Modeling the Effects of Climate Change on Streamflow in a Sub-basin of the Lower Churchill River, Labrador PDF Download

Author: Amy Pryse-Phillips
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Category :
Languages : en
Pages : 276

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Author: Jonas Roberts
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Languages : en
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This manuscript thesis presents four stand-alone papers which all contribute to the investigation of projected impacts of climate change on the hydrology of Labrador's Churchill River Basin. The overarching goal of this undertaking was to provide useful information to Nalcor Energy, a hydroelectric developer, regarding the change in the amount and timing of water in the Churchill River between a base period (1971-2000) and a future period (2041-2070). Three separate multi-model approaches used data from the North American Regional Climate Change Assessment Program to look at the impacts of climate change on the Churchill River: (i) Bias-corrected precipitation and temperature data forced a hydrologic model to investigate the changes in mean daily streamflow for the Pinus River, a subbasin of the Churchill River; (ii) A new approach (dubbed "fullstream analysis") took advantage of the full range of simulated hydrological variables from each ensemble member and was used to study the expected changes in mean annual runoff of the entire basin, and; (iii) Weighted multi-model ensembles examined the simulated impacts of climate change on mean monthly runoff for the entire basin. Several results were common across the various approaches. Ensemble mean annual increases in runoff were found to be similar, between 8.9% and 14.6%. Further to this, an increase in cold-season runoff amounts, an earlier onset of the spring melt (though not necessarily a larger spring melt) and no discernable change in the late summer and early fall runoff were found. In an effort to further understand sources of error and uncertainty of the climate models used, water balances were investigated and the annual cycle of residuals quantified. Residual magnitudes varied widely between months and models and were dependent on whether one examined atmospheric or terrestrial balances. Water balance residuals remained relatively consistent between time periods implying they are systemic and not climate dependent.

Author: Katherine Mary Clarke
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Category : Salmonidae
Languages : en
Pages : 132

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The Stillaguamish River in northwest Washington State is an important regional water resource for local agriculture, industry, and First Nations tribes and a critical habitat for several threatened and endangered salmonid species, including the Chinook salmon. The river is currently subject to a temperature total maximum daily load, so it is important to understand how projected climate change will affect future stream temperatures and thus salmon populations. Snowpack is the main contributor to spring and summer streamflow and helps to mitigate stream temperatures as air temperatures rise through the summer in the South Fork of the Stillaguamish River. I used gridded historical meteorological data to calibrate the physically-based Distributed Hydrology Soil Vegetation Model and River Basin Model and then applied downscaled, gridded projected climate data to predict how a changing climate will influence hydrology and stream temperature in the South Fork basin through the end of the 21st century.

Author: Fei Tang
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Languages : en
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" In the Nicolet River watershed of Southern Quebec, Canada, runoff resulting from snowmelt is responsible for the spring peak flow, which may result in flooding when temperature rises rapidly in a short time. In this study, streamflow modeling for the Nicolet River watershed was conducted, then the impacts of climate change on the hydrology of this basin were studied by comparing the streamflow characteristics of historical and projected future climate data under a wide range of climate change scenarios. The Soil and Water Assessment Tool (SWAT), was calibrated and validated against the observed streamflow for the period of 1986-1990 and 1991-2000, respectively. The ArcSWAT model was shown to be a reliable tool for simulating the stream flow (PBIAS within 15%, Nash-Sutcliffe efficiency (NSE) > 0.50 and RMSE-observations standard deviation ratio (RSR)

Author: Ioannis Kamarinas
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Category : Streamflow
Languages : en
Pages : 132

