Staff
Dr John Crowther, M.A. ( Cambridge), Ph.D. ( Hull)
John Crowther has research interests in two areas of environmental science:
(1) Statistical modelling of microbial water quality
Research in this field is currently being undertaken in his capacity of Senior Consultant with CREH (Centre for Research into Environment & Health), based at the University of Wales, Aberystwyth. His specialist expertise is in the development of statistical models to predict faecal indicator organism concentrations in rivers and coastal bathing waters from catchment land use/farm management data and antecedent weather conditions. He has completed more than 30 research contracts with CREH for a range of external agencies in the UK and Channel Islands, including: Anglian Water, Environment Agency, Environment Agency (NW Region), Scottish Environment Protection Agency, Severn-Trent Water, States of Jersey Public Services Department, Welsh Water, West of Scotland Water and Yorkshire Water.
Publications on microbial water quality
Kay, D., Crowther, J., Stapleton, C.M., Wyer, M.D., Fewtrell, L., Anthony, S., Bradford, M., Edwards, A., Francis, C.A., Hopkins, M., Kay, C., McDonald, A.T., Watkins, J. and Wilkinson, J. (2008) Faecal indicator organism concentrations and catchment export coefficients in the UK. Water Research, 42, 2649-2661.
Stapleton, C.M., Wyer, M.D., Crowther, J., McDonald, A.T., Kay, D., Greaves, J., Wither, A., Watkins, J., Francis, C., Humphrey, N. and Bradford, M. (2008) Quantitative catchment profiling to apportion faecal indicator organism budgets for the Ribble system, the UK’s sentinel drainage basin for Water Framework Directive research. Journal of Environmental Management, 87, 535-550.
Kay, D, Crowther, J., Fewtrell, L., Francis, C.A., Hopkins, M., Kay, C., McDonald, A.T., Stapleton, C.M., Watkins, J., Wilkinson, J. and Wyer, M.D. (2008) Quantification and control of microbial pollution from agriculture: a new policy challenge? Environmental Science & Policy, 11, 171-184.
Kay, D., Crowther, J., Stapleton, C.M., Wyer, M.D., Fewtrell, L., Edwards, A., Francis, C.A., McDonald, A.T., Watkins, J. and Wilkinson, J. (2008) Faecal indicator organism concentrations in sewage and treated effluents. Water Research, 42, 442-454.
Stapleton, C.M., Wyer, M.D., Kay, D., Crowther, J., McDonald, A.T., Walters, M., Gawler, A. and Hindle, T. (2007) Microbial source tracking: a forensic technique for microbial source identification? Journal of Environmental Monitoring, 9, 427-439.
Kay, D., Aitken, M., Crowther, J., Dickson, I., Edwards, A.C., Francis, C., Hopkins, M., Jeffrey, W., Kay, C., McDonald, A.T., McDonald, D., Stapleton, C.S., Watkins, J., Wilkinson, J. and Wyer, M.D. (2007) Reducing fluxes of faecal indicator compliance parameters to bathing waters from diffuse agricultural sources: the Brighouse Bay study, Scotland. Environmental Pollution, 147, 138-149.
Kay, D., Edwards, A.C., McDonald, A.T., Stapleton, C.S., Wyer, M.D. and Crowther, J. (2007) Catchment microbial dynamics: the emergence of a research agenda. Progress in Physical Geography, 31, 1-18.
Kay, D., Stapleton, C.M., Wyer, M.D., McDonald, A.T. and Crowther, J. (2006) Total maximum daily loads: The USEPA approach to managing faecal indicator fluxes to receiving waters: Lessons for UK environmental regulation? Proceedings of Biennial International Water Association/Scottish Agricultural College/Scottish Environment Protection Agency Conference: IV. Agriculture and the Environment (L. Gairns, C. Crighton, and B. Jeffrey, eds). Edinburgh, pp. 23-33.
Wither, A., Greaves, J., Dunhill, I., Wyer, M.D., Stapleton, C., Kay, D., Humphrey, N., Watkins, J., Francis, C., McDonald, A.T. and Crowther, J. (2005) Estimation of diffuse and point source microbial pollution in the Ribble catchment discharging to bathing waters in the north west of England. Water Science and Technology 15(3-4), 191-198.
