scholarly journals Performance and uncertainties of TSS stormwater sampling strategies from online time series

2018 ◽  
Vol 78 (6) ◽  
pp. 1407-1416
Author(s):  
Santiago Sandoval ◽  
Jean-Luc Bertrand-Krajewski ◽  
Nicolas Caradot ◽  
Thomas Hofer ◽  
Günter Gruber
Keyword(s):  
Time Series ◽  
Suspended Solids ◽  
Sampling Strategy ◽  
Sampling Strategies ◽  
Sampling Errors ◽  
Time Step ◽  
Sewer System ◽  
Time Intervals ◽  
Combined Sewer ◽  
One Year

Abstract The event mean concentrations (EMCs) that would have been obtained by four different stormwater sampling strategies are simulated by using total suspended solids (TSS) and flowrate time series (about one minute time-step and one year of data). These EMCs are compared to the reference EMCs calculated by considering the complete time series. The sampling strategies are assessed with datasets from four catchments: (i) Berlin, Germany, combined sewer overflow (CSO); (ii) Graz, Austria, CSO; (iii) Chassieu, France, separate sewer system; and (iv) Ecully, France, CSO. A sampling strategy in which samples are collected at constant time intervals over the rainfall event and sampling volumes are pre-set as proportional to the runoff volume discharged between two consecutive sample leads to the most representative results. Recommended sampling time intervals are of 5 min for Berlin and Chassieu (resp. 100 and 185 ha area) and 10 min for Graz and Ecully (resp. 335 and 245 ha area), with relative sampling errors between 7% and 20% and uncertainties in sampling errors of about 5%. Uncertainties related to sampling volumes, TSS laboratory analyses and beginning/ending of rainstorm events are reported as the most influent sources in the uncertainties of sampling errors and EMCs.

Washoff behavior of in-sewer deposit in combined sewer system through artificial flushing experiment

2010 ◽  
Vol 61 (11) ◽  
pp. 2835-2842 ◽  
Author(s):  
W. J. Kim ◽  
S. Managaki ◽  
H. Furumai ◽  
F. Nakajima
Keyword(s):  
Time Series ◽  
Flow Rate ◽  
Enteric Viruses ◽  
Pathogenic Microorganisms ◽  
Combined Sewer Overflows ◽  
Sewer System ◽  
Bacterial Indicators ◽  
Sewer Systems ◽  
Combined Sewer

In-sewer deposits in combined sewer systems (CSSs) are closely related with the behavior of first foul flush and combined sewer overflows. However, the research paying attention to the role of in-sewer deposits is quite rare, furthermore, their contributions for the washoff patterns of each pollutant including pathogenic microorganisms are almost never discussed so far. The artificial flushing experiment separating the washoff of in-sewer deposits from the inflow of surface pollutants was carried out to simulate the first foul flush in a CSS. The washoff behaviors of each pollutant including bacterial indicators and enteric viruses were investigated. Several morphological analyses for the concentration and load curves of each parameter were conducted and all patterns were classified according to their washoff characteristics and first foul flush patterns. The washoff behaviors of each pollutant and microorganism are different from each other and categorized into several groups according to their (i) time-series concentration and load curves and (ii) concentration vs. flow rate curves, respectively. The first foul flush patterns of each parameter were to be categorized into typical 3 groups; strong-, partial-, and no first foul flush group. The order of these groups signifies the strength of the first foul flush phenomena and the runoff priority as well.

scholarly journals Methods for water quality sampling and load estimation in monitoring of Norwegian agricultural catchments

2006 ◽  
Vol 37 (1) ◽  
pp. 81-92 ◽  
Author(s):  
Trond Knapp Haraldsen ◽  
Per Stålnacke
Keyword(s):  
Water Quality ◽  
Suspended Solids ◽  
Sampling Strategy ◽  
Nordic Countries ◽  
Sampling Strategies ◽  
Composite Sampling ◽  
Point Sampling ◽  
Agricultural Catchments ◽  
Lower Load ◽  
Sampling Procedures

Different sampling procedures are applied to monitor water quality in agricultural catchments in the Nordic countries. The need for comparing monitoring results from the Nordic countries was the incentive for establishing a project aimed at comparing estimates of nutrient losses determined using different sampling strategies. Three different sampling methods were compared in three Norwegian catchments: weekly flow-proportional composite sampling (FPCS), weekly composite sampling with temporally equidistant subsampling every second hour (TECS) and temporally equidistant weekly point sampling (PS). Differences in load estimated between the three tested sampling strategies were smaller for nitrogen than for phosphorus or suspended solids. Point sampling tended to miss some of the peaks in concentrations of phosphorus and suspended solids, particularly during flow events, causing significantly lower load estimates for phosphorus and suspended solids by point sampling compared with composite sampling strategies. Flow-proportional composite sampling gave the most reliable data for event-responsible compounds or when the predictability of peaks was low. Based on this investigation, and similar studies in the other Nordic countries, a flow-proportional sampling strategy is recommended for studies of water quality in agricultural streams.

