武汉汉阳地区城市集水区尺度降雨径流污染过程与排放特征

2005年4月至8月对武汉市汉阳地区十里铺集水区进行了8次径流污染过程的水量、水质研究.结果表明,城市集水区尺度径流污染过程是降雨径流对整个集水区地表、排水系统中累积污染物的冲刷、携带过程,受集水区累积污染物数量、污染物可冲刷性和降雨径流特征的共同影响.城市降雨径流中初期污染物浓度显著高于后期,污染物浓度的峰值提前于径流的峰值,具有明显的初期冲刷效应.8次监测结果的算术平均值,初期5 mm、10 mm和15 mm降雨径流中TSS的负荷分别占总负荷的48%、68%和78%.初期径流中TSS的负荷与晴天累积天数呈线性正相关关系.     

明清苏浙沿海台风风暴潮灾害序列重建与特征分析

在系统搜集、整理明清苏浙沿海潮灾记录基础上,建立风暴潮频率辨识方法,复原台风风暴潮灾害750次,据此建立逐年风暴潮频率序列。分析显示,1460~1480年、1570~1595年、1715~1745年、1785~1810年、1880~1890年为风暴潮活跃期。明清苏浙沿海风暴潮存在45 a、25 a、14 a三种时间尺度周期,其中45 a周期最为显著。气候跃变分析表明,1402年、1457年、1566年、1624年、1652年、1711年、1846年、1880年风暴潮活动趋于活跃;1444年、1477年、1543年、1634年、1799年、1856年风暴潮趋于平静。与1470年以来温度距平曲线对比显示,气候冷暖与风暴潮发生频率有一定正相关性,全球变暖背景下苏浙沿海可能面临更为严重的风暴潮威胁。苏浙地区明清时期风暴潮灾害空间分布差异明显,大部分风暴潮记载集中于长三角、杭州湾地区,苏北地区风暴潮数量少但影响范围广,浙东地区受地形和经济发展程度影响,风暴潮记载数量少且集中于滨海。     

Media Storms and Policy Expertise: How Environmental Beat Journalists Gained Influence During a Shale Gas Controversy

This article examines the conditions under which environmental beat journalists can gain credibility as expert informants. It shows that media storms foster a particular dynamic that can add to this credibility. Comparing a media storm over shale gas development in Quebec with regular coverage of the same issue in British Columbia, this article shows that the coverage space given to environmental beat journalists during a media storm can render their alliance with protest groups mutually beneficial. Beat journalists can benefit from the willingness of these groups to participate in their stories, while the groups benefit from increased visibility. Beat journalists also benefit by being perceived as expert informants in policy networks, a role that they use to encourage policy-makers to take the concerns of protest groups seriously. This dynamic also increases the negativity of the news coverage. The article makes a contribution to knowledge on the role of environmental journalists in policy-making processes.     

三峡上游地区一次西南涡暴雨过程中尺度特征诊断和数值模拟

结合高空、地面实况观测数据以及1°×1°NCEP客观再分析资料,对2009年6月28日20时至29日20时(北京时)发生在三峡上游地区的一次区域暴雨过程进行了中尺度特征诊断,结果表明本次过程是东北低涡和副高稳定少动的大尺度环流背景形势下,由于高原低值系统在东移过程中与西南涡结合而产生的强降水天气过程。高原上不稳定能量的扰动和下传为西南涡的产生提供了必要能量条件,高低层的水汽平流和水汽辐合的交汇地带与最强降水带存在较好的一致性。另外,利用WRF中尺度数值模式对该次过程进行了数值模拟,结果显示在同化了地面和高空常规观测资料后,模式模拟效果得到明显改善,模拟降水能够大致体现该次过程的总的降水演变和分布情况,但后期模拟降水偏大。数值诊断结果发现,盆地西部与上升气流相伴的正涡度柱的演变过程与强降水的发生过程密切相关,该因子对于正确预报降水发生时间具有指示意义。     

城市环境水文问题分析

城市化对水环境污染是一个具有普遍性和严重性的问题.城市水环境污染分为点污染和面污染两类.本文针对城市降雨径流污染(城市面源污染)作了系统分析.其内容包括城市化对降雨径流的影响,城市面污染的积累和暴雨径流的冲刷,以及推求城市暴雨径流污染负荷过程的模拟途径.     

USE OF RADAR TO DERWE A STORM INTENSITY-DURATION CURVE1

ABSTRACT: Rainstorms which exceed the design capacity of conveyance systems and cause extensive damage to structures and property, occur frequently in Alberta. After such a severe storm, an early and quick assessment of the storm's location and magnitude and the corresponding frequency for various duration (storm intensity-duration curve) is often required to estimate the damage. The storm intensity-duration curve is produced with information obtained from a sparse network of recording raingages, thus, creating a high degree of uncertainty in the result. Short-duration precipitation is usually quite variable in Alberta; hencea very dense network of recording precipitation stations would be required to provide precise measurements of the storm intensity-duration curve at all locations. Such a dense network does not exist in Alberta; it would be very expensive to install, maintain, and thus difficult to justify financially. One solution for obtaining a large amount of closely spaced in-intensity-duration values is to use weather radar. Using weather radar data, intensity-duration curves could be produced routinely for any set of prespecified locations. The radar data thus have the potential for facilitating the identification of the return period of rainfall events quickly, cheaply, and precisely when the long-term intensity-duration curves are available. As a pilot project to demonstrate the feasibility of the method and the potential of the radar data, computer software was developed to derive from archived radar data, intensity-duration values for up to a 2,500 2 area for a given storm.     

