Addressing flash flood risks in Namibia
Flash floods have become a significant and increasingly frequent natural disaster in Namibia, driven by the dual pressures of climate change and urbanisation. To safeguard lives, infrastructure and livelihoods, it is essential to understand the causes and impacts of flash floods while adopting effective mitigation strategies.
What are flash floods?
Flash floods are sudden and intense flooding events that occur within hours of heavy rainfall, often with little to no warning. These floods can transform typically dry areas into raging torrents, thereby overwhelming drainage systems and inundating roads, homes and critical infrastructure. The phenomenon typically occurs when rain falls at a rate faster than the ground can absorb it or when existing drainage systems become clogged or insufficient to handle the volume of water.
Causes of flash floods
The causes of flash floods can be categorised into natural and human-induced or anthropogenic factors:
• Natural causes: These include intense rainfall from thunderstorms or tropical storms. In Namibia, heavy rains often result from seasonal weather patterns influenced by regional climatic conditions. The region’s topography, particularly in areas with steep terrain, can exacerbate runoff into rivers and streams.
• Anthropogenic causes: Human activities such as deforestation, urbanisation and poor land management can exacerbate the risk of flash floods. Urban areas with extensive impervious surfaces (like roads and buildings) prevent water absorption, leading to increased surface runoff and clogging of drainage systems.
Impacts of flash floods in Namibia
Over the past two decades, Namibia has experienced numerous flash floods that have had devastating effects on communities.
For instance, according to the World Meteorological Organisation, Windhoek recorded 95 mm of rainfall within 24 hours on 15 December 2022. This led to a massive flooding disaster that damaged buildings and swept away vehicles in the city.
Several buildings were damaged, including a police station in Otjomuise and the Wernhill Park shopping centre. Dozens of cars parked in the shopping centre were flooded while many vehicles were swept away by the flood. Local media reported that fast-flowing rivers wreaked severe havoc in the suburbs and informal areas of the city while tragically claiming lives, including two street children whose bodies were discovered near Goreangab Dam by police and City of Windhoek emergency services.
In recent incidents, including those in January, flash floods have displaced over 1 000 residents in Windhoek alone. Historical data indicates that hundreds have lost their lives due to sudden flooding events across various regions. The agricultural sector has also been severely affected by flooding. In regions like Oshana, floods have destroyed crops and livestock, leading to food insecurity for many families.
The destruction of infrastructural facilities is also another consequence of floods. Flash floods have caused significant damage to roads, bridges and homes. For example, the 2009 floods near the northern border with Angola affected over 200 000 people, washing away vital infrastructure and disrupting communities.
Economic strain is also another consequence of floods that is worth noting. The economic fallout from flash floods includes losses for small businesses, increased emergency response costs, and long-term recovery expenses, placing a burden on government resources and private enterprises alike.
These impacts highlight the urgent need for effective strategies to prevent flooding and mitigate its effects in Namibia.
Mitigation strategies
To effectively mitigate the impact of flash floods in Namibia, a multi-faceted approach is necessary:
1.Improved urban planning: Implementing flood-conscious land-use planning, avoiding construction in flood-prone areas and ensuring drainage systems are adequately designed to handle heavy rainfall are strategies that must be put in place to mitigate the impact of floods.
2.Community awareness programmes: Educating communities about flood risks and preparedness is crucial. Residents in informal settlements must be properly educated on the need to avoid construction of temporary or permanent structures in flood-prone areas. Initiatives should also focus on informing residents about emergency procedures, such as creating evacuation plans and maintaining emergency supplies. Particular attention should be dedicated to the informal settlements and those dwelling close to riverbanks.
3.Infrastructure development: Investing in resilient infrastructure is vital. This includes upgrading drainage systems to handle heavy rainfall and constructing retention basins to absorb excess water during storms.
4.Improved early warning systems: Establishing effective early warning systems that utilise technology to monitor weather patterns can provide timely alerts to communities at risk. This allows for proactive measures to be taken before flooding occurs.
5.Environmental conservation: Protecting natural ecosystems such as wetlands can help absorb excess rainwater and reduce runoff. Reforestation efforts can also play a role in stabilising soil and enhancing water absorption capacity.
6.Policy development: The government should develop and enact comprehensive policies aimed at disaster risk reduction that incorporate climate change adaptation strategies. This includes regulations on building codes that require flood-resistant designs.
7.Collaboration with NGOs: Partnering with non-governmental organizations can enhance resource mobilisation for flood preparedness initiatives and community resilience programs.
Conclusion
Flash floods are an escalating threat to Namibia’s safety, economy and environment, with devastating consequences for lives, livelihoods and infrastructure. Addressing these risks demands collective and urgent action. Effective urban planning, resilient infrastructure, community education and early warning systems can significantly reduce the impacts of these disasters. At the same time, environmental conservation and robust policy frameworks can help ensure long-term sustainability and resilience.
Importantly, the fight against flash floods in Namibia is a shared responsibility. Government agencies must lead with strategic investments and enforceable regulations, while communities must remain vigilant, proactive and adaptable. Partnerships with NGOs, private entities and international organisations can amplify resources and expertise to foster a holistic approach to the management of disasters like flash floods.
The time to act is now, especially since more downpour is expected within the next few days!
