Publications
1.
Boo, Gianluca; Darin, Edith; Chamberlain, Heather R.; Hosner, Roland; Akilimali, Pierre K.; Kazadi, Henri Marie; Nnanatu, Chibuzor C.; Lázár, Attila N.; Tatem, Andrew J.
In: PLOS Global Public Health , 2025.
Abstract | Links | BibTeX | Tags:
@article{nokey,
title = {Tackling public health data gaps through Bayesian high-resolution population estimation: A case study of Kasaï-Oriental, Democratic Republic of the Congo},
author = {Gianluca Boo and Edith Darin and Heather R. Chamberlain and Roland Hosner and Pierre K. Akilimali and Henri Marie Kazadi and Chibuzor C. Nnanatu and Attila N. Lázár and Andrew J. Tatem},
url = {https://doi.org/10.1371/journal.pgph.0005072},
year = {2025},
date = {2025-09-04},
journal = {PLOS Global Public Health },
abstract = {Most low- and middle-income countries face significant public health challenges, exacerbated by the lack of reliable demographic data supporting effective planning and intervention. In such data-scarce settings, statistical models combining geolocated survey data with geospatial datasets enable the estimation of population counts at high spatial resolution in the absence of dependable demographic data sources. This study introduces a Bayesian model jointly estimating building and population counts, combining geolocated survey data and gridded geospatial datasets. The model provides population estimates for the Kasaï-Oriental province, Democratic Republic of the Congo (DRC), at a spatial resolution of approximately one hectare. Posterior estimates are aggregated across health zones and health areas to offer probabilistic insights into their respective populations. The model exhibits a –0.28 bias, 0.47 inaccuracy, and 0.95 imprecision using scaled residuals, with robust 95% credible intervals. The estimated population of Kasaï-Oriental for 2024 is approximately 4.1 million, with a credible range of 3.4 to 4.8 million. Aggregations by health zones and health areas reveal significant variations in population estimates and uncertainty levels, particularly between the provincial capital, Mbuji-Mayi and the rural hinterland. High-resolution Bayesian population estimates allow flexible aggregation across spatial units while providing probabilistic insights into model uncertainty. These estimates offer a unique resource for the public health community working in Kasaï-Oriental, for instance, in support of a better-informed allocation of vaccines to different operational boundaries based on the upper bound of the 95% credible intervals.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Most low- and middle-income countries face significant public health challenges, exacerbated by the lack of reliable demographic data supporting effective planning and intervention. In such data-scarce settings, statistical models combining geolocated survey data with geospatial datasets enable the estimation of population counts at high spatial resolution in the absence of dependable demographic data sources. This study introduces a Bayesian model jointly estimating building and population counts, combining geolocated survey data and gridded geospatial datasets. The model provides population estimates for the Kasaï-Oriental province, Democratic Republic of the Congo (DRC), at a spatial resolution of approximately one hectare. Posterior estimates are aggregated across health zones and health areas to offer probabilistic insights into their respective populations. The model exhibits a –0.28 bias, 0.47 inaccuracy, and 0.95 imprecision using scaled residuals, with robust 95% credible intervals. The estimated population of Kasaï-Oriental for 2024 is approximately 4.1 million, with a credible range of 3.4 to 4.8 million. Aggregations by health zones and health areas reveal significant variations in population estimates and uncertainty levels, particularly between the provincial capital, Mbuji-Mayi and the rural hinterland. High-resolution Bayesian population estimates allow flexible aggregation across spatial units while providing probabilistic insights into model uncertainty. These estimates offer a unique resource for the public health community working in Kasaï-Oriental, for instance, in support of a better-informed allocation of vaccines to different operational boundaries based on the upper bound of the 95% credible intervals.
2.
Chamberlain, Heather R; Pollard, Derek; Winters, Anna; Renn, Silvia; Borkovska, Olena; Musuka, Chisenga Abel; Membele, Garikai; Lazar, Attila N; Tatem, Andrew J
In: International Journal of Health Geographics, vol. 24, no. 1, pp. 13, 2025.
Abstract | Links | BibTeX | Tags:
@article{chamberlain2025assessing,
title = {Assessing the impact of building footprint dataset choice for health programme planning: a case study of indoor residual spraying (IRS) in Zambia},
author = {Heather R Chamberlain and Derek Pollard and Anna Winters and Silvia Renn and Olena Borkovska and Chisenga Abel Musuka and Garikai Membele and Attila N Lazar and Andrew J Tatem},
url = {https://doi.org/10.1186/s12942-025-00398-7},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {International Journal of Health Geographics},
volume = {24},
number = {1},
pages = {13},
publisher = {Springer},
abstract = {The increasing availability globally of building footprint datasets has brought new opportunities to support a geographic approach to health programme planning. This is particularly acute in settings with high disease burdens but limited geospatial data available to support targeted planning. The comparability of building footprint datasets has recently started to be explored, but the impact of utilising a particular dataset in analyses to support decision making for health programme planning has not been studied. In this study, we quantify the impact of utilising four different building footprint datasets in analyses to support health programme planning, with an example of malaria vector control initiatives in Zambia.
Using the example of planning indoor residual spraying (IRS) campaigns in Zambia, we identify priority locations for deployment of this intervention based on criteria related to the area, proximity and counts of building footprints per settlement. We apply the same criteria to four different building footprint datasets and quantify the count and geographic variability in the priority settlements that are identified.
We show that nationally the count of potential priority settlements for IRS varies by over 230% with different building footprint datasets, considering a minimum threshold of 25 sprayable buildings per settlement. Differences are most pronounced for rural settlements, indicating that the choice of dataset may bias the selection to include or exclude settlements, and consequently population groups, in some areas.
The results of this study show that the choice of building footprint dataset can have a considerable impact on the potential settlements identified for IRS, in terms of (i) their location and count, and (ii) the count of building footprints within priority settlements. The choice of dataset potentially has substantial implications for campaign planning, implementation and coverage assessment. Given the magnitude of the differences observed, further work should more broadly assess the sensitivity of health programme planning metrics to different building footprint datasets, and across a range of geographic contexts and health campaign types.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The increasing availability globally of building footprint datasets has brought new opportunities to support a geographic approach to health programme planning. This is particularly acute in settings with high disease burdens but limited geospatial data available to support targeted planning. The comparability of building footprint datasets has recently started to be explored, but the impact of utilising a particular dataset in analyses to support decision making for health programme planning has not been studied. In this study, we quantify the impact of utilising four different building footprint datasets in analyses to support health programme planning, with an example of malaria vector control initiatives in Zambia.
