Mutual relationships of suspended sediment, turbidity and visual clarity in New Zealand rivers

Abstract. Many river water quality monitoring programmes do not measure suspended particulate matter (SPM) mass concentrations despite significant interest in its multiple effects on aquatic ecosystems. Regular monthly sampling usually intercepts rivers in baseflow when suspended sediment mass concentrations and fluxes are relatively low and not of particular interest. New Zealand’s National Rivers Water Quality Network (NRWQN) is probably typical in not measuring SPM mass, although visual clarity and nephelometric turbidity are routinely measured. In order to better characterize SPM in NZ rivers, total suspended sediment (TSS) was temporarily added to the NRWQN. Turbidity, visual clarity and TSS are mutually inter-related over all 77 sites, although with considerable data scatter. However, within individual rivers turbidity and visual clarity are typically fairly closely related to TSS and provide fair to excellent surrogates. Therefore, TSS need not be measured routinely because it can be estimated with sufficient precision for many purposes from visibility or turbidity.

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Light attenuation – a more effective basis for the management of fine suspended sediment than mass concentration?

Water Science & Technology ◽

10.2166/wst.2014.096 ◽

2014 ◽

Vol 69 (9) ◽

pp. 1867-1874 ◽

Cited By ~ 14

Author(s):

Robert J. Davies-Colley ◽

Deborah J. Ballantine ◽

Sandy H. Elliott ◽

Andrew Swales ◽

Andrew O. Hughes ◽

...

Keyword(s):

Suspended Sediment ◽

Mass Concentration ◽

Light Attenuation ◽

Sediment Concentration ◽

Fine Sediment ◽

Optical Measurements ◽

Suspended Particulate ◽

Sediment Mass ◽

Fine Suspended Sediment ◽

Mass Concentrations

Fine sediment continues to be a major diffuse pollution concern with its multiple effects on aquatic ecosystems. Mass concentrations (and loads) of fine sediment are usually measured and modelled, apparently with the assumption that environmental effects of sediment are predictable from mass concentrations. However, some severe impacts of fine sediment may not correlate well with mass concentration, notably those related to light attenuation by suspended particles. Light attenuation per unit mass concentration of suspended particulate matter in waters varies widely with particle size, shape and composition. Data for suspended sediment concentration, turbidity and visual clarity (which is inversely proportional to light beam attenuation) from 77 diverse New Zealand rivers provide valuable insights into the mutual relationships of these quantities. Our analysis of these relationships, both across multiple rivers and within individual rivers, supports the proposition that light attenuation by fine sediment is a more generally meaningful basis for environmental management than sediment mass. Furthermore, optical measurements are considerably more practical, being much cheaper (by about four-fold) to measure than mass concentrations, and amenable to continuous measurement. Mass concentration can be estimated with sufficient precision for many purposes from optical surrogates locally calibrated for particular rivers.

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Field Spectroscopy Measurements over Asprokremmos Dam in Cyprus Intended for Water Quality Monitoring

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.500.813 ◽

2012 ◽

Vol 500 ◽

pp. 813-819 ◽

Cited By ~ 1

Author(s):

Christiana Papoutsa ◽

Diofantos G. Hadjimitsis

Keyword(s):

Water Quality ◽

Ground Truth ◽

Water Quality Monitoring ◽

Quality Parameters ◽

Ground Truth Data ◽

Suspended Particulate ◽

Fibre Optic Probe ◽

High Concentrations ◽

Optic Probe ◽

Remote Sensing Techniques

High concentrations of suspended particulate matter in reservoir waters directly affect the water treatment plants by occurring damages to the filters during the pretreatment. The objective of this project is to define the support that can be derived from the use of remote sensing techniques in order to determine the spatial variations of Total Suspended Solids (TSS) in Asprokremmos Dam in Paphos District in Cyprus. Such techniques have been successfully applied to the retrieval of TSS concentration and other water quality parameters in various geographical locations and environmental settings. This paper describes the results obtained by an existing running campaign in which in-situ spectroradiometric measurements and water sampling measurements of turbidity have been acquired at the study area. A GER-1500 field sperctro-radiometer equipped with a fibre optic probe is used to retrieve the spectral signatures of the Asprokremmos Dam and a portable turbidity meter is used for the determination of turbidity values. Ground-truth data based on the spectro-radiometric measurements were simulated to comply with the Landsat TM/ETM+ visible and infrared bands, so that identification of the ‘best-suited’ spectral region in which turbidity can be retrieved, was performed.

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The use of bed sediments in water quality studies and monitoring programs

Proceedings of the International Association of Hydrological Sciences ◽

10.5194/piahs-375-11-2017 ◽

2017 ◽

Vol 375 ◽

pp. 11-17 ◽

Cited By ~ 1

Author(s):

Arthur J. Horowitz ◽

Kent A. Elrick

Keyword(s):

Water Quality ◽

Suspended Sediment ◽

Water Quality Monitoring ◽

Flood Plain ◽

Quality Monitoring ◽

Sediment Chemistry ◽

Regulatory Requirements ◽

Bed Sediments ◽

Monitoring Programs

Abstract. In most water quality monitoring programs, either filtered water (dissolved) or suspended sediment (either whole water or separated suspended sediment) are the traditional sample media of choice. This results both from regulatory requirements and a desire to maintain consistency with long-standing data collection procedures. Despite the fact that both bed sediments and/or flood plain deposits have been used to identify substantial water quality issues, they rarely are used in traditional water quality monitoring programs. The usual rationale is that bed sediment chemistry does not provide the temporal immediacy that can be obtained using more traditional sample media (e.g., suspended sediment, water). However, despite the issue of temporal immediacy, bed sediments can be used to address/identify certain types of water quality problems and could be employed more frequently for that purpose. Examples where bed sediments could be used include: (1) identifying potential long-term monitoring sites/water quality hot spots, (2) establishing a water quality/geochemical history for a particular site/area, and (3) as a surrogate for establishing mean/median chemical values for suspended sediment.

