Assessment of annual pollutant loads in combined sewers from continuous turbidity measurements: Sensitivity to calibration data

Lacour, C.; Joannis, Claude; Chebbo, Ghassan

doi:10.1016/j.watres.2009.02.017

Cited by 34 publications

(21 citation statements)

References 23 publications

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“…If we can establish empirical relationships between turbidity levels and the concentrations of TSS or POC, as shown in Figure 6, the relatively cost-effective and robust turbidity measurement system can be employed as a surrogate to estimate the concentrations and fluxes of suspended sediment or organic carbon in streams and rivers. While turbidity time series data have been widely used to estimate suspended sediment loads in polluted waters (e.g., [51]), this study provided a rare empirical relationship between turbidity and the concentrations of POC. Sediment surges in drinking water source areas during extreme rainfall events can have devastating impacts on drinking water facilities and aquatic ecosystems.…”

Section: Discussionmentioning

confidence: 99%

Multiple Time-Scale Monitoring to Address Dynamic Seasonality and Storm Pulses of Stream Water Quality in Mountainous Watersheds

Lee

Chun

Shope

et al. 2015

Water

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Rainfall variability and extreme events can amplify the seasonality and storm pulses of stream water chemistry in mountainous watersheds under monsoon climates. To establish a monitoring program optimized for identifying potential risks to stream water quality arising from rainfall variability and extremes, we examined water chemistry data collected on different timescales. At a small forested watershed, bi-weekly sampling lasted over two years, in comparison to three other biweekly sampling sites. In addition, high-frequency continuous measurements of pH, electrical conductivity, and turbidity were conducted in tandem with automatic water sampling at 2 h intervals during eight rainfall events. Biweekly monitoring showed that during the summer monsoon period, electrical conductivity (EC), dissolved oxygen (DO), and dissolved ion concentrations generally decreased, but total suspended solids (TSS) slightly increased. A noticeable variation from the usual seasonal pattern was that DO levels substantially decreased during an extended drought. Bi-hourly storm event samplings exhibited large changes in the concentrations of TSS and particulate and dissolved organic carbon (POC; DOC) during intense rainfall OPEN ACCESSWater 2015, 7 6118 events. However, extreme fluctuations in sediment export during discharge peaks could be detected only by turbidity measurements at 5 min intervals. Concomitant measurements during rainfall events established empirical relationships between turbidity and TSS or POC. These results suggest that routine monitoring based on weekly to monthly sampling is valid only in addressing general seasonal patterns or long-lasting phenomena such as drought effects. We propose an "adaptive" monitoring scheme that combines routine monitoring for general seasonal patterns and high-frequency instrumental measurements of water quality components exhibiting rapid responses pulsing during intense rainfall events.

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Section: Discussionmentioning

confidence: 99%

Multiple Time-Scale Monitoring to Address Dynamic Seasonality and Storm Pulses of Stream Water Quality in Mountainous Watersheds

Lee

Chun

Shope

et al. 2015

Water

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“…Because turbidity is strongly related to suspended sediment concentration (e.g. Gippel, 1995;Lewis, 1996;Pavanelli and Pagliarani, 2002;Holliday et al, 2003;Lacour et al, 2009;Métadier and Bertrand-Krajewski, 2012), the two datasets, when available at the same location, can be combined to obtain a 5 high frequency SSC dataset. In our case, punctual manual measurements of SSC are collected twice per week at the outlet of the Rhone Basin and continuous measurements of Nephelometric Turbidity Units (NTU) are available for an overlapping period in 2013-2017 at the same location.…”

Section: Estimate Of Daily Suspended Sediment Concentration 25mentioning

confidence: 99%

Hydroclimatic control on suspended sediment dynamics of a regulated Alpine catchment: a conceptual approach

