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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Investigation of Changes in Hydrological Processes using a Regional Climate Model

Bhuiyan, AKM Hassanuzzaman 23 August 2013 (has links)
This thesis evaluates regional hydrology using output from the Canadian Regional Climate Model (CRCM 4.1) and examines changes in the hydrological processes over the Churchill River Basin (CRB) by employing the Variable Infiltration Capacity (VIC) hydrology model. The CRCM evaluation has been performed by combining the atmospheric and the terrestrial water budget components of the hydrological cycle. The North American Regional Reanalysis (NARR) data are used where direct observations are not available. The outcome of the evaluation reveals the potential of the CRCM for use in long-term hydrological studies. The CRCM atmospheric moisture fluxes and storage tendencies show reasonable agreement with the NARR. The long-term moisture flux over the CRB was found to be generally divergent during summer. A systematic bias is observed in the CRCM precipitation and temperature. A quantile-based mapping of the cumulative distribution function is applied for precipitation adjustments. The temperature correction only involves shifting and scaling to adjust mean and variance. The results indicate that the techniques employed for correction are useful for hydrological studies. Bias-correction is also applied to the CRCM future climate. The CRCM bias-corrected data is then used for hydrological modeling of the CRB. The VIC-simulated streamflow exhibits acceptable agreement with observations. The VIC model's internal variables such as snow and soil moisture indicate that the model is capable of simulating internal process variables adequately. The VIC-simulated snow and soil moisture shows the potential of use as an alternative dataset for hydrological studies. Streamflow along with precipitation and temperature are analyzed for trends. No statistically significant trend is observed in the daily precipitation series. Results suggest that an increase in temperature may reduce accumulation of snow during fall and winter. The flow regime may be in transition from a snowmelt dominated regime to a rainfall dominated regime. Results from future climate simulations of the A2 emission scenario indicate a projected increase of streamflow, while the snow depth and duration exhibit a decrease. Soil moisture response to future climate warming shows an overall increase with a greater likelihood of occurrences of higher soil moisture.
2

Investigation of Changes in Hydrological Processes using a Regional Climate Model

Bhuiyan, AKM Hassanuzzaman 23 August 2013 (has links)
This thesis evaluates regional hydrology using output from the Canadian Regional Climate Model (CRCM 4.1) and examines changes in the hydrological processes over the Churchill River Basin (CRB) by employing the Variable Infiltration Capacity (VIC) hydrology model. The CRCM evaluation has been performed by combining the atmospheric and the terrestrial water budget components of the hydrological cycle. The North American Regional Reanalysis (NARR) data are used where direct observations are not available. The outcome of the evaluation reveals the potential of the CRCM for use in long-term hydrological studies. The CRCM atmospheric moisture fluxes and storage tendencies show reasonable agreement with the NARR. The long-term moisture flux over the CRB was found to be generally divergent during summer. A systematic bias is observed in the CRCM precipitation and temperature. A quantile-based mapping of the cumulative distribution function is applied for precipitation adjustments. The temperature correction only involves shifting and scaling to adjust mean and variance. The results indicate that the techniques employed for correction are useful for hydrological studies. Bias-correction is also applied to the CRCM future climate. The CRCM bias-corrected data is then used for hydrological modeling of the CRB. The VIC-simulated streamflow exhibits acceptable agreement with observations. The VIC model's internal variables such as snow and soil moisture indicate that the model is capable of simulating internal process variables adequately. The VIC-simulated snow and soil moisture shows the potential of use as an alternative dataset for hydrological studies. Streamflow along with precipitation and temperature are analyzed for trends. No statistically significant trend is observed in the daily precipitation series. Results suggest that an increase in temperature may reduce accumulation of snow during fall and winter. The flow regime may be in transition from a snowmelt dominated regime to a rainfall dominated regime. Results from future climate simulations of the A2 emission scenario indicate a projected increase of streamflow, while the snow depth and duration exhibit a decrease. Soil moisture response to future climate warming shows an overall increase with a greater likelihood of occurrences of higher soil moisture.
3

An assessment of Pinus contorta seed production in British Columbia: Geographic variation and dynamically-downscaled climate correlates from the Canadian Regional Climate Model

