CIWARS CCI News covers climate change, conflict, and infrastructure news focus on water, food, extreme weather, sea level rise, migrants/refugees and destabilizing conflicts. Center for Infrastructural Warfare Studies including cyber infrastructure
Tanzania: The Impact of Climate Change in Road Design
analysis By Simon Njau
Climate change is a large-scale, long-term shift in the planet's weather patterns or average temperatures. The climate change includes, higher temperatures, changing rainfall pattern, changes in nature, sea level rises, retreating glaciers, sea ice and ice sheets.
Climate change may be due to natural processes or to persistent human induced changes in the composition of the atmosphere or in land use. Climate in a narrow sense is defined as the average weather, or more rigorously, as its statistical description in terms of the mean and variability of surface variables such as temperature, precipitation and wind over a period of time.
Weather refers to the conditions in the atmosphere and the air around us at a particular moment, including temperature, rain, sun and wind. Our assets, including highways and main roads are subjected to the effects of climate change and need to be adapted to make sure they are available for the community in years to come. The way we do business also has the potential to contribute to emergent climate issues meaning we must consider better, more sustainable ways to manage and operate the road network.
The climate change effect hasn't been given proper impact in the design, construction, maintenance and operation of roads infrastructure in Tanzania a result of which can have a very serious impact.
In order to ensure that the strategic road network can meet the challenge of a changing climate, the potential effects of climate change must be considered as part of the design. In some cases, such as highway surfacing and landscape planning design and climate change considerations will form part of the detail design process. At the preliminary design stage, the main climate change considerations relate to the drainage design and flood plain compensation issues.
Tanzania Road Agency (TANROADS) must put in place strategy on climate change, which should be set as Climate Change Adaptation Strategy and Framework, (Tanroads Agency Policy), to include a desire to ensure that climate change considerations are factored in Tanroads business, including design, construction, maintenance and operations.
The drainage design in the highways and road network is highly dependent on the climate change thus should be based on the TANROADS requirement that the rainfall intensities used to calculate design storms for the design of any element of road drainage, must include an allowance for the effects of climate change.
Where rainfall data excludes such an allowance, then sensitivity testing on the design of the drainage system must be carried out by increasing rainfall intensities of the design storms by 20 per cent.
The treatment of surface runoff would involve a combination of systems and (where applicable) would address key processes including sedimentation, separation and vegetated treatment processes.
There would be balancing and treatment ponds along the scheme and roadside storage ditches must be provided which would also be used for attenuation and treatment.
Attenuation would be provided prior to discharge of highway drainage outflows to watercourses in accordance with agreed criteria by Environmental Council. Sustainable drainage systems (SuDS) would be used wherever practicable in line with highways best practice criteria as detailed in the available design manuals and standards.
Balancing ponds and similar storage facilities would also be designed to sufficient volume following best practice criteria. Road drainage would include an allowance for the effects of climate change by increasing rainfall intensities of the design storms by 20 per cent over and above current design rainfall intensities.
All local access road drainage would be designed and constructed to current adoptable highways standards as detailed in the design Notes and Manuals locally and internationally available.
The drainage systems employed on minor rural roads can be retained and reused. There are various locations where watercourses would be substantially diverted as part of the scheme, including main rivers, streams, valleys and water bodies available along the proposed roads.
An ordinary watercourse is defined as a watercourse that is not a 'main river.' Award drains are awarded for maintenance to local authorities. In new and existing highway and roads projects, design and construction must always have provision for drainage structures to facilitate drainage of the storm-water runoff.
These include new culverts provided in the scheme and some extensions to existing culverts. New culverts under the mainline roads would generally be formed using pipes of either concrete, AMCO, box culverts depending on the amount of discharge of storm water runoff.
The diameter of the culverts must be adequately large enough to facilitate maintenance and minimise risk of blockages. Crossings requiring a large flow capacity would generally be constructed as box culverts. All major crossing of the rivers crossing the proposed roads would be a bridge structure.
The landscape mitigation must be designed to incorporate the watercourse diversions and their associated maintenance access requirements. Other drainage facilities provided in rehabilitated highway and roads depending on the nature and type of terrain of that particular area where the roads are passing including, side drains, mitre drains, cut-off drains, drifts and erosion checks.
The drains can either be lined with paving slabs, concrete paving or unlined depending on the nature of the slope at that particular site. In Tanzania, in recent years during El-Niño and La-Nina rains we have experienced a number of derailments of railway lines and huge damages in the highways and roads in areas like Same, Kilimanjaro Region and Kilosa in Morogoro Region and many other areas in the country, as a result of non-consideration of climate change in the design, construction, maintenance and operation.
TANROADS should provide guidance as will be agreed with the National Environmental Management Council (NEMC) the baseline flood event to assess the with-scheme flood risk against annual excellence probability (AEP) event. Any mitigation measures to have included an allowance for climate change of an additional 20 per cent in rainfall intensity or peak river flow.
