Student Award 2011 - Prize Winners
21/10/2011
2011 Student Award
BHS launched its annual student award in 2002 to promote the study of hydrology and raise awareness of the Society at undergraduate level. Prizes are awarded on the achievement, relevance, originality and presentation of submitted final-year dissertations addressing scientific and applied issues in hydrology, judged by a panel drawn from the BHS Main Committee.
Gemma Coxon (University of Bristol) was judged to be the winner of the competition for her work ‘An evaluation of multiple hydrological model hypotheses in the UK using a framework for understanding structural errors’. Gemma is continuing at Bristol to study for a PhD.
Runner-up prizes were also awarded to Alexandra Semproni (Southampton University) for ‘A morphological investigation of step-pools using flume experiments’ and to David Morrell (Lancaster University) for ‘Using geochemical isotopic indicators to characterise the glacial drainage system and identify subglacial volcanism, Sólheimajökull, Iceland’.
Abstracts from these three dissertations are given below.
Look out for details of the 2012 award from April next year.
Abstracts of the winning dissertations
Gemma Coxon (University of Bristol)
An evaluation of multiple hydrological model hypotheses in the UK using a framework for understanding structural errors
Hydrological models are important predictive tools for operational purposes and hydrological research. However, little consideration has been made in the hydrological literature over which hydrological model to choose for a given application. It is demonstrated in this dissertation how multiple flexible model structures can be used to assess model structural errors and model structure identification. As an example application, eight UK catchments, assumed to represent a range of different climate and hydrological characteristics, are applied within a Framework for Understanding Structural Errors (FUSE). Model structure and parameter uncertainty is assessed through a Monte Carlo framework. A set of behavioural models is then used to look at multiple model structures in a regionalisation context.
FUSE has been shown to perform reasonably well in UK catchments with a maximum Nash-Sutcliffe efficiency of 0.89 for some of the catchments. Significant model structural uncertainty is found, whereby a large range of different model structures are able to fit the observed data well. Although a range of different model structures is shown to perform well for certain catchments, FUSE is unable to produce reasonable results for three of the catchments. This is attributed to input data errors or a limitation of the lumped conceptual models that are used as part of FUSE.
The study clearly justifies the use of multiple model structures in hydrological modelling methodologies in order to gain an understanding of model structural error and reduce model bias. However, significant challenges remain. The findings highlight the inherent limitations of discriminating between multiple model structures using rainfall-runoff data with large errors. The need for better diagnostic tools to test models is also clearly demonstrated.
Alexandra Semproni (Southampton University)
A morphological investigation of step-pools using flume experiments
Step-pool systems are predominantly present in steep channels where lateral erosion and incision are high. To reduce the potential energy of the water, the step-pool sequences encourage tumbling flow, which dissipates energy. This investigation considers step-pool morphology through a series of flume experiments. The relationships between key variables are investigated and compared with the findings in the literature. The variables are normalised by other key variables which are thought to have some control, removing scale and dimensions. Dimensionless variables are important as this is the only method by which findings from different studies can be compared adequately. Without the issue of scale, trends and relationships can be easily identified. This investigation found a number of strong correlations; the strongest of which is between step height and keystone size (R2 = 0.87). Wavelength/step height and slope illustrated correlations shared by this investigation, Chin (1999) and Curran and Wohl (2003). Future research progressing from this study will be to conduct a wider, more in depth comparison of dimensionless variables of previous findings. This has the potential to improve the management and restoration of step-pool systems.
David Morrell (Lancaster University)
Using geochemical isotopic indicators to characterise the glacial drainage system and identify subglacial volcanism, Sólheimajökull, Iceland
Up until now most research concerning glacial stability and longevity has focused on the top-down approach to parameterise melting. However, this approach disregards bottom-up forcing and resultant melt. In particular the role of subglacial volcanism has received little attention but is understood to have potentially significant effects upon an ice mass’ stability and dynamics. An understanding of this is of major importance as many of the world glaciated areas overlie volcanically active zones such as the Icelandic Ice Caps and the West Antarctic Ice Sheet.
In this study hydrological and geochemical indicators collected over two short field seasons during 2009 and 2010 were used in order to gain an understanding of the hydrological system associated with Sólheimajökull, Iceland. A number of sample sites were chosen in order to gain the fullest characterisation possible of the hydrological system. Hydrological data was taken from an automatic logger mounted on a bridge at the terminus of the proglacial system provided by the Icelandic Metrological Office and gave a continuous time series for the period studied allowing more detailed temporal analysis. This in turn was used to gain a knowledge of the processes that occurred within the system. Sulphate concentrations coupled with conductivity readings allowed identification of subglacial upwellings and seeps. A proportion of this was attributed to geothermal melting through the use of sulphur isotopes as definitive indicators of geothermal activity. The δ34S values together with sulphate concentration aided by δ18O and δD values allowed 3 end members of the system to be identified; supra glacial inputs, inputs from Jökulsárgil, and subglacial melt water, of which a proportion was identified as being from a subglacial geothermal origin through analysis of the isotopic indicators.
For further information contact Claire Walsh claire.walsh@ncl.ac.uk.
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