Using the example of planning indoor residual spraying (IRS) campaigns in Zambia, we identify priority locations for deployment of this intervention based on criteria related to the area, proximity and counts of building footprints per settlement. We apply the same criteria to four different building footprint datasets and quantify the count and geographic variability in the priority settlements that are identified.
We show that nationally the count of potential priority settlements for IRS varies by over 230% with different building footprint datasets, considering a minimum threshold of 25 sprayable buildings per settlement. Differences are most pronounced for rural settlements, indicating that the choice of dataset may bias the selection to include or exclude settlements, and consequently population groups, in some areas.
The results of this study show that the choice of building footprint dataset can have a considerable impact on the potential settlements identified for IRS, in terms of (i) their location and count, and (ii) the count of building footprints within priority settlements. The choice of dataset potentially has substantial implications for campaign planning, implementation and coverage assessment. Given the magnitude of the differences observed, further work should more broadly assess the sensitivity of health programme planning metrics to different building footprint datasets, and across a range of geographic contexts and health campaign types.
Using the example of planning indoor residual spraying (IRS) campaigns in Zambia, we identify priority locations for deployment of this intervention based on criteria related to the area, proximity and counts of building footprints per settlement. We apply the same criteria to four different building footprint datasets and quantify the count and geographic variability in the priority settlements that are identified.
We show that nationally the count of potential priority settlements for IRS varies by over 230% with different building footprint datasets, considering a minimum threshold of 25 sprayable buildings per settlement. Differences are most pronounced for rural settlements, indicating that the choice of dataset may bias the selection to include or exclude settlements, and consequently population groups, in some areas.
The results of this study show that the choice of building footprint dataset can have a considerable impact on the potential settlements identified for IRS, in terms of (i) their location and count, and (ii) the count of building footprints within priority settlements. The choice of dataset potentially has substantial implications for campaign planning, implementation and coverage assessment. Given the magnitude of the differences observed, further work should more broadly assess the sensitivity of health programme planning metrics to different building footprint datasets, and across a range of geographic contexts and health campaign types.
3.
Nnanatu, Chibuzor Christopher; Bonnie, Amy; Joseph, Josiah; Yankey, Ortis; Cihan, Duygu; Gadiaga, Assane; Voepel, Hal; Abbott, Thomas; Chamberlain, Heather R; Tia, Mercedita; others,
Estimating small area population from health intervention campaign surveys and partially observed settlement data Journal Article
In: Nature Communications, vol. 16, no. 1, pp. 4951, 2025.
Abstract | Links | BibTeX | Tags:
@article{nnanatu2025estimating,
title = {Estimating small area population from health intervention campaign surveys and partially observed settlement data},
author = {Chibuzor Christopher Nnanatu and Amy Bonnie and Josiah Joseph and Ortis Yankey and Duygu Cihan and Assane Gadiaga and Hal Voepel and Thomas Abbott and Heather R Chamberlain and Mercedita Tia and others},
url = {https://doi.org/10.1038/s41467-025-59862-4},
year = {2025},
date = {2025-01-01},
urldate = {2025-01-01},
journal = {Nature Communications},
volume = {16},
number = {1},
pages = {4951},
publisher = {Nature Publishing Group UK London},
abstract = {Effective governance requires timely and reliable small area population counts. Geospatial modelling approaches which utilise bespoke microcensus surveys and satellite-derived settlement maps and other spatial datasets have been developed to fill population data gaps in countries where censuses are outdated and incomplete. However, logistics and costs of microcensus surveys and tree canopy or cloud cover obscuring settlements in satellite images limit its wider applications in tropical rural settings. Here, we present a two-step Bayesian hierarchical modelling approach that can integrate routinely collected health intervention campaign data and partially observed settlement data to produce reliable small area population estimates. Reductions in relative error rates were 32–73% in a simulation study, and ~32% when applied to malaria survey data in Papua New Guinea. The results highlight the value of demographic data routinely collected through health intervention campaigns or household surveys for improving small area population estimates, and how biases introduced by satellite data limitations can be overcome.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Effective governance requires timely and reliable small area population counts. Geospatial modelling approaches which utilise bespoke microcensus surveys and satellite-derived settlement maps and other spatial datasets have been developed to fill population data gaps in countries where censuses are outdated and incomplete. However, logistics and costs of microcensus surveys and tree canopy or cloud cover obscuring settlements in satellite images limit its wider applications in tropical rural settings. Here, we present a two-step Bayesian hierarchical modelling approach that can integrate routinely collected health intervention campaign data and partially observed settlement data to produce reliable small area population estimates. Reductions in relative error rates were 32–73% in a simulation study, and ~32% when applied to malaria survey data in Papua New Guinea. The results highlight the value of demographic data routinely collected through health intervention campaigns or household surveys for improving small area population estimates, and how biases introduced by satellite data limitations can be overcome.
4.
Chamberlain, Heather R.; Darin, Edith; Adewole, Wole Ademola; Jochem, Warren C.; Lazar, Attila N.; Tatem, Andrew J.
Building footprint data for countries in Africa: To what extent are existing data products comparable? Journal Article
In: Computers, Environment and Urban Systems, vol. 110, 2024.
