Dissertations / Theses on the topic 'Stream temperature'
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1
Richards, John. "Alpine proglacial stream temperature dynamics." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/5039.
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This study was motivated by an interest in understanding the effects of glacier retreat on late
summer stream temperatures in an above-treeline proglacial stream and lake system in the
southern Coast Mountains of British Columbia, Canada. Fieldwork was carried out during
August and September of 2007 and focused on thermal processes controlling water temperature
in the proglacial lake and a 1 km alpine reach directly downstream of the lake outlet. The
proglacial lake was small (0.07 km²), featured a single inflow and outflow channel and had a
residence time of approximately 4 days. The alpine reach featured continual cascading flow
(25% channel gradient), marked diurnal fluctuations in discharge and variable terrain shading.
It was found that warming between the inflow and outflow of the lake (1.8°C, on average)
was controlled by the total heat content of the lake and cycles of mixing and stratification.
A heat budget analysis indicated that the heat content of the lake was dominantly controlled
by absorbed shortwave radiation and the advective effect of the inflow and outflow streams.
Application of a dynamic reservoir model (DYRESM) to model observed lake temperatures
(inflow, outflow and a temperature-depth profile), and comparison to other studies, suggested
that suspended sediment concentration in the inflow had a dominant control on lake mixing
and stratification.
Based on equations developed from low-gradient channels, a stream energy budget model
failed to replicate observed downstream warming rates. A spatially distributed net radiation
model, along with statistical modification of the energy budget, provided insight into the processes that control stream temperatures in alpine areas. The final hybrid model showed a good match with observed downstream warming. This model accounted for the variation of width
and albedo with discharge, and the spatial variability in net radiation due to topographic shading and the slope and aspect of the channel. The model also included parameters that increased
the sensible and latent heat fluxes relative to values calculated from standard equations, which
is consistent with the hypothesis that these fluxes are enhanced by cascading flow.
2
Buck, Christina Rene. "Managing Groundwater for Environmental Stream Temperature." Thesis, University of California, Davis, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3565483.
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This research explores the benefits of conjunctively managed surface and groundwater resources in a volcanic aquifer system to reduce stream temperatures while valuing agricultural deliveries. The example problem involves advancing the understanding of flows, stream temperature, and groundwater dynamics in the Shasta Valley of Northern California. Three levels of interaction are explored from field data, to regional simulation, to regional management optimization. Stream temperature processes are explored using Distributed Temperature Sensing (DTS) data from the Shasta River and recalibrating an existing physically-based flow and temperature model of the Shasta River. DTS technology can collect abundant high resolution river temperature data over space and time to improve development and performance of modeled river temperatures. These data also identify and quantify thermal variability of micro-habitat that temperature modeling and standard temperature sampling do not capture. This helps bracket uncertainty of daily temperature variation in reaches, pools, side channels, and from cool or warm surface or subsurface inflows. The application highlights the influence of air temperature on stream temperatures, and indicates that physically-based numerical temperature models, using a heat balance approach as opposed to statistical models, may under-represent this important stream temperature driver. The utility of DTS to improve model performance and detailed evaluation of hydrologic processes is demonstrated.
Second, development and calibration of a numerical groundwater model of the Pluto's Cave basalt aquifer and Parks Creek valley area in the eastern portion of Shasta Valley helps quantify and organize the current conceptual model of this Cascade fracture flow dominated aquifer. Model development provides insight on system dynamics, helps identify important and influential components of the system, and highlights additional data needs. The objective of this model development is to reasonably represent regional groundwater flow and to explore the connection between Mount Shasta recharge, pumping, and Big Springs flow. The model organizes and incorporates available data from a wide variety of sources and presents approaches to quantify the major flow paths and fluxes. Major water balance components are estimated for 2008-2011. Sensitivity analysis assesses the degree to which uncertainty in boundary flow affects model results, particularly spring flow.
Finally, this work uses optimization to explore coordinated hourly surface and groundwater operations to benefit Shasta River stream temperatures upstream of its confluence with Parks Creek. The management strategy coordinates reservoir releases and diversions to irrigated pasture adjacent to the river and it supplements river flows with pumped cool groundwater from a nearby well. A basic problem formulation is presented with results, sensitivity analysis, and insights. The problem is also formulated for the Shasta River application. Optimized results for a week in July suggest daily maximum and minimum stream temperatures can be reduced with strategic operation of the water supply portfolio. These temperature benefits nevertheless have significant costs from reduced irrigation diversions. Increased irrigation efficiency would reduce warm tail water discharges to the river instead of reducing diversions. With increased efficiency, diversions increase and shortage costs decrease. Tradeoffs and sensitivity of model inputs are explored and results discussed.
3
Holthuijzen, Maike F. "A Comparison of Five Statistical Methods for Predicting Stream Temperature Across Stream Networks." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6535.
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The health of freshwater aquatic systems, particularly stream networks, is mainly influenced by water temperature, which controls biological processes and influences species distributions and aquatic biodiversity. Thermal regimes of rivers are likely to change in the future, due to climate change and other anthropogenic impacts, and our ability to predict stream temperatures will be critical in understanding distribution shifts of aquatic biota. Spatial statistical network models take into account spatial relationships but have drawbacks, including high computation times and data pre-processing requirements. Machine learning techniques and generalized additive models (GAM) are promising alternatives to the SSN model. Two machine learning methods, gradient boosting machines (GBM) and Random Forests (RF), are computationally efficient and can automatically model complex data structures. However, a study comparing the predictive accuracy among a variety of widely-used statistical modeling techniques has not yet been conducted.
My objectives for this study were to 1) compare the accuracy among linear models (LM), SSN, GAM, RF, and GBM in predicting stream temperature over two stream networks and 2) provide guidelines in choosing a prediction method for practitioners and ecologists. Stream temperature prediction accuracies were compared with the test-set root mean square error (RMSE) for all methods. For the actual data, SSN had the highest predictive accuracy overall, which was followed closely by GBM and GAM. LM had the poorest performance overall. This study shows that although SSN appears to be the most accurate method for stream temperature prediction, machine learning methods and GAM may be suitable alternatives.
4
Garner, Grace. "River and stream temperature in a changing climate." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5418/.
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There is major concern that river temperature changes driven by a changing climate and associated hydrological changes will have profound impacts on freshwater ecosystems. To identify the rivers most sensitive to change and implement effective strategies to mitigate high thermal extremes, this thesis aims to improve understanding of the influences of hydrometeorology and riparian landuse on river temperature dynamics, controls and processes within a UK context. Four studies are presented within a multi-scale research design which aimed to improve understanding of: (1) spatial patterns and inter-annual variability in the shape and magnitude of annual river temperature regimes across England and Wales, and regime sensitivity to air temperature and river basin properties, (2) the effects of riparian vegetation on water temperature under a range of hydrometeorological conditions, (2) the processes by which cool water refugia are produced beneath semi-natural, deciduous forest canopies, and (4) how minimal riparian planting can be used to produce thermal refugia in reaches of differing aspect and hydraulic characteristics. The aims are achieved by combining observational, statistical and deterministic modelling techniques. The outcomes of the research contribute significant new knowledge and tools for evidence based management of river and stream temperature under present and future climates.
5
Leach, Jason A. "Stream temperature dynamics following riparian wildfire : effects of stream-subsurface interactions and standing dead trees." Thesis, University of British Columbia, 2008. http://hdl.handle.net/2429/1411.
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The primary objectives of this study were to address how stream temperature is influenced by (1) spatial variability in energy exchanges, (2) reach-scale stream-subsurface water interactions and (3) the net radiation dynamics associated with standing dead riparian vegetation. Stream temperature, riparian microclimate, and hydrology were characterized for a 1.5 km reach of Fishtrap Creek, located north of Kamloops, British Columbia. Within-reach air temperature and humidity variability was small, while wind speed, net radiation and surface-subsurface interactions exhibited considerable spatially variability. The field data were used to drive a deterministic energy budget model to predict stream temperature. The model was evaluated against measured stream temperature and performed well. The model indicated that the spatially complex hydrology was a significant control on the observed stream temperature patterns. A modelling exercise using three canopy cover scenarios revealed that post-disturbance standing dead trees reduce daytime net radiation reaching the stream surface by one third compared to complete vegetation removal. However, standing dead trees doubled daytime net radiation reaching the stream compared to pre-wildfire conditions. The results of this study have highlighted the need to account for the spatial variability of energy exchange processes, specifically net radiation and surface-subsurface water interactions, when understanding and predicting stream thermal regimes.
6
Hill, Ryan A. "Modeling USA stream temperatures for stream biodiversity and climate change assessments." Thesis, Utah State University, 2013. http://pqdtopen.proquest.com/#viewpdf?dispub=3587567.
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Stream temperature (ST) is a primary determinant of individual stream species distributions and community composition. Moreover, thermal modifications associated with urbanization, agriculture, reservoirs, and climate change can significantly alter stream ecosystem structure and function. Despite its importance, we lack ST measurements for the vast majority of USA streams. To effectively manage these important systems, we need to understand how STs vary geographically, what the natural (reference) thermal condition of altered streams was, and how STs will respond to climate change. Empirical ST models, if calibrated with physically meaningful predictors, could provide this information. My dissertation objectives were to: (1) develop empirical models that predict reference- and nonreference-condition STs for the conterminous USA, (2) assess how well modeled STs represent measured STs for predicting stream biotic communities, and (3) predict potential climate-related alterations to STs. For objective 1, I used random forest modeling with environmental data from several thousand US Geological Survey sites to model geographic variation in nonreference mean summer, mean winter, and mean annual STs. I used these models to identify thresholds of watershed alteration below which there were negligible effects on ST. With these reference-condition sites, I then built ST models to predict summer, winter, and annual STs that should occur in the absence of human-related alteration (r2 = 0.87, 0.89, 0.95, respectively). To meet objective 2, I compared how well modeled and measured ST predicted stream benthic invertebrate composition across 92 streams. I also compared predicted and measured STs for estimating taxon-specific thermal optima. Modeled and measured STs performed equally well in both predicting invertebrate composition and estimating taxon-specific thermal optima (r2 between observation and model-derived optima = 0.97). For objective 3, I first showed that predicted and measured ST responded similarly to historical variation in air temperatures. I then used downscaled climate projections to predict that summer, winter, and annual STs will warm by 1.6 °C - 1.7 °C on average by 2099. Finally, I used additional modeling to identify initial stream and watershed conditions (i.e., low heat loss rates and small base-flow index) most strongly associated with ST vulnerability to climate change.
