lesson about the current events in Palestine. It is intended to be for intermediate students who wish to increase their listening skills through a short lesson in power point.
Instructions for Submissions thorugh G- Classroom.pptxJheel Barad
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How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdf
Riverine thermal regimes
1. Riverine Thermal Regimes
An Integral Component of Environmental Flows
Julian D. Olden
School of Aquatic and Fishery Sciences
University of Washington
2. Ecologically Sustainable
Water Management
Meeting the fresh water
demands of a growing human
population while ensuring
ecosystem integrity has
emerged as one of the world’s
primary resource issues.
Shifting focus from humans as
exploiters of the environment
to a world where riverine
systems are legitimate “users”
of fresh water.
3. The Science of Environmental Flows
Scientists are becoming increasingly engaged in the development
of environmental flow recommendations.
An environmental flow is can be defined as the
quantity, quality and timing of water flows
required to maintain the components,
functions, processes and resilience of aquatic
systems which provide goods and services that
are valued by society.
Efforts in environmental flow research have thus
far have focused primarily on water quantity,
whereas issues involving water quality, such as
water temperature, have received little
consideration.
4. Why has temperature been overlooked
in environmental flow science?
Society is largely unaware of the ecological importance of a
river’s thermal regime for freshwater biodiversity and
ecosystem function.
Scientists have their hands full with understanding how
freshwater ecosystems respond to hydrologic modification
and how best to use this information to inform the
science of environmental flows.
The impacts of river regulation on
downstream thermal regimes are
considered to be small compared to the
potential for flow alteration.
5. Objectives
The scientific community must broaden its perspective on
ecologically sustainable water management to include
aspects of the thermal regime in the science of
environmental flows.
1. Review the concept of the natural thermal regime.
2. Illustrate how river regulation has modified thermal
regimes and discuss the ecological impacts.
3. Challenge us to expand our perspective on environmental
flows to include the management of thermal regimes for
riverine ecosystem integrity.
6. Water Temperature
Stream temperature
is dependent on:
Energy budget
- the amount of heat
energy added or loss
to the channel.
Thermal capacity
- the volume of water
to be heated or
cooled.
7. The Natural Thermal Regime
Stream temperatures show marked annual and diurnal fluctuations
in response to seasonal and daily rhythms in the flux of heat
energy gained and lost by a stream and the volume and source of
runoff contributing to discharge.
Bullpasture River, Virginia, USA
8. The natural thermal regime can be discomposed into its
components of magnitude, frequency, duration, timing, and rate
of change, and be summarized using statistics that describe the
central tendency and variability in distributions of water
temperatures.
Mean annual T and CV
Predictability/Constancy
Magnitude
Mean monthly T and CV
Frequency
1-/3-/7-/30-day maxima T
1-/3-/7-/30-day minima T
Descriptors of the Thermal Regime Duration
High pulse count and duration
Low pulse count and duration
Timing
Maximum and minimum T
Rate of Change
Rise and fall rates
# reversals
9. Ecological Importance of Temperature
Water temperature directly influences the metabolic rates,
physiology, and life-history traits of aquatic species and
helps determine rates of important ecological processes.
Freshwater fishes and aquatic macroinvertebrates utilize a
diverse array of thermal habitats to meet their specific
temperature requirements for survival, growth and
reproduction.
Components of the thermal regime have different ecological
significance.
10. Thermal Modification in
Lotic Ecosystems
Human activities may strongly alter spatial and temporal
patterns in water temperatures by modifying the energy
budget and thermal capacity of the river.
Sources of “warmwater pollution”
Forestry, agriculture, and urbanization
• Industrial effluents
• Irrigation diversions
11. Coldwater Pollution below Dams
River regulation by dams can greatly modify water
temperatures depending on their mode of operation and
specific mechanism of water release.
Large dams directly modify thermal
regimes by releasing water that
greatly differs in temperature
from natural conditions (Storage
Effect).
By changing the volume of water,
dams also influence temperature
by affecting energy fluxes
(Regulation Effect).
Arthur Rylah Institute
12. Keepit Dam - Namoi River, Australia
Annual maximum daily temperature was 5.0°C lower and
occurred 3 weeks later compared to pre-dam conditions.
Magnitude of thermal alteration decreased with distance
downstream from dam.
Preece and Jones (2002)
13. Blowering Dam – Tumut River, Australia
Reductions in natural summer temperatures of 13.0°C to
16.0°C.
Contributes to coldwater pollution for 80 river km below
the dam and >200 km in the Murrumbidgee River.
Lugg (1999), Preece (2004)
14. Vilui Dam - Lena River, Siberia
Post-dam temperatures were 2-5°C higher in early-
summer and 2-3°C lower in mid-summer.
Lui et al. (2005)
15. Flaming Gorge Dam – Green River, USA
Summer temperatures (June-Aug) were, on average,
12.0°C lower compared to pre-dam conditions.
Annual maximum daily temperature was 14.0°C lower and
its timing shifted from end-July to mid-December.
Vinson (2001)
16. Gathright Dam – Jackson River, USA
Summer temperatures (June-Aug) were, on average,
6.0°C lower compared to pre-dam conditions.
Annual maximum daily temperature was 8.0°C lower.
Olden et al. (in review)
17. Ecological Implications of
Coldwater Pollution
Cold water releases can have lethal and sub-lethal effects.
Water temperatures below tolerance limits result in species
extirpation, and sub-lethal impacts include a slowing of
physiological processes such as reproduction and growth.