*Prof Oluibukun Gbenga Ajayi is an associate professor in geoinformation technology at the department of land and spatial sciences at the Namibia University of Science and Technology (NUST). He writes from Windhoek and can be reached via [email protected]. The views expressed in this article are his own and not those of NUST.
What are flash floods?
Flash floods are sudden and intense flooding events that occur within hours of heavy rainfall, often with little to no warning. These floods can transform typically dry areas into raging torrents, thereby overwhelming drainage systems and inundating roads, homes and critical infrastructure. The phenomenon typically occurs when rain falls at a rate faster than the ground can absorb it or when existing drainage systems become clogged or insufficient to handle the volume of water.
Causes of flash floods
The causes of flash floods can be categorised into natural and human-induced or anthropogenic factors:
• Natural causes: These include intense rainfall from thunderstorms or tropical storms. In Namibia, heavy rains often result from seasonal weather patterns influenced by regional climatic conditions. The region’s topography, particularly in areas with steep terrain, can exacerbate runoff into rivers and streams.
• Anthropogenic causes: Human activities such as deforestation, urbanisation and poor land management can exacerbate the risk of flash floods. Urban areas with extensive impervious surfaces (like roads and buildings) prevent water absorption, leading to increased surface runoff and clogging of drainage systems.
Impacts of flash floods in Namibia
Over the past two decades, Namibia has experienced numerous flash floods that have had devastating effects on communities.
For instance, according to the World Meteorological Organisation, Windhoek recorded 95 mm of rainfall within 24 hours on 15 December 2022. This led to a massive flooding disaster that damaged buildings and swept away vehicles in the city.
Several buildings were damaged, including a police station in Otjomuise and the Wernhill Park shopping centre. Dozens of cars parked in the shopping centre were flooded while many vehicles were swept away by the flood. Local media reported that fast-flowing rivers wreaked severe havoc in the suburbs and informal areas of the city while tragically claiming lives, including two street children whose bodies were discovered near Goreangab Dam by police and City of Windhoek emergency services.
In recent incidents, including those in January, flash floods have displaced over 1 000 residents in Windhoek alone. Historical data indicates that hundreds have lost their lives due to sudden flooding events across various regions. The agricultural sector has also been severely affected by flooding. In regions like Oshana, floods have destroyed crops and livestock, leading to food insecurity for many families.
The destruction of infrastructural facilities is also another consequence of floods. Flash floods have caused significant damage to roads, bridges and homes. For example, the 2009 floods near the northern border with Angola affected over 200 000 people, washing away vital infrastructure and disrupting communities.
Economic strain is also another consequence of floods that is worth noting. The economic fallout from flash floods includes losses for small businesses, increased emergency response costs, and long-term recovery expenses, placing a burden on government resources and private enterprises alike.
These impacts highlight the urgent need for effective strategies to prevent flooding and mitigate its effects in Namibia.
Mitigation strategies
To effectively mitigate the impact of flash floods in Namibia, a multi-faceted approach is necessary:
1.Improved urban planning: Implementing flood-conscious land-use planning, avoiding construction in flood-prone areas and ensuring drainage systems are adequately designed to handle heavy rainfall are strategies that must be put in place to mitigate the impact of floods.
2.Community awareness programmes: Educating communities about flood risks and preparedness is crucial. Residents in informal settlements must be properly educated on the need to avoid construction of temporary or permanent structures in flood-prone areas. Initiatives should also focus on informing residents about emergency procedures, such as creating evacuation plans and maintaining emergency supplies. Particular attention should be dedicated to the informal settlements and those dwelling close to riverbanks.
3.Infrastructure development: Investing in resilient infrastructure is vital. This includes upgrading drainage systems to handle heavy rainfall and constructing retention basins to absorb excess water during storms.
4.Improved early warning systems: Establishing effective early warning systems that utilise technology to monitor weather patterns can provide timely alerts to communities at risk. This allows for proactive measures to be taken before flooding occurs.
5.Environmental conservation: Protecting natural ecosystems such as wetlands can help absorb excess rainwater and reduce runoff. Reforestation efforts can also play a role in stabilising soil and enhancing water absorption capacity.
6.Policy development: The government should develop and enact comprehensive policies aimed at disaster risk reduction that incorporate climate change adaptation strategies. This includes regulations on building codes that require flood-resistant designs.
7.Collaboration with NGOs: Partnering with non-governmental organizations can enhance resource mobilisation for flood preparedness initiatives and community resilience programs.
Conclusion
Flash floods are an escalating threat to Namibia’s safety, economy and environment, with devastating consequences for lives, livelihoods and infrastructure. Addressing these risks demands collective and urgent action. Effective urban planning, resilient infrastructure, community education and early warning systems can significantly reduce the impacts of these disasters. At the same time, environmental conservation and robust policy frameworks can help ensure long-term sustainability and resilience.
Importantly, the fight against flash floods in Namibia is a shared responsibility. Government agencies must lead with strategic investments and enforceable regulations, while communities must remain vigilant, proactive and adaptable. Partnerships with NGOs, private entities and international organisations can amplify resources and expertise to foster a holistic approach to the management of disasters like flash floods.
The time to act is now, especially since more downpour is expected within the next few days!
*Prof Oluibukun Gbenga Ajayi is an associate professor in geoinformation technology at the department of land and spatial sciences at the Namibia University of Science and Technology (NUST). He writes from Windhoek and can be reached via [email protected]. The views expressed in this article are his own and not those of NUST.
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