Thank you for your interest!

The two studentships below are currently being advertised for on the UEA-ENV Studentship pages through which you can apply for either of these studentships.

You can also contact me for any queries you might have.

_____________________

Quantifying the hydrological impacts of permafrost degradation in the 21st century

Primary supervisor: Dr. V.F. Bense

Forced by the ongoing rise in annual surface temperatures the (sub)-Arctic is undergoing an exceptional amount of environmental change. In the terrestrial water cycle at high latitudes groundwater is expected to play an increasingly important role as permafrost degradation should lead to phenomena such as deeper groundwater flow paths, enhanced infiltration of melt water, development of more widespread thaw lakes and a more significant contribution of groundwater to total fresh water discharge through Arctic rivers. Recently, compelling evidence has been reported that groundwater flow systems are indeed being reactivated under the influence of ongoing surface warming. However, the dynamics to be expected of the hydrological response of Arctic systems during permafrost degradation is not well understood and therefore difficult to forecast. There is a clear need for studies which seek to elucidate and quantify groundwater dynamics in permafrost regions and its role in hydrological and environmental change in light of climate warming. Recently developed groundwater models [Bense et al., 2009] provide ample opportunity for further development and provide excellent tools to generate valuable new insight in system behaviours and surface hydrological responses. This project will primarily focus on the latter task in combination with a thorough analysis of field data available while at a later stage within this project collection of further field data will probably be carried out.

Reference:

Bense, V.F., G. Ferguson and H. Kooi (2009), Evolution of shallow groundwater flow systems in areas of degrading permafrost, Geophysical Rersearch Letters, doi:10.1029/2009GL039225

_____________________

Distributed Temperature Sensing along fibre-optic cables in environmental monitoring

Primary supervisor: Dr. V.F. Bense

Detailed measurements of the spatial and temporal variability of water temperature in lakes, streams and underground are of great interest to hydrologists, ecologists and geochemists studying the dynamics of these water bodies. The localities of enhanced groundwater-surface water interaction can be mapped by measuring temperatures along lake/stream beds. Such places can be expected to form the location of ecological niches controlling habitat architecture in a stream. Since groundwater normally has an anomalous temperature compared to the surface water in the stream or lake, there is typically a shift in water temperature around places of groundwater seepage. Repeated measurement can, moreover, be used to quantify fluid fluxes across this interface [e.g. Bense and Kooi, 2004]. While these point measurements along horizontal lines yield valuable information, temperature variations with depth both in the subsurface as well as in open-water bodies can be used to quantify another suite of processes. These range from vertical mixing rates in open-water bodies while temperature-depth measurements from borehole and/or groundwater observation wells can be used for the reconstruction of palaeo surface temperatures [e.g. Huang et al., 2000], quantification of groundwater flow rates and the underground temperature effects of deforestation and urbanization [e.g. Bense and Beltrami, 2007]. Both types of measurements described above, would normally require instrumentation to either probe for temperature at closely spaced points along a set profile (horizontal profiling), or to slower lower a temperature probe into open water or a bore-hole to obtain a vertical  profile. Both methodologies are very labor-intensive even more so if time-series would be needed. Relatively recently, reports have emerged in the literature about the use of a distributed temperature system (DTS) using optical principles along fibre cables to determine with astounding accuracy and speed the temperature distribution along the cable [e.g. Selker et al., 2006]. The principle behind DTS is that a pulse of light (laser) with a certain frequency and wavelength will be sent through the cable of which part is then reflected back. The time it takes for the signal to return is a function of the location where the light was reflected, but moreover, frequency shifts in the reflected signal (the anti-Stokes components of the signal) are a linear function of the temperature of the cable. Using input signals with varying wavelength/frequencies, the temperature along the cable can now be measured accurately within a couple of minutes. The accuracy of the measurement improves considerably when repeated measurements are done. Using DTS, temperature distribution along 10 km long cables can be efficiently measured to 0.01 oC with a spatial accuracy of 1 meter [Selker et al., 2006], something that would be practically impossible using any other current methodology to measure streambed temperatures. The School of Environmental Sciences has recently acquired a DTS system and this studentship will explore a suite of applications in environmental monitoring, e.g. surface-water groundwater interaction, using this system in combination with numerical modelling of those systems as well as in combination with additional data sets.

References:

Bense, V., and H. Beltrami (2007), Impact of horizontal groundwater flow and localized deforestation on the development of shallow temperature anomalies, Journal of Geophysical Research, 112, F04015, doi:10.1029/2006JF000703.

Bense, V.F. and H. Kooi (2004), Temporal and spatial variations of shallow subsurface temperature as a record of lateral variations in groundwater flow, Journal of Geophysical Research, VOL. 109, B04103, doi:10.1029/2003JB002782

Huang, S., Pollack, H. N., and Shen, P.Y., 2000. Temperature trends over the past five centuries reconstructed from borehole temperatures. Nature, 403: 756-758.

Selker, J.S., van de Giesen, N., Westhoff, M., Luxemburg, W, and Parlange, M. 2006. Fiber Optics Opens Window on Stream Dynamics. Geophysical Research Letters, doi:10.1029/2006GLO27979.

_____________________