Stephen Grebby

Dr. Stephen Grebby

Nottingham Geospatial Institute, University of Nottingham, Nottingham NG7 2TU, UK
orcid

Research Focus & Metrics

Academic Career Length

21Years (2006-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

View All Publications
1 July 2014 in Journal of Hydrology
Verified
Journal Article
Open access
JMJames D. Miller
James D. Miller
HKHyeonjun Kim
Hyeonjun Kim
TKThomas R. Kjeldsen
Thomas R. Kjeldsen
JPJohn Packman
John Packman
SGStephen Grebby
Stephen Grebby
RDRachel Dearden
Rachel Dearden
This paper investigates changes in storm runoff resulting from the transformation of previously rural landscapes into peri-urban areas. Two adjacent catchments (∼5km2) located within the town of Swindon in the United Kingdom were monitored during 2011 and 2012 providing continuous records of rainfall, runoff and actual evaporation. One catchment is highly urbanized and the other is a recently developed peri-urban area containing two distinct areas of drainage: one with mixed natural and storm drainage pathways, the other entirely storm drainage. Comparison of observed storm hydrographs showed that the degree of area serviced by storm drainage was a stronger determinant of storm runoff response than either impervious area or development type and that little distinction in hydrological response exists between urban and peri-urban developments of similar impervious cover when no significant hydraulic alteration is present. Historical levels of urbanization and impervious cover were mapped from the 1960s to the 2010s based on digitized historical topographic maps and were combined with a hydrological model to enable backcasting of the present day storm runoff response to that of the catchments in their earlier states. Results from the peri-urban catchment showed an increase in impervious cover from 11% in the 1960s to 44% in 2010s, and introduction of a large-scale storm drainage system in the early 2000s, was accompanied by a 50% reduction in the Muskingum routing parameter k, reducing the characteristic flood duration by over 50% while increasing peak flow by over 400%. Comparisons with changes in storm runoff response in the more urban area suggest that the relative increase in peak flows and reduction in flood duration and response time of a catchment is greatest at low levels of urbanization and that the introduction of storm water conveyance systems significantly increases the flashiness of storm runoff above that attributed to impervious area alone. This study demonstrates that careful consideration is required when using impervious cover data and when designing flood mitigation measures, particularly in peri-urban areas where a widespread loss in pervious surfaces and alteration of drainage pathways can significantly alter the storm runoff response. Recommendations include utilizing more refined urban land use typologies that can better represent physical alteration of hydrological pathways

1 August 2016 in Journal of Geochemical Exploration
Verified
Journal Article
Closed access
CKCharlie Kirkwood
Charlie Kirkwood
MCMark Cave
Mark Cave
DBDavid Beamish
David Beamish
SGStephen Grebby
Stephen Grebby
AFAntonio Ferreira
Antonio Ferreira

1 April 2018 in Food Research International
Verified
Journal Article
Open access
NCNicola Caporaso
Nicola Caporaso
MWMartin B. Whitworth
Martin B. Whitworth
SGStephen Grebby
Stephen Grebby
IFIan D. Fisk
Ian D. Fisk
Hyperspectral imaging (HSI) is a novel technology for the food sector that enables rapid non-contact analysis of food materials. HSI was applied for the first time to whole green coffee beans, at a single seed level, for quantitative prediction of sucrose, caffeine and trigonelline content. In addition, the intra-bean distribution of coffee constituents was analysed in Arabica and Robusta coffees on a large sample set from 12 countries, using a total of 260 samples. Individual green coffee beans were scanned by reflectance HSI (980-2500nm) and then the concentration of sucrose, caffeine and trigonelline analysed with a reference method (HPLC-MS). Quantitative prediction models were subsequently built using Partial Least Squares (PLS) regression. Large variations in sucrose, caffeine and trigonelline were found between different species and origin, but also within beans from the same batch. It was shown that estimation of sucrose content is possible for screening purposes (R2=0.65; prediction error of ~0.7% w/w coffee, with observed range of ~6.5%), while the performance of the PLS model was better for caffeine and trigonelline prediction (R2=0.85 and R2=0.82, respectively; prediction errors of 0.2 and 0.1%, on a range of 2.3 and 1.1% w/w coffee, respectively). The prediction error is acceptable mainly for laboratory applications, with the potential application to breeding programmes and for screening purposes for the food industry. The spatial distribution of coffee constituents was also successfully visualised for single beans and this enabled mapping of the analytes across the bean structure at single pixel level.

21 October 2006 in Geophysical Research Letters
Verified
Journal Article
Closed access
PDF file
DCDickson Cunningham
Dickson Cunningham
SGStephen Grebby
Stephen Grebby
KTKevin Tansey
Kevin Tansey
AGAndrej Gosar
Andrej Gosar
VKVanja Kastelic
Vanja Kastelic

1 June 2018 in Journal of Food Engineering
Verified
Journal Article
Open access
Nicola CaporasoNicola Caporaso
Nicola Caporaso
MWMartin B. Whitworth
Martin B. Whitworth
SGStephen Grebby
Stephen Grebby
IFIan D. Fisk
Ian D. Fisk
Hyperspectral imaging (1000–2500 nm) was used for rapid prediction of moisture and total lipid content in intact green coffee beans on a single bean basis. Arabica and Robusta samples from several growing locations were scanned using a “push-broom” system. Hypercubes were segmented to select single beans, and average spectra were measured for each bean. Partial Least Squares regression was used to build quantitative prediction models on single beans (n = 320–350). The models exhibited good performance and acceptable prediction errors of ∼0.28% for moisture and ∼0.89% for lipids.

4 January 2021 in Communications Earth & Environment
Verified
Journal Article
Open access
PDF file
SGStephen Grebby
Stephen Grebby
ASAndrew Sowter
Andrew Sowter
JGJon Gluyas
Jon Gluyas
DTDavid Toll
David Toll
DGDavid Gee
David Gee
RGRenoy Girindran
Renoy Girindran
Catastrophic failure of a tailings dam at an iron ore mine complex in Brumadinho, Brazil, on 25th January 2019 released 11.7 million m3 of tailings downstream. Although reportedly monitored using an array of geotechnical techniques, the collapse occurred without any apparent warning. It claimed more than 200 lives and caused considerable environmental damage. Here we present the Intermittent Small Baseline Subset (ISBAS) technique on satellite-based interferometric synthetic aperture radar (InSAR) data to assess the course of events. We find that parts of the dam wall and tailings were experiencing deformation not consistent with consolidation settlement preceding the collapse. Furthermore, we show that the timing of the dam collapse would have been foreseeable based on this observed precursory deformation. We conclude that satellite-based monitoring techniques may help mitigate similar catastrophes in the future.