Hydraulic simulation of low skeletonisation, large-scale urban water distribution networks: a case of naguru water supply area, Kampala

Abstract

Hydraulic simulation (HS) offers functionality that could greatly enhance the resolution of the recurring technical challenges experienced by the Kampala Water distribution Network (KWN). Unfortunately, HS technology is in its infancy in the developing world and Uganda in particular, and thus no large-scale implementation of the technology exists to validate its applicability in the local context. This research therefore sought to implement the internationally recommended hydraulic modelling (HM) guidelines and subject them to prevailing local conditions in the Kampala water distribution network (using the Naguru area network as the prototype), in order to evaluate their suitability. The process necessitated the construction of a large-scale, low-skeletonisation hydraulic model of a selected representative study network; calibrating the model; and performing several post-calibration accuracy assessment tests. The construction process involved CAD to DXF drawing conversions, meter-aggregation and flowdistribution demand allocation, database-to-model synchronisation and preliminary model performance evaluation. Calibration and post-calibration field tests generated several datasets of network hydraulic parameters that were necessary for the analysis of the model’s accuracy and consistency. The inferences indicated first; that large-scale hydraulic simulation can be feasibly effected for the KWN using the internationally proposed guidelines, although, the calibrated hydraulic models are not automatically immune to extraneous discrepancies. In addition, the achieved accuracy levels are variable across the network, exceeding 50% variation in some locations. Secondly, out of over 120 test locations, only 3 cases of gross discrepancy were observed, yet the internationally proposed calibration limits were fulfilled by only 1 of the 6 test datasets. This revealed that the existing international calibration-accuracy guidelines are mostly suitable for high-accuracy simulation and may erroneously discard valid simulation data when the objective lies within moderate accuracy, which is common for utilities in the developing world. In general, the research findings derived from this study ultimately provide a yard-stick and platform for the subsequent application of the technology throughout the KWN service area and Uganda in general.