7
Su, Yibing. "Real-time prediction of stream water temperature for Iowa." Thesis, University of Iowa, 2017. https://ir.uiowa.edu/etd/5653.
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In the agricultural state of Iowa, water quality research is of great importance for monitoring and managing the health of aquatic systems. Among many water quality parameters, water temperature is a critical variable that governs the rates of chemical and biological processes which affect river health. The main objective of this thesis is to develop a real-time high resolution predictive stream temperature model for the entire state of Iowa. A statistical model based solely on the water-air temperature relationship was developed using logistic regression approach. With hourly High Resolution Rapid Refresh (HRRR) air temperature estimations, the implemented stream temperature model produces current state-wide estimations. The results are updated hourly in real-time and presented on a web-based visualization platform: the Iowa Water Quality Information System, Beta version (IWQIS Beta). Streams of 4th order and up are color-coded according to the estimated temperatures. Hourly forecasts for lead time of up to 18 hours are also available.
A model was developed separately for spring (March to May), summer (June to August), and autumn (September to November) seasons. 2016 model estimation results generate less than 3 °C average RMSE for the three seasons, with a summer season RMSE of below 2 °C. The model is transferrable to basins of different catchment sizes within the state of Iowa and requires hourly air temperature as the only input variable. The product will assist Iowa water quality research and provide information to support public management decisions.
8
Lund, David Charles. "Gulf Stream temperature, salinity and transport during the last millennium /." Cambridge, Mass. : Woods Hole, Mass. : Massachusetts Institute of Technology ; Woods Hole Oceanographic Institution, 2006. http://hdl.handle.net/1912/1774.
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Originally issued as the author's thesis (Ph. D.)--Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 2006."February 2006". "Doctoral dissertation." "Department of origin: Geology and Geophysics." "Joint Program in Oceanography/Applied Ocean Science and Engineering"--Cover. Includes bibliographical references.
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Lund, David Charles. "Gulf stream temperature, salinity and transport during the last millennium." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/34567.
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Thesis (Ph. D.)--Joint Program in Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), February 2006.Includes bibliographical references.
Benthic and planktonic foraminiferal [delta]18O ([delta 18Oc) from a suite of well-dated, high-resolution cores spanning the depth and width of the Straits of Florida reveal significant changes in Gulf Stream cross-current density gradient during the last millennium. These data imply that Gulf Stream transport during the Little Ice Age (LIA: 1200-1850 A.D.) was 2-3 Sv lower than today. The timing of reduced flow is consistent with cold conditions in Northern Hemisphere paleoclimate archives, implicating Gulf Stream heat transport in centennial-scale climate variability of the last 1,000 years. The pattern of flow anomalies with depth suggests reduced LIA transport was due to weaker subtropical gyre wind stress curl. The oxygen isotopic composition of Florida Current surface water ([delta]18Ow) near Dry Tortugas increased 0.4%0/ during the course of the Little Ice Age (LIA: -1200-1850 A.D.), equivalent to a salinity increase of 0.8-1.5 psu. On the Great Bahama Bank, where surface waters are influenced by the North Atlantic subtropical gyre, [delta]18Ow increased by 0.3%o during the last 200 years. Although a portion (-O. 1%o) of this shift may be an artifact of anthropogenically-driven changes in surface water [Epsilon]CO2, the remaining [delta]18Ow signal implies a 0.4 to 1 psu increase in salinity after 200 yr BP.
(cont.) The simplest explanation of the [delta]18Ow, data is southward migration of the Atlantic Hadley circulation during the LIA. Scaling of the [delta]18Ow records to salinity using the modern low-latitude 180,w-S slope produces an unrealistic reversal in the salinity gradient between the two sites. Only if [delta]18Ow is scaled to salinity using a high-latitude [delta]18Ow-S slope can the records be reconciled. Changes in atmospheric 14C paralleled shifts in Dry Tortugas [delta]18Ow, suggesting that variable solar irradiance paced centennial-scale Hadley cell migration and changes in Florida Current salinity during the last millennium.
by David C. Lund.
Ph.D.
10
Makarowski, Kathryn Elizabeth. "An investigation of spatial and temporal variability in several of Montana's reference streams working toward a more holistic management strategy /." Diss., [Missoula, Mont.] : The University of Montana, 2009. http://etd.lib.umt.edu/theses/available/etd-08252009-120501.
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Amoruso, Kenneth. "Independent control of a molten stream temperature and mass flow rate." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/40008.
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Watz, Johan. "Winter behaviour of stream salmonids: effects of temperature, light, and ice cover." Licentiate thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-26809.
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In boreal streams, stream salmonids typically face low water temperatures and variable ice conditions during winter, and thus stream salmonids are expected to use different behavioural strategies to cope with these environmental conditions. The studies presented in this thesis explore how temperature, light intensity, and surface ice affect salmonid behaviour, with focus on drift-feeding and ventilation rates. The first paper reports results from a laboratory study designed to measure prey capture probabilities and reaction distances of drift-feeding Atlantic salmon, brown trout, and European grayling at light intensities simulating daylight and moonlight at seven temperatures ranging from 2 to 11°C. There was a positive relationship between water temperature and prey capture probability for all three species at both light levels, but the temperature-dependence did not scale according to the Metabolic Theory of Ecology. Reaction distance was also positively related to temperature for the three species, which may explain the temperature effects on prey capture probability. The results from this study should be of interest for those working with energetic-based drift-foraging models. In the second paper, the effects of ice cover on the diel behaviour and ventilation rate of brown trout were studied in a laboratory stream. Ice cover is believed to afford protection against endothermic predators, and thus the need for vigilance should be reduced under ice cover. This hypothesis was tested by observing ventilation rates at night, dawn, and during the day in the presence and absence of real, light-permeable surface ice. Further, trout were offered drifting prey during the day to test if ice cover increased daytime foraging activity. Ice cover reduced ventilation rates at dawn and during the day, but not at night. Moreover, trout made more daytime foraging attempts in the presence of ice cover than in its absence. These results suggest that ice cover affects the behaviour of brown trout and presumably has a positive effect on winter survival. Global warming, by reducing the extent or duration of surface ice, may therefore have negative consequences for many lotic fish populations in boreal streams.BAKSIDESTEXT In boreal streams, salmonids typically face low water temperatures and variable ice conditions from autumn to spring. The studies presented in this thesis explore how temperature, light intensity, and ice cover affect salmonid behaviour, with focus on drift-feeding and ventilation rates. In Paper I, drift-foraging was studied at light intensities simulating daylight and moonlight at seven temperatures ranging from 2 to 11°C. There was a positive relationship between temperature and foraging success at both light levels, but the temperature-dependence did not scale according to the Metabolic Theory of Ecology. Moreover, reaction distance was positively related to temperature. In Paper II, the effects of ice cover on behaviour and ventilation rate of brown trout were studied. Ice cover is believed to afford protection against predators, and thus the need for vigilance should be reduced under ice. This hypothesis was tested by observing ventilation rates at night, dawn, and during the day in the presence and absence of surface ice. Ice cover reduced ventilation rates and increased daytime foraging activity, suggesting that ice cover presumably has a positive effect on winter survival.
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Tyrrell, Jennie L. "The effect of water temperature on in-stream sediment concentration and transport rate." Thesis, Michigan Technological University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10004794.
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Global climate change may result in rising temperatures. As a result, ecological health and the human use of rivers may be impacted. The hydrologic cycle, watershed hydrology, and in-stream hydraulics are dynamic systems, influenced by human activities, natural events, and climate. Although known drivers like precipitation and stream velocity govern sediment processes, the effect of water temperature on sediment transport remains unclear. In-stream sediment movement could lead to blocked harbors, flooding, and degradation of vulnerable fish habitat. To better understand how fluctuations in water temperature affect sediment dynamics, six transport models were analyzed on the Niobrara River, with water temperatures ranging 1° to 40° C. The results indicate that as water warms sediment transport decreases, according to an inverse, non-linear law, with the highest reduction at colder water temperatures. The results given here can help predict changes in sediment transport for rivers with similar characteristics at various water temperatures.
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Leach, Jason Andrew. "Winter stream temperature in the rain-on-snow zone of the Pacific Northwest." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/51261.
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Stream temperature dynamics during winter are less well studied than summer thermal regimes, but the winter season thermal regime can be critical for fish growth and development. The winter thermal regimes of Pacific Northwest headwater streams, which provide vital winter habitat for salmonids and their food sources, may be particularly sensitive to changes in climate because they can remain ice-free throughout the year and are often located in rain-on-snow zones. This study examined winter stream temperature patterns and controls in small headwater catchments within the rain-on-snow zone at the Malcolm Knapp Research Forest, near Vancouver, British Columbia, Canada.
A diagnostic energy budget analysis highlighted that advective fluxes associated with hillslope throughflow inputs were a dominant control on the winter stream thermal regime. In addition, stream temperatures during rain-on-snow events were generally lower than during rain-on-ground events after controlling for air temperature. Methods for estimating throughflow temperatures embedded in stream temperature models were evaluated against field observations, and were found either not to account for the role of snow or to under- or over-predict throughflow temperatures by up to 5 °C. Therefore, a conceptual-parametric hillslope throughflow temperature model that coupled hydrologic and thermal processes, and accounted for the role of snow was developed and evaluated against field observations of throughflow temperatures. The hillslope throughflow temperature model was linked to stream energy exchange processes in order to predict stream temperature. The stream temperature model accurately predicted streamflow and winter stream temperature at three study catchments. The model also simulated lower throughflow temperatures during rain-on-snow versus rain-on-ground events, although the magnitude of cooling was less than suggested by empirical results. A key implication of this research is that climatic warming may generate higher winter stream temperatures in the rain-on-snow zone due to both increased temperature of throughflow inputs and reduced cooling effect of snow cover.Arts, Faculty of
Geography, Department of
Graduate
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Gossiaux, Alice. "Effets des changements environnementaux sur le fonctionnement des ruisseaux de tête de bassin versant." Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0260.
