非饱和土边坡稳定的安全分析及进展

笔者基于基质吸力和土抗剪强度之间的关系和非饱和土力学理论 ,以基质吸力问题为中心 ,通过工程实例对影响非饱和土边坡滑动的各种内在及外界因素进行了参数分析 ,尤其对降雨入渗和裂隙影响的定量分析新进展进行了研究。研究结果表明 :非饱和土边坡稳定分析应加强考虑基质吸力对抗剪强度的折减影响 ,修正极限平衡方法对考虑降雨入渗 ,裂隙影响及暂态渗流的非饱和土边坡稳定性研究具有工程意义和实用价值。     

Distribution of polycyclic aromatic hydrocarbons in urban stormwater in Queensland, Australia

This paper reports the distribution of Polycyclic Aromatic Hydrocarbons (PAHs) in wash-off in urban stormwater in Gold Coast, Australia. Runoff samples collected from residential, industrial and commercial sites were separated into a dissolved fraction (<0.45 μm), and three particulate fractions (0.45-75 μm, 75-150 μm and >150 μm). Patterns in the distribution of PAHs in the fractions were investigated using Principal Component Analysis. Regardless of the land use and particle size fraction characteristics, the presence of organic carbon plays a dominant role in the distribution of PAHs. The PAHs concentrations were also found to decrease with rainfall duration. Generally, the 1- and 2-year average recurrence interval rainfall events were associated with the majority of the PAHs and the wash-off was a source limiting process. In the context of stormwater quality mitigation, targeting the initial part of the rainfall event is the most effective treatment strategy. The implications of the study results for urban stormwater quality management are also discussed.     

Computer simulation of the cumulative effects of brushland fire-management policies

A mathematical model simulates the cumulative volume of debris produced from brushland watersheds. Application of this model to a 176-km² (0.678 = mi²) watershed along the southern flank of the Central San Gabriel Mountains permits assessment of expected debris production associated with alternative fire-management policies. The political implications of simulated debris production are evaluated through a conceptual model that links interest groups to particular successional stages in brushland watersheds by means of the resources claimed by each group. It is concluded that in theory, a rotation burn policy would provide benefits to more interest groups concerned about southern California's brushland watersheds than does the current fire exclusion policy.This research was supported by the College of Agriculture and Life Sciences, University of Wisconsin-Madison, and by the Office of Water Research and Technology, USDI, under the Allotment program of Public Law 88–379, as amended, and by the University of California. Water Resources Center, as a part of Office of Water Research and Technology Project No. A-058-CAL and Water Resources Center Project UCAL-WRC-499. Support was also provided by the California Agricultural Experiment Station, Berkeley, California.     

福建省主要流域的暴雨洪涝特征

利用1989-1999年近11年的水文、气象资料分析了福建省6个主要流域主控站水位与降水量的关系和洪涝的时间变化规律,进而分析了暴雨致洪的特征,结果表明:(1)福建省6个主要流域洪峰水位与上游有关气象站前期平均总降水量相关显著,暴雨是福建省洪涝发生的主要原因;(2)根据闽江(竹歧站)、九龙江(浦南)、交溪(白塔)、木兰溪(濑溪)4个站的达警戒水位或危险水位的降水指标,可利用暴雨预报作为洪涝预警预测的依据。(3)上世纪80年代后,洪水的高低变化有增大的趋势,应进一步完善抗洪防洪预警系统,提高抗洪防洪的应变能力。     

Modelling vegetation greenness responses to climate variability in a Mediterranean terrestrial ecosystem

Accurate knowledge of the quality and environmental impact of the highway runoff in Pear River Delta, South China is required to assess this important non-point pollution source. This paper presents the quality characterization and environmental impact assessment of rainfall runoff from highways in urban and rural area of Guangzhou, the largest city of Pear River Delta over 1 year’s investigation. Multiple regression and Pearson correlation analysis were used to determine influence of the rainfall characteristics on water quality and correlations among the constituents in highway runoff. The results and analysis indicates that the runoff water is nearly neutral with low biodegradability. Oil and grease (O&G), suspended solids (SS) and heavy metals are the dominant pollutants in contrast to the low level of nutrient constituents in runoff. Quality of highway runoff at rural site is better than that of at urban site for most constituents. Depth and antecedent dry period are the main rainfall factors influencing quality of highway runoff. The correlation patterns among constituents in highway runoff at urban site are consistent with their dominant phases in water. Strong correlations (r ≥ 0.80) are found among chemical oxygen demand (COD), total phosphorus, Cu and Zn as well as conductivity, nitrate nitrogen and total nitrogen. O&G, COD, SS and Pb in highway runoff at urban site substantially exceed their concentrations in receiving water of Pear River. The soil directly discharged by highway runoff at rural site has contaminated seriously by heavy metals in surface layer accompanying with pH conversion from original acidic to alkaline at present.     

