Building channel networks in flat regions of digital elevation models (DEMs) is important for watershed delineation and hydrological modeling, particularly for areas with gently-sloped terrain, such as the Canadian Prairies. Existing drainage analysis methods cannot effectively address the spatial correlations of elevation across the flat regions, and the quality of the DEM-derived channel network is mainly evaluated through visual inspection. In this study a hydrological correction method is developed that integrates elevation information from both the existing digital channel network and the original DEM. A set of geomorphological indices is then introduced for quantitative evaluation of DEM-derived channel networks from the perspectives of flow direction and drainage pattern. Both the DEM correction and network assessment methods are implemented in a GIS environment. Their performance is demonstrated through a case study in southern Saskatchewan, Canada. The generated channel network is consistent with the known hydrological information and contains fewer parallel channels compared with existing methods. The developed methods could be valuable for a wide range of applications using the Canadian Digital Elevation Data (CDED) within the context of the Canadian Prairie region.

This paper focuses on the condition evaluation of asbestos cement (AC) pipe samples from three utilities located in different geographic regions and climatic zones in the USA and Canada. Various means of examination and testing were used to evaluate the condition of the samples. These included visual inspection, hardness testing, phenolphthalein testing, crush testing, and scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS). Climate and soil information was also collected for the areas where the three utilities are located to assess the external environments facing the AC pipes. The condition evaluation results were correlated with the external soil characteristics and internal water quality data, collected through a survey, to identify factors contributing to the deterioration of the AC pipes belonging to these utilities. The paper also discusses the variation in the deterioration of the AC water mains from the three utilities.

An analytical method to produce profiles of bacterial biomass fatty acid methyl esters (FAME) was developed employing rapid agitation followed by static incubation (RASI) using selective media of wastewater microbial communities. The results were compiled to produce a unique library for comparison and performance analysis at a Wastewater Treatment Plant (WWTP). A total of 146 samples from the aerated WWTP, comprising 73 samples of each secondary and tertiary effluent, were included analyzed. For comparison purposes, all samples were evaluated via a similarity index (SI) with secondary effluents producing an SI of 0.88 with 2.7% variation and tertiary samples producing an SI 0.86 with 5.0% variation. The results also highlighted significant differences between the fatty acid profiles of the tertiary and secondary effluents indicating considerable shifts in the bacterial community profile between these treatment phases. The WWTP performance results using this method were highly replicable and reproducible indicating that the protocol has potential as a performance-monitoring tool for aerated WWTPs. The results quickly and accurately reflect shifts in dominant bacterial communities that result when processes operations and performance change.

OBJECTIVE: The overall objective of this research study was to explore the current conditions and state of the art in management of asbestos cement (AC) water main assets and develop a practical, comprehensive guidance manual to be used by the owners of these assets. Issues to be addressed included pipe deterioration and failure, condition assessment, remaining service life prediction, rehabilitation and replacement, and health and waste management protocols.

Eutrophication of small prairie reservoirs presents a major challenge in water quality management and has led to a need for predictive water quality modeling. Studies are lacking in effectively integrating watershed models and reservoir models to explore nutrient dynamics and eutrophication pattern. A water quality model specific to small prairie water bodies is also desired in order to highlight key biogeochemical processes with an acceptable degree of parameterization. This study presents a Multi-level Watershed-Reservoir Modeling System (MWRMS) to simulate hydrological and biogeochemical processes in small prairie watersheds. It integrated a watershed model, a hydrodynamic model and an eutrophication model into a flexible modeling framework. It can comprehensively describe hydrological and biogeochemical processes across different spatial scales and effectively deal with the special drainage structure of small prairie watersheds. As a key component of MWRMS, a three-dimensional Willows Reservoir Eutrophication Model (WREM) is developed to addresses essential biogeochemical processes in prairie reservoirs and to generate 3D distributions of various water quality constituents; with a modest degree of parameterization, WREM is able to meet the limit of data availability that often confronts the modeling practices in small watersheds. MWRMS was applied to the Assiniboia Watershed in southern Saskatchewan, Canada. Extensive efforts of field work and lab analysis were undertaken to support model calibration and validation. MWRMS demonstrated its ability to reproduce the observed watershed water yield, reservoir water levels and temperatures, and concentrations of several water constituents. Results showed that the aquatic systems in the Assiniboia Watershed were nitrogen-limited and sediment flux played a crucial role in reservoir nutrient budget and dynamics. MWRMS can provide a broad context of decision support for water resources management and water quality protection in the prairie region.