scholarly journals Relationship between turbidity and total suspended solids concentration within a combined sewer system

2011 ◽  
Vol 64 (12) ◽  
pp. 2445-2452 ◽  
Author(s):  
A. Hannouche ◽  
G. Chebbo ◽  
G. Ruban ◽  
B. Tassin ◽  
B. J. Lemaire ◽  
...  
Keyword(s):  
Suspended Solids ◽  
Total Suspended Solids ◽  
Weather Conditions ◽  
Sewer System ◽  
Calibration Dataset ◽  
Solids Concentration ◽  
Sampling Campaign ◽  
Combined Sewer ◽  
Wet Weather ◽  
Strong Linear Relationship

This article confirms the existence of a strong linear relationship between turbidity and total suspended solids (TSS) concentration. However, the slope of this relation varies between dry and wet weather conditions, as well as between sites. The effect of this variability on estimating the instantaneous wet weather TSS concentration is assessed on the basis of the size of the calibration dataset used to establish the turbidity – TSS relationship. Results obtained indicate limited variability both between sites and during dry weather, along with a significant inter-event variability. Moreover, turbidity allows an evaluation of TSS concentrations with an acceptable level of accuracy for a reasonable rainfall event sampling campaign effort.

scholarly journals Accuracy Analysis of Point Velocities Determined by Different Software Packages and GNSS Measurement Processing Methods

2020 ◽  
Vol 14 (4) ◽  
pp. 446-457
Author(s):  
Margareta Premužić ◽  
Almin Đapo ◽  
Željko Bačić ◽  
Boško Pribičević
Keyword(s):  
Time Series ◽  
Noise Analysis ◽  
Tectonic Activity ◽  
Scientific Software ◽  
Time Intervals ◽  
Software Packages ◽  
Processing Strategies ◽  
Zagreb Area ◽  
One Year ◽  
Gnss Measurements

The paper analyzes the geodynamic network of the City of Zagreb for periodic campaigns carried out from 2006 to 2009 which were processed by different software packages. The first computations and processing results were obtained by using the scientific software Gamit/Globk and indicate the ongoing tectonic activity of the area. In this paper, all calculations were performed by using the scientific software Bernese. Processing strategies and applied error models in the Gamit and Bernese solution are analyzed. The results of the previous analyses show the need to perform GNSS measurements at intervals of up to one year, which is necessary for understanding the mechanism of the structural frame of the wider Zagreb area. The research and analysis performed in this paper indicate certain uncertainties in determining the velocities from periodic one-year GNSS measurements. When periodic GNSS observations are analyzed at time intervals shorter than 2.5 years, annual signals can cause significant errors in determining point velocities. The accuracy of determining velocities between annual time intervals depends on a number of factors: noise level in GNSS measurements, measurement sessions quantity and applied computation strategies. Previously, the time series analysis of observations was a key procedure in the context of geodynamic and geokinematic research and the FODITS algorithm was used for the analysis. A noise analysis on the daily time series of coordinates was performed for the purpose of understanding all influences on geodynamic points. Moreover, a correlation between the time series of observations was determined in order to estimate the final velocity uncertainty error. The purpose of this paper is to demonstrate the applicability of the methods and procedures used to determine the coordinates and velocities of points that can be reliably used for geodynamic and geokinematic analyses and consequently, timely responses to various geophysical phenomena due to earthquakes or other natural phenomena.

scholarly journals How large are temporal representativeness errors in paleoclimatology?

2020 ◽  
Vol 16 (1) ◽  
pp. 325-340 ◽  
Author(s):  
Daniel E. Amrhein
Keyword(s):  
Time Series ◽  
Published Data ◽  
Time Interval ◽  
Model Data ◽  
Sampling Errors ◽  
Spectral Character ◽  
Time Duration ◽  
Time Intervals ◽  
Paleoclimate Reconstruction ◽  
Sampling Procedures

Abstract. Ongoing work in paleoclimate reconstruction prioritizes understanding the origins and magnitudes of errors that arise when comparing models and data. One class of such errors arises from assumptions of proxy temporal representativeness (TR), i.e., how accurately proxy measurements represent climate variables at particular times and time intervals. Here we consider effects arising when (1) the time interval over which the data average and the climate interval of interest have different durations, (2) those intervals are offset from one another in time (including when those offsets are unknown due to chronological uncertainty), and (3) the paleoclimate archive has been smoothed in time prior to sampling. Because all proxy measurements are time averages of one sort or another and it is challenging to tailor proxy measurements to precise time intervals, such errors are expected to be common in model–data and data–data comparisons, but how large and prevalent they are is unclear. This work provides a 1st-order quantification of temporal representativity errors and studies the interacting effects of sampling procedures, archive smoothing, chronological offsets and errors (e.g., arising from radiocarbon dating), and the spectral character of the climate process being sampled. Experiments with paleoclimate observations and synthetic time series reveal that TR errors can be large relative to paleoclimate signals of interest, particularly when the time duration sampled by observations is very large or small relative to the target time duration. Archive smoothing can reduce sampling errors by acting as an anti-aliasing filter but destroys high-frequency climate information. The contribution from stochastic chronological errors is qualitatively similar to that when an observation has a fixed time offset from the target. An extension of the approach to paleoclimate time series, which are sequences of time-average values, shows that measurement intervals shorter than the spacing between samples lead to errors, absent compensating effects from archive smoothing. Nonstationarity in time series, sampling procedures, and archive smoothing can lead to changes in TR errors in time. Including these sources of uncertainty will improve accuracy in model–data comparisons and data comparisons and syntheses. Moreover, because sampling procedures emerge as important parameters in uncertainty quantification, reporting salient information about how records are processed and assessments of archive smoothing and chronological uncertainties alongside published data is important to be able to use records to their maximum potential in paleoclimate reconstruction and data assimilation.

