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251.
Empirical Estimation of Stream Discharge Using Channel Geometry in Low‐Gradient,Sand‐Bed Streams of the Southeastern Plains
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Stephen A. Sefick Latif Kalin Ely Kosnicki Brad P. Schneid Miller S. Jarrell Chris J. Anderson Michael H. Paller Jack W. Feminella 《Journal of the American Water Resources Association》2015,51(4):1060-1071
Manning's equation is used widely to predict stream discharge (Q) from hydraulic variables when logistics constrain empirical measurements of in‐bank flow events. Uncertainty in Manning's roughness (nM) is the major source of error in natural channels, and sand‐bed streams pose difficulties because flow resistance is affected by flow‐dependent bed configuration. Our study was designed to develop and validate models for estimating Q from channel geometry easily derived from cross‐sectional surveys and available GIS data. A database was compiled consisting of 484 Q measurements from 75 sand‐bed streams in Alabama, Georgia, South Carolina, North Carolina (Southeastern Plains), and Florida (Southern Coastal Plain), with six New Zealand streams included to develop statistical models to predict Q from hydraulic variables. Model error characteristics were estimated with leave‐one‐site‐out jackknifing. Independent data of 317 Q measurements from 55 Southeastern Plains streams indicated the model (Q = AcRH0.6906S0.1216; where Ac is the channel area, RH is the hydraulic radius, and S is the bed slope) best predicted Q, based on Akaike's information criterion and root mean square error. Models also were developed from smaller Q range subsets to explore if subsets increased predictive ability, but error fit statistics suggested that these were not reasonable alternatives to the above equation. Thus, we recommend the above equation for predicting in‐bank Q of unbraided, sandy streams of the Southeastern Plains. 相似文献
252.
Removal of PFOS, PFOA and other perfluoroalkyl acids at water reclamation plants in South East Queensland Australia 总被引:3,自引:0,他引:3
Thompson J Eaglesham G Reungoat J Poussade Y Bartkow M Lawrence M Mueller JF 《Chemosphere》2011,82(1):9-17
This paper examines the fate of perfluorinated sulfonates (PFSAs) and carboxylic acids (PFCAs) in two water reclamation plants in Australia. Both facilities take treated water directly from WWTPs and treat it further to produce high quality recycled water. The first plant utilizes adsorption and filtration methods alongside ozonation, whilst the second uses membrane processes and advanced oxidation to produce purified recycled water. At both facilities perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate (PFHxS), perfluorohexanoic acid (PFHxA) and perfluorooctanoic acid (PFOA) were the most frequently detected PFCs. Concentrations of PFOS and PFOA in influent (WWTP effluent) ranged up to 3.7 and 16 ng L−1 respectively, and were reduced to 0.7 and 12 ng L−1 in the finished water of the ozonation plant. Throughout this facility, concentrations of most of the detected perfluoroalkyl compounds (PFCs) remained relatively unchanged with each successive treatment step. PFOS was an exception to this, with some removal following coagulation and dissolved air flotation/sand filtration (DAFF). At the second plant, influent concentrations of PFOS and PFOA ranged up to 39 and 29 ng L−1. All PFCs present were removed from the finished water by reverse osmosis (RO) to concentrations below detection and reporting limits (0.4-1.5 ng L−1). At both plants the observed concentrations were in the low parts per trillion range, well below provisional health based drinking water guidelines suggested for PFOS and PFOA. 相似文献
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254.
Graham W. Prescott William J. Sutherland Daniel Aguirre Matthew Baird Vicky Bowman Jake Brunner Grant M. Connette Martin Cosier David Dapice Jose Don T. De Alban Alex Diment Julia Fogerite Jefferson Fox Win Hlaing Saw Htun Jack Hurd Katherine LaJeunesse Connette Felicia Lasmana Cheng Ling Lim Antony Lynam Aye Chan Maung Benjamin McCarron John F. McCarthy William J. McShea Frank Momberg Myat Su Mon Than Myint Robert Oberndorf Thaung Naing Oo Jacob Phelps Madhu Rao Dietrich Schmidt‐Vogt Hugh Speechly Oliver Springate‐Baginski Robert Steinmetz Kirk Talbott Maung Maung Than Tint Lwin Thaung Salai Cung Lian Thawng Kyaw Min Thein Shwe Thein Robert Tizard Tony Whitten Guy Williams Trevor Wilson Kevin Woods Alan D. Ziegler Michal Zrust Edward L. Webb 《Conservation biology》2017,31(6):1257-1270
Political and economic transitions have had substantial impacts on forest conservation. Where transitions are underway or anticipated, historical precedent and methods for systematically assessing future trends should be used to anticipate likely threats to forest conservation and design appropriate and prescient policy measures to counteract them. Myanmar is transitioning from an authoritarian, centralized state with a highly regulated economy to a more decentralized and economically liberal democracy and is working to end a long‐running civil war. With these transitions in mind, we used a horizon‐scanning approach to assess the 40 emerging issues most affecting Myanmar's forests, including internal conflict, land‐tenure insecurity, large‐scale agricultural development, demise of state timber enterprises, shortfalls in government revenue and capacity, and opening of new deforestation frontiers with new roads, mines, and hydroelectric dams. Averting these threats will require, for example, overhauling governance models, building capacity, improving infrastructure‐ and energy‐project planning, and reforming land‐tenure and environmental‐protection laws. Although challenges to conservation in Myanmar are daunting, the political transition offers an opportunity for conservationists and researchers to help shape a future that enhances Myanmar's social, economic, and environmental potential while learning and applying lessons from other countries. Our approach and results are relevant to other countries undergoing similar transitions. 相似文献