The impacts of climate change, such as droughts and floods in Africa is projected to increase and become more severe in the future. Throughout my blog, I have attempted to explore the ways in which climate change will affect water resources and its availability in different areas, and how different communities adapt, or will need to adapt to these future projected impacts. Climate change impacts on water resources and the hydrological system varies between different communities and infrastructures, for example, cities may not feel the impacts of climate change as readily as small communities or farmers who may experience it more directly, such as intense rainfall periods and floods. However, it is important to recognise that climate change impacts are real even if some groups do not feel the impacts yet - this is to ensure that communities will, to some extent, be resilient to these impacts and be more readily able to adapt to these changes, especially given that climate change and land use change does not appear to be slowing down. Interestingly, climate change also appears to benefit some areas in Africa, such as increased rainfall and groundwater recharge, so it would be advantageous for communities or farmers to capitalise on these changes.
Coming to the end of my blogs, I have realised that the impacts of climate change on water resources in Africa is highly dynamic and variable. Hence further research on how climate change may impact Africa's water resources is imperative to influencing the necessary socio-economic and political changes to ensure that water security is not threatened across Africa.
Adapting to climate change is not only important in
agricultural practices, but it is also important for urban cities to adapt as
well. In this blog, I want to briefly introduce the different ways in which
adaptive measures to climate change are adopted by comparing two case studies of
two cities.
The first case study is Kampala city, this is the largest
city in Uganda and it is expected to experience greater incidences of flooding
as a result of climate change; flood-related problems such as pollution of
water supplies, health risks and the spread of diseases are more likely to
occur (Lwasa, 2010). Lwasa (2010) stresses the importance of identifying the
impacts of climate change on urban populations, and subsequently determining the
vulnerability of the urban population before attempting to apply adaptive
measures. For example, in 2007, there were eight flood events and urban poor
settlements such as Natete and Katwe were most vulnerable to these floods. This
is because these settlements were informal and lacked the necessary
infrastructure to withstand such floods. Hence, improving urban infrastructure,
and addressing runoff and floods through building dams or planning crop cover
to reduce storm flow are some adaptive measures that can be adopted. Other
secondary impacts of the floods must not be ignored; worsening health
conditions, economic damages and disrupted transport networks, and the overall
lowering of the water table of Lake Victoria, can equally worsen livelihoods in
many communities. Communities are willing to adapt but lack the means to do so,
hence local and national governments must also be willing to take part in
helping communities to adapt to climate change impacts. The Kampala City
Council has an important role in governing the funds and allocation of
resources, and the decision-making processes to adapting to climate change but
cooperation with the community and their knowledge is also required to
effectively increase the resilience of many communities to climate change
impacts. Lwasa (2010) stresses the importance of understanding the context of
urban cities and communities before choosing suitable adaptation strategies.
The second case study is Cape Town, South Africa, whereby water
quantity, access and quality are the main problems that will occur because of
climate change. Cape Town relies on surface and groundwater resources in the
local area, however climate change scenarios such as an increase in average
temperature by 1C by 2050 in Western Cape, or a general drying in most seasons in
the south-eastern region of Western Cape can make these resources highly
vulnerable (Ziervogal et al., 2010). Ziervogel et al. (2010) case study in Cape
Town explains that while lower rainfall yields are a problem, the increasing
demand for water due to population increases, poor wastewater management and
underinvestment in infrastructure remains the largest problems and threats to
water security in the city. To address these issues, climate change scenarios
are incorporated into water management policies and planning, however, actors (communities,
local governments, and national government actors) at all levels will need to
agree that climate change adaptation is required and how it should be
implemented. A combination of both supply and demand-side policies should be
used; supply-side policies include building larger dams, improve water
treatment processes, and exploiting other water resources, and demand-side
policies include limiting water consumption and distribution. Ziervogel et al. (2010)
noted that supply-side policies raised the cost of water and thus was too
expensive for locals, and demand-side policies were more favourable and
effective such that after the restrictions was imposed the demand for water
reduced.