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Modelling Transport of Heavy Metals in Geita Wetland along Mamubi River

Tanzania Journal of Engineering and Technology ◽

10.52339/tjet.v37i1.484 ◽

2018 ◽

Vol 37 (1) ◽

pp. 72-88

Author(s):

Ezrael J. Massawe ◽

Richard Kimwaga

Keyword(s):

Heavy Metals ◽

Water Quality ◽

Lake Victoria ◽

Field Measurements ◽

Water Quality Monitoring ◽

Model Parameters ◽

Prediction Errors ◽

Water Quality Simulation ◽

Suspended Particulate ◽

Monitoring Stations

The modelling of heavy metals in rivers is highly dependent on hydrodynamics, the transport of suspended particulate matter and the partition between dissolved and particulate phases. This paper presents the development of hydrodynamic model DUFLOW, which is a one dimensional flow and water quality simulation package, that describes the processes governing transformations and transport of heavy metals (Hg, Ni and Cu) along Mabubi River in the Geita wetland. Two monitoring stations were established along Mabubi River at the inlet (MBSP1) and outlet (MBSP2) of the wetland. A set of DUFLOW model inputs representative of the water conditions were collected from the established monitoring stations. The model was calibrated and validated for the prediction of flow and heavy metals (Hg, Ni, and Cu) transport, against a set of measured mean monthly monitoring data. Sensitive model parameters were adjusted within their feasible ranges during calibration to minimize model prediction errors. At the gauging station MBSP2, the calibration results showed the model predicted mean monthly flow within 17% of the measured mean monthly flow while the r2 coefficient and Nash-Sutcliffe (NSE) were 0.83 and 0.79 respectively. At the water quality monitoring station MBSP2, the calibration results showed the model predicted heavy metals (Hg, Ni and Cu) concentrations within 13% and 17% of their respective measured mean monthly concentrations. The mean monthly comparisons r 2 values for heavy metals ranged from 0.75 to 0.88 while the NSE values were between 0.70 and 0.82. The model results and field measurements demonstrated that about 40% of the annual heavy metals loadings which would otherwise reach the Lake Victoria are retained in the wetland. The Mabubi river model can therefore be used for prediction of heavy metals (Hg. Ni and Cu) transformation processes in the Geita wetland.

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Development of tools to assess and mitigate the impacts of peat harvesting on aquatic ecosystems

10.5194/egusphere-egu21-3397 ◽

2021 ◽

Author(s):

André St-Hilaire ◽

Sophie Duchesne ◽

Claude Fortin ◽

Sabiha Hafdi ◽

Hermine Bettis ◽

...

Keyword(s):

Water Quality ◽

Suspended Sediment ◽

Aquatic Ecosystems ◽

Ecosystem Health ◽

Ionic Composition ◽

Organic Content ◽

Trapping Efficiency ◽

Low Flow ◽

Settling Pond ◽

The Impact

Peat harvesting in an important industry in northern Europe and in North America. In Canada peat is harvested to be used as a horticulture substrate. The harvesting is generally done by vacuuming the thin dried upper layer of peat found below the acrotelm, after removing the latter and draining the water. Drained water is typically routed to settling basins prior to being released in neighbouring natural water courses. This communication summarizes our research efforts to develop tools to optimize settling pond design and minimize suspended sediment loads and to provide the industry with means to assess the health of aquatic ecosystems that receive the drained water.Current settling pond designs are based on simple rules of thumb (e.g. 25 m3/ha of harvested peatland). In our study, a hydraulic model was used to test different basin configurations (basins with and without weirs at the outlet, basins in series, basins equipped with a geotextile curtain). It was found that while the trapping efficiency was not significantly improved by adding a second basin compared to a single one, adding a geotextile curtain improved the trapping of coarser sediments. Our results moreover showed that fine sediments deposited during low flow periods, in the downstream end of the basins, could be easily resuspended during and after rainfall events, thus showing the importance of frequent maintenance. There are also some strong indications that wind erosion could be a major source of sediments in the drainage water.Different indicators of stream ecosystem health were compared to quantify the impact of peat harvesting on the receiving water bodies. They included 1) using fish abundance and species richness; 2) quantifying sediment deposition and its organic content; 3) determining ionic composition of effluents and receiving waters; and 4) developing a water quality index (WQI) based on multiple physico-chemical measurements (ammonia, conductivity, pH and suspended sediment concentrations). The developed WQI was shown to be the most promising indicator of ecosystem health and allows for a simple classification of water quality downstream of the confluence between the drain outlet and the receiving stream.

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