Lake Ontario Water Chemistry Atlas

This atlas contains a broad assessment of the results of phosphorus loading reduction in Lake Ontario in the 1970s, including the in-lake phosphorus concentration reduction. It also describes trends of other indicators of recovery from eutrophication. The summer Secchi depths and summer oxygen depletion rates were fairly stable in the 1970s, whereas they would have worsened without phosphorus control. Particulate organic carbon in offshore surface waters during August/September declined steadily by 20% from 1975 to 1981. Also illustrated are the chemical/biological aspects of the spring time thermal bar, and lakewide upwelling/downwelling in response to winds in summer. In July 1972, there was a prominent lakewide chlorophyll maximum at a depth of about 10m. The spring time diatom crop was located near the lake bottom in summer, as indicated by abundant particulate organic matter and near-bottom release of soluble reactive silica. March/April nitrate+ nitrite had steadily increasing values, from 215 p.g N /L in 1968 to 340 p.g N /L in 1981. There was a residual level of nitrate + nitrite in surface waters during late summer in the later years, amounting to about 100 p.g N /L, which, along with decreased phosphorus and increased N:P ratios, means that troublesome blue-green algal blooms and scums will not occur. In summary, the phosphorus control program and a fortuitous increase of soluble reactive nitrogen have resulted in very good metabolic conditions in Lake Ontario, with moderate phosphorus and plankton con tent, prevention of troublesome plankton blooms, and excellent oxygen conditions. It is strongly recommended that the phosphorus loading control program for Lake Ontario and upstream Lake Erie be continued, to maintain the presently ideal trophic conditions in Lake Ontario

Climate Change and Water : final prospectus report

This report was prepared by the International Development Research Centre’s Climate Change and Water (CCW) program (2010-2015) as part of the program’s external evaluation. At the time of submission, the program’s portfolio included 121 projects across Africa, Asia, and Latin America and the Caribbean, for a combined value of $75.3 million. Recognizing that climate change adaptation is a new concept, the program focused on three outcome areas: knowledge generation, capacity building and leadership, and informing climate change policy. Close to 1000 researchers have benefitted from the sustained support of the CCW program over the course of the program

Burst detection in water networks using principal component anlysis

The following work presents a multivariate statistical technique applied to the control of water inflows into district metering areas (DMAs) of urban networks. This technique, called principal-component analysis (PCA), allows for a sensitive and quick analysis of the inflows into a DMA without hassling mathematical algorithms. The PCA technique simplifies the original set of flow rate data recorded by the supervisory control and data acquisition (SCADA) system, synthesizing the most significant information into a statistical model that is able to explain most of the behavior of the water distribution network. The PCA technique also allows for the establishment of control charts that help system operators in the identification of anomalous behaviors regarding water use, bursts, or illegal connections. The described technique has been proven to offer high detection sensitivity to bursts or other unexpected consumptions.Palau Estevan, CV.; Arregui De La Cruz, F.; Carlos Alberola, MDM. (2012). Burst detection in water networks using principal component anlysis. Journal of Water Resources Planning and Management. 138(1):47-54. doi:10.1061/(ASCE)WR.1943-5452.0000147S4754138

Risk-cost optimization of buried pipelines using subset simulation

On the basis of time-dependent reliability analysis, a computational framework called subset simulation (SS) has been applied for risk-cost optimization of flexible underground pipeline networks. SS can provide better resolution for rare failure events that are commonly encountered in pipeline engineering applications. Attention in this work is devoted to scrutinize the robustness of SS in risk-cost optimization of pipelines. SS is first employed to estimate the reliability of flexible underground pipes subjected to externally applied loading and material corrosion. Then SS is extended to determine the intervention year for maintenance and to identify the most appropriate renewal solution and renewal priority by minimizing the risk of failure and whole life-cycle cost. The efficiency of SS compared to genetic algorithm has been demonstrated by numerical studies with a view to prevent unexpected failure of flexible pipes at minimal cost by prioritizing maintenance based on failure severity and system reliability. This paper shows that SS is a more robust method in the decision-making process of reliability-based management for underground pipeline networks

Technology Showcases: Africa RISING project in the Ethiopian Highlands

United States Agency for International Developmen

Alleviating health risks associated with rainwater harvesting

Perceived and real public health risks associated with the quality of water from alternative water sources and supply systems, such as rainwater harvesting (RWH) and grey water reuse, continue to restrict their uptake in many countries. One option to alleviate these health risks is to treat alternative water to potable standard at the point of use (POU) as opposed to the point of supply, as undertaken in centralised systems. This paper presents the results of three international empirical field trials of a novel POU RWH treatment device. The results indicate that where the harvested rainwater did not contain elevated levels of pesticides or physico-chemical determinands, the POU device was able to reduce levels in outlet water to meet UK, EU and World Health Organization potable standards. Regarding microbiological determinands, such as total viable counts and coliforms, and microbial pathogens, such as Pseudomonas aeruginosa and Legionella spp., the device achieved reduction to potable standard and full pathogen removal, respectively. Thus, while it is possible to treat harvested rainwater to potable standard with a POU device, whether it is desirable to do so to alleviate risks for all end uses remains a question for further debate

Long‐term phosphorus accumulation and removal efficiency in a land‐based wastewater treatment system in the UK

The study aims to assess the long‐term phosphorus (P) removal in a land treatment system (LTS) in the UK. Different sections of the site have been irrigated with wastewater effluent for different periods of time for up to 85 years. The amounts of P discharged and accumulated were calculated from historical data, estimations of water consumption, composition and soil measurement. The total P input during the study period was estimated to be 90 010 kg, the average P removal was 4% and there was no significant difference in the total P accumulated between plots irrigated for different periods, indicating that the sorption capacity of the soil might be saturated. Despite the low P retention rates in the LTS, there is no evidence that emissions from this system are affecting P concentrations in either the nearby river or the local chalk aquifer. Gaps remain, however, in performance optimisation and longevity forecasting