Adapting to climate change requires an understanding of the socio-economic
background, and more specifically how climate change will have an impact on the
urban city. The Kamapla case study saw the direct impacts of climate change on
the city through floods and health-related impacts, which acted as a stronger
incentive for adaptive measures. The Cape Town case study, however, experienced
threats to their water supply through higher temperature and evapotranspiration
rates, so it was more difficult to experience the impacts of climate change in
the immediate term and this led to discussions about the priority of addressing
and adapting to the impacts of climate change. This blog very briefly
introduced how urban cities adapt to climate change through two examples but
adaptation is much more complex than what was explained here, but I wanted to
highlight the different factors and incentives that may govern the way an urban
city would react to climate change.
In my previous blog, I explored the impacts of climate
change on agricultural farmers through the changes of rainfall and temperature
across Africa. In the recent COP22 negotiations in Marrakech, agricultural adaptation
to climate change was put at the forefront by 28 countries; Ban-Ki Moon
explains that “Adaptation is not a luxury. It is a cautious investment in our
future” (AAA, 2016a). A positive product of these negotiations saw the
development of an initiative called the ‘Adaptation of African Agriculture
(AAA) Initiative’ where the importance of climate change impacts on African
agriculture is raised. This initiative focuses on implementing specific
projects to improve Africa’s agriculture on all levels, ranging from soil
management, agricultural water control, risk management and capacity building
(AAA, 2016b). Perhaps, this negotiation can prove to be a pivotal point in
elevating the concerns regarding agriculture and water availability. In this
blog I want to explore the ways in which these farmers adapt to climate change,
specifically exploring the small-scale farming techniques and adaptive measures
to changing rainfall patterns and water availability for irrigation.
Rainwater Harvesting –
Soil Moisture Conservation
This clip below provides a brief insight into the impacts of
climate change and a farmers’ response to short rainfall, intense heat and the
drying of soils through rainwater harvesting.
Agriculture in many countries across Africa is highly
dependent on rainwater and so climate change threatens a significant number of
people’s livelihoods (Yosef & Asmamaw, 2015). Rainwater harvesting through
storage in the soil profile is a form of in-situ water conservation whereby
rainwater is held in the place that it falls. The amount of water stored in the
soil is limited by the soil holding capacity and rate of infiltration, and in
arid and semi-arid areas where coarse soils and high hydraulic conductivity,
the amount of water stored in the soil is extremely limited and thus may not be
a useful adaptive method (Yosef & Asmamaw, 2015). However, soil practices
can be used to change the condition of the soil and thus improve the soil
moisture retention. For example, in the drought affected areas of Ethiopia,
stone bunds of 30cm wide and a height of 0.74m stone bunds are used to reduce
runoff and soil erosion, and to increase soil moisture (Biazin et al., 2012).
Other techniques such as terraces and trenches are also effective in increasing
soil moisture and was widely adopted in traditional agricultural practices in
many African countries. In Burkina Faso, the depth of soil pits was deepened
and compost/manure was applied, this changed the composition of the soils, thus
enabling the conservation of more water in the soil (Baizan et al., 2012). A
study by Birru et al. (2012) found that farm yard manure and mulching
significantly enhanced soil moisture retention. Soil moisture storage with
mulch treatments of 6 ton ha-1 of mulch retained 216.11mm of water,
39.15mm more water than soil without mulch treatment. 4 ton ha-1 of
straw mulch treatment retained 215.40mm of water, which is similar to the mulch
treatment, thus showing that the straw mulch treatment has higher soil water
retention capacities greater than mulch treatment.
Rainwater Harvesting
– Macro-catchment
Larger rainwater harvesting techniques consists of
collecting rainwater or runoff and diverting this water to a storage structure
and target area through a macro-catchment system (Biazin et al., 2012). A study
by Lebel et al. (2015) explains that rainwater harvesting techniques can prove
to be a ‘valuable adaption strategy to climate change’, more specifically for
maize crops because these techniques can address large issues concerning water
deficits in the future. The study predicts that under RCP8.5 climate scenarios
(highest greenhouse gas emissions during 2050s), maize yields have the
potential to increase by 14-50% due to rainwater harvesting techniques meeting
the demands required for productivity in Africa. Although, this study notes
that in semi-arid and arid regions, rainwater harvesting techniques are
unlikely to mitigate the impacts of intense temperatures and lack of rainfall,
so other adaptive techniques are required.