Various types of microorganisms have been found to inhabit the inner surfaces of asbestos cement (AC) pipe and their activities can cause significant structural damage. They cause a patina to form on the inside surface of AC pipes as a distinctively continuous coating, commonly 2-5 mm in thickness and generally pigmented as yellow, orange, brown or black depending on the metallic cations that have been incorporated into the surface of biofilm (bioaccumulation). Four sublayers can be identified in the patina, from the outer sublayer that directly interacts with the conveyed drinking water to the inner sublayer that is in proximity of the intact cement matrix. The microbes in the outer sublayer are composed mainly of inactive biomass that separates the aerobic environment of the flowing water from the anaerobic conditions inside the patina. The bacteriological community structure shifts from mixed heterotrophic bacteria (HAB), iron-related bacteria (IRB) and slime-forming bacteria (SLYM) in the outer layer, to a more diverse community with IRB, acid-producing bacteria (APB) and SLYM and HAB in the middle sublayer, and further to the SLYM dominated in the inner sublayer. By directly interacting with cementitious materials, including generating organic acids, IRB and APB play important roles in the leaching of free lime and the dissolution of calcium (Ca)-bearing hydrated components of AC pipes, creating porous structure and reducing the pipe strength. Scanning electron microscopy with an energy dispersive X-ray has revealed that bacterial activity on the internal AC pipe wall had resulted in a significant loss of hydrated cement matrix, which can cause pipe failure when stresses imposed on the pipe exceed the remaining pipe strength. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.

Changing climatic conditions contribute to a time varying nature of hydrological responses over different temporal scales. The temporal dynamics of hydrological systems bring uncertainties into hydrological simulation which are different to uncertainties from spatial heterogeneity of soil and land use. This study develops a new approach to improve the calibration of hydrological based on hydroclimatic similarities. Six climatic indexes are integrated using Principal Component Analysis and Fuzzy C-mean Clustering methods to transform hydrological years into hydroclimatic periods. Parameter sets of SWAT model are calibrated independently for each period and used together to generate continuous simulation for a prairie watershed in southern Canada. Results indicate that the multi-period model exhibits comprehensive advantages over the traditional single-period model under various flow conditions. The simulation ability of the model is improved through using period-specific parameter sets in fitting the observations to compensate for deficiencies in the model structure or input data. (C) 2011 Elsevier Ltd. All rights reserved.

Scanning electron microscopy (SEM) with energy dispersive X-ray (EDX) microanalysis technique has distinct advantages in providing high resolution images for identification of microscopic structure changes in hydrated cement matrix and the chemical compositions. Therefore, this technique can be a very useful tool for characterization of asbestos cement (AC) pipe deterioration. Microscopic structural changes in AC pipes can be related to leaching, chemical and biological processes, which include the free lime leaching, secondary gypsum and ettringite formation, acid attack, and the microorganism induced deterioration. These processes have resulted in losses of free lime, cracks in cement matrix, dissolution of Ca-bearing minerals and increased porosity in the cement paste. Carbonation, as calcite precipitation, on the other hand, is more often observed on the outer surface of the pipe in an alkaline soil environment, and may help to protect AC pipes. This paper is focused on the SEM evidence of these deterioration processes. With the elemental composition data from EDX technique, SEM can be used to quantitatively evaluate AC pipe deterioration. A four stage of deterioration of AC pipes in drinking water distribution system is proposed based on the morphology and elemental compositions of the pipe samples. The understanding of degradation mechanisms provides a scientific basis for the development of operational practices and management strategies that can be used to extend the service life of AC pipes.

