A GIS based methodology for developing a hydraulic network model Case study of Karen, Nairobi Kenya

Abstract

The main aim of every water distribution system is to deliver water to the consumer when it is necessary, in the correct quantity and in accordance with relevant quality standards. Obviously, a mathematical model that can simulate a water distribution system behavior as closely as possible is of great importance for every WDS authority. Development of hydraulic network models is seen as the best way in which to provide a planning and decision support system for the existing infrastructure and map flows to different areas. By hydraulic simulation, the model is capable of flagging areas with abnormal water usage and predicting anomalies in the distribution system. The role of Geographic Information System (GIS) in the analysis of a distribution system is to provide up-to-date and accurate data to be used in the engineering analysis. In this project Gis was used in data preparation and developing nodal water demands by generating Voronoi polygons and in calculating proportional areas for purposes of allocating demands to the specific nodes. In this project, the hydraulic model was simulated by use of watercad software and results from the model were displayed by use of the GIS for better visualization and analysis. During analysis of results, areas which had adequate supply were easily picked, while at the same time highlighting pockets within the distribution network which do not get water under the current distribution regime. The study concluded that for most areas of Karen, 60% of the water demand requirements are met safe for isolated pockets within the distribution network, where water shortages are not as a result of leakages - but rather due to shortcomings in the pipe distribution network. The study recommends a more detailed study incorporating smaller diameter pipes and incorporating the effect of the individual tanks in the future modelling.