Abstract | Links | BibTeX | Tags:
@article{nokey,
title = {Building footprint data for countries in Africa: To what extent are existing data products comparable?},
author = {Heather R. Chamberlain and Edith Darin and Wole Ademola Adewole and Warren C. Jochem and Attila N. Lazar and Andrew J. Tatem},
url = {https://doi.org/10.1016/j.compenvurbsys.2024.102104},
doi = {10.1016/j.compenvurbsys.2024.102104},
year = {2024},
date = {2024-03-22},
journal = {Computers, Environment and Urban Systems},
volume = {110},
abstract = {Growth and developments in computing power, machine-learning algorithms and satellite imagery spatiotemporal resolution have led to rapid developments in automated feature-extraction. These methods have been applied to create geospatial datasets of features such as roads, trees and building footprints, at a range of spatial scales, with national and multi-country datasets now available as open data from multiple sources. Building footprint data is particularly useful in a range of applications including mapping population distributions, planning resource distribution campaigns and in humanitarian response. In settings with well-developed geospatial data systems, such datasets may complement existing authoritative sources, but in data-scarce settings, they may be the only source of data. However, knowledge on the degree to which building footprint data products are comparable and can be used interchangeably, and the impact of selecting a particular dataset on subsequent analyses remains limited. For all countries in Africa, we review the available multi-country building footprint data products and analyse their similarities and differences in terms of building area and count metrics. We explore the variation between building footprint data products across a range of spatial scales, including sub-national administrative units and different settlement types. Our results show that the available building footprint data products are not interchangeable. There are clear differences in counts and total area of building footprints between the assessed data products, as well as considerable spatial heterogeneity in building footprint coverage and completeness.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Growth and developments in computing power, machine-learning algorithms and satellite imagery spatiotemporal resolution have led to rapid developments in automated feature-extraction. These methods have been applied to create geospatial datasets of features such as roads, trees and building footprints, at a range of spatial scales, with national and multi-country datasets now available as open data from multiple sources. Building footprint data is particularly useful in a range of applications including mapping population distributions, planning resource distribution campaigns and in humanitarian response. In settings with well-developed geospatial data systems, such datasets may complement existing authoritative sources, but in data-scarce settings, they may be the only source of data. However, knowledge on the degree to which building footprint data products are comparable and can be used interchangeably, and the impact of selecting a particular dataset on subsequent analyses remains limited. For all countries in Africa, we review the available multi-country building footprint data products and analyse their similarities and differences in terms of building area and count metrics. We explore the variation between building footprint data products across a range of spatial scales, including sub-national administrative units and different settlement types. Our results show that the available building footprint data products are not interchangeable. There are clear differences in counts and total area of building footprints between the assessed data products, as well as considerable spatial heterogeneity in building footprint coverage and completeness.
5.
Qader, Sarchil; Chamberlain, Heather; Kuepie, Mathias; Hunt, Freja K.; and Andrew J. Tatem, Attila Lazar
Field testing of pre-Enumeration Areas created using semi-automated delineation approach, Democratic Republic of Congo Technical Report
2023.
Abstract | Links | BibTeX | Tags:
@techreport{nokey,
title = {Field testing of pre-Enumeration Areas created using semi-automated delineation approach, Democratic Republic of Congo},
author = {Sarchil Qader and Heather Chamberlain and Mathias Kuepie and Freja K. Hunt and Attila Lazar and Andrew J. Tatem},
url = {https://eprints.soton.ac.uk/475327/},
doi = {10.5258/SOTON/WP00759},
year = {2023},
date = {2023-03-15},
urldate = {2023-03-15},
abstract = {This report details the main outcomes of the field testing of pre-Enumeration Areas (EAs) created from WorldPop and Flominder’s semi-automated EA approach that took place across three test sites in the provinces of Kinshasa and Kongo-Central, Democratic Republic of the Congo in December 2019. The field testing was conducted over four days by the BCR technical staff with participation from UNFPA and WorldPop staff.
Generally, EA boundaries from one census will form the basis for the EAs in the next census, with updates needed to account for new settlements and changes in population density. However, in countries where there hasn’t been a census for many years, often due to conflict or insecurity, EA boundaries can be incomplete, outdated, or missing altogether. The delineation of EAs is, therefore, a crucial pre-census activity but can often be particularly challenging and highly resource intensive. Creating EAs requires consideration of population and area size within each unit to ensure that they have approximately equal-sized populations and are a manageable size to be covered by census enumeration staff. To respond to this challenge, WorldPop has developed a semi-automatic approach of delineating pre-EAs to support census cartography. This approach utilises high-resolution gridded population estimates and digitised geographic features, including administrative boundaries, and natural and man-made features, such as rivers and roads, to divide the regions into small areas which are then merged to meet criteria specified for population size and geographic area.
The last census in DRC was conducted in 1984; consequently, a recent, national, digital EA dataset which can be used for cartography planning does not exist. GRID3 is supporting the realisation of a fully digital 2020 round census in the DRC and is working closely with the National Institute of Statistics and the DRC Census Bureau (Bureau Central de Recensement, BCR) to provide technical guidance regarding options for incorporating geospatial methodologies into census planning and census cartography. As the DRC Census Bureau prepares for the 2nd National Population and Housing Census (RGPH2), a new dataset of EA boundaries is needed. As part of GRID3’s work with the BCR, a field test was conducted to assess the feasibility of using a semi-automated approach for the delineation of pre-EA boundaries.
A preliminary pre-EA dataset was produced for the three test sites (Site 1: Quartier Kingu, Kinshasa (urban), Site 2: Quartier Dumi, Kinshasa (sub-urban), Site 3: Secteur Kasangulu, Kongo-Central (rural)) that span both rural and urban contexts. The geographic area covered by the three sites totalled 1,190 km2 and was sub-divided into approximately 312 pre-EAs. The pre-EAs created for the three test sites were classified as classes 1-3 depending on the degree to which the pre-EA boundaries followed visible features (e.g. roads). Class 1 being those pre-EAs with boundaries which fully followed visible features, class 2 boundaries followed visible features in part, and class 3 which didn’t follow visible features at all. A visual assessment was carried out by comparing the pre-EA boundaries with recent high-resolution satellite imagery. A subset of the pre-EAs (15 pre-EAs), covering classes 1, 2 and 3 were selected, and assessed in the field to check how the boundaries related to ground features and their feasibility as units for population enumeration. Class 1 pre-EAs were only found in urban contexts and tended to be bounded fully by roads, which were found to be simple for the field teams to follow. In class 2 and class 3 pre-EAs, the field teams were generally able to follow roads or tracks throughout the pre-EA to reach settlements, and ascertain when they had reached the boundary of the pre-EA using the maps and GPS location indicator on the tablets. The pre-EA boundaries were also created to avoid splitting settlements and therefore even in rural areas, the field teams were able to know where housing units needed to be enumerated.