Asbestos reinforced concrete (ARC) pipes were commonly used for drinking water distribution networks in North American, primarily from middle1940s to early 1980s. In the City of Regina, Canada approximately 68% of all water mains are ARC pipes, to a total length of 535 km. In this preliminary research it was found that bacteriological activities within the internal surface coating (patina) as well as within the concrete could induce bio-deterioration, which eventually leads to pipe failures. Identification of the bacterial consortia was performed using the S43048 protocols for the chromatographic detection of the C5 to C20 fatty acids methyl esters (FAME). Using proprietary library software, high similarity indexes were statistically generated, confirming the ubiquitous nature of the bacterial community (consortium) within the patina (a distinctively fibrous internal coating) of various pipe samples. Bacteriological activities caused deterioration to the ARC pipes was primarily related to acid producing bacteria. . These bacteria are fermentative in the reductive environments, generating sufficient fatty acids that would reduce the pH into the acidic range of 3.5 to 5.5 and could cause structural failures in the concrete.

Asbestos cement (AC) water mains, generally considered as non-friable asbestos-containing materials (ACMs), are not believed to represent a significant hazard to public health in normal use. However, repair, rehabilitation and removal of AC pipes involve cutting, polishing, and demolition can release asbestos fibers into the air, posing risks to public health. Many water utilities in North America currently have significant portions of their water mains composed of AC pipes. A comprehensive survey was conducted with 20 water utilities in the United States of America and Canada to understand the existing conditions of AC water mains in North America and to determine current management practices related to AC pipe repair, rehabilitation, and replacement. The survey was conducted through questionnaires that covered various areas: pipe inventory; environmental working conditions; current practices in pipe repair, rehabilitation and replacement; and safety/health protection practices used in working with, and disposing of AC pipe. This paper focuses on the survey results related to safety and disposal issues, including existing regulations related to testing and concentrations of asbestos fibers in drinking water, AC pipe project management, worker protection measures, and existing disposal practices for broken AC pipes. Results indicate that some utilities do not have well-established procedures to provide suitable protection for workers and the general public during AC pipe projects. Some current practices can also lead to potential problems for future site development. For example, less than half of the utilities reported having a formal procedure specifically for dealing with AC pipe in water distribution systems. When replacing broken AC pipes, more than half of the utilities had abandoned broken pipes and buried them in place as their primary method of disposal. Standardized procedures, which can be critical for the safety of workers, the public and future site development, are needed by water utilities for handling AC pipes during the repair, rehabilitation, and replacement of AC water mains.

Asbestos cement (AC) pipe constitutes a significant portion of the water distribution pipes still in service in many North American cities. To understand the state of the AC pipe inventory in North America, a survey was conducted of utilities with a large percentage of AC pipes in their water distribution systems. The survey included questions about pipe inventory, breakage, working environments, rehabilitation/replacement practices, and safety- and health-related management practices. This paper summarizes data from the inventory, breakage, and working environment portions of the survey. The survey obtained relatively complete inventory information for pipe length, size, years of service, breakage condition, and water quality. Information about the nature of the soils surrounding AC pipes was limited. The survey indicated that utility managers' perceptions of water and soil environments were not always consistent with water and soil test results. Survey data analysis identified pipe age, water quality, and pipe size as important factors contributing to the failure of AC pipes in North America.

