The Flooding of Urban Communities in Accra, Ghana: Assessing Population at Risk, Behavioral Response, and Fecal Contamination 公开
Schaupp, Amanda Noelle (2013)
Published
Abstract
Purpose: As the world becomes more urbanized, there is an
increased risk of exposure to natural hazards such as flooding due
to impervious surface areas without adequate parallel increases in
the number of drainage networks. Flooding may also increase an
individual's risk of exposure to fecal contamination containing an
enteric pathogen. This study was performed to gather data to
identify how many people in urban neighborhoods of Accra are at
risk for exposure to flooding, why the flooding occurs, document
the behaviors that could cause exposure to floodwater, and
determine whether people living in a flood zone are at risk for
exposure to increased fecal contamination.
Methods: Four different data collection procedures were
used: 1) GIS mapping of flood areas, 2) Calculating the population
at risk in each community by using census boundaries, 3) Household
questionnaire on behavioral practices in response to flooding, and
4) Microbiological testing of water and soil samples for general
E. coli and enteric viruses that indicate human fecal
contamination.
Results:The percentage of area that flooded in Alajo,
Bukom, Old Fadama, and Shiabu were 28.98%, 33.02%, 87.36%, and
48.51%, respectively. Soil, drain, and floodwater samples had high
concentrations of E. coli and only a few detected norovirus
contamination. In a linear regression model for E. coli
concentration of soil samples both the community Old Fadama and
distance to the latrine were significant. For Old Fadama the
E. coli concentration increased by 4.8*103 CFU
per gram and within 20 meters of a latrine it increased by
8.5*105 CFU per gram of soil.
Discussion: A resident's contact to drain water is more
likely to be sporadic compared to floodwater where exposure is
almost guaranteed. There are potential risk factors such as
distance to a latrine and differences between communities, which
influence the amount of fecal contamination. However, a resident's
behavioral response to flooding can put them at an increased or
decreased risk for E. coli or norovirus exposure. Short-term
preventive factors such as bucketing out water during flooding
could potentially increase the risk of exposure to
fecal-contaminated floodwater compared to long-term preventive
factors such as cement walls.
Table of Contents
Table of Contents
Chapter 1: Introduction- 1
Chapter 2: Literature Review- 6
Definition and causes of flooding- 6
Flooding in Accra, Ghana- 8
Historical examples of the impact of flooding- 9
Health outcomes of flooding- 11
Mortality- 11
Injuries- 12
Toxic Exposure- 12
Mental Health- 13
Rodent-borne Disease- 14
Vector-borne Disease- 14
Enteric Disease- 15
Bangladesh 1988- 16
Khartoum Sudan 1988- 17
Mozambique 2000- 19
The impact of flooding on microbial exposure- 20
Evidence of increased exposure to diarrheal pathogens from floodwater- 21
Behavioral response to flooding- 24
Chapter 3: Research Objectives and Rationale- 26
Student contribution- 28
Chapter 4: Manuscript- 29
Materials and Methods- 29
Study sites- 29
SaniPath microbiological data- 29
GIS mapping- 29
Flood areas- 29
Drain density in each flood area- 30
Distance of environmental samples from public latrine- 30
Determination of the population at risk for flooding- 31
Survey methods- 31
Cause of flooding- 31
Preventive measures in response to flooding- 33
Sample collection and microbial analysis- 34
Field collection- 34
Processing of soil samples- 34
Processing of drain water and floodwater samples- 35
E. coli membrane filtration for samples- 35
RNA and DNA extraction- 36
Quantitative PCR for norovirus GI and GII- 37
Data management- 37
Analytical methods- 37
Descriptive analysis- 37
Linear regression models- 39
Results- 40
Mapping of flood areas- 40
Percentage of area that floods and number of residents affected- 41
Causes of flooding- 42
Reported duration of flooding- 45
Behavioral responses to flooding- 46
Prevention of flooding in homes- 46
Behavioral practices for leaving the home during flooding- 47
Behavioral patterns for removing floodwaters from the home- 48
Effect of season on feces disposal in community drains- 49
E. coli concentration in environmental samples from the four study communities- 50
Multivariable linear regression model- 53
Norovirus concentration in environmental samples collected from the four study communities- 54
Discussion- 56
Community liaison as an effective way to determine flooding- 56
Number of people affected by floodwater- 57
Behavioral response and increase risk of exposure to floodwater- 57
Drain contamination with fecal matter and exposure risk posed after flooding- 59
E. coli and norovirus concentration in soil, drain water, and floodwater- 60
Linear regression modeling of E. coli concentration in soil samples- 60
Strength and Limitations- 62
Summary and Conclusions- 63
Chapter 5: Lessons Learned and Recommendations- 65
References- 66
Appendices- 74
Appendix A- 74
Appendix B- 77
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