The TANROADS response to the challenge of climate change must therefore involve both mitigation (taking action to reduce greenhouse gas emissions) and adaptation (changing behaviour so that it is more appropriate to the expected future climate). Many of the Agency's activities are either directly affected or influenced by climate.
Simon Theobald Njau is an Engineer with S&F Consultancy Limited.
--> Reuters JOHANNESBURG The United Nations' food agency said on Thursday it needed $730 million over the next 12 months for relief in seven southern African countries hit hard by a blistering drought and faced a $610 million shortfall. The World Food Programme ...…
Response to El Niño Must Be Ramped Up Amid Preparedness for La Niña's Likely Knock-On Effect - UN
Failure to prepare for and adapt to the 'new normal' of increasing climate-linked emergencies such as El Niño could put global development targets at risk and deepen widespread human suffering in areas already hard hit by floods and droughts, top United Nations officials said in Rome today.
Calling for governments and the international community to ramp up efforts to strengthen resilience and safeguard livelihoods in the wake of El Niño's devastating effects, the heads of the three Rome-based UN agencies, along with the newly-appointed UN Special Envoy on El Niño & Climate, warned that more than 60 million people worldwide, about 40 million in East and Southern Africa alone, are projected to be food insecure due to the impact of the El Niño climate event.
The agency chiefs also urged greater preparedness to deal with the possible occurrence later this year of a La Niña climate event, closely related to the El Niño cycle that has had a severe impact on agriculture and food security. The Horn of Africa, Southern Africa, Central America's Dry Corridor, Caribbean islands, Southeast Asia and Pacific islands have been hit the hardest.
According to the UN, scientists are predicting an increasing likelihood of the opposite climate phenomenon, La Niña, developing. This will increase the probability of above average rainfall and flooding in areas affected by El Niño-related drought, whilst at the same time making it more likely that drought will occur in areas that have been flooded due to El Niño.
The UN estimates that without the necessary action, the number of people affected by the combined impacts of the El Niño/La Niña could top 100 million.
To coordinate responses to these challenges and to mobilize the international community to support the affected governments, UN agencies and other partners met at the Rome headquarters of the UN Food and Agriculture Organization (FAO) today. The meeting included the International Fund for Agricultural Development (IFAD) and the World Food Programme (WFP).
The meeting called for action to recover agricultural livelihoods that have been severely damaged by the droughts associated with El Niño. Acting now will ensure that farmers have sufficient levels of agricultural inputs for upcoming planting seasons.
Furthermore, FAO, IFAD and WFP said that they are redoubling efforts to mitigate the negative impacts and capitalize on positive opportunities of a likely La Niña phenomenon in the coming months. This means acting decisively to prepare for above-average rainfall in some areas and potential drought conditions in others.
FAO Director-General José Graziano da Silva warned that the impact of El Niño on agricultural livelihoods has been enormous and with La Niña on the doorsteps the situation could worsen.
"El Nino has caused primarily a food and agricultural crisis," he said, announcing that FAO will therefore mobilize additional new funding to "enable it to focus on anticipatory early action in particular, for agriculture, food and nutrition, to mitigate the impacts of anticipated events and to strengthen emergency response capabilities through targeted preparedness investments."
Mobilizing resources for rapid action now can save lives and minimize damage while reducing costs in the future, said WFP Executive Director Ertharin Cousin. "Farms have failed, opportunities for work have evaporated, and nutritious food has become increasingly inaccessible for many communities," Ms. Cousin stressed.
"But new humanitarian crises are not inevitable if we invest in support for communities and provide the tools and skills required to endure climate-related shocks," she added.
IFAD Associate Vice-President, Lakshmi Menon, reminded the global community not to forget about small-scale farmers, who are the most vulnerable to these extreme weather events. "Small-scale farmers in rural areas are disproportionally impacted by these natural disasters because many of them depend on rain-fed agriculture for their lives and livelihoods, and they do not have the capacity to bounce back from shocks. We need to invest in building their long-term resilience so when the next El Niño and La Niña cycles hit, they are better prepared and can continue to grow food for their families," she said.
UN Special Envoy for El Niño and Climate, Ambassador Macharia Kamau, a keynote speaker at the event, said: "It is clear that these types of extreme weather events are stressing already-vulnerable communities, threatening to undermine development gains of recent decades and impede achievement of the Sustainable Development Goals (SDGs)."
He noted that the humanitarian community in partnership with governments and regional authorities have developed a number of plans in order to respond to the current El Niño event, and that these plans are multisectoral and require longer-term, predictable funding in order to ensure they are fully implemented.
In closing his remarks Ambassador Kamau concluded by calling on governments, development partners, UN Resident Coordinators and UN Country Teams to closely assess the situation in their countries - employing a holistic human security approach to look at what plans can be adjusted or adapted to attend to both urgent needs and future threats.
"This is not a matter to put to one side for another day, we do not have the luxury of time. Our development and humanitarian systems need to be deeply integrated, climate-proofed and fit for purpose. A failure to deliver on this mission will have ripples felt for generations. If we do not succeed we will be letting down the people that need us most," he said.