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Dans le contexte actuel des changements environnementaux, de nombreuses pressions menacent le fonctionnement et l’intégrité des milieux naturels. Parmi ces pressions, l’augmentation des températures et les modifications de la disponibilité des nutriments sont au cœur des préoccupations, en particulier concernant les écosystèmes aquatiques d’eau douce. Pour les ruisseaux de tête de bassin versant, qui sont des écosystèmes fragiles dont le fonctionnement est déterminant pour les masses d’eau situées à l’aval, les conséquences de ces changements sont primordiales à anticiper afin de prévoir des mesures de gestion et de conservation de ces milieux qui rendent de nombreux services écosystémiques. Le fonctionnement de ces cours d’eau repose principalement sur la décomposition de matière organique d’origine allochtone, qui constitue l’apport majeur de carbone des réseaux trophiques benthiques. Dans une moindre mesure, la production primaire y est représentée par les organismes autotrophes du biofilm. En utilisant différentes approches (microcosmes, mésocosmes, in natura), les travaux de cette thèse visent d’abord à comprendre comment les compartiments microbiens et macro-invertébrés, impliqués dans le fonctionnement des cours d’eau de tête de bassin, réagissent à l’augmentation des températures, puis tentent d’en démêler les effets conjoints de la modification de la disponibilité en nutriments, de la saisonnalité, de l’identité des espèces et des interactions biotiques sous-jacentes. Les résultats obtenus lors de cette thèse démontrent que la température et les nutriments ont des effets complexes—potentiellement faibles, non-linéaires et parfois opposés aux résultats de la littérature—sur les processus de décomposition des litières dans les cours d’eau. De plus, ces travaux soulignent l’importance de considérer les effets saisonniers et la dynamique temporelle pour mieux appréhender les processus mesurés en milieux naturels ou semi-naturels. Enfin, l’identité des espèces (litières, micro- et macro-organismes), leur rôle dans la communauté (groupes fonctionnels) et leurs interactions (antagonistes, facilitatrices) jouent un rôle clef dans la variabilité des réponses observées, en modulant, par exemple, l’importance de la voie brune et verte dans le fonctionnement de ces systèmes. Finalement, la variabilité des effets de l’augmentation de la température et de la disponibilité en nutriments sur le fonctionnement des cours d’eau de tête de bassin versant, fortement liée au contexte et au niveau d’organisation biologique, ouvre de nombreuses perspectives de recherche, et notamment dans le cadre des sciences participativesIn the current context of environmental changes, many pressures threaten the functioning and integrity of natural environments. Among these pressures, concerns about increasing temperatures and changes in nutrients availability are rising, particularly for freshwater aquatic ecosystems. The consequences of these changes on headwater streams, which contribute to downstream water bodies and provide many ecosystem services, are essential to anticipate in order to plan management and conservation measures. Headwater streams functioning is mainly based on the decomposition of allochthonous organic matter, which is the major carbon input for benthic food webs. To a lesser extent, primary production is represented by the autotrophic organisms of biofilm. Using different approaches (microcosms, mesocosms, in natura), this thesis aims at understanding how microbial and macro-invertebrate compartments, involved in the functioning of headwater streams, react to temperature increases, and at disentangling the combined effects of nutrients availability changes, seasonality, species identity and underlying biotic interactions. The results of this thesis demonstrate that temperature and nutrients have complex effects on stream litter decomposition processes (potentially weak, non-linear and sometimes opposed to the results of the literature). In addition, these studies highlight the importance of taking seasonal effects and temporal dynamics into account in order to improve the understanding of the measured processes in natural or semi-natural environments. Finally, species identity (litter, micro and macro-organisms), species roles in the community (functional groups) and interactions among them (antagonists, facilitators) play a key role in the variability of observed responses, by modulating, for example, the importance of the brown and green pathways in the functioning of these systems. Finally, the variability of the effects of temperature increase and nutrient availability on the functioning of headwater streams, which is strongly linked to the context and level of biological organization, leads to many research opportunities, and in particular for citizen science
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Garrett, Jessica D. "Pervasive Thermal Consequences of Stream-Lake Interactions in Small Rocky Mountain Watersheds, USA." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/841.
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Limnologists and stream ecologists acknowledge the fundamental importance of temperature for regulating many ecological, biological, chemical, and physical processes. I investigated how water temperatures were affected by hydrologic linkages between streams and lakes at various positions along surface water networks throughout several headwater basins in the Sawtooth and White Cloud Mountains of Idaho (USA). Temperatures of streams and lakes were measured for up to 27 months in seven 6 – 41 km2 watersheds, with a range of lake influence. When they were ice-free, warming in lakes resulted in dramatically warmer temperatures at lake outflows compared to inflow streams (midsummer average 6.4°C warming, but as much as 12.5°C). Temperatures cooled as water traveled downstream from lakes, as rapidly as 9°C km-1. Longitudinal stream cooling was usually not strong enough, however, to reduce temperatures to baseline conditions. In early spring, lakes had the opposite effect on streams, as they released water from beneath the ice at near 0°C. Early spring stream water warmed as it flowed downstream from lakes, influenced by additional groundwater inflows. In addition to lakes, other watershed characteristics influenced temperatures, though effects differed seasonally. Multiple regression analyses indicated that lake size, distance from nearest upstream lake, and stream shading were most important in explaining stream temperatures, but the relative importance of each variable changed seasonally.
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Willard, Eric Hillman Tharsing. "Temperature and relative humidity gradients of intermittent and perennial tributaries in Northern California." [Chico, Calif. : California State University, Chico], 2009. http://hdl.handle.net/10211.4/108.
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Mouzon, Nathaniel R. "Effects of Environmental Water Rights Purchases on Dissolved Oxygen, Stream Temperature, and Fish Habitat." DigitalCommons@USU, 2016. https://digitalcommons.usu.edu/etd/4986.
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Human impacts from land and water development have degraded water quality and altered the physical, chemical, and biological integrity of Nevada's Walker River. Reduced instream flows and increased nutrient concentrations affect native fish populations through warm daily stream temperatures and low nightly dissolved oxygen concentrations. Environmental water purchases are being considered to maintain instream flows, improve water quality, and enhance habitat for native fish species, such as Lahontan cutthroat trout. This study uses the River Modeling System (RMSv4), an hourly, physically-based hydrodynamic and water quality model, to estimate streamflows, temperatures, and dissolved oxygen concentrations in the Walker River. Stream temperature and dissolved oxygen changes were simulated from potential environmental water purchases to prioritize the time periods and locations that water purchases most enhance stream temperatures and dissolved oxygen concentrations for aquatic habitat. Environmental water purchases ranged from 0.03 cms to 1.41 cms average daily increases. Modeling results indicate that increased water purchases generally affect dissolved oxygen in two ways. First, environmental water purchases increase the thermal mass of the river, cooling daily stream temperatures and warming nightly temperatures. This prevents conditions that cause the lowest nightly dissolved oxygen concentrations (moderate production impairment thresholds are
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Snow, Camilla J. "Impact of Beaver Ponds on Stream Temperature and on Solar Radiation Penetration in Water." DigitalCommons@USU, 2014. https://digitalcommons.usu.edu/etd/3858.
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Beaver dams alter streams characteristics in a way that promotes the diversity of aquatic species and provides a wide distribution of temperatures within beaver ponds. In order to quantify the spatial distribution of these temperatures, a process-based temperature model was developed for a beaver pond in Northern Utah. This model provided insight into the processes and characteristics that are driving these temperatures. Solar radiation is one of these processes that is often the primary driver of stream temperature. There is a need to develop methods to measure the fate of solar radiation within the water to better represent solar radiation within stream temperature models. Black-body pyranometers are instruments that measure solar radiation in air, but require corrections for use underwater. Studies were conducted investigating methods for correcting these instruments. Based on the results of these studies it is suggested that these corrections are dependent on the spectrum of the light source and that the instrument needs further corrections when the light source is measured from different angles; therefore there is a need for further investigation into pyranometer corrections in order to measure the fate of solar radiation in natural water bodies. Combined, this research provides methods and suggests additional research opportunities for more accurately quantifying and predicting stream temperatures for waters impacted by beaver.
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Watson, Eric Craig. "Use of Distance Weighted Metrics to Investigate Landscape-Stream Temperature Relationships Across Different Temporal Scales." PDXScholar, 2016. http://pdxscholar.library.pdx.edu/open_access_etds/3117.
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Stream ecosystems have experienced significant negative impacts from land use, resource exploitation, and urban development. Statistical models allow researchers to explore the relationships between these landscape variables and stream conditions. Weighting the relevant landscape variables based on hydrologically defined distances offers a potential method of increasing the predictive capacity of statistical models. Using observations from three grouped watersheds in the Portland Metro Area (n=66), I have explored the use of three different weighting schemes against the standard method of taking an areal average. These four different model groups were applied to four stream temperature metrics: mean seven-day moving average maximum daily temperature (Mean7dTmax), number of days exceeding 17.8 °C (Tmax7d>17.8), mean daily range in stream temperature (Range_DTR), and the coefficient of variation in maximum daily temperature (CV_Tmax). These metrics were quantified for the 2011 dry season. The strength of these model groups were also examined at a monthly basis for each of the four months within the dry season. The results demonstrate mixed effectiveness of the weighting schemes, dependent on both the stream temperature metric being predicted as well as the time scale under investigation. Models for Mean7dTmax showed no benefit from the inclusion of distance weighted metrics, while models for Range_DTR consistently improved using distance weighted explanatory variables. Trends in the models for 7dTmax>17.8 and CV_Tmax varied based on temporal scale. Additionally, all model groups demonstrated greater explanatory power in early summer months than in late summer months.