A range of limitations with this work have been identified, both with the methods and equipment used in the field data collection and the methods and input data used to produce the pre-EA boundaries. Despite the identified limitations and the challenges encountered in the field, the findings from the field test were generally consistent, with the pre-EAs created by the semi-automated approach found to be suitable for population enumeration in the field. Overall the fieldwork was successfully conducted and expectations were met and even exceeded: the BCR found that the pre-EA outputs were found to help facilitate enumeration, as the BCR team could navigate within the pre-EA boundaries and know which housing units to enumerate. The findings of the field test indicate this semi-automated approach to creating pre-EAs has the potential to be used by the BCR to create pre-EAs in preparation for census cartography, and offers large savings in terms of time, labour and cost. Nonetheless, it would be expected that the pre-EA outputs created in the approach are carefully reviewed in the lab, and manually edited as needed prior to census cartography. Then whilst in the field, the pre-EA boundaries should be validated. Limitations associated with input datasets can be addressed through a comprehensive review of existing datasets, incorporating newly available feature extraction datasets as appropriate. Further development of the approach and potential solutions and suggestions to overcome the identified limitations are outlined and discussed in detail in the report.
We expect the findings of the field test in DRC to be transferable to other similar contexts, with the approach having applicability in countries with no recent digital EAs. We also expect the approach could be adapted to update digital EA boundaries in contexts with outdated EA datasets, but this should be explored through further research and testing in such contexts.
Worth noting that in close collaboration with GeoData at the University of Southampton, UNFPA and multiple national statistical offices around the world, WorldPop has now converted the automatic delineation script to a user-friendly tool which require minimal GIS skill to run.},
howpublished = {eprints Soton},
keywords = {},
pubstate = {published},
tppubtype = {techreport}
}
This report details the main outcomes of the field testing of pre-Enumeration Areas (EAs) created from WorldPop and Flominder’s semi-automated EA approach that took place across three test sites in the provinces of Kinshasa and Kongo-Central, Democratic Republic of the Congo in December 2019. The field testing was conducted over four days by the BCR technical staff with participation from UNFPA and WorldPop staff.
Generally, EA boundaries from one census will form the basis for the EAs in the next census, with updates needed to account for new settlements and changes in population density. However, in countries where there hasn’t been a census for many years, often due to conflict or insecurity, EA boundaries can be incomplete, outdated, or missing altogether. The delineation of EAs is, therefore, a crucial pre-census activity but can often be particularly challenging and highly resource intensive. Creating EAs requires consideration of population and area size within each unit to ensure that they have approximately equal-sized populations and are a manageable size to be covered by census enumeration staff. To respond to this challenge, WorldPop has developed a semi-automatic approach of delineating pre-EAs to support census cartography. This approach utilises high-resolution gridded population estimates and digitised geographic features, including administrative boundaries, and natural and man-made features, such as rivers and roads, to divide the regions into small areas which are then merged to meet criteria specified for population size and geographic area.
The last census in DRC was conducted in 1984; consequently, a recent, national, digital EA dataset which can be used for cartography planning does not exist. GRID3 is supporting the realisation of a fully digital 2020 round census in the DRC and is working closely with the National Institute of Statistics and the DRC Census Bureau (Bureau Central de Recensement, BCR) to provide technical guidance regarding options for incorporating geospatial methodologies into census planning and census cartography. As the DRC Census Bureau prepares for the 2nd National Population and Housing Census (RGPH2), a new dataset of EA boundaries is needed. As part of GRID3’s work with the BCR, a field test was conducted to assess the feasibility of using a semi-automated approach for the delineation of pre-EA boundaries.
A preliminary pre-EA dataset was produced for the three test sites (Site 1: Quartier Kingu, Kinshasa (urban), Site 2: Quartier Dumi, Kinshasa (sub-urban), Site 3: Secteur Kasangulu, Kongo-Central (rural)) that span both rural and urban contexts. The geographic area covered by the three sites totalled 1,190 km2 and was sub-divided into approximately 312 pre-EAs. The pre-EAs created for the three test sites were classified as classes 1-3 depending on the degree to which the pre-EA boundaries followed visible features (e.g. roads). Class 1 being those pre-EAs with boundaries which fully followed visible features, class 2 boundaries followed visible features in part, and class 3 which didn’t follow visible features at all. A visual assessment was carried out by comparing the pre-EA boundaries with recent high-resolution satellite imagery. A subset of the pre-EAs (15 pre-EAs), covering classes 1, 2 and 3 were selected, and assessed in the field to check how the boundaries related to ground features and their feasibility as units for population enumeration. Class 1 pre-EAs were only found in urban contexts and tended to be bounded fully by roads, which were found to be simple for the field teams to follow. In class 2 and class 3 pre-EAs, the field teams were generally able to follow roads or tracks throughout the pre-EA to reach settlements, and ascertain when they had reached the boundary of the pre-EA using the maps and GPS location indicator on the tablets. The pre-EA boundaries were also created to avoid splitting settlements and therefore even in rural areas, the field teams were able to know where housing units needed to be enumerated.
A range of limitations with this work have been identified, both with the methods and equipment used in the field data collection and the methods and input data used to produce the pre-EA boundaries. Despite the identified limitations and the challenges encountered in the field, the findings from the field test were generally consistent, with the pre-EAs created by the semi-automated approach found to be suitable for population enumeration in the field. Overall the fieldwork was successfully conducted and expectations were met and even exceeded: the BCR found that the pre-EA outputs were found to help facilitate enumeration, as the BCR team could navigate within the pre-EA boundaries and know which housing units to enumerate. The findings of the field test indicate this semi-automated approach to creating pre-EAs has the potential to be used by the BCR to create pre-EAs in preparation for census cartography, and offers large savings in terms of time, labour and cost. Nonetheless, it would be expected that the pre-EA outputs created in the approach are carefully reviewed in the lab, and manually edited as needed prior to census cartography. Then whilst in the field, the pre-EA boundaries should be validated. Limitations associated with input datasets can be addressed through a comprehensive review of existing datasets, incorporating newly available feature extraction datasets as appropriate. Further development of the approach and potential solutions and suggestions to overcome the identified limitations are outlined and discussed in detail in the report.
