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Hydraulic behavior and pollutant removal efficiency of three stormwater end-of-pipe control structures were evaluated and compared. Three detention basins (wet, dry, and semi-dry, i.e. dry with a wet central channel) were monitored within three sites of Southern Quebec, Canada. Water samples were collected upstream and downstream of the basins and analyzed for total suspended solids (TSS), nitrogen, total phosphorous, and ions related to de-icing salts. Generalized linear models and hydrological/hydraulic (SWMM) models were developed to compute the long-term TSS and total phosphorous load removal efficiency for two of the studied basins. Results indicate that even when considering uncertainties, removal rates are the highest for the wet basin and the lowest for the dry one. The addition of a wet channel in the semi-dry basin leads to higher removal efficiency than in the dry basin (e.g. median TSS concentration removal of 69% and 14%, respectively, for the semi-dry and dry basins). [ABSTRACT FROM AUTHOR]

This paper presents a methodology to estimate free residual chlorine concentrations (FRCC) in full-scale water distribution system (WDS) using different degradation kinetics according to pipe material, age and diameter. Intensive field sampling campaigns and laboratory-scale tests were carried out to estimate total and bulk volume FRCC in three WDS. Bulk kinetic constants were estimated for water temperatures typical of different seasons in the Quebec City area (Canada). With field-measured FRCC at all sampling sites and an estimation of travel times through the use of a hydraulic model, total, bulk and pipe wall kinetic constants were obtained with ranges of 10.2 to 130.4, 4.1 to 43.8 and 8.5 to 114.9 10−3/h, respectively. Pipe wall kinetics tend to dominate the total degradation process for older grey and ductile cast-iron pipes, followed by newer ductile iron pipes and then PVC and pre-stressed concrete pipes (mostly installed from 1990). The developed methodology and results will be useful to improve the prediction of FRCC through hydraulic and water quality modelling. [ABSTRACT FROM AUTHOR]

This paper presents a methodology to assess and reduce water residence times in a water distribution system in order to improve water quality. The methodology was developed and validated on Quebec City's main distribution system. A tracer study was conducted to evaluate real residence times and results are presented in the 'companion paper' (Part I) in this issue. A hydraulic model was then built to simulate the mean residence times (MRT) and develop strategies to reduce them. An optimization algorithm (hybrid discrete dynamically dimensioned search, HD-DDS) was used to calibrate the model using flows and pressures measured in the distribution system. Results show that the suggested methodology can lead to significant reductions in MRT (25.6%) in parts of the distribution system, but could also lead to significant loss in pressure, which should be monitored closely. [ABSTRACT FROM AUTHOR]

Ensemble rainfall forecasts are of high interest for decision making, as they provide an explicit and dynamic assessment of the uncertainty in the forecast. However, for hydrological forecasting, their low resolution currently limits their use to large watersheds. To bridge this gap, various implementations of a spatial statistical downscaling method were compared, bringing Environment Canada's global ensemble rainfall forecasts from a 100 × 70-km resolution down to 6 × 4-km while increasing each pixel's rainfall variance and preserving its original mean. This was applied for nine consecutive days of summer 2009 with strong rain events over Quebec City, Canada. For comparison purposes, simpler methods were also implemented such as the bilinear interpolation, which disaggregates global forecasts without modifying their variance. The meteorological products were evaluated, using different scores and diagrams, against observed values taken from Quebec City rain gauge network. The most important conclusions of this work are that the overall quality of the forecasts was preserved during the disaggregation procedure and that the disaggregated products using the variance-enhancing method were of similar quality than bilinear interpolation products. However, variance and dispersion of the different members were, of course, much improved for the variance-enhanced products, compared with the bilinear interpolation, which is a decisive advantage. Therefore, there is an interest in implementing variance-enhancing methods to disaggregate global ensemble rainfall forecasts. Copyright © 2012 Her Majesty the Queen in right of Canada. Published by John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

After only a few years of operation, an extensive rain gauge network provides fruitful information on temporal patterns of local storms, helping urban water, managers with in the difficult choice of appropriate design storms. A total of 1470 1-h storms were identified for the period 1999-2005 in Québec City based on rainfall depth and interevent time criteria. Taking advantage of a clustering technique, the Kohonen neural network, 1-h storms were divided into 16 clusters depending on similarities in their temporal patterns, and then lumped into four groups. The database revealed that about one-third of all storms have a uniform intensity, one-third are early-peaking, and one-third are either symmetrical or late-peaking. Early-peaking patterns include the highest maximal 5-min intensity: 0.22-0.30 of the rainfall depth range, therefore in the same range as common Canadian 10-year design storms. [ABSTRACT FROM AUTHOR]

This paper identifies the main sediment sources to the Beaudet Reservoir in Quebec (Canada) using sediment fingerprinting. The reservoir, which is built on the Bulstrode River and provides drinking water to Victoriaville, has decreased in capacity by 35% in the past 35 years. This study provides new data on fingerprinting in large and complex watersheds, a first in the province of Quebec. Nine sampling sites on the Bulstrode River and its three main tributaries were selected and five sampling campaigns were conducted. Samples from river bank profiles and adjacent fields, along with suspended sediments, were collected. All samples were sieved to 2 mm and analyzed for 137Caesium, 15 geochemical elements and sieved to 63 μm for color analysis. Source classification, based on an ANOVA test to verify the independence hypothesis and iterative linear discriminant analysis to optimize the ratio of inter-group/within-group variability, resulted in four sample classes: agricultural soils, forested soils, stream bank bottom and stream bank top. A Kruskal-Wallis H test then identified 21 out of the 32 tracers with p value < 0.05. The linear discriminant analysis led to a set of 14 tracers, namely 137Cs and 13 color coefficients with a discriminating result of 94%. That combination of 137Cs and color coefficients proved to be a cost-effective fingerprint. Based on MixSIAR modeling results, this sediment fingerprinting study has demonstrated that the main sediment sources varied within the watershed but, generally, forested soil particles dominated (33 to 49%), then agricultural soils (43 to 50%) reflecting the land use changes, followed by stream bank bottoms (82%) at the Beaudet Reservoir. [ABSTRACT FROM AUTHOR]