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Kozarek, Jessica Lindberg. "Channel Morphology and Riparian Vegetation Influences on Fluvial Aquatic Habitat." Diss., Virginia Tech, 2011. http://hdl.handle.net/10919/77172.
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As public awareness of river degradation has grown in recent years, the number of stream restoration activities has increased dramatically. Anthropogenic influences at a range of spatial scales from watershed landuse to riparian vegetation management to local channel morphology can have hierarchical relationships to local (meso- and macro-) in-stream habitat characteristics. This research examined these influences first by examining the influence of complex channel morphology on meso-scale brook trout (Salvelinus fontinalis) habitat in Shenandoah National Park, VA, and then by examining the combined influence of watershed urbanization and riparian vegetation (100-200 m reaches) on stream temperature.
Moving beyond one-dimensional (1D) averaged representations of fish habitat, this research explored the distribution of two-dimensional (2D) flow complexity metrics at the meso-habitat scale as explanatory variables for brook trout habitat preferences and as potential metrics to evaluate habitat restoration design. Spatial hydraulic complexity metrics, including area-weighted circulation and kinetic energy gradients, were calculated based on 2D depth averaged modeled velocity distributions in two 100-m reaches on the Staunton River. While there were no statistically significant correlations between kinetic energy gradients or area-weighted circulation and fish density, fish density was positively correlated to the percent of the channel dominated by protruding boulders. The structural complexity of areas with protruding boulders create complex flow patterns suggesting that flow complexity plays an important role in available brook trout habitat preferences at the local scale, although the 2D depth averaged model may not have adequately represented this complexity. The 2D distribution of flow characteristics was then investigated further to quantify areas of flow refugia (low velocity shelters) and the relationship between these areas, traditional measures of habitat quality, and fish biomass. Flow complexity in the vicinity of flow obstructions (in this case, boulders) was investigated further using patch classification and landscape ecology metrics.
The relative influence of riparian vegetation on stream temperature (another important habitat characteristic) in urban and nonurban watersheds was investigated in 27 paired forested and nonforested reaches in PA, MD, and DE. Riparian vegetation and watershed-scale urbanization both influence stream temperature, which can have profound impacts on in-stream ecosystems. Generally, increased urbanization and removal of riparian forest influenced maximum stream temperatures resulting in higher maximum summer stream temperatures (up to 1.8°C); however, the influence of riparian forests (at at 100-200 m reach scale) decreased with increasing urbanization. Extreme maximum summer temperatures, which are a concern for aquatic biota, increased in both frequency and duration in urban nonforested reaches relative to forested reaches indicating that the addition of a forested 100-200 m long buffer partially mitigated these temperature extremes even in urban watersheds. Overall, changes to channel morphology and riparian vegetation had measurable local effects on stream habitat (temperature and hydraulic complexity) yet the implications of restoration efforts at the local scale on ecosystem services at a larger (km +) scale requires further study.Ph. D.
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Fabris, Luca. "Influence of hydrology, hydraulics and temperature on Atlantic salmon habitat : modelling-based approaches for sustainable river management." Thesis, University of Aberdeen, 2018. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=239262.
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In this thesis, we improved our understanding of the effects of hydrology, stream hydraulics, and temperature on juvenile Atlantic salmon (Salmo salar L.) habitat. We demonstrated the key role played by stream morphology and flow regime on in-channel hydraulics and consequently on salmonid habitat. Additionally, we showed how riparian afforestation has potential to moderate climate change effects on stream temperature preserving freshwater ecosystems. The Girnock Burn is an upland Scottish river that has been intensively studied to investigate flow generation processes and stream temperature, and has served as a long-term monitoring site for Atlantic salmon population dynamics since 1966. The general approach applied consisted of combining different types of models including: hydraulic, fish habitat, hydrological and heat transfer models with long-term hydrological and climatic data sets, and digital terrain models (DTMs) at different spatio-temporal scales. Our results showed that the extensive presence of roughness elements (e.g. boulders and cobbles) is capable to provide some refuge areas for juvenile salmon fry for a wide range of flows. However, under extreme flow conditions, in-channel hydraulics might represent a limiting factor. Significant inter-site differences occurred and were consistent throughout the years. Evidence of long-term trend in fry habitat quality could be identified only in summer. Since more extreme flow regimes are expected in the future as a result of climate change, we also proposed a novel analytical approach that allowed us to assess the effects of hydroclimatic variation on fish populations outside the range of observations. Finally, we showed the potential of afforestation to reduce daily stream temperature range, moderating both low and high peaks of more than 2 ○C. This makes riparian shading a valuable mitigation strategy to contrast global warming effects on stream temperatures that should be considered for a sustainable catchment management.
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Krause, Colin William. "Evaluation and Use of Stream Temperature Prediction Models for Instream Flow and Fish Habitat Management." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/31229.
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The SNTEMP (U.S. Fish and Wildlife Service), QUAL2E (U.S. Environmental Protection Agency), and RQUAL (Tennessee Valley Authority) stream temperature prediction models were evaluated. All models had high predictive ability with the majority of predictions, >80% for Back Creek (Roanoke County, VA) and >90% for the Smith River tailwater (SRT) (Patrick County, VA), within 3°C of the measured water temperature. Sensitivity of model input parameters was found to differ between model, stream system, and season. The most sensitive of assessed parameters, dependent on model and stream, were lateral inflow, starting-water, air, and wet-bulb temperature. All three models predicted well, therefore, selecting a model to assess alternative water management scenarios was based on model capabilities. The RQUAL model, used to predict SRT temperatures under alternative hydropower release regimes, illustrated potential thermal habitat improvement for brown trout (Salmo trutta) compared to existing conditions. A 7-day/week morning 1 hr release was determined to best concurrently increase occurrence of brown trout optimal growth temperatures (+10.2% mean), decrease 21°C (state standard) exceedances (99% prevention), and decrease hourly changes in temperature (-1.6°C mean) compared to existing thermal conditions. The SNTEMP model was used to assess thermal habitat under flow, shade, and channel width changes occurring from future urbanization within the Back Creek watershed. Predictions reveal that additional urban development could limit thermal habitat for present fish species by elevating summer mean daily temperature up to 1°C and cause 31°C (state standard) exceedances compared to existing conditions. Temperature impacts were lessened by single rather than cumulative changes suggesting mitigation measures may maintain suitable thermal habitat.Master of Science
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Ridgeway, Julia B. "An analysis of changes in stream temperature due to forest harvest practices using DHSVM-RBM." DigitalCommons@CalPoly, 2019. https://digitalcommons.calpoly.edu/theses/2093.
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Forest harvesting has been shown to cause various changes in water quantity and water quality parameters, highlighting the need for comprehensive forest practice rules. Studies show a myriad of impacts to ecosystems as a result of watershed level changes, such as forest harvesting. Being able to better understand the impact that forest harvesting can have on stream temperature is especially critical in locations where federally threatened or endangered fish species are located. The overall goal of this research project is to assess responses in stream temperature to various riparian and forest harvest treatments in a maritime, mountainous environment. The results of this study aim to inform decision makers with additional information pertaining to the effects of forest harvest on water temperature. Modeling is done as a part of the third Caspar Creek Paired Experimental Watershed study. Located in Mendocino County, the site provides a place for California researchers and decision makers to learn about the cumulative watershed effects of forest management operations on peak flows, sediment production, anadromous fish, macro-invertebrate communities, nutrient cycling and more. Historic data was used to calibrate the Distributed Hydrology Soil Vegetation Model (DHSVM) and River Basin Model (RBM) to measured stream temperatures in the South Fork of Caspar Creek (SFC) for hydrologic years 2010-2016. Critical summer time periods, when temperatures are highest and flows are low, are the primary concern for this work. The key modeling scenarios evaluated were (1) varying percentages of Watercourse and Lake Protection Zones (WLPZ) canopy cover, (2) the 2018-2019 SFC forest harvest and (3) an experimental design converting dominant riparian vegetation along 300-yard stream reaches. Modeling results showed that stream temperatures begin to rise above third-growth conditions when canopy cover is reduced to 25% and 0% retention levels. Larger increases in Maximum Weekly Maximum Temperature (MWMT) values, compared to Maximum Weekly Average Temperature (MWAT) values, were seen across all scenarios. There was essentially no difference between altering buffer areas along only class I streams, compared to along all stream classes. At the 0% canopy retention, MWMT values consistently rose above recommended thermal limits for Coho salmon (Oncorhynchus kisutch) and state regulations prohibiting more than a 5 degree F increase in waters. Clearcutting the entire watershed produced less of an effect than simulations clearing on only the riparian area, suggesting that groundwater inflows act to mitigate stream temperature rises in the SFC. The 2018-2019 harvest showed a relatively consistent increase in MWAT values (avg. 0.11 degree C) and more varied increases in MWMT values (avg. 0.32 degree C). Simulations converting dominant riparian vegetation by clearing could not be considered conclusive due to sensitivity analyses suggesting potentially unrealistic tracking of downstream temperatures. Additional sensitivity analyses suggest that tree height and the monthly extinction coefficient (a function of Leaf Area Index) are most influential on stream temperature changes in SFC. This is consistent with other modeling studies and suggests stream temperature management focus on tall, dense buffers as opposed to wider buffer widths.
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Harper-Smith, Sarah. "Modeling relative effects of riparian cover and groundwater inflow on stream temperature in lowland Whatcom County, Washington /." Online version, 2008. http://content.wwu.edu/cdm4/item_viewer.php?CISOROOT=/theses&CISOPTR=288&CISOBOX=1&REC=6.
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Berg, Ivan. "Headwaters and forestry : Effect of riparian buffers on stream physiochemical properties." Thesis, Umeå universitet, Institutionen för ekologi, miljö och geovetenskap, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-163017.