We expect the findings of the field test in DRC to be transferable to other similar contexts, with the approach having applicability in countries with no recent digital EAs. We also expect the approach could be adapted to update digital EA boundaries in contexts with outdated EA datasets, but this should be explored through further research and testing in such contexts.
Worth noting that in close collaboration with GeoData at the University of Southampton, UNFPA and multiple national statistical offices around the world, WorldPop has now converted the automatic delineation script to a user-friendly tool which require minimal GIS skill to run.
Generally, EA boundaries from one census will form the basis for the EAs in the next census, with updates needed to account for new settlements and changes in population density. However, in countries where there hasn’t been a census for many years, often due to conflict or insecurity, EA boundaries can be incomplete, outdated, or missing altogether. The delineation of EAs is, therefore, a crucial pre-census activity but can often be particularly challenging and highly resource intensive. Creating EAs requires consideration of population and area size within each unit to ensure that they have approximately equal-sized populations and are a manageable size to be covered by census enumeration staff. To respond to this challenge, WorldPop has developed a semi-automatic approach of delineating pre-EAs to support census cartography. This approach utilises high-resolution gridded population estimates and digitised geographic features, including administrative boundaries, and natural and man-made features, such as rivers and roads, to divide the regions into small areas which are then merged to meet criteria specified for population size and geographic area.
The last census in DRC was conducted in 1984; consequently, a recent, national, digital EA dataset which can be used for cartography planning does not exist. GRID3 is supporting the realisation of a fully digital 2020 round census in the DRC and is working closely with the National Institute of Statistics and the DRC Census Bureau (Bureau Central de Recensement, BCR) to provide technical guidance regarding options for incorporating geospatial methodologies into census planning and census cartography. As the DRC Census Bureau prepares for the 2nd National Population and Housing Census (RGPH2), a new dataset of EA boundaries is needed. As part of GRID3’s work with the BCR, a field test was conducted to assess the feasibility of using a semi-automated approach for the delineation of pre-EA boundaries.
A preliminary pre-EA dataset was produced for the three test sites (Site 1: Quartier Kingu, Kinshasa (urban), Site 2: Quartier Dumi, Kinshasa (sub-urban), Site 3: Secteur Kasangulu, Kongo-Central (rural)) that span both rural and urban contexts. The geographic area covered by the three sites totalled 1,190 km2 and was sub-divided into approximately 312 pre-EAs. The pre-EAs created for the three test sites were classified as classes 1-3 depending on the degree to which the pre-EA boundaries followed visible features (e.g. roads). Class 1 being those pre-EAs with boundaries which fully followed visible features, class 2 boundaries followed visible features in part, and class 3 which didn’t follow visible features at all. A visual assessment was carried out by comparing the pre-EA boundaries with recent high-resolution satellite imagery. A subset of the pre-EAs (15 pre-EAs), covering classes 1, 2 and 3 were selected, and assessed in the field to check how the boundaries related to ground features and their feasibility as units for population enumeration. Class 1 pre-EAs were only found in urban contexts and tended to be bounded fully by roads, which were found to be simple for the field teams to follow. In class 2 and class 3 pre-EAs, the field teams were generally able to follow roads or tracks throughout the pre-EA to reach settlements, and ascertain when they had reached the boundary of the pre-EA using the maps and GPS location indicator on the tablets. The pre-EA boundaries were also created to avoid splitting settlements and therefore even in rural areas, the field teams were able to know where housing units needed to be enumerated.
A range of limitations with this work have been identified, both with the methods and equipment used in the field data collection and the methods and input data used to produce the pre-EA boundaries. Despite the identified limitations and the challenges encountered in the field, the findings from the field test were generally consistent, with the pre-EAs created by the semi-automated approach found to be suitable for population enumeration in the field. Overall the fieldwork was successfully conducted and expectations were met and even exceeded: the BCR found that the pre-EA outputs were found to help facilitate enumeration, as the BCR team could navigate within the pre-EA boundaries and know which housing units to enumerate. The findings of the field test indicate this semi-automated approach to creating pre-EAs has the potential to be used by the BCR to create pre-EAs in preparation for census cartography, and offers large savings in terms of time, labour and cost. Nonetheless, it would be expected that the pre-EA outputs created in the approach are carefully reviewed in the lab, and manually edited as needed prior to census cartography. Then whilst in the field, the pre-EA boundaries should be validated. Limitations associated with input datasets can be addressed through a comprehensive review of existing datasets, incorporating newly available feature extraction datasets as appropriate. Further development of the approach and potential solutions and suggestions to overcome the identified limitations are outlined and discussed in detail in the report.
We expect the findings of the field test in DRC to be transferable to other similar contexts, with the approach having applicability in countries with no recent digital EAs. We also expect the approach could be adapted to update digital EA boundaries in contexts with outdated EA datasets, but this should be explored through further research and testing in such contexts.
Worth noting that in close collaboration with GeoData at the University of Southampton, UNFPA and multiple national statistical offices around the world, WorldPop has now converted the automatic delineation script to a user-friendly tool which require minimal GIS skill to run.
6.
Chamberlain, Heather R.; Lazar, Attila N.; Tatem, Andrew J.
High-resolution estimates of social distancing feasibility, mapped for urban areas in sub-Saharan Africa Journal Article
In: Scientific Data, vol. 9, no. 711 (2022), 2022.
Abstract | Links | BibTeX | Tags:
@article{nokey,
title = {High-resolution estimates of social distancing feasibility, mapped for urban areas in sub-Saharan Africa},
author = {Heather R. Chamberlain and Attila N. Lazar and Andrew J. Tatem },
url = {https://doi.org/10.1038/s41597-022-01799-0
},
doi = {10.1038/s41597-022-01799-0},
year = {2022},
date = {2022-11-18},
urldate = {2023-11-18},
journal = {Scientific Data},
volume = {9},
number = {711 (2022)},
abstract = {Social distancing has been widely-implemented as a public health measure during the COVID-19 pandemic. Despite widespread application of social distancing guidance, the feasibility of people adhering to such guidance varies in different settings, influenced by population density, the built environment and a range of socio-economic factors. Social distancing constraints however have only been identified and mapped for limited areas. Here, we present an ease of social distancing index, integrating metrics on urban form and population density derived from new multi-country building footprint datasets and gridded population estimates. The index dataset provides estimates of social distancing feasibility, mapped at high-resolution for urban areas across 50 countries in sub-Saharan Africa.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Social distancing has been widely-implemented as a public health measure during the COVID-19 pandemic. Despite widespread application of social distancing guidance, the feasibility of people adhering to such guidance varies in different settings, influenced by population density, the built environment and a range of socio-economic factors. Social distancing constraints however have only been identified and mapped for limited areas. Here, we present an ease of social distancing index, integrating metrics on urban form and population density derived from new multi-country building footprint datasets and gridded population estimates. The index dataset provides estimates of social distancing feasibility, mapped at high-resolution for urban areas across 50 countries in sub-Saharan Africa.
