Uncertainty Analysis In Dissolved Oxygen Modeling in Streams

Uncertainty analysis in surface water quality modeling is an important issue. This paper presents a method based on the first-order reliability method (FORM) to assess the exceedance probability of a target dissolved oxygen concentration in a stream, using a Streeter–Phelps prototype model. Basic uncertainty in the input parameters is considered by representing them as random variables with prescribed probability distributions. Results obtained from FORM analysis compared well with those of the Monte Carlo simulation method. The analysis also presents the stochastic sensitivity of the probabilistic outcome in the form of uncertainty importance factors, and shows how they change with changing simulation time. Furthermore, a parametric sensitivity analysis was conducted to show the effect of selection of different probability distribution functions for the three most important parameters on the design point, exceedance probability, and importance factors. Note: This version was published online in June 2005 with the cover date of August 2004.     

Computer software tool REALM for sustainable water allocation and management

REALM (REsource ALlocation Model) is a generalised computer simulation package that models harvesting and bulk distribution of water resources within a water supply system. It is a modeling tool, which can be applied to develop specific water allocation models. Like other water resource simulation software tools, REALM uses mass-balance accounting at nodes, while the movement of water within carriers is subject to capacity constraints. It uses a fast network linear programming algorithm to optimise the water allocation within the network during each simulation time step, in accordance with user-defined operating rules. This paper describes the main features of REALM and provides potential users with an appreciation of its capabilities. In particular, it describes two case studies covering major urban and rural water supply systems. These case studies illustrate REALM's capabilities in the use of stochastically generated data in water supply planning and management, modelling of environmental flows, and assessing security of supply issues.     

Women and community water supply programmes: An analysis from a socio-cultural perspective

Community water supply programmes are seen as instrumental in achieving the goal of ‘safe’ water for all. Women, a principal target group of these programmes, are to be benefited with greater convenience, enhanced socio‐cultural opportunities and better health for themselves and their families, provided through improved water facilities. Water supply programmes largely consist of three essential components, namely: technology, people and institutions. Although such programmes are intended to benefit women members of local communities, scant attention is paid to the impacts of the socio‐cultural context of the community on these programmes. This article explores the influence of social and cultural intricacies on the implementation of community water supply programmes, and assesses their effectiveness. The article offers important lessons for the design and implementation of this type of programme. It concludes that the local socio‐cultural context sets the stage for programme implementation, being a dynamic factor that determines actual access to water sources, more so than mere physical availability, which is often used as a criterion for programme performance. The article stresses the urgent need to integrate socio‐cultural factors as a fourth dimension in designing community water supply programmes, and suggests practical measures for enhancing the effectiveness of such programmes.     

Design of unsurfaced roads constructed with large-size shredded rubber tires: a case study

Stockpiles of scrap tires are serious fire hazard, public health hazard, and an environmental burden. The construction of road embankments, using tire shreds as a lightweight fill, can consume large quantities of scrap tires and has certain engineering benefits. All the previous research focused on small size tire shreds (3–6 in. size) in terms of its use in civil engineering applications and determination of the engineering/environmental properties. This research specifically focuses on large size tire shreds (12 in. size) and its direct comparison with the other sizes of the tire shreds to develop mechanistic-empirical practical design model and so that the use of tire shreds in road bases could be used on regular basis with enhanced reliability instead of on an empirical basis. The research also examines the potential environmental implications of the use of shredded rubber tires and the comparison of the short-term results with other long-term monitoring studies.     

电厂山区性河流取水工程安全设计分析

通过对代表性山区河流电厂的取水工程安全实例分析 ,根据取水方式不同 ,建议应采取的措施分为 :直接在天然河道上布置取水构筑物时 ,取水头部上下端加设三角形挡沙板 ,取水口上游设导沙丁坝 ,抬高取水头高程和进水底槛高程 ,并且可考虑设置两套取水系统 ,枯水期直接利用河道取水头取水 ,洪水期从移动式泵车取水 ;在河道上设置拦河低坝取水时 ,必须设置配套取水防沙设施 ,如排沙闸或冲沙闸 ,进水闸前设导沙坝 ,冲刷闸前设导沙坎 ,泄洪闸前设冲沙廊道和导流堤 ,还可在河道上设置潜水丁坝等。     

煤层底板突水的突变理论预测方法及其应用

基于煤层底板突水的尖点突变特征 ,应用突变理论的方法 ,针对煤层底板突水预测指标监测信号 ,分析了单变量序列尖点突变模型及其稳定判据 ,提出了煤层底板突水的突变理论预测方法。实例表明 ,预测结果与现场工程实际情况相一致 ,证明了该方法可望成为预测煤层底板突水危险性的一条新的有效途径     

臭氧消毒现状与发展

阐述了臭氧消毒灭菌的基本原理、臭氧制备、消毒工艺流程以及国内外应用概况，探讨了给水采用臭氧消毒存在的主要问题及改进方向。指出臭氧消毒法有可能取代传统的氯化消毒法，尤其在给水工艺中具有广阔的应用前景。     

因子分析法在江安河地表水水质评价中的应用

因子分析法是主成份分析方法的推广和深化，是把原来多个变量化为少数几个综合指标的一种统计方法。本文通过该法对江安河四川大学双流校区段水质进行了评价，结果表明，该水体受到了不同程度的有机物污染，其中非离子氨、阴离子洗涤剂、化学耗氧量，溶解氧所占的负荷最大。     

试析《水法》下的水资源统一管理

水是关系社会可持续发展的重要资源,但是我国水管理的弊端造成水资源状况不容乐观。针对这一情况,2002年《水法》的修改重点之一是加强了水资源统一管理。本文从统一管理的必要性出发,分析了《水法》有关水资源统一管理的规定,并指出了有待完善之处。