Infrastructures are systems designed to meet relatively general human needs, often through largely or entirely public utility-type institutions. Infrastructures for industry, settlements and society include both ‘physical’ (such as water, sanitation, energy, transportation and communication systems) and ‘institutional’ (such as shelter, health care, food supply, security, and fire services and other forms of emergency protection). In many instances, such ‘physical’ and ‘institutional’ infrastructures are linked. For example, in New York City adaptations of the physical water supply systems to possible water supply variability are dependent on changes within the institutions that manage them; conversely, institutions such as health care are dependent to some degree on adjustments in physical infrastructures to maintain effective service delivery (Rosenzweig and Solecki, 2001a).
These infrastructures are vulnerable to climate change in different ways and to different degrees, depending on their state of development, their resilience and their adaptability. In general, floods induce more physical damage, while drought and heatwaves tend to have impacts on infrastructure systems that are more indirect.
Often, the institutional infrastructure is less vulnerable as it embodies less fixed investment and is more readily adapted within the time-scale of climate change. Moreover, the effect of climate change on institutional infrastructure can be small or even result in an improvement in its resilience; for example, it could help to trigger an adaptive response (e.g., Bigio, 2003).
There are many points at which impacts on the different infrastructure sectors interact. For instance, failure of flood defences can interrupt power supplies, which in turn puts water and wastewater pumping stations out of action. On the other hand, this means that measures to protect one sector can also help to safeguard the others.
126.96.36.199.1 Water supplies
Climate change, in terms of change in the means or variability, could affect water supply systems in a number of ways. It could affect water demand. Increased temperatures and changes in precipitation can contribute to increases in water demand, for drinking, for cooling systems and for garden watering (Kirshen, 2002). If climate change contributes to the failure of small local water sources, such as hand-dug wells, or to inward migration, this may also cause increased demand on regional water supplies. It could also affect water availability. Changes in precipitation patterns may lead to reductions in river flows, falling groundwater tables and, in coastal areas, to saline intrusion in rivers and groundwater, and the loss of meltwater will reduce river flows at key times of year in parts of Asia and Latin America (Chapter 3, Section 3.4.3). Furthermore, climate change could damage the system itself, including erosion of pipelines by unusually heavy rainfall.
Water supplies have a life of many years and so are designed with spare capacity to respond to future growth in demand. Allowance is also made for anticipated variations in demand with the seasons and with the time of day. From the point of view of the impacts of climate change, therefore, most water supply systems are quite able to cope with the relatively small changes in mean temperature and precipitation which are anticipated for many decades, except at the margin where a change in the mean requires a significant change in the design or technology of the water supply system, e.g., where reduced precipitation makes additional reservoirs necessary (Harman et al., 2005) or leads to saline intrusion into the lower reaches of a river. An example is in southern Africa (Ruosteenoja et al., 2003), where the city of Beira in Mozambique is already extending its 50 km pumping main a further 5 km inland to be certain of freshwater.
More dramatic impacts on water supplies are liable to be felt under extremes of weather that could arise as a result of climate change, particularly drought and flooding. Even where water-resource constraints, rather than system capacity, affect water-supply functioning during droughts, this often results from how the resource is allocated rather than absolute insufficiency. Domestic water consumption, which represents only 2% of global abstraction (Shiklomanov, 2000), is dwarfed by the far greater quantities required for agriculture. Water supply systems, such as those for large coastal cities, are often downstream of other major users and so are the first to suffer when rivers dry up. Under Integrated Water Resource Management, such urban areas would receive priority in allocation, because the value of municipal water use is so much greater than agricultural water use, and therefore they can afford to pay a premium price for the water (Dinar et al., 1997).
In many countries, additional investment is likely to be needed to counter increasing water resource constraints due to climate change. For example, Severn-Trent, one of the nine English water companies, has estimated that its output is likely to fall by 180 Megalitres/day (roughly 9% of the total) by 2030 due to climate change, making a new reservoir necessary to maintain the supply to Birmingham (Environment Agency, 2004). However, such changes will only become a major problem where they are rapid compared to the normal rate of water supply expansion, and where systems have insufficient spare capacity, as in many developing countries.
