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Research Team

Steven Sola, MSPH

Steven Sola, MSPH
PhD Student

Steven is a PhD student in the Department of Environmental Health and Engineering. His research is based in WASH (water, sanitation, and hygiene) in low-resource settings and climate resiliency. Prior to Johns Hopkins, he served as a Peace Corps Volunteer in Indonesia and later received his MSPH in Environmental Health and Epidemiology from Emory University. At Emory, he assisted with a latrine use intervention study in Odisha, India and studied the incidence of acute lower respiratory infections and diarrhea in a second cohort. After graduation from Emory, Steven completed an infectious disease epidemiology fellowship with the Council of State and Territorial Epidemiologists at the New York State Department of Health. During the course of this fellowship, he assisted with investigating outbreaks of measles, cyclosporiasis, and COVID-19.


Background: Given shifts in temperature and rainfall patterns globally with climate change, increased rates of evaporation and decreased rainfall could impact water availability and increase the burden of collecting water. Two previous studies have used Demographic and Health Surveys (DHS) to assess water collection labor. Pickering and Davis (2012) found that an increase in freshwater availability was negatively correlated with distance traveled to a water source. Graham et al. (2016) found that across the 24 countries, adult women were predominantly responsible for the water collection and female children were more likely than male children to collect water. This study uses DHS surveys from Senegal to assess associations between precipitation and evaporation on water collection labor.

Methods: Nine surveys from Senegal between 1992 and 2019 were included. All surveys included GPS coordinates for each cluster of households. Weather data were included from the Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2) from NASA. Each household cluster was assigned a specific Köppen-Geiger climate classification zone. Data from MERRA-2 were downloaded from the nasapower package, climate zones were assigned using the kgc package, and associations were estimated in R 4.2.3.

Results: The source population included 53,649 households within 380 clusters (primary sampling units) between 1992 and 2019. We excluded households in urban settings (21,508), households that had piped water nearby (13,769), and households that received water from trucks or bottles (989). We also excluded households without water collection times (3,269). We included 14,408 households in this study, and 8,807 households had data for the person who collects water.

The average water collection time across all households was 32.2 minutes. The person responsible for collecting water included 7805 adult women (88.6%), 588 adult men (6.7%), 286 female children (3.2%), and 128 male children (1.5%). The average walk time for adult women was 27.8 minutes, female children was 38.5 minutes, adult men was 69.6 minutes and male children was 50.0 minutes.

The average walk time was 22.2 minutes in the tropical climate zone and 38.0 minutes in the dry climate zone (p < 0.001). There were weak correlations between walk time and 30-day total precipitation for the tropical climate zone (r = 0.01) and the dry climate zone (r = 0.02). Additionally, there were weak correlations between walk time and 30-day total evaporation for the tropical climate zone (r = -0.03) and the dry climate zone (r = -0.04).

Discussion: This study shows that climate zone, but not precipitation and evaporation in the prior 30 days, are associated with the amount of time needed to collect water in Senegal. Additionally, men and male children walk further to collect water; however, women and female children are more likely to collect water. This study is limited in that it included only 27% of households in Senegal and that only 9 surveys were performed across the 27 year range. Future directions include modeling the relationship between water collection time, precipitation, evaporation, and temperature, in addition to including surveys from other sub-Saharan nations.


(1) Pickering, A. J. & Davis, J. Freshwater Availability and Water Fetching Distance Affect Child Health in Sub-Saharan Africa. Environ. Sci. Technol. 46, 2391–2397 (2012).
(2) Graham, J. P., Hirai, M. & Kim, S.-S. An Analysis of Water Collection Labor among Women and Children in 24 Sub-Saharan African Countries. PLOS ONE 11, e0155981 (2016).
(3) R Core Team. R: A Language and Environment for Statistical Computing. (2017).


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