Organic carbon biodegradability and heterotrophic bacteria along a combined sewer catchment during rain events

1998 ◽  
Vol 37 (1) ◽  
pp. 25-33 ◽  
Author(s):  
M. Seidl ◽  
P. Servais ◽  
M. Martaud ◽  
C. Gandouin ◽  
J. M. Mouchel
Keyword(s):  
Organic Carbon ◽  
Suspended Solids ◽  
Heterotrophic Bacteria ◽  
Oxygen Demand ◽  
Bacterial Biomass ◽  
Combined Sewer Overflows ◽  
Sewer System ◽  
Urban Catchment ◽  
Combined Sewer ◽  
Rain Events

The aim of this study was the evaluation of fluxes of organic carbon and biodegradability of waste waters during rain events in order to better predict the impacts of combined sewer overflows (CSO). The combined sewer system studied was located in a densely populated urban catchment adjacent to Paris. Five subcatchments of different size, have been monitored during several rain events for suspended solids, conductivity, ammonium, chemical and biological oxygen demand. In addition, two of these subcatchments have been evaluated for dissolved and particulate organic carbon, their biodegradable fractions, and the total bacterial biomass. Several indexes, indicate a lower degradability of waste water during dry weather at the downstream stations, accompanied by an increase of bacterial size and bacterial biomass. A further decrease of biodegradable organic carbon related to rain intensity can be seen at all stations. Our results show a higher proportion of refractory organic carbon during rain events than during dry weather with a possible contribution of the in-sewer sediments to the bacterial wet weather flux.

Monitoring runoff conditions in a combined sewer system: experience and results of ten years' application

1996 ◽  
Vol 33 (1) ◽  
pp. 257-264
Author(s):  
M. Weyand
Keyword(s):  
Monitoring System ◽  
Pilot Project ◽  
Actual Condition ◽  
Real Time Control ◽  
Sewer System ◽  
Time Control ◽  
Combined Sewer ◽  
Complete Breakdown ◽  
Short Time ◽  
Detention Facilities

To get knowledge about the runoff, storage and combined sewer overflow (CSO) conditions since 1985 a measuring and monitoring system is working in the sewer network of the community Ense-Bremen (near Dortmund). Within this semi-urban catchment seven detention facilities are fitted out with devices for monitoring information about basin outflow, grade of volume and CSO. Since October 1986 the determined data are also used for the real-time control of that sewerage. Since its installation the monitoring system works rather satisfyingly. Especially the operating staff use its possibilities to get information about the actual condition of the sewer system. Thus, differences to the normal runoff conditions can be realised in very short time. That allows an immediate reaction in order to clear malfunctions or errors as well. However, within the ten years there have also occurred some failures at the measuring devices caused by different reasons up to a complete breakdown of the whole system during thunder-storms. All in all the results of that pilot project have been positive and are now the basis for the equipment of further detention facilities in other sewer systems with monitoring devices.

The Role of Computer Modeling in Combined Sewer Overflow Abatement Planning

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1831-1840 ◽  
Author(s):  
L. A. Roesner ◽  
E. H. Burgess
Keyword(s):  
System Modeling ◽  
Cost Effective ◽  
Combined Sewer Overflows ◽  
Sewer System ◽  
New Techniques ◽  
Hydraulic Simulation ◽  
Continuous Simulation ◽  
Combined Sewer ◽  
The U.S

Increased concern regarding water quality impacts from combined sewer overflows (CSOs) in the U.S. and elsewhere has emphasized the role of computermodeling in analyzing CSO impacts and in planning abatement measures. These measures often involve the construction of very large and costly facilities, and computer simulation during plan development is essential to cost-effective facility sizing. An effective approach to CSO system modeling focuses on detailed hydraulic simulation of the interceptor sewers in conjunction with continuous simulation of the combined sewer system to characterize CSOs and explore storage-treatment tradeoffs in planning abatement facilities. Recent advances in microcomputer hardware and software have made possible a number of new techniques which facilitate the use of computer models in CSO abatement planning.

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