An interesting study by Recha et al. (2015) suggested that the adoption of
these rainwater harvesting techniques depended on the number of livelihood
options available to small-scale farmers in Tharaka, Kenya. Farmers who
depended on crops for their livelihoods was more likely to use rainwater
harvesting techniques, but other attributes such as the cropland size during
the MAM rainfall season, or the number of children per household also
influenced the adoption of rainwater harvesting techniques. This shows that
certain conditions would influence the choice of using these techniques by
farmers, only if it would maximise their productivity and optimise the use of
rainwater which would in turn improve their livelihoods.
Irrigation
Other adaptive strategies gaining momentum are irrigation
schemes. Burney et al. (2013) argues that small scale distributed irrigation schemes,
such as community level catchments, tubewells, sprinklers and drip lines, has
five-times the cost-benefit than large centralised irrigation schemes such as
dams. Yol et al. (2011) found that the internal rate of returns for large-scale
irrigation schemes averages to 7% whereas small-scale irrigation schemes have a
rate of 28%. This is because small-scale irrigation can benefit more from areas
with high rainfall potentials, unlike large-scale irrigation which may have
lower rainfall rates. Other benefits of small-scale irrigation include being
able to adapt these schemes to local needs and thus maximise freshwater use for
agriculture, whereby many small scale farmers can access this resource.
Concluding Thoughts
There are many adaptive strategies that small scale farmers
can adopt to mitigate the impacts of climate change on their agriculturally
based livelihoods, ranging from soil based moisture conservation (mulching,
manure, terracing and trenches), macro-catchment rainwater harvesting and irrigation
schemes. These techniques have been adopted in indigenous practices and have
long been sustaining the African population. But given the onset of climate
change and the devastating impacts that it is predicted to have over Africa,
the COP22 negotiations can elevate the importance of adaptive strategies to a
higher level, which may attract investment and development of these adaptive
strategies and farmer’s adaptive capacities.
Climate change largely influences surface water sources
through altered rainfall patterns, evaporation rates and changing temperatures,
whereas groundwater resources are more resilient to climate change and thus
offers a reliable supply of water (Calow et al., 2010). Groundwater resources
can provide an important buffer to climate change because despite aquifers
being highly unevenly distributed across Africa, the smallest or poorest
aquifers can still contain enough water for pumping to local communities during
dry rainfall seasons or long periods of drought (MacDonald, 2012). In this
blog, I would like to explore how groundwater resources respond to climate
change and thus the role of groundwater resources as an adaptive measure.
Groundwater resources typically store a certain amount of
water depending on the geology, geomorphology, and effective rainfall of the
aquifer, which in turn influences the transmissivity, porosity, saturated thickness,
and recharge rates of the aquifer (MacDonald et al., 2012). The largest
aquifers in the African continent lies in the northern region, where countries
like Libya, Algeria, and Egypt have the largest reserves of groundwater (Figure
1). Aquifers with lower storage capacities varies across the continent due to
different rock formations; the lowest groundwater storages are underlain by
Precambrian basement rocks (MacDonald et al., 2012). However, despite some
areas having large or small storage capacities, the yield of the aquifer and
borehole limit the productivity of these aquifers. The yield of a borehole or
hand pump to the aquifer will limit how much water can be abstracted and used,
therefore even though some countries have large aquifers, the productivity of
these aquifers may be low where little water can be abstracted and used. Figure
2 shows the productivity of aquifers, and comparing this to figure 1 for example,
shows that the aquifer underlying the South Sudan region has a relatively high
groundwater storage of 25,000-50,000 mm, however it has a moderate productivity
level of 1/5 ls-1.
Figure 1. Groundwater Storage (MacDonald et al., 2012) Figure 2. Aquifer Productivity (MacDonald et al., 2012)
Climate change rarely impacts the geology and geomorphology
of groundwater resources; however, climate change directly influences
groundwater resources through groundwater recharge processes (Taylor et al.,
2012). The replenishment of groundwater resources relies upon recharge from
either rainfall or the leakage from surface water resources. The IPCC’s fifth
assessment report predicts that rainfall patterns are likely to become more
highly variable, both spatially and temporally where droughts and intense
rainfall periods are likely to occur (IPCC, 2014), and this in turn will likely
influence groundwater recharge.