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Forest management practices usually preserves riparian buffers along watercourses in order to protect stream water from physical, chemical and ecological changes caused by clear-cutting. The purpose of this thesis was to investigate whether there is a relationship between the size of the riparian buffer zone along small streams, i.e., headwaters, and a number of physical and chemical attributes of these streams. Twelve headwaters in the Västerbotten county and twelve in Jönköpings county were investigated. These headwaters had a range of buffer widths from “No buffer” (no trees left), Thin buffer” (< 5 m wide), to “Moderate buffer” (>5 m wide) and “Reference” (no harvest) streams were also included. Tested physical and chemical conditions were light in the riparian zone, air and water temperature, stream bed cover and water chemistry. Buffer width had a significant effect on reducing light levels and temperature in the riparian zone; a buffer width over 13 m on each side of the stream was needed to maintain light and air temperature as in reference conditions. Regarding water temperature, increasing sedimentation and water quality, no significant reducing effect of increasing riparian buffer width was found.
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Li, Han. "Statistical Modeling and Analysis of Bivariate Spatial-Temporal Data with the Application to Stream Temperature Study." Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/70862.
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Water temperature is a critical factor for the quality and biological condition of streams. Among various factors affecting stream water temperature, air temperature is one of the most important factors related to water temperature. To appropriately quantify the relationship between water and air temperatures over a large geographic region, it is important to accommodate the spatial and temporal information of the steam temperature. In this dissertation, I devote
effort to several statistical modeling techniques for analyzing bivariate spatial-temporal data in a stream temperature study.
In the first part, I focus our analysis on the individual stream. A time varying coefficient model (VCM) is used to study the relationship between air temperature and water temperature for each stream. The time varying coefficient model enables dynamic modeling of the relationship, and therefore can be used to enhance the understanding of water and air temperature relationships. The proposed model is applied to 10 streams in Maryland, West Virginia, Virginia, North Carolina and Georgia using daily maximum temperatures. The VCM approach increases the prediction accuracy by more than 50% compared to the simple linear regression model and the nonlinear logistic model.
The VCM that describes the relationship between water and air temperatures for each stream is represented by slope and intercept curves from the fitted model. In the second part, I consider water and air temperatures for different streams that are spatial correlated. I focus on clustering multiple streams by using intercept and slope curves estimated from the VCM. Spatial information is incorporated to make clustering results geographically meaningful. I further propose a weighted distance as a dissimilarity measure for streams, which provides a flexible framework to interpret the clustering results under different weights. Real data analysis shows that streams in same cluster share similar geographic features such as solar radiation, percent forest and elevation.
In the third part, I develop a spatial-temporal VCM (STVCM) to deal with missing data. The STVCM takes both spatial and temporal variation of water temperature into account. I develop a novel estimation method that emphasizes the time effect and treats the space effect as a varying coefficient for the time effect. A simulation study shows that the performance of the STVCM on missing data imputation is better than several existing methods such as the neural network and the Gaussian process. The STVCM is also applied to all 156 streams in this study to obtain a complete data record.Ph. D.
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Wood, Jessica R. "Stream Temperature Monitoring and Modeling to Inform Restoration: A Study of Thermal Variability in the Western US." DigitalCommons@USU, 2017. https://digitalcommons.usu.edu/etd/6898.
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Water temperature is an important variable for aquatic ecosystems. Salmonid population numbers and distribution are heavily influenced by stream temperature, and there is growing concern about the health of salmonid populations with anticipated climate change. Managers are looking to efficiently evaluate options to maintain stream temperatures needed by salmonids. This study evaluated and compared stream temperature restoration alternatives in two streams with warm temperatures using stream temperature monitoring and modeling.
The first study identified pockets of cold water that are important to native fish species in Nevada’s Walker River. Comparison of monitoring results with existing basin-scale model outputs identified two habitat features, beaver dams and irrigation return flow channels, that maximize stream temperature variability. Restoration should maintain and enhance these features, although different restoration approaches may be needed at different locations. This study may provide guidance for the interpretation of stream temperature results from other basin-scale models.
The second study quantified stream temperature effects of wildfire and restoration plantings in Oregon’s Meadow Creek with current and projected mid-21st century climate. A stream temperature model developed and applied using Heat Source found restoration eliminated days above the lethal threshold (25°C) for salmonids and decreased the number of days exceeding spawning criteria during spawning periods. Days exceeding salmonid spawning (13°C) and rearing (18°C) thresholds were reduced by all vegetation restoration scenarios, but elimiated by none. Results highlights the importance of the length and location of restoration, which can maximize pockets of cold water for salmonids or alleviate the impact of warm water sections.
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Garner, Christopher B. "Modeling the effect of riparian shading on water temperature for portions of the Carson River, western Nevada, USA." abstract and full text PDF (free order & download UNR users only), 2007. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1442841.
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Jones, Leslie Anne. "Using a spatially explicit stream temperature model to assess potential effects of climate warming on bull trout habitats." Thesis, Montana State University, 2012. http://etd.lib.montana.edu/etd/2012/jones/JonesL0512.pdf.
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As the Flathead River Basin (FRB) undergoes change caused by a warming climate, scientific studies evaluating habitats and species most susceptible to the impacts of climate change will become increasingly important. Here, we seek to identify biologically meaningful physiological thresholds of bull trout in the FRB by modeling stream temperature and using the model as a tool to predict thermal changes caused by a warming climate. Specifically, we developed a spatially explicit stream temperature model to quantify and explore the potential range of thermal warming effects, using the case study of bull trout populations in the FRB. Our objectives were to: i) compare spatial and non-spatial statistical models used to predict stream temperatures throughout the FRB; ii) apply a spatially explicit model to estimate thermal thresholds for spawning and rearing and foraging migrating and overwintering bull trout habitats; iii) predict thermal changes under a range of future climate scenarios; and iv) investigate model behavior and inform future research decisions. Development of spatially explicit models, such as the one described here, will create an ideal opportunity to build collaborative relationships through research so that scientists can further understand how climate change will impact freshwater aquatic ecosystems. In particular, model results may be used to perform ecosystem assessments; inform future research needs; and develop conservation plans with broad applications that reach beyond the Flathead system. 'Co-authored by Clint C. Muhlfeld, Lucy A. Marshall, Brian L. McGlynn and Jeffrey L. Kershner'
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Collis, Lyndsie Michele. "Does nutrient availability mediate the temperature dependence of gross primary production?: An evaluation using side-stream experimental channels." The Ohio State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=osu1534507613269229.
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Vonada, Whitney. "Assessing Spatiotemporal Stream Temperature Trends and Drivers through Integrated Longitudinal Thermal Profiling and Stationary Data Logger Methodology on the Upper Chehalis River, WA." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4560.
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This study encompasses 25 kilometers of the Chehalis River in Washington, USA that currently has sections under a Total Maximum Daily Load (TMDL) plan for stream temperature impairments that exceed 18°C, a regulatory standard set at the time of the listing to protect salmonid spawning, rearing, and migration. Using information integrated from stationary data loggers (n=22) that collected stream temperature information from August 4-September 10, 2017, and longitudinal thermal profiling performed on July 29-30, August 4-5, and September 9-10, 2017, this study aimed to quantify the spatial distribution of stream temperature, evaluate relative consistencies of the riverine thermal regime over time, and identify which independent variables (land cover, aspect, canopy cover, impervious surfaces, channel width, discharge and air temperature) are correlated with stream temperature metrics using Spearman's rank correlation and stepwise linear regression modeling. Stream temperature was found to be strongly correlated with all air temperature metrics. The strongest model from stepwise linear regression (R2 = 0.711) found width, shrub/scrub, mixed forest, and cultivated crop land cover to be the strongest explanatory variables with the seven day average of the daily maximum stream temperature (7DADMaxTw) at the 22 sites. Tributaries had overall cooler average maximum stream temperatures than main stem sites. Thermal profiling identified seven cold-water patches (defined as the cumulative stream temperature ≥1°C cooler than the surrounding water). Integrating longitudinal thermal profiling and stationary data loggers allows resource managers to understand spatiotemporal stream temperature trends and influences and can assess more effective mitigation strategies to combat rising stream temperatures.
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Vance, Linda Katherine. "Stream temperature dynamics and impacts on the distribution of salmonid fishes in the Garcia River Watershed, Mendocino County, California /." For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2004. http://uclibs.org/PID/11984.
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Ketley, Zoma Anne. "Stream invertebrates and water temperature : evaluating thermal tolerances in the Cape floristic region (South Africa) - implications of climate change." Master's thesis, University of Cape Town, 2009. http://hdl.handle.net/11427/8973.
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Includes bibliographical references.Temperature is an important environmental variable for aquatic invertebrates as it affects their development, reproduction and survival. Temperature also affects the abundance and distribution of individuals in a stream or river. Stream temperatures are affected by human impacts which include not only impacts such as pollution, abstraction of water and the removal of riparian vegetation, but also the affects of climate change. In the Western Cape Province, South Africa, it is predicted that air temperatures will increase and winter rainfall will decrease. This in turn will affect water availability and water temperatures in streams and rivers. Thermally sensitive species are threatened by increases in water temperature, but currently very little information exists on the thermal tolerances of aquatic invertebrates in South Africa. In order to rectify this problem baseline data on thermal tolerances of aquatic species needs to be collected, together with stream temperature and associated invertebrate community data. An attempt was made to collect some of these much needed data in the Western Cape Province. Two methods, namely Critical Thermal Maxima (CTM) and LT₅₀ experiments, were used to determine the thermal tolerances for a range of aquatic insect nymph species from the southwest fynbos bioregion and the south coast fynbos bioregion. The results from the experiments provided information on the relative thermal sensitivities of the species. Overall Aphanicerca capensis (form C and undescribed form), Notonemouridae ranked as the most thermally sensitive for both experiments. The A. capensis species complex (and possible other notonemourid stoneflies) may potentially be used as an indicator of changing stream temperatures in the Western Cape Province. To rapidly determine thermal sensitivities the CTM experiments are recommended rather than the more time consuming LT₅₀ experiments as the relative thermal tolerance for the species tested ranked the same for both experiments. It is suggested that LT₅₀ experiments of longer duration be investigated in order to compare the experiments to naturally-occurring thermal stress. Stream temperature and community composition data were collected from Window Gorge Stream, on Table Mountain, to provide baseline data for future monitoring and understanding of potential changes in thermal profiles. Temperature loggers were placed at six sites along the stream. Stream temperatures were fairly low but the stream ran dry during the late summer months (February through to April/May). From the community composition data collected the highest diversity was found during the winter months, as expected. The community composition did change down the length of the stream, with the species composition found near the source being quite different to that of the species composition found lower down the mountain. Temperature and associated oxygen saturation were two important variables related to the community composition down the length of the stream. It is important that experimental data be combined with field data, enabling field sampling to focus on the collection of information on the abundance of the thermally sensitive species (e.g. A. capensis species complex). Recorded stream temperatures also provide reference conditions for the species tested in the laboratory. Climate change is likely to have an affect not only on stream temperatures but also on water availability, which will both influence stream communities and ecosystems and it is important to understand what these potential effects might be.
