Journal cover Journal topic
Hydrology and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Hydrol. Earth Syst. Sci., 15, 3093-3100, 2011
http://www.hydrol-earth-syst-sci.net/15/3093/2011/
doi:10.5194/hess-15-3093-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
Technical note
11 Oct 2011
Technical Note: Assessing a 24/7 solution for monitoring water quality loads in small river catchments
P. Jordan1,3 and R. Cassidy2 1School of Environmental Sciences, University of Ulster, Coleraine, Northern Ireland, UK
2School of Planning, Architecture and Civil Engineering, Queen's University, Belfast, Northern Ireland, UK
3Agricultural Catchments Programme, Teagasc, Johnstown Castle, Wexford, Republic of Ireland
Abstract. Quantifying nutrient and sediment loads in catchments is difficult owing to diffuse controls related to storm hydrology. Coarse sampling and interpolation methods are prone to very high uncertainties due to under-representation of high discharge, short duration events. Additionally, important low-flow processes such as diurnal signals linked to point source impacts are missed. Here we demonstrate a solution based on a time-integrated approach to sampling with a standard 24 bottle autosampler configured to take a sample every 7 h over a week according to a Plynlimon design. This is evaluated with a number of other sampling strategies using a two-year dataset of sub-hourly discharge and phosphorus concentration data. The 24/7 solution is shown to be among the least uncertain in estimating load (inter-quartile range: 96% to 110% of actual load in year 1 and 97% to 104% in year 2) due to the increased frequency raising the probability of sampling storm events and point source signals. The 24/7 solution would appear to be most parsimonious in terms of data coverage and certainty, process signal representation, potential laboratory commitment, technology requirements and the ability to be widely deployed in complex catchments.

Citation: Jordan, P. and Cassidy, R.: Technical Note: Assessing a 24/7 solution for monitoring water quality loads in small river catchments, Hydrol. Earth Syst. Sci., 15, 3093-3100, doi:10.5194/hess-15-3093-2011, 2011.
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