A study by Owor et al. (2009) attempted to determine a
relationship between groundwater recharge and climate change using a rare set
of data, which consists of daily rainfall and groundwater levels in the Upper
Nile Basin of Uganda. The study related the magnitude of recharge events to the
sum of daily and annual sum of daily rainfall exceeding a threshold of 10mm-1,
and they have found that groundwater recharge is better related to heavy
rainfall periods, exceeding a threshold of 10mm-1, compared to daily
rainfall rates. Their conclusion of this analysis suggested that climate change
may indeed have a positive influence on groundwater recharge because the
predicted increased frequency in rainfall intensity can promote increases in
groundwater recharge instead of restricting it. Similarly, another study by
Mileham et al. (2009) found that groundwater recharge was higher when intense
rainfall was accounted for when modelling the influence of climate change
projections on groundwater recharge. A mean monthly delta factor of climate
change was applied to the SMBM while using a historical rainfall distribution (period
1960-1990), groundwater recharge is projected to decrease by 55%, whereas
runoff is predicted to increase by 86%. However, when this historical rainfall
distribution is adjusted to account for the projected increase in intense
rainfall patterns for a future period (2070-2100), groundwater recharge and
runoff is predicted to increase by 53% and 137% respectively. Hence, this also
shows that groundwater recharge is positively influenced by intense rainfall,
and the distribution of daily rainfall is also an important factor when
modelling groundwater recharge.
These studies have shown that the projected intense rainfall
will likely improve groundwater recharge and thus the amount of groundwater
stored. This in turn can prove to be a reliable source of freshwater, especially
during periods of drought. An article by Oliver Balch (2016) agrees that the
increased use of Africa’s aquifers can help to reduce water stress and
insecurity. Initiatives by the International Water Management Institute and the
Groundwater Solutions Initiative for Policy and Practice aims to enhance the
use of groundwater resources for agricultural and domestic needs, to reach the
UN Sustainable Development Goals in reducing water scarcity. However, the
article stresses the importance of overexploitation and sustainable consumption
of groundwater, noting that the Saiss aquifer water table has fallen by an
annual average of 3meters over the past 20 years (Balch, 2016). It is important
to recognise that despite groundwater being a reliable source and adaptive
strategy to climate change, it is important that groundwater use is sustainable.
A study by Knuppe (2011) conducted interviews with management experts in South
Africa to determine the key challenges in the sustainable use and management of
groundwater resources. Climate change will have uncertain consequences on
groundwater resources but the stress and exploitation on this resource will increase
due to the undervaluation of groundwater, the need for information at all
levels in a community, the centralisation of power, governance and management,
and the disregard for ecosystems and its services. A water planning expert,
Callist Tindimugaya in the Balch article says that groundwater resources are an
“invisible commons” because there is a lack of information amongst the people
using this resource, and thus they do not comprehend how to use this resource
sustainably. A lack of central planning and policies leads to inefficiencies, and
ultimately poor management resulting in intensive and exploitative use of groundwater.
Therefore, it is also important to consider the combination of socio-economic
and physical context of using groundwater resources, especially when using
groundwater as an adaptive strategy to climate change.
Agriculture is a very important aspect of many people’s
livelihoods in Africa, and my previous blog explored the impacts of climate
change on agriculture and the vulnerability of Africa’s population to these
impacts. Addressing the impacts is definitely an important aspect to maintain
people’s livelihoods, but now I am interested in exploring the future of
Africa’s agricultural sector in terms of land use change. How does climate
change influence the way land is used? What are the drivers for land use change
and to what type of land use is being used? What are the implications on
hydrological processes and water availability if land is increasingly being
used for agriculture? These are some questions that I would like to explore.
Land use change and climate change are both factors that
contributes to global environmental change, however, both of these factors
affect each other (Dale, 1997). Firstly, land use change and patterns
influences climate change due to changes in the atmospheric flux of CO2 and secondly,
land use can be altered by climate change due to unfavourable conditions for
certain human uses and activities. Hence, land use can be seen as a causal
factor to climate change, but it can also be seen as an adaptive measure to
climate change (Dale, 1997).
The World Bank estimates that as of 2013, approximately
43.86% of land in Sub-Saharan Africa is used for agricultural purposes. Agricultural
transformation in Africa has an important role for economic transformation and
in recent years Africa has seen large increases in investment by governments in
this sector. Africa Agriculture Status Report (2016) explains that Africa’s
agricultural sector is driving changes in Africa’s economic prosperity, and
hence these socio-economic drivers will continue intensify the changes in land
use for agricultural purposes. I will not go into detail about the history and
development of Africa’s agricultural sector in this blog, but instead, I would
like to highlight another an alternative driver of land use change in Africa.