Kay, D., Wyer, M.D., Crowther, J., Stapleton, C., Bradford, M., McDonald, A.T., Greaves, J., Francis, C. and Watkins, J. (2005) Predicting faecal indicator fluxes using digital land use data in the UK’s sentinel Water Framework Directive catchment: the Ribble study. Water Research, 39, 3967-3981.
Kay, D., Wyer, M.D., Crowther, J., Wilkinson, J., Stapleton, C. and Glass, P. (2005) Sustainable reduction in the flux of microbial compliance parameters to bathing waters by a wetland ecosystem produced by a marine flood defence structure. Water Research, 39, 3320-3332.
Kay, D., Stapleton, C.M., Wyer, M.D., McDonald, A.T., Crowther, J., Paul, N., Jones, K., Francis, C., Watkins, J., Humphrey, N., Lin, B., Yang, L., Falconer, R.A. and Gardner, S. (2005) Decay of intestinal enterococci concentrations in high energy estuarine and coastal waters: towards real-time T90 values for modelling faecal indicators in recreational waters. Water Research, 39, 655-667.
Crowther, J., Wyer, M.D., Bradford, M., Kay, D. and Francis, C.A. (2003) Modelling faecal indicator concentrations in large rural catchments using land use and topographic data. Journal of Applied Microbiology, 94, 962-973.
Stapleton, C.S., Wyer, M.D., Crowther, J., Francis, C., Watkins, J., Rushby, L., Wilkinson, J. and Kay, D. (2002) Towards dynamic modelling of bacterial concentrations in the near-shore zone: I. Driving models with dynamic input variables and assumptions. Proceedings of the 13th International Association for Hydraulic Research/APD Congress, Singapore. World Scientific Vol II, pp. 1025-1029.
Crowther, J., Kay, D. and Wyer, M.D. (2002) Faecal-indicator concentrations in waters draining lowland pastoral catchments in the UK: relationships with land use and farming practices. Water Research, 36, 1725-1734.
Crowther, J., Kay, D. and Wyer, M.D. (2001) Relationships between microbial water quality and environmental conditions in coastal recreational waters: the Fylde coast, UK. Water Research, 35, 4029-4038.
Kay, D., Wyer, M., Crowther, J. and Fewtrell, L. (2000) Faecal indicator impacts on recreational waters. Pp. 269-277 in Proceedings of British Hydrological Society, 2nd Inter-Celtic Colloquium – Water in the Celtic World: Managing Resources for the 21st Century. British Hydrological Society Occasional Paper, 11.
Kay, D., Wyer, M., Crowther, J. and Fewtrell, L. (1999) Faecal indicator impacts on recreational waters: budget studies and diffuse source modelling. Journal of Applied Microbiology, Symposium Supplement,85, 70S-82S.
Kay, D., Wyer, M., Crowther, J., G. O'Neill, G. Jackson, J.M. Fleisher and L. Fewtrell (1999) Changing standards and catchment sources of faecal indicators in nearshore bathing waters. Pp. 47-64 in Water Quality: Processes and Policy (S.T. Trudgill, D.E. Walling and B.W. Webb, eds). Wiley.
Wyer, M., Kay, D., Crowther, J., Whittle, J., Spence, A., Huen, V., Wilson, C., Carbo, P. and Newsome, J. (1998) Faecal-indicator budgets for recreational coastal waters: a catchment approach. Journal of the Chartered Institution of Water and Environmental Management, 12, 414-424.
Wyer, M., O'Neill, G., Kay, D., Crowther, J., Jackson G. and Fewtrell, L. (1997) Non-outfall sources of faecal indicator organisms affecting the compliance of coastal waters with Directive 76/160/EEC. Water Science and Technology, 35, 151-156.
(2) Karst landscapes: geomorphology and environmental studies
Early research was concerned with tropical karst landscapes in Peninsular Malaysia – funded by a NERC studentship. The main focus was spatial and temporal variations in groundwater hydrology, geochemistry and temperatures. However, what distinguished (and still distinguishes) this study from other tropical karst water studies was the range of data generated on aspects of the environment of the limestone outcrops that affect groundwater chemistry. This pioneering work was achieved through a combination of detailed surveys of hillslope topography, soils, and vegetation; and a monitoring programme covering microclimate, ecosystem dynamics (productivity, litterfall and nutrient cycling), soil carbon dioxide concentrations, and weathering rates on bare and covered limestone surfaces (based on surface and soil water chemistry, and use of erosional weight-loss tablets). Studies were subsequently undertaken on aspects of karst geomorphology in Britain, notably in Yorkshire and South Wales.