Lower spring/summer water temperatures compromise the structure
and life-history of stream macroinvertebrate assemblages, and
decrease the survival of egg, larval and adult fishes.
Delayed timing of peak spring temperatures disrupt critical cues for
initiating fish spawning and insect reproduction and emergence.
18. Thermal regimes do not satisfy the
spawning requirements of native fishes
Pre-dam
Post-dam
Gathright Dam, Jackson River, USA
19. Five major challenges to developing
comprehensive environmental flow
assessments that incorporate the
critical temperature requirements of
riverine ecosystems.
20. CHALLENGE 1
Improve our understanding of spatiotemporal
variability in riverine thermal regimes
Previous attempts to explore similarities in thermal
regimes among rivers and develop formal classification
systems have been limited.
Quantifying thermal variability in undeveloped rivers is
essential for establishing regional benchmarks needed to
successful incorporating water temperature into
environmental flow management.
The paucity of continuous water temperature data
represents a significant information gap, requiring a
greater dependence on statistical modeling.
21. CHALLENGE 2
Quantify the degree to which dams alter
riverine thermal regimes
In general, the scientific community has inadequately
quantified the magnitude and geographic extent of dam-
induced thermal alteration.
Formal investigations of how dams are altering the various
facets of the thermal regime are needed, including
ecologically-relevant components of magnitude, frequency,
duration, timing and rate of change in temperature events.
This research is critical for mounting a convincing
argument that temperature should play a significant role in
the science and management of environmental flows.
22. Flaming Gorge Dam – Green River, USA
Green River is the largest tributary
of the Colorado River.
Flaming Gorge dam was constructed
in 1962 for hydroelectric power and
flood control.
23. Degree of Thermal Alteration
Daily water temperature records
• Pre-dam: 1958-1962
• Post-dam: 1963-1977
Mean annual temperature
decreased 2.5°C from
8.8°C to 6.3°C.
Annual variability in water
temperatures (CV) decreased
from 89% to 34%.
Thermal regimes were >2 times
more predictable in post-dam
years.
26. Why has temperature been overlooked
in environmental flow science?
Society is largely unaware of the ecological importance of a
river’s thermal regime for freshwater biodiversity and
ecosystem function.
Scientists have their hands full with understanding how
freshwater ecosystems respond to hydrologic modification
and how best to use this information to inform the
science of environmental flows.
The effects of river regulation on downstream
thermal regimes are considered to be
smaller compared to the potential for
flow alteration.
27. Thermal vs. Hydrologic Alteration
↑Thermal Alteration
1-/3-/7-/30-day minimum
Dec (Winter)
Jan (Winter)
Feb (Winter)
90-day minimum
Nov (Winter)
Mar (Winter)
↑Hydrologic
Alteration
Date of maximum July - Oct (Summer)
Date of minimum
Rise and fall rates
Lower pulse count
Olden and Naiman (in prep)
28. CHALLENGE 2 …
• Data limitation is a significant problem.
• “Desk-top” assessments have been used
to identify and rank large dams based
on potential to cause coldwater
pollution according to intake depth,
discharge, storage, etc …
Queensland: 18 dams (Brennan, in prep)
NSW: 9 dams (Preece 2004)
Victoria: 24 dams (Ryan et al. 2001)
DIPNR (2004)
29. CHALLENGE 3
Quantify the ecological consequences of
altered thermal regimes
• Systematic assessments of
the relationship between
biological condition and
the degree of thermal
alteration are needed.
Place the ecological
impacts of thermal
pollution in the context of
broader ecological
disturbances associated
with dams.
30. CHALLENGE 4
Demonstrate the availability and success of
thermal pollution remediation strategies
Various mitigation measures are available:
• Multi-level outlet structures
• Artificial destratification (large propellers that pump cold
bottom water toward the surface)
• Trunnions (piping system that draw water from different
levels in the water column)
• Surface pumps (large propellers that pump warm surface
water into existing outlets)
• Draft tube mixers
• Submerged curtains (large curtains extending upwards from
the bottom of the reservoir forcing all the release water to
originate from the surface)
• Stilling basins
31. Thermal Restoration below
Flaming Gorge Dam – Green River, USA
Daily water temperature records
Pre-dam: 1958-1962
Post-restoration: 1978-2006
Mean annual temperature
decreased 0.3°C from
8.8°C to 8.5°C.
Annual variability in water
temperatures (CV) decreased
from 89% to 42%.
Thermal regimes were >2 times
more predictable in post-dam
years.
33. CHALLENGE 5
Develop a multi-faceted perspective on
environmental flows
Understand the relationships between flow alteration,
thermal alteration, (other dam-induced drivers of
environmental change), and the integrity of riverine
ecosystems.
Develop conceptual models and assess different
environmental flow strategies that include prescriptions for
both flow and temperature regimes.
34. B
A
A. Thermal restoration below Flaming Gorge Dam (Vinson 2001)
B. Flow restoration below Clanwilliam Dam (King et al. 1998)
35.
36. Take Home Message
• Dams can substantially modify riverine thermal regimes,
which can result in significant ecological impacts.
• The degree of thermal alteration below dams may greatly
exceed the level of flow alteration.
• The benefits of environment flows may not be fully
realized unless critical aspects of the thermal regime are
also considered.
• Incorporating aspects of water quality into environmental
flow science and management represents a necessary step
forward in ecologically sustainable water management.