Ahmed et al. (2016) highlights the importance of climate change as another
important factor in shaping agricultural land use. As previously mentioned,
Dale (1997) explains that there is a dual relationship between land use change
and climate change, and Ahmed et al. (2016) models both socio-economic and
climate change factors as the drivers of Africa’s agricultural future. The
study found that a reduction in crop yields caused by climate change, alongside
an increasing demand for food in the future will inevitably result in an
increase in land used for agriculture in West Africa to meet these demands. The
eastern region of West Africa will experience a decline in both forests and
grassland covers to cropland covers, whereas the western region will experience
a larger decline in forest cover overall. The study projected that for Nigeria,
average cropland cover will increase from 39.4 to 84.5% as a result of climate
change, and an increase in crop cover of 37.3-40.9% is likely to occur along
the Gulf of Guinea. These results show that under a purely climate change
scenario, land use change will move from natural vegetation to crop cover,
however, these results were determined without accounting for the adaptive
capacities of farmers and communities. This study does mention these
limitations and it was useful in attempting to show how much land will change
as a result of climate change, but we cannot simply ignore the combination of
other socio-economic factors and adaptive strategies of farmers to climate change
scenarios, which this study concludes as the largest factor in driving land use
change.
Changing land from one land cover to another is likely to
have large implications on water resources, and especially in arid and
semi-arid regions of Sub-Saharan Africa. Evaporation and runoff components of a
catchment are usually influenced the most by land-use change, which in turn
influences runoff and recharge rates into aquifers. A case study in southwest
Niger shows that the water table has been increasing for many decades, despite
there being a decline of 23% of the monsoonal rainfall seasons (Favreau et al.,
2009). This was because land clearing of natural savannah to be used for millet
crops had significantly increased surface runoff; the study modelled runoff and
concluded that runoff had increased by threefold the normal rate, irrespective
of climate conditions. Higher rates of runoff leads to higher recharge rates,
the study found that recharge rates increased to 7mm/area after land was
cleared compared to a rate of 2mm/area before land was cleared for crops. Not
only does land use change influence rates of recharge and runoff, it also
affects the quality of groundwater resources whereby there was a rising trend
in nitrate concentrations by 4% (Favreau et al., 2009). Hence, when decisions
are made to convert natural land to agricultural land crops, the impacts of
this change needs to be carefully considered, especially because of the impacts
of water resources and if these impacts will infringe upon the sustainability
of that resource.
Concluding thoughts:
Land use change, climate change and water resources has more
complicated drivers, interactions and consequences than has been explored in
this blog. In this blog, I wanted to focus on the climate perspective of land
use change and the consequences of this change, but despite making attempts to
just focus on this perspective, I could not ignore the socio-economic drivers
that influences land use change. Indeed, when analysing the drivers and
consequences of land use change, one should look at both the human and climate
factors of this change. Undoubtedly, land use change will have consequences on
water resources such as groundwater levels and the quality of water resources
and so farmers will need to carefully consider why they are changing land-use
for agricultural purposes and if it will outweigh the consequences of water
resources.
In my previous blogs, I have discussed the impacts of
climate change on rainfall patterns. In this blog, I want to explore how these
changes in rainfall patterns will affect Africa’s agricultural sector and the
economic and social consequences of changing agricultural yields and
productivity.
A huge concern of climate change impacts in Africa
especially is centred on food security. Food security is understood as the
physical and economic access to safe and sufficient food to meet dietary needs
(FAO, 2006) and climate change threatens to worsen food security conditions. Africa’s
economy and people relies largely on agricultural products for their economy or
sustenance and the prospects of climate change altering rainfall patterns poses
a large threat to Africa’s agriculture because crop production relies hugely on
rainfall to water their crops. Many large organisations such as the Food and
Agriculture Organisation of the United Nations, the World Bank or the
International Food Policy Research Institute (IFPRI), have all predicted that
the prospects of Africa’s agricultural sector are bleak. For example, the FAO
reports that rural development is expected to be hit hardest due to financial
downturns and food crisis associated with loss in agricultural productivity. The
FAO predicts that agricultural yields will reduce by up to 50%, and therefore, crop
revenue will decline by as much as 90% by 2100 (FAO, 2009). The World Bank
estimates that sensitive crops to high temperatures such as maize and wheat
would be highly effected and thus crop yields will diminish. Furthermore, arable
land would decrease by 40–80% (WorldBank, 2012). Similarly, IFPRI (2013) predicts
that crops such as wheat will diminish in productivity, although increases in
rainfall in certain areas are likely to experience slightly increased rain-fed
maize and rice crops. Overall, these predictions share a common trend whereby
crop productivity and yields are expected to decrease, and in conjunction with Africa’s
population estimated to increase to 2 billion people within the next few
decades (AfricaRenewal, 2014) will only worsen the food crisis and security in
Africa. However, I should caution that the impacts of climate change on
agriculture will vary across Africa just like how the impacts of climate change
on rainfall patterns also vary across the African continent.
