Publication

Climate change refers to any significant change in the measures of climate lasting for an extended period of time. It includes major changes in climatic parameters like temperature, precipitation, or wind patterns, among other effects, that occur over several decades or longer. The longevity of transportation infrastructure, the long-term nature of climate change, and the potential impacts identified by recent studies warrant serious attention to climate change in planning new or rehabilitated transportation systems.

Climate change may cause more flooding of roads, bridges and airport runways, especially in low land areas as a result of erratic rains. A range of adaptation responses can be employed to reduce risks through redesign or relocation of infrastructure, increased redundancy of critical services, and operational improvements. Roads, bridges, tunnels and railway lines will be vulnerable to increased precipitation, groundwater levels, temperatures and winds.

Higher groundwater levels associated with extreme precipitation will mean an increased risk of landslides on excavation slopes. There is a risk that the bearing capacity of bridge and tunnel foundations, supporting walls and sheet pilings will be reduced by increased groundwater levels. This can be a great problem, especially for foundations on sand. Modern safety installations are significantly more sensitive to temperature increases than older installations and this presents a particular problem. Autonomous adaptation to climate change is important because of the complexity and long lifetime of roads. Furthermore, improved maintenance in the form of cleaning existing road drainage systems can retain drainage capacity corresponding to that of a new installation.

The road transport sector is a key area that contributes to climate change by way of greenhouse gas emissions. However, the transport sector is in turn itself affected by climate change. Whilst, transport systems and infrastructure are designed to withstand typical weather patterns, climate change impacts arising in the near and longer-term can have an impact on the efficiency of transport operations and ability of infrastructure to withstand extreme events.

For the incorporation of the climate change impacts associated adaptation should be in done during the detail engineering design period considering the potential effects of climate change. From a road development perspective in Nepal, impact of climate change mainly takes the form of concentrated high rainfall resulting in the accelerated surface run-off from slopes and increased flows in gullies, drainage channels, streams, and rivers. These phenomena have a consequent effect on the stability and performance of road sections, bridges, and other structures. Taking care on the topographical features of Nepal especially two nature containing impacts could be found.

The associated impacts and their adaptation measures are categories based on the topographical nature of the road where located. In our country mainly it is found that there is the mountain ecosystem associated topography and plain area associated topography.

Effects of climate change could include the possibility of flash floods/rapids, mud flows in rivers/streams, and an increase in incidence of landslides along the alignment close to the Siwaliks and flooding and inundation in the plain areas. Numbers of existing roads in the Terai are also susceptible to flooding due to the limited drainage capability because of flat topography. Natural drainage pattern in the Terai makes the roads with an east-west alignment generally less susceptible to flooding than the roads with a north-south alignment. For this reason, particular consideration should be given in the detailed design of road formation and embankment heights and the size of waterways and soffit levels of bridges.

During detailed design, detail hydrological study/analysis should be conducted to determine water ways, span/length and height (i.e. soffit, invert levels) of bridges and major cross-drainage works. Design flood should be calculated considering long terms time period return period for cross drainage as well as for side drains. The road structures should be designed considering the probability of natural hazards (i.e. floods, earthquakes etc). Pavement surface should be designed considering the effect of temperature variation. Similarly, adequate expansion joints are provisioned in the design of bridges to account for the possible expansion and contraction due to temperature changes.

To ameliorate the impact on micro-climate due to cutting of trees, plantation should be proposed in this vicinity of the road project, which will also help to reduce the level of GHG in atmosphere.

Climate change does not affect only in a single sector. It affects over all aspects of earths cycling. Road itself is taken as development measure. So the impact of climate change on road sector is a crucial issue.

Together with it the impacts and adaptation measures are not on specific way.

But these include multi sectors. To cope with such all impacts individual and organizational steps are key steps.