Abstract:
Nairobi city has been facing sanitation problems related to sewage outflows and sewage pipe
bursts. Nairobi City Water and Sewerage Company (NCWSC), a state owned water utility, uses Operation and
Maintenance Information System (OMIS) in sewer chokes analysis in order to reduce the number of chokes
occurring within their jurisdiction. This study focused on spatial sewer choke analysis in Nairobi's Western
Region using Geographic Information Systems (GIS) which would enable easier spatial understanding of the
chokes as well as improve on visual interpretation of otherwise complicated and detailed raw data. Data on
causes of chokes was collected through field surveys and interviews and the frequency of these causes
determined. Hot spot analysis on the data spatially revealed the hot and cold spots in the region. GIS was found
to be useful as it spatially reflected the relationship and strength of each factor to choke formation. Further,
Geographic Weighted Regression (GWR) was used to spatially reveal the trends offactors that influence choke
occurrences. High population density, poverty level, number of households, vandalism and water supply were
the major factors that contributed to high choke volumes in the region