These predictions from the FAO or the WB are continent wide
predictions which ignores regional scale differences, although, IFPRI estimates
that Southern Africa is expected to be one of the worst hit by climate change
due to rising temperatures and declining rainfall levels (2013). Countries like
Malawi for example are predicted to see declines in average yields in maize
productivity by 7–14% by 2050 due to an overall decline in rainfall (Msowoya et
al., 2016). Countries in Eastern Africa are experiencing the same decline in
crop productivity but in a different manner aside from an overall decline in
rainfall. Instead, the Manyoni district in Tanzania are experiencing lower crop
productivity due to unpredictable rainfall whereby delays or earlier onsets of
the rainy season leads to poor germination of seeds and thus total crop failure
(Lema & Majule, 2009). Moreover, problems such as increases in the number
of pests and diseases contributes to declining crop productivity.
The consequences of declining crop productivity affect the
social and economic conditions of countries in Africa. In Sub-Saharan Africa,
agriculture accounts for up to 50% of GDP in most countries, however
agricultural practices are small scale, has low inputs with limited use of
fertilisers and high dependence on rainfall (Asafu-Adjaye, 2014).
Msowoya et al. (2016) study has identified a strong correlation between Malawi’s
maize productivity and the national GDP. From 2000 and 2005, low rainfall
levels reduced overall maize productivity and in 2005, maize production was 40%
below the national average. This decline in productivity was followed by a
large decrease in the national GDP production potential from maize. Given that
Malawai’s food production is highly dependent on rainfall, and maize is a core
crop in agriculture, the impacts of climate change has large ramifications on
the socio-economic standing of Malawi. Lower productivity will inevitably
increase the prices of crops and this can worsen conditions for poor groups of
people who may no longer be able to afford to pay for crops. An overall
decrease in crop productivity places stress of socio-economic development in
areas that need it, and it also places stress in urban areas for alternative to
agriculture employment opportunities.
Interestingly however, most agricultural output in
Sub-Saharan Africa and the associated economic value is influenced not only by
rainfall conditions, but technological and market conditions in Africa. The opportunities
in agricultural output that fertilisers can provide are not seen due to the
lack of using fertilisers because of its high prices (Asafu-Adjaye, 2014).
Furthermore, farmers who does not have access to larger markets to sell their
goods to, or the technology and means to store their goods effectively eliminates
the potential of achieving high transaction costs due to the need to sell their
products immediately. Rural markets are less likely to benefit from trading
with larger markets due to segregation and isolation.
Concluding thoughts
The direct impacts of climate change such as the lack of
rainfall as well as the temporally and spatially variable rainfall patterns has
huge consequences on agricultural output, which is an overall declining trend
across Africa. This can worsen economic and social conditions whereby the
national economic output can decline; individual farmers have lower levels of
income thus affecting social conditions such as the ability to pay for
electricity or school and daily necessities. Moreover, lower agricultural
output can result in the migration of people from rural farming lands to urban
areas in search of other jobs, further complicate living conditions in these
areas. There is no doubt that climate change has the potential to affect
agriculture, but it is also important to recognise that human structures and
policies can play a large part in an agricultural economy, and the vulnerability
of small scale and large scale farmers.
My previous blog explored the impacts of climate change in
rainfall in terms of droughts, and more specifically in West Africa and the
Sahelian region. This blog continues to explore the impacts of climate change
in Africa but in terms of floods. The first thing that comes to my mind when I
associate climate change with rainfall in Africa are the ideas of drought and
famine, thus ideas concerning extreme rainfall and increased flood extent, I
find, is very intriguing. In this blog, I want to look at floods associated
with climate change and the impacts.
