ENHANCING FECAL COLIFORM TOTAL MAXIMUM DAILY LOAD MODELS THROUGH BACTERIAL SOURCE TRACKING1

ABSTRACT: Surface water impairment by fecal coliform bacteria is a water quality issue of national scope and importance. In Virginia, more than 400 stream and river segments are on the Commonwealth's 2002 303(d) list because of fecal coliform impairment. Total maximum daily loads (TMDLs) will be developed for most of these listed streams and rivers. Information regarding the major fecal coliform sources that impair surface water quality would enhance the development of effective watershed models and improve TMDLs. Bacterial source tracking (BST) is a recently developed technology for identifying the sources of fecal coliform bacteria and it may be helpful in generating improved TMDLs. Bacterial source tracking was performed, watershed models were developed, and TMDLs were prepared for three streams (Accotink Creek, Christians Creek, and Blacks Run) on Virginia's 303(d) list of impaired waters. Quality assurance of the BST work suggests that these data adequately describe the bacteria sources that are impairing these streams. Initial comparison of simulated bacterial sources with the observed BST data indicated that the fecal coliform sources were represented inaccurately in the initial model simulation. Revised model simulations (based on BST data) appeared to provide a better representation of the sources of fecal coliform bacteria in these three streams. The coupled approach of incorporating BST data into the fecal coliform transport model appears to reduce model uncertainty and should result in an improved TMDL.     

MODELING THE IMPACTS OF WATER LEVEL CHANGES ON A GREAT LAKES COMMUNITY1

ABSTRACT: Recent research that couples climate change scenarios based on general circulation models (GCM) with Great Lakes hydrologic models has indicated that average water levels are projected to decline in the future. This paper outlines a methodology to assess the potential impact of declining water levels on Great Lakes waterfront communities, using the Lake Huron shoreline at Goderich, Ontario, as an example. The methodology utilizes a geographic information system (GIS) to combine topographic and bathymetric datasets. A digital elevation surface is used to model projected shoreline change for 2050 using water level scenarios. An arbitrary scenario, based on a 1 m decline from February 2001 lake levels, is also modeled. By creating a series of shoreline scenarios, a range of impact and cost scenarios are generated for the Goderich Harbor and adjacent marinas. Additional harbor and marina dredging could cost as much as CDN $7.6 million. Lake freighters may experience a 30 percent loss in vessel capacity. The methodology is used to provide initial estimates of the potential impacts of climate change that can be readily updated as more robust climate change scenarios become available and is adaptable for use in other Great Lakes coastal communities.     

REGION,LANDSCAPE, AND SCALE EFFECTS ON LAKE SUPERIOR TRIBUTARY WATER QUALITY1

ABSTRACT: In 1998 and 1999, third‐order watersheds in high mature forest (HMF) and low mature forest (LMF) classes were selected along gradients of watershed storage within each of two hydrogeomorphic regions in the Lake Superior Basin to evaluate threshold effects of storage on hydrologic regimes and watershed exports. Differences were detected between regions (North and South Shore) for particulates, nutrients, and pH, with all but silica values higher for South Shore streams (p < 0.05). Mature forest effects were detected for turbidity, nutrients, color, and alkalinity, with higher values in the LMF watersheds, that is, watersheds with less that 50 percent mature forest cover. Dissolved N, ammonium, N:P, organic carbon, and color increased, while suspended solids, turbidity, and dissolved P decreased as a function of storage. Few two‐way interactions were detected between region and mature forest or watershed storage, thus threshold based classification schemes could be used to extrapolate effects across regions. Both regional differences in water quality and those associated with watershed attributes were more common for third‐order streams in the western Lake Superior drainage basin as compared with second‐order streams examined in an earlier study. Use of ecoregions alone as a basis for setting regional water quality criteria would have led to misinterpretation of reference condition and assessment of impacts in the Northern Lakes and Forest Ecoregion.     

清代后期湖南的虫灾、风灾、雹灾和冰冻雪灾

除水旱灾害之外,清代后期对湖南危害较大的灾种主要为虫灾,风灾、雹灾、冰冻雪灾偶有发生.本文对上述灾害的灾情进行了论述.     

陕西石泉ML4.9级地震建筑物震害分析

2003年4月24日陕西省石泉县红卫乡一带发生ML4.9级地震.这次地震对石泉、汉阴等县建筑物特别是农村建筑物造成一定程度的破坏,本文统计了不同类型的房屋建筑破坏情况,并对此进行了分析和探讨.     

五大连池老黑山火山的两次喷发活动

老黑山是五大连池火山群中最年轻的火山.通过对老黑山火山锥体结构及其形态分析指出,老黑山火山并非单锥,而是由先、后不同时期形成的两个锥体叠加组成的复合锥,表明它有两次喷发活动.通过对新发掘出的史料的分析,进一步指出,老黑山火山的第一次喷发时间为1720(不是1719年)-1721年,第二次可能为1776年.两次喷发活动的确认为研究老黑山火山喷发历史、喷发过程、喷发危险性评价和灾害预测等提供了新依据.     

水质灾害成因及控制对策

水质灾害作为灾害的一种具体表现形式,和其它灾害一样能给人类生活带来巨大的负面影响.为规避灾害风险,必须加强对水质灾害成因的研究.详细分析了水质灾害的成因,考察了形成水质灾害的致灾机制;提出了水质灾害的预防措施和灾后的控制策略,同时提出了预测水质灾害的工作方法;最后,总结了今后应该深人研究的重点.     

给水管道振动信号的小波分析及消振研究

某核发电厂部分蒸汽和给水管道振动情况非常严重 ,以致影响到正常的安全生产。笔者从给水管道的测振出发 ,并利用 3层Daubechise对振动信号进行了小波消噪、滤波、重构处理 ,以找到影响管系振动的激励源的主要频域成分。进而利用比较成熟的结构分析软件ANSYS对管系进行了模态分析 ,得到系统的低阶固有频率和振型。根据管道振动的原因 ,在不改变管系主要特征的基础上 ,给出了简单易行的消振措施 ,实际运行情况表明消振方法效果良好。     

烟花爆竹生产安全问题探析

烟花爆竹生产由于行业的特殊性，危险性很大。近年来，烟花爆竹安全生产形势严峻，事故频发，危害严重。笔者在调查研究的基础上，分析了烟花爆竹生产的危险性以及引发事故的主要原因。着重讨论了烟花爆竹安全生产的可行性途径，强调提高准入门槛，严格安全生产许可证的核发；加大监督管理力度，严格规章制度的落实；发展地方经济，从根本上防止非法生产；并通过对湖南浏阳花炮生产安全管理的分析，探讨安全文化建设在烟花爆竹这一高危行业的作用，认为烟花爆竹行业要发展，要尽可能减少事故的发生，一定要注重安全管理，注重企业安全文化建设，注重提高从业人员的安全文化素质。     

复杂矿井通风系统角联风路自动识别方法的研究

角联风路的识别与稳定性分析是矿井通风系统稳定性与可靠性分析理论中的核心内容之一。笔者对通风系统角联风路进行了深入的研究;分析了通路法的局限性,简化了角联风路的数学模型,提出了快速、准确、灵活的角联风路自动识别的新方法——节点位置法;编写了角联风路自动识别软件,并应用现场数据进行测试,将其结果与通路法的结果进行了比较分析;证明了节点位置法是切实可行的。