A variety of water-quality models have been developed to help assess the impact of land use on wa... more A variety of water-quality models have been developed to help assess the impact of land use on water quality. Initially, most models proposed were deterministic. However, as modelers acquired more information on the functioning of lake-watershed systems, and as engineers and planners inquired about the reliability of the models, considerations of uncertainty began to appear. Modelers who examined uncertainty in their models, and planners who demanded an estimate of the uncertainty in the techniques that they used, realized that they must have a measure of the reliability of their methods. Without this, there was no way to assess the value of the information provided by a model. Under those conditions, inefficient or incorrect decisions were more apt to be made because the model results were given too much or too little weight.
Journal of the Fisheries Research Board of Canada, Feb 1, 1979
Data from North Temperate lakes were used to estimate the uncertainty of a phosphorus loading mod... more Data from North Temperate lakes were used to estimate the uncertainty of a phosphorus loading model. A number of graphical representations of the uncertainty were developed to demonstrate the importance of including probabilistic information in phosphorus loading calculations. Key words: limnology, lake management, phosphorus, eutrophication, models, statistics, probability, loading, lakes, prediction
For rivers and streams, the impact of rising water temperature on biochemical oxygen demand (BOD)... more For rivers and streams, the impact of rising water temperature on biochemical oxygen demand (BOD) assimilative capacity depends on the interplay of two independent factors: the waterbody’s dissolved oxygen (DO) saturation and its self-purification rate (i.e., the balance between BOD oxidation and reaeration). Although both processes increase with rising water temperatures, oxygen depletion due to BOD oxidation increases faster than reaeration. The net result is that rising temperatures will decrease the ability of the world’s natural waters to assimilate oxygen-demanding wastes beyond the damage due to reduced saturation alone. This effect should be worse for nitrogenous BOD than for carbonaceous BOD because of the former’s higher sensitivity to rising water temperatures. Focusing on streams and rivers, the classic Streeter–Phelps model was used to determine the magnitude of the maximum or “critical” DO deficit that can be calculated analytically as a function of the mixing-point BO...
International Journal of Environmental Research and Public Health, 2019
Public health has always been, and remains, an interdisciplinary field, and engineering was close... more Public health has always been, and remains, an interdisciplinary field, and engineering was closely aligned with public health for many years. Indeed, the branch of engineering that has been known at various times as sanitary engineering, public health engineering, or environmental engineering was integral to the emergence of public health as a distinct discipline. However, in the United States (U.S.) during the 20th century, the academic preparation and practice of this branch of engineering became largely separated from public health. Various factors contributed to this separation, including an evolution in leadership roles within public health; increasing specialization within public health; and the emerging environmental movement, which led to the creation of the U.S. Environmental Protection Agency (EPA), with its emphasis on the natural environment. In this paper, we consider these factors in turn. We also present a case study example of public health engineering in current pr...
As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of bl... more As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of blue-green algae (Cyanobacteria) are becoming larger and more frequent in freshwater lakes. In the past half century, aquatic scientists have devoted much effort to understanding the causes of such blooms and how they can be prevented or reduced. Here we review the evidence, finding that numerous long-term studies of lake ecosystems in Europe and North America show that controlling algal blooms and other symptoms of eutrophication depends on reducing inputs of a single nutrient: phosphorus. In contrast, small-scale experiments of short duration, where nutrients are added rather than removed, often give spurious and confusing results that bear little relevance to solving the problem of cyanobacteria blooms in lakes.
A variety of water-quality models have been developed to help assess the impact of land use on wa... more A variety of water-quality models have been developed to help assess the impact of land use on water quality. Initially, most models proposed were deterministic. However, as modelers acquired more information on the functioning of lake-watershed systems, and as engineers and planners inquired about the reliability of the models, considerations of uncertainty began to appear. Modelers who examined uncertainty in their models, and planners who demanded an estimate of the uncertainty in the techniques that they used, realized that they must have a measure of the reliability of their methods. Without this, there was no way to assess the value of the information provided by a model. Under those conditions, inefficient or incorrect decisions were more apt to be made because the model results were given too much or too little weight.
Journal of the Fisheries Research Board of Canada, Feb 1, 1979
Data from North Temperate lakes were used to estimate the uncertainty of a phosphorus loading mod... more Data from North Temperate lakes were used to estimate the uncertainty of a phosphorus loading model. A number of graphical representations of the uncertainty were developed to demonstrate the importance of including probabilistic information in phosphorus loading calculations. Key words: limnology, lake management, phosphorus, eutrophication, models, statistics, probability, loading, lakes, prediction
For rivers and streams, the impact of rising water temperature on biochemical oxygen demand (BOD)... more For rivers and streams, the impact of rising water temperature on biochemical oxygen demand (BOD) assimilative capacity depends on the interplay of two independent factors: the waterbody’s dissolved oxygen (DO) saturation and its self-purification rate (i.e., the balance between BOD oxidation and reaeration). Although both processes increase with rising water temperatures, oxygen depletion due to BOD oxidation increases faster than reaeration. The net result is that rising temperatures will decrease the ability of the world’s natural waters to assimilate oxygen-demanding wastes beyond the damage due to reduced saturation alone. This effect should be worse for nitrogenous BOD than for carbonaceous BOD because of the former’s higher sensitivity to rising water temperatures. Focusing on streams and rivers, the classic Streeter–Phelps model was used to determine the magnitude of the maximum or “critical” DO deficit that can be calculated analytically as a function of the mixing-point BO...
International Journal of Environmental Research and Public Health, 2019
Public health has always been, and remains, an interdisciplinary field, and engineering was close... more Public health has always been, and remains, an interdisciplinary field, and engineering was closely aligned with public health for many years. Indeed, the branch of engineering that has been known at various times as sanitary engineering, public health engineering, or environmental engineering was integral to the emergence of public health as a distinct discipline. However, in the United States (U.S.) during the 20th century, the academic preparation and practice of this branch of engineering became largely separated from public health. Various factors contributed to this separation, including an evolution in leadership roles within public health; increasing specialization within public health; and the emerging environmental movement, which led to the creation of the U.S. Environmental Protection Agency (EPA), with its emphasis on the natural environment. In this paper, we consider these factors in turn. We also present a case study example of public health engineering in current pr...
As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of bl... more As human populations increase and land-use intensifies, toxic and unsightly nuisance blooms of blue-green algae (Cyanobacteria) are becoming larger and more frequent in freshwater lakes. In the past half century, aquatic scientists have devoted much effort to understanding the causes of such blooms and how they can be prevented or reduced. Here we review the evidence, finding that numerous long-term studies of lake ecosystems in Europe and North America show that controlling algal blooms and other symptoms of eutrophication depends on reducing inputs of a single nutrient: phosphorus. In contrast, small-scale experiments of short duration, where nutrients are added rather than removed, often give spurious and confusing results that bear little relevance to solving the problem of cyanobacteria blooms in lakes.
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Papers by Steven Chapra