During the last century, mean precipitation in all four seasons of the year has tended to decrease in all the main arid and semi-arid regions of the world, e.g., northern Chile and the Brazilian North-East, West Africa and Ethiopia, the drier parts of Southern Africa and Western China (Folland et al., 2001). If these trends continue, water resource limitations will become more severe in precisely those parts of the world where they are already most likely to be critical (Rhode, 1999).
Flooding by rivers and tidal surges can do lasting damage to water supplies. Water supply abstraction and treatment works are sited beside rivers, because it is not technically advisable to pump raw water for long distances. They are therefore often the first items of infrastructure to be affected by floods. While sedimentation tanks and filter beds may be solid enough to suffer only marginal damage, electrical switchgear and pump motors require substantial repairs after floods, which cannot normally be accomplished in less than two weeks. In severe riverine floods with high flow velocities, pipelines may also be damaged, requiring more extensive repair work.
188.8.131.52.2 Sanitation and urban drainage
Some of the considerations applying to water supply also apply to sewered sanitation and drainage systems, but in general the effect of climate change on sanitation is likely to be less than on water supply. When water supplies cease to function, sewered sanitation also becomes unusable. Sewer outfalls are usually into rivers or the sea, and so they and any sewage treatment works are exposed to damage during floods (PAHO, 1998). In developing countries, sewage treatment works are usually absent (WHO/Unicef, 2000) or involve stabilisation ponds, which are relatively robust. Sea-level rise will affect the functioning of sea outfalls, but the rise is slow enough for the outfalls to be adapted to the changed conditions at modest expense, by pumping if necessary. Storm drainage systems are also unlikely to suffer serious storm damage, but they will be overloaded more often if heavy storms become more frequent, causing local flooding. The main impact of climate change on on-site sanitation systems such as pit latrines is likely to be through flood damage. However, they are more properly considered as part of the housing stock rather than items of community infrastructure. The main significance of sanitation here is that sanitation infrastructures (or the lack of them) are the main determinant of the contamination of urban flood water with faecal material, presenting a substantial threat of enteric disease (Ahern et al., 2005).
184.108.40.206.3 Transport, power and communications infrastructures
A general increase in temperature and a higher frequency of hot summers are likely to result in an increase in buckled rails and rutted roads, which involve substantial disruption and repair costs (London Climate Change Partnership, 2004). In temperate zones, less salting and gritting will be required, and railway points will freeze less often. Most adaptations to these changes can be made gradually in the course of routine maintenance, for instance by the use of more heat-resistant grades of road metal when resurfacing. Transport infrastructure is more vulnerable to effects of extreme local climatic events than to changes in the mean. For instance, 14% of the annual repair and maintenance budget of the newly-built 760 km Konkan Railway in India is spent repairing damage to track, bridges and cuttings due to extreme weather events such as rain-induced landslides. This amounts to more than Rs. 40 million, or roughly US$1 million annually. In spite of preventive targeting of vulnerable stretches of the line, operations must be suspended for an average of seven days each rainy season because of such damage (Shukla et al., 2005). Parry (2000) provides an assessment of the impact of severe local storms on road transportation, much of which also applies to rail.
Of all the possible impacts on transportation, the greatest in terms of cost is that of flooding. The cost of delays and lost trips would be relatively small compared with damage to the infrastructure and to other property (Kirshen et al., 2006). In the last ten years, there have been four cases when flooding of urban underground rail systems have caused damage worth more than ¤10 m (US$13m) and numerous cases of lesser damage (Compton et al., 2002)
Infrastructure for power transmission and communications is subject to much the same considerations. It is vulnerable to high winds and ice storms when in the form of suspended overhead cables and cell phone transmission masts, but is reasonably resilient when buried underground, although burial is significantly more expensive. In developing countries, a common cause of death associated with extreme weather events in urban areas is electrocution by fallen power cables (Few et al., 2004). Such infrastructure can usually be repaired at a fraction of the cost of repairing roads, bridges and railway lines, and in much less time, but its disruption can seriously hinder the emergency response to an extreme event.