Costa¹,

Anghileri²,

Molnár³

2018

Preprint

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Abstract.We analyse the control of hydroclimatic factors on suspended sediment concentration (SSC) in Alpine catchments by differentiating among the potential contributions of erosion and suspended sediment transport driven by erosive rainfall, defined as liquid precipitation over snow free surfaces, icemelt from glacierized areas, and snowmelt on hillslopes. We account for the potential impact of hydropower by intercepting sediment fluxes originated in areas diverted to hydropower reservoirs, and by considering the contribution of hydropower releases to SSC. We obtain the hydroclimatic variables from 10 daily gridded datasets of precipitation and temperature, implementing a degree-day model to simulate spatially distributed snow accumulation and snow-ice melt. We estimate hydropower releases by a conceptual approach with a unique virtual reservoir regulated on the basis of a target-volume function, representing normal reservoir operating conditions throughout a hydrological year. An Iterative Input Selection algorithm is used to identify the variables with the highest predictive power for SSC, their explained variance, and characteristic time lags. On this basis, we develop a hydroclimatic multivariate rating 15 curve (HMRC) which accounts for the contributions of the most relevant hydroclimatic input variables mentioned above. We calibrate the HMRC with a gradient-based nonlinear optimization method and we compare its performance with a traditional discharge-based rating curve. We apply the approach in the upper Rhone Basin, a large Swiss Alpine catchment, heavily regulated by hydropower. Our results show that the three hydroclimatic processes -erosive rainfall, icemelt, and snowmeltare significant predictors of mean daily SSC, while hydropower release does not have a significant explanatory power for 20 SSC. The characteristic time lags of the hydroclimatic variables correspond to the typical flow concentration times of the basin. Despite not including discharge, the HMRC performs better than the traditional rating curve in reproducing SSC seasonality, especially during validation at the daily scale. While erosive rainfall determines the daily variability of SSC and extremes, icemelt generates the highest SSC per unit of runoff, and represents the largest contribution to total suspended sediment yield. Finally, we show that the HMRC is capable of simulating climate-driven changes in fine sediment dynamics 25 in Alpine catchments. In fact, HMRC can reproduce the changes in SSC in the past 40 years in the Rhone Basin connected to air temperature rise, even though the simulated changes are more gradual than those observed. The approach presented is this paper, based on the analysis of the hydroclimatic control on suspended sediment concentration, allows the exploration of climate-driven changes in fine sediment dynamics in Alpine catchments. The approach can be applied to any Alpine catchment with a pluvio-glacio-nival hydrological regime and adequate hydroclimatic datasets. 30Hydrol. Earth Syst. Sci. Discuss., ...

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Section: Ssc and Hydroclimatic Data Modellingmentioning

confidence: 99%

A Process–Based Rating Curve to model suspended sediment concentration in Alpine environments

Costa

Anghileri

Molnár

2017

Preprint

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Abstract.A Process-Based Rating Curve (PBRC) approach to simulate mean daily suspended sediment concentration (SSC) as a function of different sediment sources and their activation by erosive rainfall (ER), snowmelt (SM), and icemelt (IM) in an Alpine catchment is presented. Similarly to the traditional rating curve, the PBRC relates SSC to the three main hydroclimatic variables through power functions. We obtained the hydroclimatic variables from daily gridded datasets of precipitation and temperature, implementing a degree-day model to simulate spatially distributed snow accumulation and 10 snow-ice melt. We calibrated the PBRC parameters by an Iterative Input Selection algorithm to capture the characteristic response time lags, and by a gradient-based nonlinear optimization method to minimize the errors between SSC observations and simulations. We apply our approach in the upper Rhône Basin, a large Alpine catchment in Switzerland.Results show that all three hydroclimatic processes ER, SM, and IM are significant predictors of mean daily SSC (explaining 75%, 12% and 3% of the total observed variance). Despite not using discharge in prediction, the PBRC performs better than 15 the traditional rating curve, especially during validation at the daily scale and in reproducing SSC seasonality. The characteristic time lags of the three variables in contributing to SSC reflect the typical flow concentration times of the corresponding hydrological processes in the basin. Erosive rainfall determines the daily variability of SSC, icemelt generates the highest SSC per unit of runoff, and snowmelt-driven fluxes represent the largest contribution to total suspended sediment yield. Finally, we show that the PBRC is able to simulate changes in SSC in the past 40 years in the Rhône Basin connected 20 to air temperature rise, even though these changes are more gradual than those detected in observations. We argue that a sediment source perspective on suspended sediment transport such as the PBRC may be more suitable than traditional discharge-based rating curves to explore climate-driven changes in fine sediment dynamics in Alpine catchments. The PBRC approach can be applied to any Alpine catchment with a pluvio-glacio-nival hydrological regime and adequate hydroclimatic datasets. 25Hydrol. Earth Syst. Sci. Discuss., https://doi

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Assessment of annual pollutant loads in combined sewers from continuous turbidity measurements: Sensitivity to calibration data

Cited by 34 publications

References 23 publications

Multiple Time-Scale Monitoring to Address Dynamic Seasonality and Storm Pulses of Stream Water Quality in Mountainous Watersheds

Multiple Time-Scale Monitoring to Address Dynamic Seasonality and Storm Pulses of Stream Water Quality in Mountainous Watersheds

Hydroclimatic control on suspended sediment dynamics of a regulated Alpine catchment: a conceptual approach

A Process–Based Rating Curve to model suspended sediment concentration in Alpine environments

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