FLOODPLAIN ANALYSIS,SIMPLIFIED VS. COMPLEX METHODS: A CASE STUDY1

ABSTRACT: The accurate and reliable determination of floodplains, floodway boundaries, and flood water elevations are integral requirements of Flood Insurance Studies. These studies are intended to be used for determining the flood insurance rates. Therefore, the accuracy of the water surface profiles are important. To ensure the high degree of accuracy, the HUD Flood Insurance Administration has developed standards which must be met in the analysis of water surface profiles. A somewhat less accurate study is required for the preparation of Flood Emergency Plans. As part of the flood insurance studies of eight locations in the State of North Dakota, various flood hazard and floodplain information reports were reviewed. The hydrologic and hydraulic analyses, especially the computation of the 100-year water surface profiles, were completed using both simplified and complex hydraulic computation methods. Significant differences were found (1 to 3 feet) between the profiles computed by the SCS simplified method and those computed by HEC-2 computer program. However, the floodplain boundaries determined by both methods were found to be similar. Approximate methods are recommended for rapid determination of the floodplain, floodway boundaries, and inundation area mapping, while sophisticated computer programs (HEC-2) are recommended to be used for developing areas where the 100-year flood elevation has a significant impact on the cost of land development.     

Tubular electrostatic precipitators of two-stage design

Although the “two stage” electrostatic precipitator concept was first developed in 1910, until recently most of their use was confined to in-plant air cleaning. In the last decade, plate type designs have been modified to make them suitable for industrial applications involving organic emissions, most notably in asphalt saturating, plastic curing, food processing, printing, textile finishing, and heat treating industries. However, plate type designs are inadequate in applications where very high loading and/or high particulate content are involved.Tubular design with wider spacing and higher voltages incorporates the best features of both the single stage and two stage type precipitators. These units have been used in molybdenum roasting, zirconium calcining, ammonia scrubbing of oxides of sulfur, meat broiling, foundry exhaust, etc.The paper discusses design parameters, field test data, and operating data on these units. Comparisons with single-stage type precipitators are made wherever applicable. Advantages and disadvantages of two stage precipitators are also discussed.     

Surface and subsurface water quality appraisal for irrigation

Use of irrigation water available from various sources in agriculture is justified on agronomic and economic grounds but care must be taken to minimize its adverse environmental and health impacts. During the study 44 water samples, available from the various resources viz., canal, sewage pipe line, tube wells in confined aquifers, tube wells in unconfined aquifers, and wells in the Chaka block district Allahabad, were chemically analyzed to check its suitability for irrigation and to classify it according to amount of salts present. The analysis reveals that most of the samples were within the lower alkalinity limit (pH 7.17–8.42), except sewage water (pH 7.34–9.04). The electrical conductivity of the samples ranged from 0.26 to 1.37 millimhos/cm. Potassium, sodium, calcium, and phosphorus are all found to be in permissible range except one sample in the village Kuria in which Na percentage was found in doubtful category. The other parameters like sodium adsorption ratio, SAR (1.17–2.74), residual sodium carbonate, RSC (?4.46 to ?1.07), and soluble sodium percentage, SSP (63.97–28.15) were also found below the permissible limit.     

Assessing the spatial distribution of nitrogen dioxide in London,Ontario

Land use regression (LUR) models have been widely used to characterize the spatial distribution of urban air pollution and estimate exposure in epidemiologic studies. However, spatial patterns of air pollution vary greatly between cities due to local source type and distribution. London, Ontario, Canada, is a medium-sized city with relatively few and isolated industrial point sources, which allowed the study to focus on the contribution of different transportation sectors to urban air pollution. This study used LUR models to estimate the spatial distribution of nitrogen dioxide (NO₂) and to identify local sources influencing NO₂ concentrations in London, ON. Passive air sampling was conducted at 50 locations throughout London over a 2-week period in May–June 2010. NO₂ concentrations at the monitored locations ranged from 2.8 to 8.9 ppb, with a median of 5.2 ppb. Industrial land use, dwelling density, distance to highway, traffic density, and length of railways were significant predictors of NO₂ concentrations in the final LUR model, which explained 78% of NO₂ variability in London. Traffic and dwelling density explained most of the variation in NO₂ concentrations, which is consistent with LUR models developed in other Canadian cities. We also observed the importance of local characteristics. Specifically, 17% of the variation was explained by distance to highways, which included the impacts of heavily traveled corridors transecting the southern periphery of the city. Two large railway yards and railway lines throughout central areas of the city explained 9% of NO₂ variability. These results confirm the importance of traditional LUR variables and highlight the importance of including a broader array of local sources in LUR modeling. Finally, future analyses will use the model developed in this study to investigate the association between ambient air pollution and cardiovascular disease outcomes, including plaque burden, cholesterol, and hypertension.

Implications: Monitoring and modeling of NO₂ throughout the city of London represents an important step toward assessing air pollution health effects in a mid-sized Canadian city. The study supports the introduction of railways to LUR modeling of NO₂. Railways explained approximately 9% of the variability in ambient NO₂ concentrations in London, which suggests that local sources captured by land-use indicators may contribute to the efficacy of LUR models. These findings provide insights relevant to other medium and smaller sized cities with similar land use and transportation infrastructure. Furthermore, London is a central hub for medical research and treatment in southwestern Ontario, with facilities such as the Robarts Research Institute, London Regional Cancer Program (LRCP), and Stroke Prevention & Atherosclerosis Research Centre (SPARC). The models developed in this study will provide estimates of exposure for future analyses examining air pollution health effects in this data-rich population.     

An Evaluation of the LPG Vehicles Program in the Metropolitan Area of Mexico City

ABSTRACT

The environmental agency in the metropolitan area of Mexico City has launched a program to introduce more energy-efficient modes of transport, one of which is the use of alternative and less polluting fuels. With that perspective in mind, a liquefied petroleum gas (LPG) fleet of vehicles is exempt of the mandatory "one day without a car" program if the emission of pollutants is below the standard authorized for that specific purpose. Today, about 28,000 light-duty vehicles and heavy-duty trucks circulate in the area, most of them as aftermarket converted vehicles. In this work, we evaluated regulated exhaust emission and other parameters on 134 representative vehicles of that fleet. From the data obtained, an estimate of emission factors and their contribution to the global emission in the metropolitan area is provided. It is concluded that more than 95% of the in-use vehicles using LPG presented regulated emissions which exceeded in one or more the environmental regulations values required for certification. The poor maintenance of the vehicles and the type of conversion kit installed could be the culprits of the results obtained.     

A study on consumer consciousness and behavior to the plastic bag ban in Kenya

Journal of Material Cycles and Waste Management - Single use plastics pose environmental and socioeconomic problems in our life and ecosystems. After a 14 year attempt, Kenya successfully...     

Association between occupational exposure to domestic solid waste and dental caries: a cross-sectional study

Environmental Science and Pollution Research - Studies have shown that domestic waste collectors are exposed to toxicants including infectious pathogens, which may be linked to their oral health...     

The connection between urbanization and carbon emissions: a panel evidence from West Africa

Environment, Development and Sustainability - This study examined the nexus between urbanization and carbon emissions in West Africa. Second-generation econometric techniques that are robust to...