Lew, Alicia 28 April 2015 (has links)
Lodgepole pine (Pinus contorta Douglas ex Louden) is the most widespread pine in North America and the single most abundant tree species in British Columbia (BC). Its vast distribution, diversity and economic value make it an important species for timber harvest and subsequent reforestation. Climate change raises serious concerns over the adaptability and effective management of BC’s future forests. The majority of lodgepole pine seedlings requested for replanting are produced from seed obtained from wild stands, but the relationship between climate variation and the seed production of natural populations has yet to be assessed. The purpose of this study is to determine if variation in P. contorta seed yield is related to the climate of BC. Historical cone collection data were obtained from archived records of 1948 seedlots in 22 different natural stand seed planning zones (SPZs) of BC. Collections were made between 1963 and 2013 and seed yield (kg fresh seed/hL cone) was determined for each seedlot. First, natural variation in seed production of lodgepole pine was examined in 18 different SPZs. The Nass Skeena Transition (NST) represents a unique intersection between continental and maritime ecosystems and was found to have a significantly higher mean seed yield compared to all other zones, with the exception of Hudson Hope (HH). However, variance in seed yield for NST was found to be an order of magnitude higher than that of other SPZs, indicating that seed production in this region is exceptionally variable. These findings provide a valuable geographic baseline for the reproductive fitness of lodgepole pine, suggesting that climate adaptation and mitigation strategies for some areas of the province may need to be region-specific. In addition, the relationship between climate variation and the seed production of P. contorta in BC was evaluated. The climate of each region was described using dynamically-downscaled Global Circulation Model (GCM) and reanalysis climate output from the Canadian Regional Climate Model (CRCM). Annual, winter, and summer means were explored for each of the climate variables of interest: total precipitation (mm) and surface air temperature (°C). Temporal correlations between the mean annual seed yield anomaly and the anomaly of both climate variables were significant under a variety of climate schemes in a number of SPZs. Significant overall trends in climate variables were also captured using GCM-driven CRCM output. While these two analyses independently highlighted significant relationships between seed yield and climate, their joint implications were unclear. Shifts in the CRCM boundary conditions revealed that the results lacked robustness during the historical period, inhibiting the investigation of future projections. Ambiguous age ranges for each cone collection and temporal restrictions of the seed collection data may be partially responsible for these inconclusive results. Results from the first half of this thesis suggest that, with few exceptions, seed production is relatively stable across SPZs spanning a wide range of climate regimes. Thus, the investigation of the relationship between reproductive fitness and climate may be complicated by the extraordinary adaptability of lodgepole pine and the high genetic variation in natural populations. / Graduate
4

Present and Future Wind Energy Resources in Western Canada

Daines, Jeffrey Thomas 17 September 2015 (has links)
Wind power presently plays a minor role in Western Canada as compared to hydroelectric power in British Columbia and coal and natural gas thermal power generation in Alberta. However, ongoing reductions in the cost of wind power generation facilities and the increasing costs of conventional power generation, particularly if the cost to the environment is included, suggest that assessment of the present and future wind field in Western Canada is of some importance. To assess present wind power, raw hourly wind speeds and homogenized monthly mean wind speeds from 30 stations in Western Canada were analyzed over the period 1971-2000 (past). The hourly data were adjusted using the homogenized monthly means to attempt to compensate for differences in anemometer height from the standard height of 10m and changes in observing equipment at stations. A regional reanalysis product, the North American Regional Reanalysis (NARR), and simulations conducted with the Canadian Regional Climate Model (CRCM) driven with global reanalysis boundary forcing, were compared to the adjusted station wind-speed time-series and probability distributions. The NARR had a better temporal correlation with the observations, than the CRCM. We posit this is due to the NARR assimilating regional observations, whereas the CRCM did not. The NARR was generally worse than the CRCM in reproducing the observed speed distribution, possibly due to the crude representation of the regional topography in NARR. While the CRCM was run at both standard (45 km) and fine (15 km) resolution, the fine grid spacing does not always provide better results: the character of the surrounding topography appears to be an important factor for determining the level of agreement. Multiple simulations of the CRCM at the 45 km resolution were also driven by two global climate models (GCMs) over the periods 1971-2000 (using only historic emissions) and 2031-2060 (using the A2 emissions scenario). In light of the CRCM biases relative to the observations, these simulations were calibrated using quantile-quantile matching to the adjusted station observations to obtain ensembles of 9 and 25 projected wind speed distributions for the 2031-2060 period (future) at the station locations. Both bias correction and change factor techniques were used for calibration. At most station locations modest increases in mean wind speed were found for most of the projected distributions, but with a large variance. Estimates of wind power density for the projected speed distributions were made using a relationship between wind speed and power from a CRCM simulation for both time periods using the 15km grid. As would be expected from the wind speed results and the proportionality of wind power to the cube of wind speed, wind power at the station locations is more likely than not to increase in the 2031-2060 period from the 1971-2000 period. Relative changes in mean wind speeds at station locations were found to be insensitive to the station observations and choice of calibration technique, suggesting that we estimate relative change at all 45km grid points using all pairs of past/future mean wind speeds from the CRCM simulations. Overall, our results suggest that wind energy resources in Western Canada are reasonably likely to increase at least modestly in the future. / Graduate / 0725 / 0608 / jtdaines@uvic.ca

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