Asbestos cement (AC) pipes were commonly installed in the drinking water distribution systems from the mid 1920s to the late 1980s. In recent years, an increase in the number of water main breaks has occurred in the AC portions of some pipe networks, which can be partially attributed to the corrosion of the aged pipes. This study evaluated the potential role that microorganisms may have played in the degeneration and failure of AC pipes. In this study, a fresh AC pipe section was collected from the distribution network of the City of Regina, Canada and examined for microbiological activities and growth on inside surfaces of pipe sample. Black slime bacterial growths were found to be attached to inner pipe surfaces and a distinctively fibrous internal coating (patina) with iron oxides was formed over the time. The microbial populations inside the patina and the black slime were tested with BART (TM) testers. Heterotrophic aerobic bacteria (HAB) and slime forming bacteria (SLYM) dominated in both the black growths and inside the patina. Iron related bacteria, denitrification bacteria and sulfate reducing bacteria were also commonly present. Microbial challenge assays were conducted by submerging the cut segments of the AC pipe into selected bacterial cultures for a period of 10 days under both aerobic and anaerobic environments. Weight changes were determined and the surface morphology was examined for each of the assayed pipe segments. Results indicated that acid producing bacteria, SLYM and HAB could facilitate the pipe weight loss under anaerobic environments.

Asbestos cement (AC) pipe was first introduced in North America in 1929 and became a common choice for potable water main construction from the 1940s to the 1970s. To understand the condition of AC pipe in North America, a survey was conducted that obtained information about AC pipe inventory, pipe conditions, working environments, rehabilitation/replacement methods, and safety and health-related management practices. This paper summarizes the AC condition assessment techniques used by the surveyed utilities. It also reviews other available condition assessment methods for AC pipes.

With increasing evidences of climate change in the prairie region, there is an urgent need to understand the future climate and the responses of small prairie wetlands. This study integrated two regional climate models (RCMs), two weather generators and a distributed hydrological model to examine uncertainties in hydrological responses to climate change in the Assiniboia watershed, Canada. Comparing to baseline conditions (1971–2000), annual water yield and evapotranspiration in the period of 2041–2070 were generally unchanged, while annual reservoir storage was generally reduced. However, projected hydrological regimes were less consistent at monthly level, particularly for March and July. Such uncertainties in simulated hydrological responses were derived from the implementations of different integrated downscaling methods, reflecting our imperfect knowledge of the future climate. We identified a warming temperature trend from climatic projections, but had less confidence in the future pattern of precipitation. Uncertainties in integrated downscaling were primarily derived from the choice of RCM, and were amplified through the incorporation of different weather generators. Results of any climate change study based on only one RCM and/or one weather generator should be interpreted with caution, and the ensemble framework should be advised to generate a comprehensive vision of the future climate. This study demonstrated that the incorporation of precipitation occurrence change contributed to a full translation of RCM outputs, but also introduced additional uncertainty. A balance is thus desired between the information loss and the additional uncertainty in order to effectively utilize RCM outputs.

Asbestos cement (AC) pipe was first introduced in North America in the late 1920s and became a common choice for potable water main construction from the 1940s to the 1970s. The use of AC pipe was largely discontinued in North America in the early 1980s but AC pipe is still a significant portion of the water distribution systems in many North American cities. As the pipes deteriorate and fail to meet service requirements, appropriate rehabilitation/replacement methods need to be determined. This paper summarizes survey data on the rehabilitation/replacement methods for AC pipes provided by 19 water utilities in the United States and Canada. The paper also reviews current available rehabilitation/replacement methods to provide some background of the current practices used by the utilities. The survey indicates that trenching is the main method used to repair, rehabilitate, and replace AC pipes. Cost was cited as the main reason for utilities to choose a particular repair/rehabilitation/replacement method. Although most of the rehabilitation/replacement methods have potential social and environmental effects because of possible release of asbestos fibers, the effects were generally not given high priority when selecting methods for renewing AC pipes.

This study evaluated three different dehydrated media for simultaneous detection and enumeration of total coliform (TC) and Escherichia coli in drinking water samples with a standard membrane filtration procedure. The experiment indicated that the differential coliform agar (DCA) medium was the most effective among the tested media in enumerating TC and E. coli, without the need for extensive accompanying confirmation tests. The results for DCA medium were highly reproducible for both TC and E. coli with standard deviation of 6.0 and 6.1, respectively. A high agreement (82%) was found between DCA and m-Endo media on 152 drinking water samples in terms of TC positive. The DCA medium also reduced concealment of background bacteria.