降雨与植被耦合关系对土壤侵蚀的影响分析——以密云水库上游为例

基于TRMM降雨降雨资料时间序列数据和MODIS-NDVI16d合成产品的时间序列数据,分析密云水库上游降雨与植被的耦合关系对侵蚀的影响。结果表明：（1）侵蚀将发生在降雨强度大,同时植被覆盖差的时段,而密云水库上游地区植被的年内生长曲线形态与降雨的分布形态相似性较大,表明研究区的植被具有较好的保护水土能力;（2）研究区侵蚀主要发生在7—8月,而在1—3月以及11—12月几乎不会发生侵蚀;（3）研究区侵蚀的发生与植被覆盖有很紧密的联系,大部分的侵蚀发生在植被覆盖差的＂其他＂类内。研究方法可以清楚地了解研究区内降雨与植被的耦合关系及对侵蚀的影响,研究的结果将为在年内选择具有代表性的时段分析侵蚀状况提供很好的参考资料。     

Verification of the geographical origin of modeled air-mass trajectories by means of the isotope composition of rainwater during the SALLJEX experiment

The SALLJEX experiment was held during the summer 2002–2003. It consisted of three-dimensional observation of the atmosphere to study the structure of the low level jet along the eastern slopes of the Andes. Daily precipitation water samples were collected at two stations (Resistencia and Salta) in northern Argentina and isotope content was analyzed. The isotope data were used in conjunction with air parcel trajectories obtained from a 3-D kinematic model (3D-MTC) developed by the University of Sao Paulo, Brazil. Values of deuterium excess were related with air masses of continental origin, whilst low values were associated with air masses with longer oceanic trajectories. Furthermore, although data are scarce, results show that oxygen-18 and deuterium excess in rainwater are related with the occurrence of the low level jet.     

镇江市城区降雨径流水质分析

雨水径流污染是城市面源污染的主要形式,通过对镇江市城区2011年10场降雨径流水质监测,分析了镇江市城区降雨径流水质。结果表明,镇江市城区降雨径流存在一定污染,直接排入城市地表水体会对其造成污染。其主要污染指标为COD、BOD5、NH3-N、TP和总悬浮颗粒物,重金属含量较低,基本不存在重金属污染。各种不同类型雨水径流水质污染程度差异较大,天然降雨、屋面径流,大市口路面径流水质相对较好,基本能达到Ⅲ或Ⅳ类水体的水质标准;泵站、排口径流、河道径流污染较重,大多属于超Ⅴ类水体;南门大街路面径流污染最为严重,部分水质指标接近工业废水。     

In-between soil erosion and sustainable land management: climate aridity and vegetation in a traditional agro-forest system (Costiera Amalfitana,southern Italy)

The delineation of bioclimatic areas is a key tool in informing sustainable land management strategies, especially in the light of climate change. It requires an in-depth analysis of climate data but also of the physical and biological factors that affect the distribution of natural vegetation. The present study applies an exploratory data analysis aimed at defining bioclimatic conditions in an area characterized by steep slopes and prone to soil erosion (Amalfi Coast, southern Italy). To this end, we analyzed long-term (1959–1999) monthly rainfall and temperature data measured at 28 gauging stations within the study area using a geographic information system and multivariate statistical tools. Then, we analyzed how the spatial distribution of rainfall and temperature data relates to topography, vegetation cover, and soil erosion. We also derived bioclimatic indicators from the geostatistical analysis. We then identify and comment on drawbacks found in the procedure used in the present study, discussing possible solutions to overcome such problems. We finally discuss the potential contribution of this study to the development of sustainable land management policies for socio-ecological systems with complex topography.     

城市河流重金属元素对降雨径流的动态响应

以海口市美舍河市区河段为研究对象,于2020年雨季分别采集降雨径流以及降雨径流汇入后的河流瞬时水样,测定并分析主要重金属元素的浓度及其变化规律,探讨其对降雨径流的动态响应。研究结果表明：降雨径流对河流可溶态污染元素质量浓度的贡献不突出,对可溶态锌（Zn）、砷（As）、镉（Cd）、硒（Se）具有一定稀释作用,排水口下游 3 m处是可溶态铬(Cr）、锰（Mn）、钴（Co）对降雨径流响应最显著区域;降雨径流对各悬浮态元素质量浓度贡献较大,排水口下游7 m处是绝大多数悬浮态元素对降〖JP〗雨径流响应最显著区域;Mn、Zn、Cr、镍（Ni）、As、Co、Cd 7种元素的总质量浓度对降雨径流的动态响应表现为先上升后下降。其中,排水口下游3 m处是Cr、As总质量浓度对降雨径流响应最显著区段,排水口下游7 m处是Mn、Co、Ni、Zn及Cd总质量浓度对降雨径流响应最显著区段。降雨径流对河流主要污染元素年输入总量估算结果表明,海口市建成区降雨径流向美舍河等受纳水体直接年输入量最大的是Mn和Zn,其次是Cr、As、Ni,Se与Cd的年输入量最小。