Although karst is no longer a major research focus, a programme of work was completed between 1995 and 1998 on the surface roughness of individual karren features and the detailed form of rillenkarren, based on case studies in Mallorca.
In total, 27 papers have been published in refereed journals/volumes, including: Catena, Earth Surface Processes and Landforms, Journal of Biogeography, Journal of Hydrology and Zeitschrift für Geomorphologie.
Selection of key publications
Crowther, J. (1982) Ecological observations in tropical karst terrain, West Malaysia. I. Variations in topography, soils and vegetation. Journal of Biogeography, 9, 65-78.
Crowther, J. and Pitty, A.F. (1982) Water temperature variability as an indicator of shallow- depth groundwater behaviour in limestone areas in West Malaysia. Journal of Hydrology, 57, 137-46.
Crowther, J. (1983) A comparison of the rock tablet and water hardness methods for determining chemical erosion rates on karst surfaces. Zeitschrift für Geomorphologie N.F., 27, 55-64.
Crowther, J. (1983) Carbon dioxide concentrations in some tropical karst soils, West Malaysia. Catena, 10, 27-39.
Crowther, J. (1983) Hydrology of autogenic percolation systems in some tropical karst outcrops, West Malaysia. Journal of Hydrology, 60, 227-42.
Crowther, J. and Pitty, A.F. (1983) An index of microrelief roughness, illustrated with examples from tropical karst terrain in West Malaysia. Revue de Géomorphologie Dynamique, 32, 69-74.
Crowther, J. (1984) Meso-topography and soil cover in tropical karst terrain, West Malaysia. Zeitschrift für Geomorphologie N.F., 28, 219-34.
Crowther, J. (1984) Karst water studies in Gua Batu (Batu Caves), Malaysia. Studies in Speleology, 5, 39-52.
Crowther, J. (1984) Soil carbon dioxide and weathering potentials in tropical karst terrain, Peninsular Malaysia: a preliminary model. Earth Surface Processes and Landforms, 9, 397-407.
Crowther, J. (1986) Chemical erosion in tower karst terrain, Kinta Valley, Peninsular Malaysia. Pp. 427-41 in New Directions in Karst (K. Paterson and M.M. Sweeting, eds). Geo Books Ltd., Norwich.
Crowther, J. (1987) Ecological observations in tropical karst terrain, West Malaysia. II. Rainfall interception, litterfall and nutrient cycling. Journal of Biogeography, 14, 145-56.
Crowther, J. (1987) Ecological observations in tropical karst terrain, West Malaysia. III. Dynamics of the vegetation-soil-bedrock system. Journal of Biogeography, 14, 157-64.
Crowther, J. (1988) Magnesium and calcium in carbonate bedrock and groundwaters, Peninsular Malaysia. Journal of Southeast Asian Earth Sciences, 2, 189-200.
Crowther, J. (1989) Karst geomorphology of South Wales. Pp. 20-39 in Limestones and Caves of Wales (T.D. Ford, ed.). Cambridge University Press .
Crowther, J. (1989) Groundwater chemistry and cation budgets of tropical karst outcrops, Peninsular Malaysia. I. Calcium and magnesium. Journal of Hydrology, 107, 169-92.
Crowther, J. (1996) Roughness (mm-scale) of limestone surfaces: examples from coastal and mountain karren features in Mallorca. Pp 149-160 in Karren Landforms (J.J. Fornos and À. Ginés, eds), Proceedings of International Geographical Union Commission on Environmental Changes in Karst Areas: International Symposium on Karren Landforms, Soller, Mallorca. UIB Press, Mallorca.
Crowther, J. (1997) Surface roughness and the evolution of karren forms at Lluc, Serra de Tramuntana, Mallorca. Zeitschrift für Geomorphologie N.F., 41, 393-407.
Crowther, J. (1998) New methodologies for investigating rillenkarren cross sections: a case study at Lluc, Mallorca. Earth Surface Processes & Landforms, 23, 333-344.