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Author: Amy Dietrich
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Languages : en
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Climate change is one of the most significant global environmental drivers threatening the quality and quantity of future water resources. Global temperature increases will have significant effects on the hydrologic regime of northern regions due to changes in snowfall and snowmelt. Considerable research has been conducted in western Canada to rigorously quantify snowmelt-driven streamflow processes, however, less focus has been directed towards understanding these processes in eastern Canada and Ontario. In the southern Ontario Grand River Watershed (GRW), snowmelt contributions to streamflow (freshet) make up a significant portion of the annual water yield, and the period of snowmelt is also of key concern for flood mitigation. This thesis aims to quantify historical and projected changes to timing and streamflow during freshet in the Nith River, an unregulated tributary of the Grand River. Climate data (temperature, rainfall, snowfall, and snow proportion) from observations and future scenarios were analyzed to quantify the contributions of climate conditions surrounding the timing and volume of the freshet. The annual timing of snowmelt-driven streamflow was quantified using centre time (CT), and streamflow volumes were quantified by various percentiles of streamflow (Qn) during four periods of the water year (October-December, January-February, March-April, and May-September). Historical trends in streamflow and climate data were examined using hydrometric data (1914-2016) of a stream gauge from the Water Survey of Canada, and climate data (1950-2016) from Environment and Climate Change Canada at two stations. Projected climate data were from an ensemble of models used in the Intergovernmental Panel on Climate Change's Fourth Assessment Report (AR4). A total of nine distinct models ran two scenarios from AR4 for the 2050s; moderate (B1) and high (A1B). These time-slice projections were then used to force the hydrologic model GAWSER to simulate future streamflow data. The results show that CT in the Nith River has advanced by 17 days, on average, from 1914 to 2016 (P=0.036), and the advance is projected to continue as a function of future emissions scenario (approximately 12 days for scenario B1, and 17 days for A1B). Historical CT was weakly negatively correlated with temperature (-0.51, P

Author: Evan A. Paul
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Category : Climatic changes
Languages : en
Pages : 0

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The Nooksack River in northwest Washington State provides freshwater for agriculture, municipal, and industrial use and serves as a vital habitat for endangered salmon, a resource that is of cultural and economic importance to the Nooksack Indian Tribe and the surrounding region. Due to the complex topography in the basin and the mild maritime climate of the Puget Sound region, streamflow in the Nooksack River is highly sensitive to fluctuations in air temperature. Global climate models (GCMs) project an increase in air temperatures for the Puget Sound region, and previous modeling within the Nooksack basin projects a reduction in snowpack extent through the 21st century and an increase in winter streamflow magnitude. As more landscape becomes exposed to rain rather than snow and heavy winter precipitation events intensify, peak flows and sediment delivery to streams will likely increase due to rapid runoff, resulting in salmon habitat degradation and increased flood risk. Thus, anticipating the effect of climate change on peak flows is crucial for salmon habitat restoration efforts and flood mitigation planning. To quantify the timing and magnitude of future peak flows, I use a calibrated Distributed Hydrology Soil Vegetation Model (DHSVM) and meteorological forcings from an ensemble of high-emission GCMs dynamically-downscaled using the Weather Research and Forecasting (WRF) model. Due to the variability of climate scenarios depicted by GCMs, a range of streamflow and snowpack magnitude changes in the Nooksack River basin are projected by the hydrology simulations. By the end of the 21st century, results indicate a decrease in annual peak snow-water equivalent (-72% to -82%), a shift in the timing of peak snow-water equivalent to approximately one month earlier, an increase in winter flows (+31% to +56%), a decrease in summer flows (-37% to -72%), and the disappearance of the snowmelt derived spring peak in the hydrograph as the basin transitions from transient to rain-dominant. These results are consistent with previous modeling in the Nooksack River basin and other regional climate change studies in the Pacific Northwest and Puget Sound region. Due to more precipitation falling as rain rather than snow and heavy rain events becoming more frequent and intense, future peak flows are projected to increase in magnitude by 34-60% across all flow durations and return periods that were analyzed, with the largest changes occurring in the high relief subbasins. The frequency of high magnitude, flood-inducing peak flows will also increase into the future, lengthening the flood season by approximately three months.