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Gaona, Garcia Jaime. "Groundwater-stream water interactions: point and distributed measurements and innovative upscaling technologies." Doctoral thesis, Università degli studi di Trento, 2019. http://hdl.handle.net/11572/242544.
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The need to consider groundwater and surface water as a single resource has fostered the interest of the scientific community on the interactions between surface water and groundwater. The region below and alongside rivers where surface hydrology and subsurface hydrology concur is the hyporheic zone. This is the region where water exchange determines many biogeochemical and ecological processes of great impact on the functioning of rivers. However, the complex processes taking place in the hyporheic zone require a multidisciplinary approach.
The combination of innovative point and distributed techniques originally developed in separated disciplines is of great advantage for the indirect identification of water exchange in the hyporheic zone. Distributed techniques using temperature as a tracer such as fiber-optic distributed temperature sensing can identify the different components of groundwater-surface water interactions based on their spatial and temporal thermal patterns at the sediment-water interface. In particular, groundwater, interflow discharge and local hyporheic exchange flows can be differentiated based on the distinct size, duration and sign of the temperature anomalies. The scale range and resolution of fiber-optic distributed temperature sensing are well complemented by geophysics providing subsurface structures with a similar resolution and scale. Thus, the use of fiber-optic distributed temperature sensing to trace flux patterns supported by the exploration of subsurface structures with geophysics enables spatial and temporal investigation of groundwater-surface water interactions with an unprecedented level of accuracy and resolution.
In contrast to the aforementioned methods that can be used for pattern identification at the interface, other methods such as point techniques are required to quantify hyporheic exchange fluxes. In the present PhD thesis, point methods based on hydraulic gradients and thermal profiles are used to quantify hyporheic exchange flows. However, both methods are one-dimensional methods and assume that only vertical flow occurs while the reality is much more complex. The study evaluates the accuracy of the available methods and the factors that impact their reliability. The applied methods allow not only to quantify hyporheic exchange flows but they are also the basis for an interpretation of the sediment layering in the hyporheic zone.
For upscaling of the previous results three-dimensional modelling of flow and heat transport in the hyporheic zone combines pattern identification and quantification of fluxes into a single framework. Modelling can evaluate the influence of factors governing groundwater-surface water interactions as well as assess the impact of multiple aspects of model design and calibration of high impact on the reliability of the simulations. But more importantly, this modelling approach enables accurate estimation of water exchange at any location of the domain with unparalleled resolution. Despite the challenges in 3D modelling of the hyporheic zone and in the integration of point and distributed data in models, the benefits should encourage the hyporheic community to adopt an integrative approach comprising from the measurement to the upscaling of hyporheic processes.
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Jian, Jun. "Predictability of Current and Future Multi-River discharges: Ganges, Brahmaputra, Yangtze, Blue Nile, and Murray-Darling Rivers." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19777.
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Thesis (Ph.D)--Earth and Atmospheric Sciences, Georgia Institute of Technology, 2008.Committee Chair: Judith Curry; Committee Chair: Peter J Webster; Committee Member: Marc Stieglitz; Committee Member: Robert Black; Committee Member: Rong Fu.
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Sauze, Martin J. "An investigation using empirical orthogonal functions and objective analysis to analyze the vertical temperature structure of a Gulf Stream meander." Thesis, Monterey, Calif. : Springfield, Va. : Naval Postgraduate School ; Available from National Technical Information Service, 1993. http://handle.dtic.mil/100.2/ADA265116.
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Callahan, Michael Kroh. "Groundwater Controls on Physical and Chemical Processes in Streamside Wetlands and Headwater Streams in the Kenai Peninsula, Alaska." Scholar Commons, 2014. https://scholarcommons.usf.edu/etd/5347.
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For this dissertation I studied groundwater and surface water interactions in the Kenai Lowlands, Alaska. In particular, I examine two important aspects of groundwater and surface water interactions: 1) Groundwater's influence on surface-water temperature; and 2) Groundwater's role in forming hydrologic flow paths that can connect uplands to streamside wetlands and streams. Chapter 2 investigates the controls on stream temperature in salmon-bearing headwater streams in two common hydrogeologic settings: 1) drainage-ways, which are low-gradient streams that flow through broad valleys; and 2) discharge-slopes, which are high gradient streams that flow through narrow valleys. The results from chapter 2 showed significant differences in stream temperatures between the two hydrogeologic settings. Observed stream temperatures were higher in drainage-way sites than in discharge-slope sites, and showed strong correlations as a continuous function with the calculated topographic metric flow-weighted slope. Additionally, modeling results indicated that the potential for groundwater discharge to moderate stream temperature is not equal between the two hydrogeologic settings, with groundwater having a greater moderating effect on stream temperature at the low gradient drainage-way sites. Chapter 3 examines the influence of groundwater on juvenile coho salmon winter habitat along the Anchor River. Two backwater habitats were selected from the larger set of 25 coho overwintering sites from a previous study for an in-depth hydrologic analysis. The results from chapter 3 showed that the type of groundwater discharge (i.e., focused versus diffuse groundwater discharge) can play an important role in determining habitat suitability in these backwater sites. During winter, focused discharge from a local groundwater seep maintained higher surface-water temperatures and higher concentrations of dissolved oxygen compared to the site with more diffuse groundwater discharge. Chapter 4 investigates the linkages along hydrologic flow paths among alder (Alnus spp.) stands, streamside wetlands, and headwater streams. Chapter 4 tested four related hypotheses: 1) groundwater nitrate concentrations are greater along flow paths with alder compared to flow paths without alder; 2) on hillslopes with alder, groundwater nitrate concentrations are highest when alder stands are located near the streamside wetlands at the base of the hillslope; 3) primary production of streamside wetland vegetation is N limited and wetlands are less N limited when alder stands are located nearby along flow paths; and 4) stream reaches at the base of flow paths with alder have higher nitrate concentrations than reaches at the base of flow paths without alder. The results from chapter 4 showed that groundwater nitrate concentrations were highest along flow paths with alder, however no difference was observed between flow paths with alder located near versus alder located further from streamside wetlands. Vegetation had a greater response to N fertilization in streamside wetlands that were connected to flow paths without alder and less when alder stands were near. Finally, higher nitrate concentrations were measured in streams at the base of flow paths with alder. The combined results of this dissertation showed that, in the Kenai Lowlands, groundwater and surface water interactions have a direct influence on the local ecology and that a fundamental understanding of the hydrology can aid in the successful management and protection of this unique and important ecosystem.
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Hill, Andrew C. "Assessing Linkages Among Landscape Characteristics, Stream Habitat, and Macroinvertebrate Communities in the Idaho Batholith Ecoregion." DigitalCommons@USU, 2010. https://digitalcommons.usu.edu/etd/774.
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Understanding the composition of lotic communities and the landscape processes and habitat characteristics that shape them is one of the main challenges confronting stream ecologists. In order to better understand the linkages among landscape processes, stream habitat, and biological communities and to understand how accurately our measurements represent important factors influencing biological communities, it is important to test explicit hypotheses regarding these linkages. Increasing our understanding of aquatic communities in a hierarchical context and recognizing how well our measurements represent factors structuring aquatic communities will help managers better evaluate the influence of land management practices on aquatic ecosystems, direct conservation strategies, and lead to better assessments of ecological condition.
In Chapter 2, we used spatial data, field-based habitat measurements, and macroinvertebrate community data to 1) examine the influence of landscape processes on two factors of stream habitat; maximum stream temperatures and fine sediment, and to 2) examine how well these landscape and habitat characteristics represent factors influencing gradients in macroinvertebrate community structure. The results of this study showed that spatially derived measurements may be effectively used to test hypotheses regarding landscape influences on stream habitat and that spatial data, used in conjunction with field measurements can provide important information regarding factors influencing gradients in biological communities. In addition, spatially derived measurements may provide the same or additional information regarding influences on community structure as field-based measurements, which suggests that further research should be done to assess how well our field measurements represent factors that are important in shaping stream communities.
The objective of Chapter 3 was to compare how well single field measurements and a combination of indicator variables hypothesized to be components of a single ecological processes or concept, known as a latent variable, represent thermal stress and fine sediment influences on macroinvertebrate communities. Results from this study showed that both single and latent variables explained relatively the same amount of variation in macroinvertebrate community structure. This suggests that while latent variables may have a potential to better refine how we represent ecological factors, a better basis for defining a priori hypotheses is needed before these variables can provide any additional information compared to single habitat measurements.
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Ensor, Breanne Leigh. "Spatial and Temporal Trends in Greenhouse Gas Fluxes from a Temperate Floodplain along a Stream-Riparian-Upland Gradient." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71424.