7.
Chamberlain, Heather R.; Lazar, Attila N.; Tatem, Andrew J.
High-resolution estimates of social distancing feasibility, mapped for urban areas in sub-Saharan Africa Journal Article
In: Scientific Data, vol. 9, no. 711, 2022.
Abstract | Links | BibTeX | Tags: Africa, covid-19, NPIs
@article{nokey,
title = {High-resolution estimates of social distancing feasibility, mapped for urban areas in sub-Saharan Africa},
author = {Heather R. Chamberlain and Attila N. Lazar and Andrew J. Tatem },
doi = {10.1038/s41597-022-01799-0},
year = {2022},
date = {2022-11-18},
journal = {Scientific Data},
volume = {9},
number = {711},
abstract = {Social distancing has been widely-implemented as a public health measure during the COVID-19 pandemic. Despite widespread application of social distancing guidance, the feasibility of people adhering to such guidance varies in different settings, influenced by population density, the built environment and a range of socio-economic factors. Social distancing constraints however have only been identified and mapped for limited areas. Here, we present an ease of social distancing index, integrating metrics on urban form and population density derived from new multi-country building footprint datasets and gridded population estimates. The index dataset provides estimates of social distancing feasibility, mapped at high-resolution for urban areas across 50 countries in sub-Saharan Africa.},
keywords = {Africa, covid-19, NPIs},
pubstate = {published},
tppubtype = {article}
}
Social distancing has been widely-implemented as a public health measure during the COVID-19 pandemic. Despite widespread application of social distancing guidance, the feasibility of people adhering to such guidance varies in different settings, influenced by population density, the built environment and a range of socio-economic factors. Social distancing constraints however have only been identified and mapped for limited areas. Here, we present an ease of social distancing index, integrating metrics on urban form and population density derived from new multi-country building footprint datasets and gridded population estimates. The index dataset provides estimates of social distancing feasibility, mapped at high-resolution for urban areas across 50 countries in sub-Saharan Africa.
8.
Chamberlain, Heather R; Macharia, Peter M; Tatem, Andrew J
Mapping urban physical distancing constraints, sub-Saharan Africa: a case study from Kenya Journal Article
In: Bulletin of the World Health Organisation, vol. 100, iss. 9, 2022.
Abstract | Links | BibTeX | Tags:
@article{nokey,
title = {Mapping urban physical distancing constraints, sub-Saharan Africa: a case study from Kenya},
author = {Chamberlain, Heather R and Macharia, Peter M and Tatem, Andrew J},
doi = {10.2471%2FBLT.21.287572},
year = {2022},
date = {2022-06-22},
urldate = {2022-06-22},
journal = {Bulletin of the World Health Organisation},
volume = {100},
issue = {9},
abstract = {With the onset of the coronavirus disease 2019 (COVID-19) pandemic, public health measures such as physical distancing were recommended to reduce transmission of the virus causing the disease. However, the same approach in all areas, regardless of context, may lead to measures being of limited effectiveness and having unforeseen negative consequences, such as loss of livelihoods and food insecurity. A prerequisite to planning and implementing effective, context-appropriate measures to slow community transmission is an understanding of any constraints, such as the locations where physical distancing would not be possible. Focusing on sub-Saharan Africa, we outline and discuss challenges that are faced by residents of urban informal settlements in the ongoing COVID-19 pandemic. We describe how new geospatial data sets can be integrated to provide more detailed information about local constraints on physical distancing and can inform planning of alternative ways to reduce transmission of COVID-19 between people. We include a case study for Nairobi County, Kenya, with mapped outputs which illustrate the intra-urban variation in the feasibility of physical distancing and the expected difficulty for residents of many informal settlement areas. Our examples demonstrate the potential of new geospatial data sets to provide insights and support to policy-making for public health measures, including COVID-19.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
With the onset of the coronavirus disease 2019 (COVID-19) pandemic, public health measures such as physical distancing were recommended to reduce transmission of the virus causing the disease. However, the same approach in all areas, regardless of context, may lead to measures being of limited effectiveness and having unforeseen negative consequences, such as loss of livelihoods and food insecurity. A prerequisite to planning and implementing effective, context-appropriate measures to slow community transmission is an understanding of any constraints, such as the locations where physical distancing would not be possible. Focusing on sub-Saharan Africa, we outline and discuss challenges that are faced by residents of urban informal settlements in the ongoing COVID-19 pandemic. We describe how new geospatial data sets can be integrated to provide more detailed information about local constraints on physical distancing and can inform planning of alternative ways to reduce transmission of COVID-19 between people. We include a case study for Nairobi County, Kenya, with mapped outputs which illustrate the intra-urban variation in the feasibility of physical distancing and the expected difficulty for residents of many informal settlement areas. Our examples demonstrate the potential of new geospatial data sets to provide insights and support to policy-making for public health measures, including COVID-19.
9.
Boo, Gianluca; Darin, Edith; Leasure, Douglas R; Dooley, Claire A; Chamberlain, Heather R; and Lázár, Attila N; Tschirhart, Kevin; Sinai, Cyrus; Hoff, Nicole A; Fuller, Trevon
High-resolution population estimation using household survey data and building footprints Journal Article
In: Nature Communications, vol. 13, no. 1330, 2022.
