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Horizontal wells installed by directional drilling in the highly permeable river bottom sediments can improve the quality of water delivered to water treatments plants by filtration of suspended solids and dilution with groundwater. Predicting the flow rates available from horizontal wells is an important step in evaluating the technology. A series of three-dimensional finite element models were developed to simulate a horizontal well located beneath a river and a parametric analysis of predicted flow as a function of pipe length, pipe diameter, depth below river bottom, and sediment hydraulic conductivity was conducted to determine optimum horizontal well configurations. The results indicated that the frictional head losses in the well screen have a significant impact on predicted withdrawal rates. Analysis of well length and pipe diameter indicates that for each specific well configuration there exists an optimum length, beyond which little increase in flow occurs. The simulations indicated maximum flows occur when horizontal wells are placed as deep as possible until they are within 0.5 to 2.5 m of an impermeable lower boundary. [ABSTRACT FROM AUTHOR]

Validation of a two-dimensional hydrothermal stratification model for 14 years for Schoharie Reservoir, N.Y., an impoundment that experiences substantial drawdown, is documented. The model is demonstrated to perform well in simulating the various features of the reservoir's thermal stratification regime in each of the years, including the timing and duration of stratification, the dimensions and temperature of the layers, and the periods of internal wave oscillations in stratified layers. The average root mean square error for temperature predictions for the 14 years is 1.30 ºC. The validated model is applied in a probabilistic manner to investigate the impacts of sedimentation on the temperature of the withdrawn water (Tw) that enters a stream with a salmonid fishery, and features of the stratification regime. The predicted effects of sedimentation include a shift toward higher Tw values, a shortening of the duration of stratification, and decrease in the depth of the epilimnion in fall. The effects on Tw are exacerbated for the reservoir because of localized sedimentation adjoining the intake that increasingly limits access to cooler layers. [ABSTRACT FROM AUTHOR]

Most engineering systems are subject to a wide range of possible uncertain future conditions. The probabilistic reliability analysis usually fails to address the problems of human error, subjectivity, and lack of system performance history and records. This paper explores the utility of the following fuzzy performance measures for evaluating the performance of a complex water supply system: (i) combined reliability–vulnerability, (ii) robustness, and (iii) resiliency. The regional water supply system for the City of London, Ontario, Canada, is used as the case study. The computational requirements for the implementation of the fuzzy performance measures and their sensitivity to different shapes of fuzzy membership functions are investigated. The study illustrates the capability of the fuzzy performance measures to handle uncertainty and identify critical system components. This can be of value in identifying the optimal level of improvement that will increase the overall system performance. [ABSTRACT FROM AUTHOR]

Beijing is located in a semiarid region, and water shortage is a common problem in the city. Along with the rapid increase in water demand, due to fast socioeconomic development and an increase in population, a shortage of water resources and a deterioration of the water environment have become obstacles to sustainable socioeconomic development in Beijing. In the long run, sustainable water resources management, water conservation, and completion of the south to north water diversion project will solve the problem. This paper introduces the water resources situation in Beijing; analyzes future water demand; and discusses the actions of water saving, nontraditional water resources exploitation, wetland construction, and water environment protection. The paper also explains the importance of the south to north water diversion project and the general layout of the water supply strategy, water distribution system, and methods to efficiently use the diverted water in Beijing. [ABSTRACT FROM AUTHOR]