The dominant projections of climate change impacts on
rainfall in terms of extreme rainfall and flooding events is that rainfall is
more likely to become highly variable in East Africa, extreme rainfall events
will become more frequent and thus result in more flooding (IPCC, 2007).
Studies such as Webster et al. (1999) and Hastenrath et al. (2007) have found
that in fact, East Africa has experienced both extreme rainfall as well as a
lack of rainfall in the region. This anomalous extreme rainfall results in more
flood events, and the frequency of flood events has increased in recent years. Shongwe
et al. (2009) analysis of the International Emergency Disaster Database shows
that almost 7 events per year of reported disasters, which was related to
increased flooding, had occurred from 2000 to 2006. The impacts of these
disasters affects economic development, poverty reduction and the well-being of
an average of two million people per year (Shongwe et al., 2011). Shongwe et
al. (2011) notes that the predicted impacts of global climate models are
already occurring now, much sooner than anticipated. And so, the impacts of
flood risk need to be analysed, and management of flooding regimes must be
properly accounted for. Just because there is an expected increase in East
Africa does not mean that this is necessarily a good thing.
The coastal city of Mombasa is located in Kenya and
currently experiences frequent floods on a near-annual basis, however the
October 2006 flood was one flood that Mombasa did not usually experience. This
flood was induced by extreme rainfall which saw the destruction of important
infrastructure, such as collapsed and flooded roads which can be seen in the
image below, and more than 60,000 people was affected by the flood (Awuor et
al., 2008). The impacts of this large flooding event worsened the social and
economic conditions of the city due to the major economic losses associated
with infrastructure damages, as well as the damages to fishing vessels. A large
majority of Kenya’s coastal population is concentrated in Mombasa – this
increased the risk of the spread of cholera (Awuor et al., 2008). The city was
notified of a cholera alert whereby thirteen cases were found positive for
cholera and an addition of two deaths by the 11 November 2006 (OCHA, 2006).
Moreover, between 15th and 17th October, high rainfall
levels of 110mm resulted in landslides which saw the death of five children.
The impacts of flooding are very severe in the short run in that homes are
almost instantaneously destroyed, many people are displaced and the death rates
of populations are widespread and the causes of these deaths range from
drowning, debris or from water-borne diseases like cholera. These impacts only
proves to show that flood management in vulnerable places is integral in a
warming world.
There is no doubt that the increases of the number of floods
in magnitude and frequency are causing huge damages to infrastructure, economic
performance and livelihoods. However, some argue that the damage and extent of
flood events is more than just the increased intensity and magnitude of floods
as a result of climate change in recent years. Studies such as Baldassarre et
al. (2010) concluded that at continental and site specific scales across
Africa, the impact of climate change in this observed increase in flood damages
is negligible. Instead, Baldassarre et al. (2010) attribute the increased
damages of floods to higher rates of urbanisation in the last decade. They
found that an increase in urban population by magnitude of 1 also saw the
increase of fatalities caused by floods by a magnitude of 1. Many studies (Hardoy
et al., 2001; Douglas et al., 2008; Jonkman, 2005) concluded that the increased
potential of flood risk with severe and irreversible consequences is a result
of intensive, rapid and unplanned urbanisation in the number of people living
in floodplain areas (Balassarre et al., 2010). For example, the growth of the
capital city of Lusaka in Zambia is prone to flooding, thus this growing city
is expected to have higher risks to flooding (Nchito, 2007).
Concluding Thoughts:
It is very important to not take these projections of
increased flood frequency and magnitude lightly, given that they are currently
happening now and not in some far distant future. Proper flood management is
required to minimise the impacts of these floods induced by climate change.
However, as many studies found, it is difficult to isolate and differentiate
the increased flood damages as a result of climate change only. Other human
factors showed to account for a large part of this increasing damage, even in a
globally warming world. Even though climate change may induce frequent floods,
climate change should not be seen as the only cause of the increased impacts of
floods in many African towns and cities. Overall, compared to droughts, the
impacts of floods on many people can be minimised with the proper management of
drainage systems and the construction of towns in a rapidly urbanisation, as
well as working in tandem with monitoring rainfall patterns and thus predicting
then floods are likely to occur as a result of intense rainfall periods.