Abstract | Links | BibTeX | Tags: Bayesian inference, Demographic and Health Surveys, Population
@article{nokey,
title = {High-resolution population estimation using household survey data and building footprints},
author = {Boo, Gianluca and Darin, Edith and Leasure, Douglas R and Dooley, Claire A and Chamberlain, Heather R and and Lázár, Attila N and Tschirhart, Kevin and Sinai, Cyrus and Hoff, Nicole A and Fuller, Trevon},
doi = {https://doi.org/10.1038/s41467-022-29094-x},
year = {2022},
date = {2022-03-14},
urldate = {2022-03-14},
journal = {Nature Communications},
volume = {13},
number = {1330},
abstract = {The national census is an essential data source to support decision-making in many areas of public interest. However, this data may become outdated during the intercensal period, which can stretch up to several decades. In this study, we develop a Bayesian hierarchical model leveraging recent household surveys and building footprints to produce up-to-date population estimates. We estimate population totals and age and sex breakdowns with associated uncertainty measures within grid cells of approximately 100 m in five provinces of the Democratic Republic of the Congo, a country where the last census was completed in 1984. The model exhibits a very good fit, with an R2 value of 0.79 for out-of-sample predictions of population totals at the microcensus-cluster level and 1.00 for age and sex proportions at the province level. This work confirms the benefits of combining household surveys and building footprints for high-resolution population estimation in countries with outdated censuses.},
keywords = {Bayesian inference, Demographic and Health Surveys, Population},
pubstate = {published},
tppubtype = {article}
}
The national census is an essential data source to support decision-making in many areas of public interest. However, this data may become outdated during the intercensal period, which can stretch up to several decades. In this study, we develop a Bayesian hierarchical model leveraging recent household surveys and building footprints to produce up-to-date population estimates. We estimate population totals and age and sex breakdowns with associated uncertainty measures within grid cells of approximately 100 m in five provinces of the Democratic Republic of the Congo, a country where the last census was completed in 1984. The model exhibits a very good fit, with an R2 value of 0.79 for out-of-sample predictions of population totals at the microcensus-cluster level and 1.00 for age and sex proportions at the province level. This work confirms the benefits of combining household surveys and building footprints for high-resolution population estimation in countries with outdated censuses.
10.
Chamberlain, H. R.; Lazar, A. N.; and Tatem, A. J
An index to map feasibility of social distancing within urban areas Conference
29th Annual GIS Research UK Conference (GISRUK), 2021.
Abstract | Links | BibTeX | Tags:
@conference{nokey,
title = {An index to map feasibility of social distancing within urban areas},
author = {Chamberlain, H.R. and Lazar, A.N. and and Tatem, A.J},
doi = {https://doi.org/10.5281/zenodo.4670091},
year = {2021},
date = {2021-05-07},
booktitle = {29th Annual GIS Research UK Conference (GISRUK)},
abstract = {The COVID-19 pandemic has brought factors affecting disease transmission into the spotlight, and required widespread use of public health measures to reduce transmission and contain outbreaks. Urban areas inherently have large concentrations of people, providing high potential for large outbreaks and rapid disease spread, necessitating extensive use of measures to reduce transmission. Social distancing, also called physical distancing, is a public health measure intended to reduce infectious disease transmission, by maintaining physical distance between individuals or households. In the context of the COVID-19 pandemic, populations in many countries around the world have been advised to maintain social distance, with distances of 6ft or 2m commonly advised. The feasibility of social distancing is affected by the availability of space and the number of people, which varies geographically. In locations where social distancing is difficult, a focus on alternative measures to reduce disease transmission should be prioritised. To help identify and map such locations at high spatial resolution, this paper describes an index to quantify ease of social distancing, applied to urban areas across sub-Saharan Africa.},
keywords = {},
pubstate = {published},
tppubtype = {conference}
}
The COVID-19 pandemic has brought factors affecting disease transmission into the spotlight, and required widespread use of public health measures to reduce transmission and contain outbreaks. Urban areas inherently have large concentrations of people, providing high potential for large outbreaks and rapid disease spread, necessitating extensive use of measures to reduce transmission. Social distancing, also called physical distancing, is a public health measure intended to reduce infectious disease transmission, by maintaining physical distance between individuals or households. In the context of the COVID-19 pandemic, populations in many countries around the world have been advised to maintain social distance, with distances of 6ft or 2m commonly advised. The feasibility of social distancing is affected by the availability of space and the number of people, which varies geographically. In locations where social distancing is difficult, a focus on alternative measures to reduce disease transmission should be prioritised. To help identify and map such locations at high spatial resolution, this paper describes an index to quantify ease of social distancing, applied to urban areas across sub-Saharan Africa.
11.
Jochem, Warren C; Leasure, Douglas R; Pannell, Oliver; Chamberlain, Heather R; Jones, Patricia; Tatem, Andrew J
Classifying settlement types from multi-scale spatial patterns of building footprints Journal Article
In: Environment and Planning B: Urban Analytics and City Science, vol. 48, no. 5, pp. 1161-1179, 2021.