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Increased floodplain and wetland restoration activity has raised concerns about potential impacts on the release of greenhouse gases (GHGs) to the atmosphere due to restored connectivity between aquatic and terrestrial ecosystems. Research has shown GHG fluxes from hydrologically active landscapes such as floodplains and wetlands vary spatially and temporally in response to primary controls including soil moisture, soil temperature, and available nutrients. In this study, we performed a semimonthly sampling campaign measuring GHG (CO2, CH4, and N2O) fluxes from six locations within a third-order stream floodplain. Site locations were based on dominant landscape positions and hydrologic activity along a topographic gradient including a constructed inset floodplain at the stream margin, the natural levee, an active slough, the general vegetated floodplain, a convergence zone fed by groundwater, and the upland area. Flux measurements were compared to abiotic controls on GHG production to determine the most significant factors affecting GHG flux from the floodplain. We found correlations between CO2 flux and soil temperature, organic matter content, and soil moisture, CH4 flux and pH, bulk density, inundation period length, soil temperature, and organic matter content. But minimal correlations between N2O flux and the measured variables. Spatially, our results demonstrate that constructed inset floodplains have higher global warming potential in the form of CH4 than any other site and for all other GHGs, potentially offsetting the positive benefits incurred by enhanced connectivity. However, at the reach scale, total CO2 flux from the soil remains the greater influence on climate since the area covered by these inset floodplains is comparatively much smaller than the rest of the floodplain.Master of Science
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Brenneman, Emma Lee. "Hydrologic Trends and Spatial Relationships of Stream Temperature and Discharge in Urbanizing Watersheds in the Portland Metropolitan Area of the Pacific Northwest." PDXScholar, 2019. https://pdxscholar.library.pdx.edu/open_access_etds/5128.
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This study explores various relationships of streamflow and stream temperature over the Portland Metropolitan area in two urbanizing watersheds. Four stream temperature and discharge metrics were derived from USGS stream gauges in the Tualatin River and Johnson Creek watersheds and were analyzed for monotonic trends. Additionally, this study explored the sensitivity of stream temperature to air temperature and streamflow to assess where locations throughout the watershed may be more sensitive to these changes. Relationships among stream temperature, air temperature, and streamflow were assessed using linear and nonlinear bivariate regression for yearly values and summer months. Additionally, this study seeks to explain the spatial variations of thermal sensitivity throughout the Johnson Creek watershed using predictors derived using different weights at the contributing watershed scale and the buffer scale. Results indicate significant increasing trends in stream temperature metrics at various locations throughout the study area. Decreasing baseflow does not appear to coincide with increasing temperature metrics. Significant increasing trends in October and November are present in runoff ratio and TQmean. In both watersheds, air temperature appears to have a greater influence than streamflow on stream temperature, though the addition of discharge generally improves model fit. Increasing thermal sensitivity in Johnson Creek is related to increasing and decreasing standard deviation of slope, increasing mean slope, increasing open water and wetlands, less forest area, increasing standard deviation of NDVI, decreasing restoration area, increasing gray infrastructure density, and increasing upstream flow length. At most, ordinary least squares explained 30% of the variance in thermal sensitivity when only including stream temperature monitoring locations in the mainstem of the creek. Modelling tributary only stream temperature monitoring locations used a variety of watershed, buffer-scale, areal average and inverse distance weighted variables. The findings of this study highlight the importance of temporal scale and complex hydro-climatic influences along an urban-rural gradient in assessing patterns of discharge and temperature. These results have important implications for watershed managers, local agencies, and stakeholders who have worked to restore Johnson Creek and help to guide future water quality planning throughout the watershed.
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Witter, Jason Daniel. "A Two Part Thesis: Diurnal Soil Temperature Effects Within the GLOBE® Program Dataset and Pharmaceutical Compounds in the Wastewater Process Stream in Northwest Ohio." University of Toledo / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1208865262.
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Akinola, Akinrotimi Idowu. "Temporal and Thermal Effects on Fluvial Erosion of Cohesive Streambank Soils." Diss., Virginia Tech, 2018. http://hdl.handle.net/10919/96768.
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In the United States, the annual cost of on-site soil erosion problems such as soil and nutrient losses, and off-site soil erosion problems such as sedimentation of lakes and river, loss of navigable waterways, flooding and water quality impairment, has been estimated at 44 billion USD (Pimentel, 1995; Telles, 2011). While eroding sediment sources can either be from land or from stream/river systems, the erosion from streambanks can be quite significant, reaching up to 80% of sediment leaving a watershed (Simon et al 2002; Simon and Rinaldi 2006). Despite many decades of research one the erosion of cohesive soils by flowing water (fluvial erosion), this significant aspect of environmental sustainability and engineering is still poorly understood. While past studies have given invaluable insight into fluvial erosion, this process is still poorly understood. Therefore, the objective of this dissertation was to examine the relationship between time and erosion resistance of remolded cohesive soils, and to quantify and model the effects soil and water temperature on the fluvial erosion of cohesive soils
First, erosion tests were performed to investigate how soil erosion resistance develops over time using three natural soils and testing in a laboratory water channel. Results showed that the erosion rate of the soils decreased significantly over the time since the soils were wetted. This study indicates researchers need to report their sample preparation methods in detail, including the time between sample wetting and sample testing.
Second, erosion tests were performed at multiple soil and water temperatures. Results showed that increases in water temperature led to increased erosion rates while increases in soil temperature resulted in decreased erosion rate. When soil and water temperatures were equal, erosion results were not significantly different. Results also showed a linear relationship between erosion rate and the difference between soil and water temperatures, indicating erosion resistance decreased as heat energy was added to the soil.
Lastly, two common erosion models (the excess shear stress and the Wilson models) were evaluated, and were modified to account for soil and water temperature effects. Results showed that, compared to the original models, the modified models were better in predicting erosion rates. However, significant error between model predictions and measured erosion rates still existed.
Overall, these results improve the current state of knowledge of how erosion resistance of remolded cohesive soils evolves with time, showing the importance of this factor in the design of cohesive erosion experiments. Also, the results show that by accounting for thermal effects on erosion rate, the usability of erosion models can be improved in their use for erosion predictions in soil and water conservation and engineering practice.PHD
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Cole, Brian D. "Transient performance of parallel-flow and cross-flow direct transfer type heat exchangers with a step temperature change on the minimum capacity rate fluid stream. /." Online version of thesis, 1995. http://hdl.handle.net/1850/11924.
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Jian, Jun. "Relationship between the Pacific Ocean SST Variability and the Ganges-Brahmaputra River Discharge." Thesis, Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6994.
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A simple correlation analysis was used to investigate the linear relationships between sea surface temperature (SST) and monthly flow of Ganges and Brahmaputra at the borders of Bangladesh and India using approximately 50 years of river discharge data. Strong correlations were found between the equatorial Pacific SST and boreal summer Ganges discharge from three-month lag to two-month lead times. The El Nio-Southern Oscillation (ENSO) explains Ganges flow variance exceeding 0.95 significance level using both the Nino 3.4 SST correlation and the composites made for El Nio (La Nina) periods.
The May SST of the southwest Pacific Ocean to the east of Australia continent has a strong correlation (>0.6) with early summer Ganges discharges. Using a lag correlation analysis of Ganges discharge and SST, we found a steady and continuous development in the Nino 3.4 SST relationship, and a strong correlation with the southwest Pacific SST which is most pronounced three-four months prior to the onset of Asian summer monsoon. These relationships mean that at least 25% of the interannual summer Ganges River discharge variability can be explained by antecedent equatorial and southwest Pacific SST. It provides a possible statistical method for linear forecasting two or three months in advance.
The Brahmaputra River discharge, on the other hand, shows weak relationships with tropical SST variability except for the Bay of Bengal and the higher northern latitudes of the Pacific.
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Larnier, Kévin. "Modélisation thermohydraulique d’un tronçon de Garonne en lien avec l’habitat piscicole : approches statistique et déterministe." Thesis, Toulouse, INPT, 2010. http://www.theses.fr/2010INPT0079/document.
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Les espèces de poissons migrateurs (saumon atlantique, Salmo salar, en particulier) requièrent des conditions thermiques bien spécifiques. Ils sont très sensibles aux températures de l’eau et aux fortes variations estivales. Sur les trente dernières années, l’étude menée sur la Garonne (France) révèle une augmentation des températures estivales associée à un allongement de la durée des périodes chaudes. L’impact de cette modification du régime thermique sur la survie et la reproduction des espèces migratoires est également mis en évidence. Cette étude est menée sur un tronçon de Garonne, situé entre l’amont de Toulouse et l’amont de la retenue deMalause. Ce secteur est fortement touché par cette problématique avec en moyenne 2°C d’écart entre l’amont et l’aval et des températures supérieures à 25°C régulièrement atteintes. Le régime hydrologique de ce tronçon est fortement déficitaire (selon le SDAGE Adour-Garonne), la sensibilité au flux de surface est forte à cause de son lit large et peu profond, les pressions anthropiques sont importantes, ce sont autant de pistes dont l’impact sur le régime thermique est étudié. Une large collection de données hydrologiques et climatiques est exploitée afin de déterminer les processus en jeu dans l’évolution du régime thermique de ce tronçon de fleuve. Des études en tendances et corrélations et des modèles statistiques permettent de mettre en évidence d’une part la relation forte qui existe entre les températures de l’air et les températures de l’eau et d’autre part l’importance des faibles débits durant les périodes estivales. L’estimation des moyennes journalières de température de l’eau à Malause au moyen de modèles statistiques et déterministes donne de bons résultats pour les températures élevées ainsi que pour les franchissements de seuils liés aux conditions de migrations des amphilalins.Enfin un modèle numérique monodimensionnel de résolution de l’équation de transport thermique et des équations de St-Venant est développé. La physique du modèle tant au niveau hydraulique (prise en compte de fortes variabilités de pente, d’ouvrages, etc.) que thermique (apports latéraux, flux de surfaces, flux de conduction avec le lit) permet d’analyser l’évolution des différents flux qui participent au réchauffement du cours d’eau. Une évolution future à l’aide des sorties des modèles de l’IPCC est explorée et des méthodes éventuelles de restauration des conditions de températures favorables pour les espèces piscicoles sont analyséesFish species with strong thermal requirements (i.e. Atlantic salmon) are very sensitive to temperature evolution and particularly to large increases. An investigation conducted on the Garonne River (France) during the last three decades revealed global water warming along with an increase of the high temperature period duration. Large impact of this evolution on the survival and breeding of migrating fish species was also reported. Study was thus conducted on a specific reach of the Garonne River located between the immediate upstream of Toulouse and the upstream of the Malause dam. The issue of water temperature warming is particularly relevant on this reach, with an average increase of 2°C between upstream and downstream and temperatures above 25°C frequently reported. Potential causes are numerous: drastic low-flow regime (quoting SDAGE Adour-Garonne), impacts of surface fluxes that are important due to bed shape (wide and shallow), anthropogenic impacts, etc. Large amount of climatic and hydraulic data are used to make a clear determination of the processes involved in the thermal regime evolution of this reach. Trend and correlation analyses and use of statistical models indicate the strong relation between stream temperature and climate. Low flows also seem to be related to water temperatures during summer periods. Statistic and deterministic models give good results in estimating high daily mean water temperatures (RMSE ranging from 0.99°C to 1.22°C) and predicting water temperatures threshold crossings related to the migrating conditions of Atlantic salmon.Finally, a one-dimensional numerical model that solves both shallow water and thermal equations is developed. Both the formulation of the St-Venant equations (high variability in slope, gates …) and the phenomena taken into account in the water temperature model (lateral influx, surface fluxes, bed conduction …) allows studying the evolution of fluxes driving water temperature evolution. Future evolution of the water temperature at the 2050 horizon is also evaluated using IPCC models output and potential solutions to restore favorable stream temperatures conditions for fishes are analyzed
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Watz, Johan. "Salmonid behaviour under winter conditions." Doctoral thesis, Karlstads universitet, Institutionen för miljö- och livsvetenskaper, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-38354.