Author: Michael John Fernandes Vieira
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Category :
Languages : en
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Author: Robert Baidoc
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Languages : en
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Watershed models are an important tool in regional planning and conservation efforts. They can provide valuable insight into the potential impacts of different land use changes and future climate change scenarios on water resources, which can lead to better, more informed decision making. Climate impacts, in particular, add a new level of uncertainty with regard to freshwater supplies as the hydrological cycle is intimately linked with changes in atmospheric temperatures. The main objective of this study is to investigate the extent of long-term climate change on streamflow and stream temperature within an agriculturally defined watershed in Northern Ontario. For this purpose, the Soil and Water Assessment Tool (SWAT) model was utilized to provide a better understanding of how hydrological processes in the Slate River Watershed will alter in response to long-term climate change scenarios. The SWAT model is a distributed/semi-distributed physically-based continuous model, developed by the USDA for the management of agricultural watersheds, and is currently one of the most popular watershed-based models used in climate change analysis of snowmelt dominated watersheds. Historic flow data was compared to a discharge model that reflected four climate models driven by SRES A1B and A2 through the middle and end of the century. Hydrology modelling was enhanced with stream temperature analysis to gain a comprehensive understanding of the extent of changing climate regimes on the Slate River. A linear regression approach representing a positive relationship between stream temperature and air temperature was used to determine the thermal classification of the Slate River. Our results indicated that the Slate River was well within the warm-water character regime. Unusual high stream temperatures were recorded at mid- August; these were accompanied by low water levels and a lack of riparian vegetative cover at the recording site, providing a possible explanation for such temperature anomalies. The results of the flow discharge modelling supported our hypothesis that tributaries within our ecosystem would experience increasing water stress in a warming climate as the average total discharge from the Slate River decreased in both climate scenarios at the middle and end of the century. Although the lack of accurate subsurface soil data within the study region prevented our discharge model from quantifying the changes in stream discharge, the strong correlation between the observed and simulated flow data as reflected by a 0.92 r2 statistic gave us confidence that discharge from the Slate River will continue to follow a decreasing trend as climate change persists into the future. This study aims to support the future endeavours of hydrologic modelling of watersheds in Northern Ontario by illustrating the current capabilities and limits of climate change analysis studies within this region.

Author: Sulochan Dhungel
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Languages : en
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A major challenge in freshwater ecosystem management is to predict future changes in streamflow regime. This thesis focused on identifying and modeling specific characteristics of streamflow that are important to stream ecosystems. The need to evaluate the potential impacts of climate change on stream ecosystems makes it important to study how streamflow regime may change. In this thesis we sought to advance understanding of the effect of climate change on streamflow regime by (1) examining the spatial variation in streamflow attributes across the continental US, (2) modeling how these streamflow attributes vary with current climate and watershed features, and (3) using this model with future climate projections of changes in precipitation and temperature to predict how streamflow attributes change with climate change. We used long-term daily flow measurements for 601 gauged streams whose watersheds were in relatively unimpaired condition to characterize streamflow regimes. Sixteen streamflow variables were identified which in our judgment sufficiently characterized aspects of the streamflow regime most relevant to stream ecosystem structure and function. These are computed for each stream. Principal component analysis with Varimax rotation reduced the dimensionality to five uncorrelated streamflow factors that quantify lowflow, magnitude, flashiness, timing and constancy. These independent factors were used to hereafter classify the streams based on distances in factor space into three broad classes which were further divided into eight classes. We used Random Forests to develop a model to predict these stream classes using watershed and climate attributes. The model had an accuracy of about 75%. Downscaled climate projections of precipitation and temperature were used to predict the changes in these stream classes by 2100 using the RF model. Thirty-three percent of selected sites were predicted to change into a different stream class by 2100. The least changes were predicted in snow-fed streams in the west while most of changes were predicted for rain-fed small perennial streams and intermittent streams in the central and eastern US. Class changes predicted, due to projected climate change provide a basis for (i) considering the extent of projected changes and (ii) formulating approaches to protect ecosystems that may be subject to change.