Global uncertainty analysis of suspended sediment monitoring using turbidimeter in a small mountainous river catchment

Navrátil, Oldřich; Estèves, Michel; Legoût, Cédric; Gratiot, Nicolas; Némery, Julien; Willmore, Simon; Grangeon, Thomas

doi:10.1016/j.jhydrol.2010.12.025

Cited by 116 publications

(109 citation statements)

References 46 publications

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“…This random high-frequency 'noise' in turbidity datasets has been observed in other water quality monitoring studies (e.g. Navratil et al 2011;Sherriff et al 2015) and is potentially linked to the temporary biofouling of the turbidity probe or debris interference around the sensor by leaves and air bubbles.…”

Section: Data Processingmentioning

confidence: 56%

Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

2016

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Purpose A small number of recent studies have linked daily cycles in stream turbidity to nocturnal bioturbation by aquatic fauna, principally crayfish, and demonstrated this process can significantly impact upon water quality under baseflow conditions. Adding to this limited body of research, we use highresolution water quality monitoring data to investigate evidence of diel turbidity cycles in a lowland, headwater stream with a known signal crayfish (Pacifastacus leniusculus) population and explore a range of potential causal mechanisms. Materials and methods Automatic bankside monitoring stations measured turbidity and other water quality parameters at 30-min resolution at three locations on the River Blackwater, Norfolk, UK, during 2013. Specifically, we focused on two 20-day periods of baseflow conditions during January and April 2013 which displayed turbidity trends typical of winter and spring seasons, respectively. The turbidity time-series, which were smoothed with 6.5-h Savitzky-Golay filters to highlight diel trends, were correlated against temperature, stage, dissolved oxygen and pH to assess the importance of abiotic influences on turbidity. Turbidity was also calibrated against suspended particulate matter (SPM) over a wide range of values via linear regression.Results and discussion Pronounced diel turbidity cycles were found at two of the three sites under baseflow conditions during April. Spring night-time turbidity values consistently peaked between 21:00 and 04:00 with values increasing bỹ 10 nephelometric turbidity units (NTU) compared with the lowest recorded daytime values which occurred between 10:00 and 14:00. This translated into statistically significant increases in median midnight SPM concentration of up to 76 % compared with midday, with night-time (18:00-05:30) SPM loads also up to 30 % higher than that recorded during the daytime (06:00-17:30). Relating turbidity to other water quality parameters exhibiting diel cycles revealed there to be neither any correlation that might indicate a causal link nor any obvious mechanistic connections to explain the temporal turbidity trends. Diel turbidity cycles were less prominent at all sites during the winter. Conclusions Considering the seasonality and timing of elevated turbidity, visual observations of crayfish activity and an absence of mechanistic connections with other water quality parameters, the results presented here are consistent with the hypothesis that nocturnal bioturbation is responsible for generating diel turbidity cycles under baseflow conditions in headwater streams. However, further research in a variety of fluvial environments is required to better assess the spatial extent, importance and causal mechanisms of this phenomenon.

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Section: Data Processingmentioning

confidence: 56%

Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

2016

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“…arable or grazing practices) which are further influenced by climate, landscape setting and topographic controls (Wass and Leeks, 1999). A comprehensive evaluation of the extent of erosion and elevated sediment supply, therefore, requires a robust determination of sediment flux (Navratil et al, 2011), knowledge of the sources and fate of fine sediments within the system (Walling, 2005), and an appreciation of the risks that elevated concentrations present to aquatic ecosystems . This evidence base can be used to better inform integrated land, water and sediment management strategies.…”

Section: S C Sherriff Et Al: Suspended Sediment Dynamics In Agricumentioning

confidence: 99%

“…Firstly, robust flow and suspended sediment concentration (SSC) data capable of accurately describing shortterm fluxes (Navratil et al, 2011). Secondly, the duration of the measurements must be sufficiently long to be "representative" of either stationary long-term averages (inclusive of natural variability), or to reveal temporal trends of increasing or decreasing loads or concentrations.…”

Section: S C Sherriff Et Al: Suspended Sediment Dynamics In Agricumentioning

confidence: 99%

Investigating suspended sediment dynamics in contrasting agricultural catchments using ex situ turbidity-based suspended sediment monitoring

Sherriff

Rowan

Melland

et al. 2015

Hydrol. Earth Syst. Sci.

