An analysis of factors that influence the spatial pattern of faecal matter flow in unsewered cities

Date published

2025-05-25

Free to read from

2025-04-24

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Volume Title

Publisher

Elsevier

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Article

ISSN

0048-9697

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Citation

Sultana MS, Waine T, Bari N, Tyrrel S. (2025) An analysis of factors that influence the spatial pattern of faecal matter flow in unsewered cities. Science of The Total Environment, Volume 978, May 2025, Article number 179440

Abstract

The management of sanitation systems in unsewered cities in low and middle income countries is a critical issue, yet it is unclear where the risk hotspots are and where interventions should be focused. This study utilised a prototype model, developed by the authors, to map the spatial pattern of faecal flow in Rajshahi city, a secondary city in northwest Bangladesh with a population around a million. This city serves as a representative example of 60 such secondary cities in Bangladesh and hundreds more in the economically developing region in Asia, Africa and Latin America. The model relies on assumptions that carry significant uncertainties; hence, the study employed a sensitivity analysis with multiple plausible scenarios to characterise these uncertainties, aiming to identify ways to improve the model further. Five major influencing factors on the spatial pattern of faecal flow were identified: the emptying of septic tanks, the use of soak pits, and sludge removal from drains, variations in faecal matter production by building types, and the presence or absence of toilets. These factors were shown to collectively have a significant impact (almost 50 % changed) on the model outcome, depending upon the assumptions made. The study offers insights that will guide future data collection efforts by emphasising the need to understand these specific influencing factors and their spatial pattern. Consequently, this research has broader implications for urban sanitation management as well as associated public health research like wastewater surveillance, risk assessment, and disease dynamics in similar urban settings, offering insights into areas of uncertainty that need to be addressed in future modelling efforts.

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Github

Keywords

37 Earth Sciences, 3704 Geoinformatics, 44 Human Society, 11 Sustainable Cities and Communities, Bangladesh, Open-source data, Spatial faecal flow, Uncertainty, Unsewered cities, Environmental Sciences

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Attribution 4.0 International

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Funder/s

This work was supported by the UKRI Engineering and Physical Science Research Council (EPSRC) through a Ph.D. studentship received by the first author (M.S.S.) as part of the EPSRC Centre for Doctoral Training in Water and Waste Infrastructure and Services Engineered for Resilience (Water-WISER). EPSRC Grant No.: EP/S022066/1.