SOME GEOMORPHIC RELATIONSHIPS AND HYDROGRAPH ANALYSIS1

ABSTRACT: First order drainage channels originate when the tractive force exerted by flowing water is sufficient to move surface sediment. The amount of runoff available to move sediment is a function of geologic and climatic characteristics. An experimental analysis showed that soils derived from fine grained rocks had lower infiltration rates and higher runoff volume than soils derived from coarser grained rocks in a semi-arid climate. Root density and penetration increased in a more humid climate and increased infiltration rates. The number of first order channels was inversely proportional to the infiltration capacity of the soil. Each first order channel acts as a source area for surface runoff. The distribution of first order channel distances from the gage determines the timing of the delivery of water to the gage. A comparison of the frequency histogram of first order channel distances for drainage basins in Pennsylvania and their hydxographs of runoff from general storms showed marked similarity. This close correspondence indicated the shape of the surface runoff hydrograph and was largely controlled by the distribution of first order channel distances.     

CONTRIBUTION OF PRECIPITATION TO QUALITY OF URBAN STORM RUNOFF1

Precipitation and runoff samples were collected for 13 storms in a nonindustrial urban area in Central Pennsylvania between July 1980 and June 1981. Runoff was collected from tree surfaces, a residential roof and street, a shopping mall parking lot, a downtown business district alley, and a heavily traveled street. Analysis of the water samples showed 10 to 25 percent of the nitrogen, 25 percent of the sulfate, and less than 5 percent of the phosphorus, potassium, and calcium in water below a tree was deposited by the precipitation. The residential roof caused insignificant changes in water chemistry. The results for the four paved areas showed that all the nitrogen, and from 16 to 40 percent of the sulfate and 13, 4, and 2 percent of the phosphorus, potassium, and calcium, respectively, in runoff was deposited by the precipitation. Precipitation can also be an important source of sulfate and phosphorus in runoff. All of the surfaces raised the pH of the runoff, with the largest increases, from a pH of 4 to about 7, occurring in runoff from the paved areas. Precipitation and runoff chemistry was not related to antecedent conditions such as the length of the preceding dry period.     

ASSESSING FLOOD MITIGATION ALTERNATIVES IN SHIJR AREA IN METROPOLITAN TAIPEI1

The Keelung River Basin in northern Taiwan lies immediately upstream of the Taipei metropolitan area. The Shijr area is in the lower basin and is subject to frequent flooding. This work applies micromanagement and source control, including widely distributed infiltration and detention/ retention runoff retarding measures, in the Wudu watershed above Shijr. A method is also developed that combines a genetic algorithm and a rainfall runoff model to optimize the spatial distribution of runoff retarding facilities. Downstream of Wudu in the Shijr area, five dredging schemes are considered. If 10‐year flood flows cannot be confined in the channel, then a levee embankment that corresponds to the respective runoff retarding scheme will be required. The minimum total cost is considered in the rule to select from the regional flood mitigation alternatives. The results of this study reveal that runoff retarding facilities installed in the upper and middle parts of the watershed are most effective in reducing the flood peak. Moreover, as the cost of acquiring land for the levee embankment increases, installing runoff retarding measures in the upper portion of the watershed becomes more economical.     

北京沙尘天气与源地气象条件的关系

本介绍了影响北京地区沙尘天气的沙尘源地,沙尘暴发生的条件和传输路径,分析了沙尘暴源地的气候要素特征及其对北京地区沙尘天气的影响,说明了北京沙尘天气发生和加剧的原因,影响北京地区沙尘天气的境外源地主要位于哈萨克斯坦,俄罗斯以及蒙古国境内,境内源地主要位于内蒙古和新疆,以及甘肃和青海的部分地区,沙尘天气发生必须具备三个条件：沙源,大风,气流辐合（垂直对流）,有沙源不一定起沙,但无沙源一定不起沙,沙尘暴源地的气候特征主要表现为冬季寒冷,夏季炎热,全年降水稀水,影响北京的沙尘传输路径,最主要的有两条,即西路传输和北路传输,北京沙尘天气与沙尘暴源地的春季降水比较结果表明,北京地区沙尘暴和浮尘天气发生次数与沙尘源区春季大气降水量有比较显的负相关关系,北京扬沙天气的发生与沙源区冬春季降水量相关关系不显,说明北京扬沙天气起因与源区降水没有明显的关系,北京扬沙天气主要受本地的自然条件和人为活动的影响。