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Abstract. Soil erosion and suspended sediment (SS) pose risks to chemical and ecological water quality. Agricultural activities may accelerate erosional fluxes from bare, poached or compacted soils, and enhance connectivity through modified channels and artificial drainage networks. Storm-event fluxes dominate SS transport in agricultural catchments; therefore, high temporal-resolution monitoring approaches are required, but can be expensive and technically challenging. Here, the performance of in situ turbidity sensors, conventionally installed submerged at the river bankside, is compared with installations where river water is delivered to sensors ex situ, i.e. within instrument kiosks on the riverbank, at two experimental catchments (Grassland B and Arable B). The in situ and ex situ installations gave comparable results when calibrated against storm-period, depth-integrated SS data, with total loads at Grassland B estimated at 12 800 and 15 400 t, and 22 600 and 24 900 t at Arable B, respectively. The absence of spurious turbidity readings relating to bankside debris around the in situ sensor and its greater security make the ex situ sensor more robust. The ex situ approach was then used to characterise SS dynamics and fluxes in five intensively managed agricultural catchments in Ireland which feature a range of landscape characteristics and land use pressures. Average annual suspended sediment concentration (SSC) was below the Freshwater Fish Directive (78/659/EEC) guideline of 25 mg L −1 , and the continuous hourly record demonstrated that exceedance occurred less than 12 % of the observation year. Soil drainage class and proportion of arable land were key controls determining flux rates, but all catchments reported a high degree of inter-annual variability associated with variable precipitation patterns compared to the long-term average. Poorly drained soils had greater sensitivity to runoff and soil erosion, particularly in catchments with periods of bare soils. Well drained soils were less sensitive to erosion even on arable land; however, under extreme rainfall conditions, all bare soils remain a high sediment loss risk. Analysis of storm-period and seasonal dynamics (over the long term) using high-resolution monitoring would be beneficial to further explore the impact of landscape, climate and land use characteristics on SS export.

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“…Since the 1990s, turbidity sensors have been utilized, either as stand-alone instruments or in multiprobes. Turbidity has been routinely used as a surrogate measure to estimate total suspended solids (Gippel 1995;Brasington and Richards 2000;Birgand et al 2004;Billotta and Brazier 2008;Minella et al 2008;Navratil et al 2011;Jones et al 2011;Thompson et al 2014) and total P concentrations (Jones et al 2011). These estimates, however, rely on relationships with turbidity derived on a station by station basis, which introduces a potentially significant source of measurement uncertainty.…”

Section: Current Research and A Glimpse Into The Futurementioning

confidence: 99%

Measuring edge-of-field water quality: Where we have been and the path forward

Harmel¹,

King²,

Busch³

et al. 2018

Journal of Soil and Water Conservation

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Heightened pressure to demonstrate the resource benefits of conservation practices and continued high-profile water quality impairments and concerns are increasing the need to quantify edge-of-field (EOF) water quality. With this in mind, this manuscript summarizes previous developments in EOF water quality sampling and presents current research and glimpses into the future. This manuscript focuses on constituent sampling at the field-scale or at the "edge-of-field;" however, many of the findings are also applicable for small stream or small watershed sampling. With development of programmable automated samplers and initiation of numerous automated sampling projects, it became readily apparent that neither equipment manufacturers nor researchers could provide guidance on design components (e.g., sample initiation, timing/intervals, and type). This was problematic as available monitoring resources are too limited and data needs too great for such projects to be designed solely based on field experience and without a scientific basis or with complete disregard for potential data quality implications. Thus practical, science-based guidance for EOF sampling was developed and fundamental understanding of the inherent uncertainty was established to assist researchers, municipalities, consulting firms, and regulatory agencies improve data quality and monitoring resource efficiency. Looking to the future, further improvements are needed related to lower cost systems, practical improvements, and enhanced in situ sampling, along with enhanced understanding and consideration of data uncertainty in modeling and decision making.

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Global uncertainty analysis of suspended sediment monitoring using turbidimeter in a small mountainous river catchment

Cited by 116 publications

References 46 publications

Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

Diel turbidity cycles in a headwater stream: evidence of nocturnal bioturbation?

Investigating suspended sediment dynamics in contrasting agricultural catchments using ex situ turbidity-based suspended sediment monitoring

Measuring edge-of-field water quality: Where we have been and the path forward

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