One of the most outstanding problems within urban drainage is to give a statistically correct description of the runoff effect from areal and temporal distributed rain storms. Due to the large number of parameters for catchments and storms involved in such a description it is important to derive dominating dimensionless quantities by combining the parameters. The paper deals with dimensionless peak flow calculations using moving block rains. Two important dimensionless parameters p1 and p2 (see Eqs. (7), (8) and (14)) and their influence on peak flow is found in a deterministic way by applying the time area model (TAM) to a linear time-area curve. Dimensionless peak flows are found as functions of p1 and p2 and results are compared with computations from the Storm Water Management Model (SWMM) version 2. TAM overestimated the peak flows by appr. 5% of the full flow capacity relative to SWMM on an average of 26 comparisons. The standard deviation is appr. 10%. Finally some perspectives are presented in relation to a general statistical runoff description of the influence of areal and temporal rain storms. The possibility is discussed of achieving such a description by combining existing knowledge within 1) synthetic point rainfall design storms, 2) areal rain depth reduction factors, 3) shape of moving storm cell isohyetographs and 4) distribution of storm direction.

This review has been prepared for the international seminar: Rain fall as the basis for urban runoff design and analysis, held in Copenhagen, 24'26 Aug. 1983. The purpose of the review is to bring a state of the art within, 1) the statistical characterization of rain fall in time and space, 2) the development of synthetic design storms and, 3) the application of both synthetic design storms and historical storms to pipe design, flooding prediction, design of detention basins and calculation of the yearly or extreme pollutiona1 load on receiving waters from combined sewer overflows. The main conclusion, primarily related to item 3), is that more attention in this context should be put on statistical analysis of the detrimental effects: flooding and pollution. This analysis is best performed by applying historical rain records. Realistic flooding prediction is believed only to be possible with a fully dynamic flow model, whereas pollution may be studied by means of simpler models like the time area approach. The outstanding problem in the statistical prediction is the distribution in space of the historical rains.

The interpretation of rain-runoff measurements from 6 small (less than 17 ha) urban catchments is described. The recording period covers mostly 1979-1983. Relations between rain- and runoff depths were developed using the traditional linear regression model as well as a new continuous model. Both models compute runoff from impervious surfaces in the same way. Calculation of runoff from semipervious surfaces accounts for infiltration through cracks, percolation from a sublayer and evaporation during dry weather. These phenomena are related to water content of the sublayer. The 10 parameters in the continuous model are calibrated and show values in good agreement with data from the literature. The continuous model fits the measured runoff depths somewhat better for the largest runoff events. For more frequent events, however, the two models are equally good. Rain intensity – duration – frequency curves have been computed. Variations of up to 20 %, for return periods 1/5 and 1/2 yr., are seen for catchments with distances approximately 5 km from each other. Peak flow statistics are compared with rain intensity. The peak runoff coefficient (cf. rational method) is mostly constant or slightly increasing with the return period.

This paper introduces two new deposition-strategies for five degrees of freedom (5DOF) and 6DOF extrusion-based additive manufacturing (AM), called the tool path projection- and parent-child-approach, respectively. The tool path projection method can be automated, and allows for the generation of concentric shells layers, which remedy geometrical deviations (known as the stair-case effect) that are typically seen in 3DOF AM processes that potentially require secondary post treatment by machining or grinding of the final part. In the parent-child approach, the designer specifies the manufacturing direction for each distinct feature, thereby helping to remove the need for support material, as well as enabling new features to be dynamically added to the part.

Overflow from combined systems constitute an increasing source of pollution of receiving waters, as compared to daily wastewater discharges which undergo treatment to a still higher extent. The receiving water problems from overflows are significant both in a long term scale (mean annual load) and in a short term scale (extreme event load). A method for computation of both annual and extreme load is presented. It is based on historical rain series and the use of a time-area model and simple pollutant mixing model in runoff calculation. Statistical calculations for both mean annual load and extreme events have been applied to the computed overflow series. Based on the computerized method simple manual calculations methods have been developed, resulting in graphs and tables for annual load and extreme load.