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from a review of the area's topography. As described above, overland flow between nodes during floods was simulated by using weir links. Predictions of hydraulic response during floods were sensitive to small changes in these weir levels. |
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Four storms were used for final verification of the model. No adjustment to any model parameter was made during these verification runs, and these storms had not been used during any of the preceding calibration process. Agreement between the predicted and observed response was reasonable. Unfortunately, none of these events were flooding events. Figure 14.3 illustrates the fit of depth and discharge in a calibration and verification storm at the outlet gauge; the fit at the midway gauge was similar. |
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14.3
The Effect of Solids Deposition on Drainage Performance |
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Once a satisfactory verified model had been developed, completing sensitivity analyses on the effects of solids deposition upon performance was relatively simple. Solids depths were specified for channel sections as fixed percentages of channel height, and the model was then used to predict performance. Performance was thus examined with solids levels set at 20, 50 and 80 per cent of channel height. A more challenging aspect of the work, however, was converting the original broad notions of performance into terms that could be effectively modelled and measured over a distributed system. In this section, findings concerning the sensitivity of depth, duration, extent and frequency of flooding are presented. An additional measure of the effect of solids upon performance, the fraction of runoff lost from the catchment as flood water, is also presented. |
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14.3.1
Depth and Duration of Flooding |
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Many nodes flooded during large events. To observe variations in flooding patterns, six nodes were selected for detailed analysis of |
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