INTEGRATING GIS AND HYDRAULIC MODELING FOR SUSTAINABLE DESIGN OF WATER DISTRIBUTION NETWORKS: A CASE STUDY OF THE CITY OF BUKAVU IN DR CONGO

Abstract

Drinking water is one of the vital needs for human beings' survival. However, access to drinking water represents strong inequalities on a global scale. While in some countries, even rural communities have access to a reliable water source, in sub-Saharan African cities, only 56 % of the population had access to tap drinking water in 2019. These inequalities are even more alarming between the different countries of the continent. An illustrative example of such conditions is the city of Bukavu in the eastern part of the Democratic Republic of Congo where access to drinking water decreased by about 90% between 2003 and 2019. The existing water treatment supplying the city was installed in 1954 with the construction of the Murhundu treatment plant, located 28km away from the city. Originally built to produce water for 50,000 residents, the treatment plant was upgraded in 1981, doubling its initial production capacity. However, the city of Bukavu currently has 1,133,000 million inhabitants, which is 20 times higher than the production capacity of the plant and its distribution network; as such, the existing water supply system is not able to handle this growth. Therefore, this study provides a solution to the current situation by estimating and forecasting the water demand and population for the city at horizon 2046, assessing the current water distribution network, and proposing a sustainable solution. The research used secondary and primary data comprising reports from the local municipal water supply company. GIS data sets and a database of the existing network designed into EPANET were used to assess the performances of the water supply system of Bukavu. The assessed model was thereafter, exported to Watergems for optimization of a proposed sustainable solution. The current water demand in Bukavu is 15.86 Mm3 / year and is expected to reach 101,1 Mm3 /year in 2046. The existing water supply system is composed of one reservoir, 3 water tanks, 5 pumping stations, and a 300,049 m long piping network that shows poor hydraulic performance in most parts of the city. To overcome this problem, two alternatives were simulated in Epanet and Watergems involving the addition of a balancing tank in the system and increasing the pumping station capacity after renovating the entire piping system. However, a combination of these alternatives was found to be more sustainable, with a total investment and maintenance cost of 88 788 548 USD. Finally, these findings serve as a master plan for the city and water corporations, as well as for investors and decision-makers to guarantee sustainable drinking water accessibility for the citizens of Bukavu.