People including children collecting water in an urban area during a cholera outbreak in Zambia 2024. Photo by Luke Dray/Getty Images.
The hidden health cost of poor urban planning and flooding in Zambia
Frequent flooding in Zambia due to rapid urbanisation and unplanned infrastructure development can have negative consequences for public health by raising the incidence of cholera and malaria – particularly among young children. However, building climate-resilient infrastructure, strengthening early warning systems and health preparedness, and collecting localised flood data can ensure development while mitigating climate risk.
As Zambia’s urban footprint rapidly increases, the interaction between unplanned infrastructure development and extreme weather events poses a significant challenge. Zambia has experienced an increase in flooding over the past two decades, particularly flash floods in peri-urban and informal settlements. This rise coincides with expansionary fiscal policies that have spurred infrastructure development – often without adequate regulatory enforcement or environmental safeguards.
A significant number of residential and commercial areas in Zambia have been built on historically protected forest reserves, floodplains and wetlands.1 Many of these developments lack proper drainage or sanitation systems, compounding their vulnerability to climate shocks.
Zambia’s flood problem presents a challenge for public health
Flooding is not a new issue in Zambia. Historical records show that the country has experienced repeated cholera outbreaks during the rainy season, when stagnant water from floods becomes a breeding ground for mosquitoes and a conduit for waterborne diseases such as malaria, cholera, typhoid, and dysentery.
As a result, Zambia faces mounting public health challenges, particularly for young children, who are most vulnerable to diseases that follow in the wake of floods.
Figure 1: Distribution of flood events across Zambia
Notes: This map shows the distribution of floods across Zambia. While there are more flood events in regions close to waterbodies, floods also occur throughout the entire country. Figure generated by the authors using satellite data from the NASA MODIS Water Product.
Previous studies in public health find that rain and poor drainage systems are associated with an increased prevalence of cholera outbreaks in the Lusaka district, with flood exposure in particular leading to increases in malaria and cholera cases. However, little is known about how flooding impacts the prevalence of diseases among children in Zambia.
Linking flood data to public health records for young children
New research funded by the International Growth Centre combines satellite flood data with national health records to investigate how flood exposure affects health outcomes in children under the age of five, specifically focusing on waterborne diseases.
The study merges satellite flood data from the NASA MODIS Water Product with recorded health outcomes from Zambia’s Health Management Information Systems. The analysis covers the years from 2012 to 2020, and focuses on disease incidence across all wards, the smallest administrative unit in the country.
This level of disaggregated analysis helps identify the impact of flood exposure on children’s health vulnerability while considering the geography of wards in Zambia – a critical input for climate-resilient planning and targeting public health resources.
The methodology accounts for confounding factors such as rainfall and temperature, elevation and proximity to waterbodies, number of operational health facilities per ward per year, and night-time lights (as a proxy for economic activity). The use of fixed effects at both the ward and year levels ensures that results are not biased by unobservable factors that do not vary over time within a ward, or that are the same for all wards in a specific year.
Flood incidence increases the risk of malaria and cholera
The results show a statistically significant increase in both cholera and malaria cases following flood events. Though baseline annual cholera incidence is very low (0.001% at the ward level), flooding increases the probability of reported cholera cases by 74%. Similarly, it increases the probability of malaria cases by 5%, starting from a high baseline incidence of 80%.
Figure 2: Incidence of cholera among children under five between 2012 and 2020
Notes: The graphs depict the number of cholera cases per 10,000 population under the age of five, and how cholera cases are distributed between flooded and non-flooded wards. Figure generated by the authors.
We did not find any effects of flood exposure on the incidence of either typhoid or dysentery. The data used for the typhoid and dysentery cases are clinical or ‘suspected’ cases, where no tests were conducted to confirm the diagnosis – information was gathered from district health office workers that we spoke to in the data collection process.
Additionally, we found no difference in the impact of floods on disease outcomes between main towns (provincial capitals) and non-main towns. This suggests that infrastructure inequalities are not just a rural problem, and urban areas are equally vulnerable due to poor drainage, overcrowding, and informal settlements.
How can Zambia strengthen systems for health and climate resilience?
1. Urban planning must integrate climate risk
Current infrastructure development often overlooks natural drainage channels and ecological buffers. Therefore, it is important to strengthen urban planning regulations, especially in high-growth areas. Local councils, in partnership with the Ministry of Local Government and Rural Development, must integrate climate vulnerability assessments into building permits and land-use planning. For example, in Rwanda, climate-resilient urban design frameworks are used as a model for integrating floodplain management into zoning decisions.
2. Early warning systems and community education
While Zambia has a Disaster Management and Mitigation Unit, the capacity for flood forecasting and localised early warning remains limited. Reports by the United Nations Office for Disaster Risk Reduction underscore the cost-effectiveness of early warning systems in saving lives and reducing economic losses. Investment in community-level systems that provide actionable information and promote household-level mitigation practices – such as water purification, mosquito control, and temporary relocation – can also reduce disease risk.
3. Expand access to localised flood data
Short-term flash floods, often the most devastating weather event, are poorly captured by national reporting systems. Investing in localised data collection, such as crowd-sourced flood maps and community sensors, can inform infrastructure decisions and help prioritise resources in high-risk wards. Collaboration with academic and private sector actors, such as universities and geographic information system (GIS) firms, can be useful for policymakers.
4. Health system preparedness
Ministry of Health strategies should incorporate climate scenarios into routine planning, including surge staffing and stockpiling medicines in flood-prone districts during the rainy season. Health surveillance systems should also be strengthened to detect and respond to disease spikes quickly.
Making flood resilience a development priority
Our work highlights the real and growing risk that floods pose to Zambia’s youngest citizens. As the effects of climate change become more pronounced, the cost of inaction will only rise. Investing in urban planning, flood forecasting, and public health preparedness is no longer just an environmental issue, but must be at the heart of Zambia’s development agenda, to ensure that children do not suffer from preventable illnesses.
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[1] In 2017, 2018, and 2019, former president Edgar C. Lungu de-gazetted parts of a historical forest reserve – Forest 27 – to be open for commercial and residential infrastructure by signing Statutory Instruments. The most controversial of the three instruments was the one in 2019, which reduced the boundaries of the reserved area from 1,764 hectares to less than half (around 716 hectares). Forest 27, initially declared a protected area by the former British colony in 1942, was meant to be a water recharge zone which could prevent floods during heavy rainfall.