7 research outputs found

    Suburban watershed nitrogen retention : estimating the effectiveness of stormwater management structures

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    Excess nitrogen (N) is a primary driver of freshwater and coastal eutrophication globally, and urban stormwater is a rapidly growing source of N pollution. Stormwater best management practices (BMPs) are used widely to remove excess N from runoff in urban and suburban areas, and are expected to perform under a wide variety of environmental conditions. Yet the capacity of BMPs to retain excess N varies; and both the variation and the drivers thereof are largely unknown, hindering the ability of water resource managers to meet water quality targets in a cost-effective way. Here, we use structured expert judgment (SEJ), a performance-weighted method of expert elicitation, to quantify the uncertainty in BMP performance under a range of site-specific environmental conditions and to estimate the extent to which key environmental factors influence variation in BMP performance. We hypothesized that rain event frequency and magnitude, BMP type and size, and physiographic province would significantly influence the experts’ estimates of N retention by BMPs common to suburban Piedmont and Coastal Plain watersheds of the Chesapeake Bay region. Expert knowledge indicated wide uncertainty in BMP performance, with N removal efficiencies ranging from 40%. Experts believed that the amount of rain was the primary identifiable source of variability in BMP efficiency, which is relevant given climate projections of more frequent heavy rain events in the mid-Atlantic. To assess the extent to which those projected changes might alter N export from suburban BMPs and watersheds, we combined downscaled estimates of rainfall with distributions of N loads for different-sized rain events derived from our elicitation. The model predicted higher and more variable N loads under a projected future climate regime, suggesting that current BMP regulations for reducing nutrients may be inadequate in the future

    Climate change impacts on asphalt road pavement construction and maintenance: An economic life cycle assessment of adaptation measures in the State of Virginia, United States

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    Pavement design and management practices must be adapted in response to future climate change. While many studies have attempted to identify different methods to adapt pavements to future climate conditions, the potential economic impacts of the adaptations still remain largely unquantified. This study presents the results of a comprehensive life-cycle cost analysis (LCCA) aimed at quantifying the potential economic impacts of a climate adaptation method, in which an upgraded asphalt binder (Performance Grade PG 76-22) is used in the construction and maintenance of flexible pavement sections in lieu of the original binder (PG 70-22) for improved resistance against high temperatures. For each of three major Virginia Department of Transportation (VDOT) districts with different climates, three case studies consisting of typical interstate, primary, and secondary pavement sections were considered. The LCCA accounted for the costs incurred during the mixture's production, maintenance, and use phases of the pavement life cycle by explicitly considering future climate projections, pavement life-cycle performance, maintenance effects, and work zone user delays. The study concludes that pavements using the upgraded binder not only perform better over time but are also economically advantageous compared to those with the original binder under the conditions of the anticipated future climate conditions (2020–2039)

    Impacts of future climate change on flexible road pavement economics: A life cycle costs analysis of 24 case studies across the United States

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    Highway agencies are facing pressure for repairing and replacing underfunded and aged road pavement networks that were initially designed for historical climatic conditions. The pavements must be updated while accounting for the impacts of climate change, which are likely to be exacerbated in the years to come, and with limited budgets. Methodologies and frameworks that help agencies incorporate the long-term effects of climate change on pavement performance and make informed decisions on how to spend their limited funds are therefore of utmost importance. This paper presents a methodological framework that combines downscaled climate projections, pavement performance prediction using AASHTOWare Pavement ME DesignTM tool, maintenance and rehabilitation strategies, and life cycle costs analysis (LCCA) in a comprehensive system. The proposed methodological framework was adopted in the LCCA of 24 case studies across the contiguous United States under four alternative periods corresponding to simulated climate projections for four 20-year periods (1981-2000, 2001-2020, 2041-2060, and 2081-2100) with a higher Representative Concentration Pathway (RCP8.5). The case study results show that climate change per Celsius degree will lead to approximately $650-700 million/year additional agency costs in the U.S. In addition, climate change will have greater impacts on the costs incurred during the maintenance and end-of-life phases

    Effects of 1.5 °C global warming on pavement climatic factors and performance

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    This study compared 11 global climate models (GCMs) in assessing the variability of predicted pavement performance in 24 cities in the U.S. under 1.5 °C global warming and presented equations to estimate the impacts of global warming on pavement performance more simply. The results show a spread among GCMs regarding their predicted pavement deterioration with some models resulting in higher deterioration values than others. Thermal cracking, fatigue cracking, total rutting, and international roughness index (IRI) for the investigated 24 cities in the U.S. are found to increase by 124 ft/mi (23.11 m/km), 24 %, 4.6 %, and 1 % on average under 1.5 °C global warming comparatively to the baseline scenario (1991–2010). Regardless of GCMs, the results reveal southern U.S. cities are expected to suffer from greater changes in IRI and thermal cracking, while global warming induced rutting and fatigue cracking will be of greater concern in northern cities than in southern cities.</p

    The effect of climate change on electricity expenditures in Massachusetts

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    Climate change affects consumer expenditures by altering the consumption of and price for electricity. Previous analyses focus solely on the former, which implicitly assumes that climate-induced changes in consumption do not affect price. But this assumption is untenable because a shift in demand alters quantity and price at equilibrium. Here we present the first empirical estimates for the effect of climate change on electricity prices. Translated through the merit order dispatch of existing capacity for generating electricity, climate-induced changes in daily and monthly patterns of electricity consumption cause non-linear changes in electricity prices. A 2 degrees C increase in global mean temperature increases the prices for and consumption of electricity in Massachusetts USA, such that the average household's annual expenditures on electricity increase by about 12%. Commercial customers incur a 9% increase. These increases are caused largely by higher prices for electricity, whose impacts on expenditures are 1.3 and 3.6 fold larger than changes in residential and commercial consumption, respectively. This suggests that previous empirical studies understate the effects of climate change on electricity expenditures and that policy may be needed to ensure that the market generates investments in peaking capacity to satisfy climate-driven changes in summer-time consumption
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