Management of a Sewerage Network in an Urban Area by Coupling GIS and Hydraulic Modeling: Case Study of Kwame Nkrumah University of Science and Technology (Ghana)

Abstract

The hydrological cycle is deeply modified by the high rate of urbanization and the population growth this affects the management of the hydraulic infrastructures and the soils’ infiltration rate during runoff. Sewage infrastructures are very important in the socio-economic development of a country and the protection of the environment. Their deterioration is more or less rapidly over time and faces serious challenges in term of management in many developing countries. In Ghana, conventional wastewater treatment plants are underused because of the poor sewage collection system. Only the small proportion of the sewage generated from urban area generally connected to a sewer line. This work aims to simulate the existing sewerage network of KNUST and come up with the management method by coupling GIS and a hydraulic model. Primary data were obtained through the field analysis and a questionnaire while secondary data were gathered from the existing literature related to the research topic, published and non-published papers, reports and databases. ArcGIS and MOUSE were used to model and simulate the network. The results of the study showed that the sewerage network of KNUST conveys black and grey water from campus, faculty and commercial areas to its wastewater treatment plant. 99.62% of the network has the normal circulation of the sewage and 0.38% do not meet the self- cleansing condition. The major portion of the sewerage network has an open channel flow circulation during the dry period. Some manholes are flooded in the wet period. In general, the management problem of the KNUST sewerage network is due to the invert slopes that cause stagnation in the pipes, the low flowrate generation in dry and the noncoverage of some manholes. To these is added the under-sizing of some conduct and some manholes and the non-update of the master plan of the network as well. The study recommended to update the sewerage network, to apply the telemonitoring system to its good management and the implication of stronger political will in the sanitation infrastructure in general for effective management.