Rainfall-driven E. coli transfer to the stream-conduit network observed through increasing spatial scales in mixed land-use paddy farming karst terrain

Buckerfield, S. J., Quilliam, R. S., Waldron, S. , Naylor, L. A. , Li, S. and Oliver, D. M. (2019) Rainfall-driven E. coli transfer to the stream-conduit network observed through increasing spatial scales in mixed land-use paddy farming karst terrain. Water Research X, 5, 100038. (doi: 10.1016/j.wroa.2019.100038) (PMID:31660535) (PMCID:PMC6807365)

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Karst aquifers have distinctive hydrology and supply 25% of the world's population with drinking water, making them a critical geological setting for understanding and managing microbial water pollution. Rainfall causes elevated concentrations and loading of faecal microorganisms, e.g. E. coli, in catchment surface and groundwater systems, increasing the risk of human exposure to faecally-contaminated water. However, effective management of microbial water quality in complex karst catchments is constrained by limited understanding of E. coli - discharge responses to rainfall. We analysed how rainfall events of varying magnitude (2.4–100 mm) control E. coli-discharge dynamics at increasing spatial scales in a mixed land-use karst catchment in southwest China. During the wet season, hourly water sampling was undertaken throughout five storm events to characterise in high detail E. coli emergence with resulting flow across multiple sites of varying catchment area, stream order, and land-use. E. coli concentration was found to increase by 1–3 orders of magnitude following rainfall events. Maximum E. coli concentration and speed of E. coli recession were influenced by rainfall (amount, intensity), timing of agricultural activities, and position in the hydrological system. For high intensity events ∼90% of the cumulative E. coli export occurred within 48 h. E. coli concentration increased with increasing discharge at all sites. E. coli concentration at low discharge was higher in the headwaters than at the catchment outlet, while the rate of increase in E. coli concentration with increasing discharge appears to follow the opposite trend, being higher at the catchment outlet than the headwaters. This was attributed to the decreasing flow path gradient and increasing degree of development of the fissure network, but further event monitoring at varying catchment scales is required to confirm this relationship. The results provide novel insight into how rainfall characteristics combine with land-use and catchment hydrology to control E. coli export in karst landscapes.

Item Type:Articles
Additional Information:This research was funded by the Natural Environment Research Council as part of the IAPETUS Doctoral Training Programme (NE/L002590/1) and has received additional assistance from NERC and the Chinese Academy of Sciences through the China-UK Critical Zone project NE/ N007425/1, and the National Natural Science Foundation of China (Grant No. 41571130072).
Glasgow Author(s) Enlighten ID:Waldron, Professor Susan and Naylor, Dr Larissa
Authors: Buckerfield, S. J., Quilliam, R. S., Waldron, S., Naylor, L. A., Li, S., and Oliver, D. M.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Water Research X
ISSN (Online):2589-9147
Published Online:10 October 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Water Research X 5:100038
Publisher Policy:Reproduced under a Creative Commons license

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
173283IAPETUS - Using bioprotective buffers to improve coastal infrastructure resilienceLarissa NaylorNatural Environment Research Council (NERC)NE/L002590/1 C RolinGES - Geography