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Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are relatively active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. In this doctoral thesis, I report the results from experimental field and laboratory studies on the behavioural ecology of juvenile salmonids under winter conditions. My results from the field show that salmonids grow more and use a broader range of habitats in the presence of surface ice than in its absence. Results from the laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions. These laboratory results may explain the positive effects of ice cover on growth that was found in the field experiment. Moreover, I show that drift-feeding ability is reduced at low temperatures, and that nocturnal drift foraging under winter conditions has a low efficiency.Vinterförhållanden kan spela en avgörande roll för förekomsten av fisk i våra vattendrag. Laxfiskar, som till exempel lax, öring och harr, är vinteraktiva och måste därför anpassa sin fysiologi och sitt beteende till en miljö som karakteriseras av låga och föränderliga vattenflöden, liten tillgång på föda, kallt vatten, is och mörker. Trots att dessa anpassningar är avgörande för chansen att överleva vintern, vet man relativt lite om laxfiskars vinterbeteende, speciellt i vattendrag som täcks av is. I denna avhandling presenterar jag resultat från fält- och laboratoriestudier av laxfiskars beteende under vinterförhållanden och resultaten visar att närvaron av yttäckande is ökar tillväxt och födointag, minskar stress samt påverkar var fiskar uppehåller sig och hur fiskarna interagerar med varandra. Jag har också undersökt hur laxfiskars beteende i rinnande vatten påverkas av ljusintensitet och vattentemperatur i samband med födointag. Resultaten visar att den minskade dagaktiviteten som laxfiskar uppvisar på vintern medför en kostnad i form av försämrad förmåga att fånga byten.
Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fish, challenging the ability of fish to physiologically and behaviourally adapt. Climate change is predicted to increase both mean temperature and temperature fluctuations, especially during winter, leading to dynamic environmental conditions in terms of river ice production and flow. Therefore, knowledge about the winter ecology of stream fish is important for predicting and mitigating anthropogenic impacts on fish production in boreal streams. Stream salmonids are active throughout winter, and behavioural responses to different winter conditions may be critical for survival. Yet, relatively little is known about overwintering behaviour of salmonids, particularly in streams with ice. This doctoral thesis focuses on the behavioural ecology of salmonids under winter conditions, and results from field and laboratory experiments show that the presence of surface ice increases food intake rates, reduces stress and affects social interactions, with effects on growth and habitat use. Moreover, drift-feeding ability is reduced at low temperatures, and nocturnal drift foraging under winter conditions has a low efficiency.
Artikel 1 i avhandlingen som manuskript. Nu publicerad.
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Mainville, Daniel Mark, and daniel mainville@dse vic gov au. "The Impacts of Agriculture and Plantation Forestry in a Selection of Upper Catchments of the Strzelecki Ranges, Victoria." RMIT University. Civil, Environmental and Chemical Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080509.162820.
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The intensive nature of land uses in the Strzelecki Ranges poses significant threats to landscape values and water quality. A comprehensive catchment strategy was developed based on sustainability science concepts incorporating the careful management of landscape values, proper land management approaches, and government policy and legislative change to ensure that agriculture, forestry and other land uses become sustainable in this sensitive environment. The readily measurable water quality indicators of turbidity, flow, electrical conductivity, and water temperature were used to determine the impacts of the major land uses in the Strzeleckis. From a water quality perspective, there was a trend of decreasing water quality with increasing intensity in land management. However, from a total sediment load perspective, the forest area contributed the highest total sediment load due to higher volumes of steam flow suggesting that natural processes in the Strzeleckis may remain the principal mechanisms for sediment movement within the catchment. An incidental but significant finding was extensive bioturbation along the riparian zone of the plantation area, the extent of which was not observed in the other catchments. This finding suggested that bioturbation may have been the most significant contributor to poorer water quality flowing from in the plantation catchment. The project developed insights into the major environmental processes active in the upper catchment of the Morwell River. Understanding of the contributions to total sediment loads from natural erosional processes and bioturbation, findings related to the impacts on water quality from agricultural practices, and encountering negligible impacts from conservative timber harvesting practices demonstrate that catchment management approaches need to be tailored to achieve sustainability in land uses across the landscape. Key recommendations include the re-establishment and protection of riparian zones in agricultural catchments, the careful assessment and setting of stream buffer zone widths for timber harvesting operations, and the need for further work to map the extent of natural processes such as bioturbation and stream bank erosion. To mitigate these issues, government policy and legislation will need to focus on the preservation and enhancement of the Crown land riparian zones. Recommended changes to current administrative land management arrangements for these sensitive areas include a move from licensing riparian zones for agricultural practices such as grazing to conservation.
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Elmore, Logan. "Effects of Environmental Water Transfers on Stream Temperatures." DigitalCommons@USU, 2015. https://digitalcommons.usu.edu/etd/4368.
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Low streamflows and warm stream temperatures, caused mainly from agricultural diversions, currently limit available habitat and productivity of trout, including native Lahontan cutthroat trout in Nevada’s Walker River Basin. Environmental water purchases, which transfer water from willing sellers to instream uses (i.e for fish), are being evaluated to improve instream habitat. To determine which environmental water purchases to prioritize, this study was undertaken to build a computer model in order to simulate stream temperatures under differing environmental water transfer scenarios. Model runs simulate a range of environmental water transfers at major diversions and reservoirs throughout the Walker River Basin. Results indicate that low flows generally coincide with critically warm stream temperatures, cooler stream temperatures exist in the East Walker River, a tributary of the Walker River, during warm seasons which provide good habitat for fish, environmental transfers can improve stream temperatures for some highly impacted reaches by up to 3°C in dry years, and environmental water transfers have a greater effect in dry years than wet years.
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Arthur, Jarred Bradley. "The influence of upstream forest on macroinvertebrate communities in pastoral landscapes." Thesis, University of Canterbury. School of Biological Sciences, 2010. http://hdl.handle.net/10092/4925.
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The conversion of native forest to agricultural land has been an on-going issue threatening the health of New Zealand’s freshwater systems. However, despite the fact that this has been occurring since early European settlement, our understanding of the mechanistic relationships between riparian vegetation and stream condition are poorly developed. This research investigated: (i) how forests affect downstream benthic macroinvertebrate communities in pasture and the environmental factors driving community change; (ii) how upstream forest size impacted the rate of change in downstream environmental drivers and associated macroinvertebrate community structure; and (iii) whether the addition of coarse particulate organic matter (a single potential driver of forest community structure) can reset community structure to that of a forested state. Physico-chemical conditions, basal energy resources, and macroinvertebrates were surveyed in several New Zealand headwater streams.
At Mount Egmont National Park, 10-12 sites were surveyed across a longitudinal forest-pasture gradient in each of five streams flowing from continuous forest to dairy farmland. My results showed that forests can have marked effects downstream. From the forest edge, water temperatures increased consistently, with a rise of approximately 0.2ºC per 100 m of downstream distance. By contrast, coarse particulate organic matter (CPOM) decreased rapidly downstream of the forest, however, low levels of “forest-derived” CPOM were still present 300m downstream from the forest edge. These environmental changes drove significant shifts in macroinvertebrate community structure. Moreover, pasture communities were
markedly different from those in forest, despite being only 100 m from the forest edge. In particular, total macroinvertebrate and EPT richness and densities decreased,
and communities shifted from evenly distributed allochthonous-based communities to autochthonous-based communities, highly dominated by molluscs (e.g., Potamopyrgus spp.)
Subsequent surveys of 6-8 sites across a longitudinal forest-pasture gradient in each of eleven streams flowing from forest fragments of different sizes into grazed
pastures throughout the Canterbury region, indicated that stream temperature increased more rapidly downstream of small- and medium-sized fragments, than larger fragments. A Berger-Parker dominance index also indicated that macroinvertebrates responded principally to water temperature, with communities being more highly dominated by temperature-tolerant molluscs in streams flowing from small-sized forest fragments.
Several headwater streams in Canterbury were also highly retentive, with marked CPOM rarely exported beyond 50 m downstream of the forest. Experimental additions of leaf litter to the pasture reaches of the same streams dramatically increased amounts of stored benthic CPOM. Although non-significant, trends indicated that EPT and shredder densities increased at litter addition sites, providing promise that CPOM can function as a mechanism directly enhancing healthy stream communities. My findings support the contention that when the replanting of entire
stream reaches is infeasible, the use of riparian management strategies which focus on the planting of intermittent patches along stream banks can potentially improve stream habitat and community health downstream.