Abstract | Links | BibTeX | Tags:
@article{doi:10.1177/2399808320921208,
title = {Classifying settlement types from multi-scale spatial patterns of building footprints},
author = {Warren C Jochem and Douglas R Leasure and Oliver Pannell and Heather R Chamberlain and Patricia Jones and Andrew J Tatem},
url = {https://doi.org/10.1177/2399808320921208},
doi = {10.1177/2399808320921208},
year = {2021},
date = {2021-01-01},
journal = {Environment and Planning B: Urban Analytics and City Science},
volume = {48},
number = {5},
pages = {1161-1179},
abstract = {Urban settlements and urbanised populations continue to grow rapidly and much of this transition is occurring in less developed countries. Remote sensing techniques are now often applied to monitor urbanisation and changes in settlement patterns. In particular, increasing availability of very high resolution imagery (<1 m spatial resolution) and computing power is enabling complete sets of settlement data in the form of building footprints to be extracted from imagery. These settlement data provide information on the changes occurring in cities, particularly in countries which may lack other data on urbanisation. While spatially detailed, extracted building footprints typically lack other information that identify building types or can be used to differentiate intra-urban land uses or neighbourhood types. This work demonstrates an approach to classifying settlement types through multi-scale spatial patterns of urban morphology visible in building footprint data extracted from very high resolution imagery. The work uses a Gaussian mixture modelling approach to select and hierarchically merge components into clusters. The results are maps classifying settlement types on a high spatial resolution (100 m) grid. The approach is applied in Kaduna, Nigeria; Kinshasa, Democratic Republic of the Congo; and Maputo, Mozambique and demonstrates the potential of computational methods to take advantage of large spatial datasets and extract meaningful information to support monitoring of urban areas. The model-based approach produces a hierarchy of potential clustering solutions, and we suggest that this can be used in partnership with local knowledge of the context when creating settlement typologies.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Urban settlements and urbanised populations continue to grow rapidly and much of this transition is occurring in less developed countries. Remote sensing techniques are now often applied to monitor urbanisation and changes in settlement patterns. In particular, increasing availability of very high resolution imagery (<1 m spatial resolution) and computing power is enabling complete sets of settlement data in the form of building footprints to be extracted from imagery. These settlement data provide information on the changes occurring in cities, particularly in countries which may lack other data on urbanisation. While spatially detailed, extracted building footprints typically lack other information that identify building types or can be used to differentiate intra-urban land uses or neighbourhood types. This work demonstrates an approach to classifying settlement types through multi-scale spatial patterns of urban morphology visible in building footprint data extracted from very high resolution imagery. The work uses a Gaussian mixture modelling approach to select and hierarchically merge components into clusters. The results are maps classifying settlement types on a high spatial resolution (100 m) grid. The approach is applied in Kaduna, Nigeria; Kinshasa, Democratic Republic of the Congo; and Maputo, Mozambique and demonstrates the potential of computational methods to take advantage of large spatial datasets and extract meaningful information to support monitoring of urban areas. The model-based approach produces a hierarchy of potential clustering solutions, and we suggest that this can be used in partnership with local knowledge of the context when creating settlement typologies.
12.
Lloyd, Christopher T.; Chamberlain, Heather; Kerr, David; Yetman, Greg; Pistolesi, Linda; Stevens, Forrest R.; Gaughan, Andrea E.; Nieves, Jeremiah J.; Hornby, Graeme; MacManus, Kytt; Sinha, Parmanand; Bondarenko, Maksym; Sorichetta, Alessandro; Tatem, Andrew J.
Global spatio-temporally harmonised datasets for producing high-resolution gridded population distribution datasets Journal Article
In: Big Earth Data, vol. 3, no. 2, pp. 108-139, 2019, (PMID: 31565697).
@article{doi:10.1080/20964471.2019.1625151,
title = {Global spatio-temporally harmonised datasets for producing high-resolution gridded population distribution datasets},
author = {Christopher T. Lloyd and Heather Chamberlain and David Kerr and Greg Yetman and Linda Pistolesi and Forrest R. Stevens and Andrea E. Gaughan and Jeremiah J. Nieves and Graeme Hornby and Kytt MacManus and Parmanand Sinha and Maksym Bondarenko and Alessandro Sorichetta and Andrew J. Tatem},
url = {https://doi.org/10.1080/20964471.2019.1625151},
doi = {10.1080/20964471.2019.1625151},
year = {2019},
date = {2019-01-01},
journal = {Big Earth Data},
volume = {3},
number = {2},
pages = {108-139},
publisher = {Taylor & Francis},
note = {PMID: 31565697},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
13.
Wardrop, N. A.; Jochem, W. C.; Bird, T. J.; Chamberlain, H. R.; Clarke, D.; Kerr, D.; Bengtsson, L.; Juran, S.; Seaman, V.; Tatem, A. J.
Spatially disaggregated population estimates in the absence of national population and housing census data Journal Article
In: Proceedings of the National Academy of Sciences, vol. 115, no. 14, pp. 3529-3537, 2018.
Abstract | Links | BibTeX | Tags:
@article{doi:10.1073/pnas.1715305115,
title = {Spatially disaggregated population estimates in the absence of national population and housing census data},
author = {N. A. Wardrop and W. C. Jochem and T. J. Bird and H. R. Chamberlain and D. Clarke and D. Kerr and L. Bengtsson and S. Juran and V. Seaman and A. J. Tatem},
url = {https://www.pnas.org/doi/abs/10.1073/pnas.1715305115},
doi = {10.1073/pnas.1715305115},
year = {2018},
date = {2018-01-01},
journal = {Proceedings of the National Academy of Sciences},
volume = {115},
number = {14},
pages = {3529-3537},
abstract = {Population numbers at local levels are fundamental data for many applications, including the delivery and planning of services, election preparation, and response to disasters. In resource-poor settings, recent and reliable demographic data at subnational scales can often be lacking. National population and housing census data can be outdated, inaccurate, or missing key groups or areas, while registry data are generally lacking or incomplete. Moreover, at local scales accurate boundary data are often limited, and high rates of migration and urban growth make existing data quickly outdated. Here we review past and ongoing work aimed at producing spatially disaggregated local-scale population estimates, and discuss how new technologies are now enabling robust and cost-effective solutions. Recent advances in the availability of detailed satellite imagery, geopositioning tools for field surveys, statistical methods, and computational power are enabling the development and application of approaches that can estimate population distributions at fine spatial scales across entire countries in the absence of census data. We outline the potential of such approaches as well as their limitations, emphasizing the political and operational hurdles for acceptance and sustainable implementation of new approaches, and the continued importance of traditional sources of national statistical data.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Population numbers at local levels are fundamental data for many applications, including the delivery and planning of services, election preparation, and response to disasters. In resource-poor settings, recent and reliable demographic data at subnational scales can often be lacking. National population and housing census data can be outdated, inaccurate, or missing key groups or areas, while registry data are generally lacking or incomplete. Moreover, at local scales accurate boundary data are often limited, and high rates of migration and urban growth make existing data quickly outdated. Here we review past and ongoing work aimed at producing spatially disaggregated local-scale population estimates, and discuss how new technologies are now enabling robust and cost-effective solutions. Recent advances in the availability of detailed satellite imagery, geopositioning tools for field surveys, statistical methods, and computational power are enabling the development and application of approaches that can estimate population distributions at fine spatial scales across entire countries in the absence of census data. We outline the potential of such approaches as well as their limitations, emphasizing the political and operational hurdles for acceptance and sustainable implementation of new approaches, and the continued importance of traditional sources of national statistical data.
