In this paper a number of proposed criteria are analyzed that predict the ultimate equilibrium bed slope in streams upstream of a check dam. The analysis is based on a comprehensive data set that includes 132 reaches in streams located in southern Italy. The results of this study show that the procedures suggested by Ferro et al. and Julien and Wargadalam do not lead to satisfactory results. Better predictions of the ultimate bed slope are achieved using the criterion suggested by Gessler, which is based on the stochastic analysis of incipient motion in nonuniform bed material. This analysis is based on a design discharge corresponding to a return period of 1.2 years and accounts for the armoring process at the bed surface. The procedure allows an estimate of the equilibrium slope of a nonhomogeneous bed material.

Many investigators have observed that in mobile sand bed streams, there is a range of hows over which two subcritical depths of flow are possible. This phenomenon is typically attributed to a hysteresis effect in which the discharge is changing more rapidly than the bed forms can adjust to the new discharge. This theory is supported by the fact that higher depths of flow are typically observed on the ascending limb of the hydrograph, while shallower depths tend to occur on the descending limb of the hydrograph. The magnitude of the discontinuity would then primarily be a function of the time rate of change in the discharge, and would not have to be a unique value. An alternative hypothesis, presented by the writers, demonstrates that in mobile sand bed channels where bed forms occur, two depths of how are numerically and physically possible. Data collected by other researchers were used to develop a bed form friction factor predictor for narrow flumes and wide sand bed channels with appropriate corrections for side roughness. The friction factor predictor is used in conjunction with Einstein's method for the separation of wall roughness from bed roughness to predict the depth of how for a given discharge. It is demonstrated that, under some hydraulic conditions, there are two numerical solutions to the system of equations used to predict the depth of how Both of the solutions appear to be physically possible. The two depths of flow are referred to as sequential depths. Application of the method to field data collected by Colby shows that the magnitudes of the sequential depths are approximately equal to the two depths observed by Colby.

Although engineering is a traditional route to public works management, the percentage of women in public works management is significantly less than the percentage of engineering graduates who are women, which seems stuck at under 20%. Serious change can be achieved when leaders in schools, colleges, and the workforce take action. A joint effort by public works and engineering communities could improve conditions for women in public works and provide opportunities to enter meaningful professions and contribute to society. Unless more women are attracted to public works management, students will lack role models and public works will remain “invisible” to them. APWA chapters working with local schools and colleges can provide leadership in programs to attract women to public works and to engineering and to increase the public's appreciation of the links between effective public works and a productive but fair society.

Friction factors of armored river beds at the discharge that forms the armor coat are investigated. The analysis shows that the friction factor is rather independent of grain‐size distribution of the material forming the bed and the maximum grain size of this material. The major controlling parameter is the slope of the energy grade line. These unexpected results are explained by the coupling of the friction factor with the incipient motion problem and the rearrangement of the grains of the coarsest fraction in the armor coat. The difference between rounded and angular material is discussed. Field data collected in irrigation canals support the results obtained from laboratory experiments.

In spite of the fact that computers are taking over increasing amounts of the engineer's computational work, selecting pipe sizes for water distribution systems remains a process based on rules of thumb and trial and error. Computerized procedures for sizing distribution system pipe are becoming available, but acceptance is limited because few optimization models are available as user‐friendly tools that can be easily applied by engineers. This article describes a computer program developed by the authors that follows the conventional trial‐and‐error approach to pipe sizing.

Several models that can be used to optimally size water distribution pipes were applied to a hypothetical system. The results are summarized in this paper. The models produced solutions with costs that were within 10% of one another, although the solutions were quite different. While the models were helpful in sizing pipes, some manual calculations and a good deal of engineering judgment were required to apply them.

: This document provides guidance on the use of a computer program WADISO (Water Distribution System Analysis and Optimization). The computer model consists of three major parts: steady state computer simulation, optimization, and extended period simulation. The steady state simulation portion computes flows and pressures in pipe networks under steady state conditions. The optimization portion optimally sizes pipes in a water distribution system and selects optimal pipes for cleaning and lining. The extended period simulation or time simulation computes pressure and flow distribution in pipe networks taking into consideration fluctuating tank water levels and varying water use patterns over time. All parts of the program can handle virtually and typical water distribution system and allow for the presence of pumps, pressure reducing valves, check valves , and multiple supply points. The program accepts input interactively from the terminal via keywords. Typically the program used is to size the pipes in an expansion of an existing system, or to improve the pressure conditions in an existing conditions by reinforcing the system through the cleaning of selected pipes or the addition of pipes parallel to existing pipes. In addition to varying tank water levels and water use patterns, the extended period simulation allows for fire lows, pumps controlled by tank water level and time, and pipes opened or closed during different times during a simulation.

: This report describes the development of a computer program WADISO (Water Distribution Systems Optimization) which can be used to optimally size pipes in water distribution systems and select optimal pipes for cleaning and lining. The program can also be used as a steady-state simulation program to calculate flows and pressures in pipe networks. The simulation portion of the program uses the node method with sparse matrix techniques to reduce computations. The optimization portion uses a bounded enumeration technique, based on minimizing the sum of pipe installation, pipe cleaning and lining, and present worth of pumping energy costs. Only discrete commercially available pipe sizes are considered. The program can handle any typical water distribution system and includes pumps, pressure reducing valves, multiple pressure zones, and check valves. To use the optimization, the user must also specify costs as a function of pipe diameter (or use default costs in the program), minimum pressures, up to five water use loadings, a list of which pipes are to be sized, and a range of sizes to be considered. The program user's guide is included as an appendix to the report. Other appendices address how to access the program, how to obtain detailed documentation, the nature of pipe sizing, existing literature on pipe optimization, and a discussion of the relationship of pipe sizing and water distribution performance criteria. Keywords: Optimization, Pipe flow, Pipe networks, Pipe sizing, Water conveyance, Water distribution.

Channels constructed in coarse alluvial material tend to develop an armor coat at the bed's surface protecting the material beneath the top layer from further erosion. A method is outlined which permit the prediction of the eroded material. Based on these results, it is possible to make an estimate on the minimum amount of material to be eroded prior to development of a stable condition resulting from amoring. An attempt is made to determine those condition which result in a finally stable bed. This leads to a design criterion for stable channels constructed in coarse nonuniform alluvial material. This design criterion integrates the stabilizing influence of all grain sizes present in a self-stabilized armor coat and permits operating the channel at a preset factor of safety.