Mega cities and rural area : Linkage and problems

A megacity is usually defined as a metropolitan area with a total population in excess of 10 million people. Some definitions also set a minimum level for population density (at least 2,000 persons/square km). A megacity can be a single metropolitan area or two or more metropolitan areas that converge. The terms conurbation, metropolis and metroplex are also applied later. Top ten megacities are tabulated here as per the data 2013 April.


List of top 10 mega cities


Administrations in the world’s largest cities are often confronted with a multitude of key problems like high urban densities, traffic congestion, energy inadequacy and managing sustainable development and climate change. In the developing world, additional problems such as a lack of basic services, illegal construction both within the city and in the periphery, informal real estate markets, creation of slums, poor natural hazards management in overpopulated areas, crime, water, soil and air pollution leading to environmental degradation, land subsidence and poor governance arrangements. These are within and surrounding megacity problems.
Megacities have large population that every inhabitant depends on the rural areas for foods and beverage, water supply, Electricity supply etc. Human resources for the factories and for services required within cities are also depends on rural area. Most of the resources are directly from rural areas or they have to come through these countryside.

Linkage

Mega city is located either in the coastal side or inland but anyway it must have to link with rural areas. All the resources and goods to be transported to megacity from rural areas are very important so linkage between rural area and megacity is main point of consideration for existence of life in mega city. Following linkage chart shows some schematic flow: 




Management of the megacity consists the management of the supply of resources and energy to the city, for that mainly following points are taken into consideration.
           Infrastructure assets management
  Railways
  Roads and tunnels
  Bridges, retaining walls
          Energy management
  Towers and transmission lines
  Pipelines
          Logistics
  Transportation system
  Vehicle management
         Environmental accounting for structures
         Water supply management and food supply system

Public infrastructures have constructed for service to people by public funds. Infrastructures for linkage of megacity to the rural areas are more important than the infrastructures within mega city. For the logistic systems roads and railways are basic for the management of vehicle routing and transportation.

FOCUS ON INFRASTRUCTURE ASSET MANAGEMENT.


Infrastructure asset management deals for the management of the linkage highways and railways. Stability of soil is more important for the stability of structures like road, tunnels, railway, bridges etc. Vulnerability of these infrastructures also covered the vulnerability caused to its vicinity. There are so many settlements that we have to consider during the safety calculation of infrastructures. Losses due to failure of infrastructure will cause interruption of supply to megacity, diversion will cause loss of time and fuel also increase environment pollution.
Problems on linkage which have to cover under infrastructure asset management are:
  • Landslides
  • Deterioration of road surface
  • Deterioration of bridges and culverts
  • Blockage on tunnels
  • Soil settlements

Landslide is the main problem for the roads and railways that block fully on its operation, which may cause due to the activities during construction, geological conditions, weather etc. Other points are mainly have to cover under periodic and routine maintenance can disturb partially or no effect to traffic movement.

Risk and mitigation of problems

Landslides (landslips, the collapse and flow of earth, mud and rock falls) often occur in times of bad weather (heavy rain, storms), earthquakes, floods, avalanches or melting snow. It is thus as difficult to distinguish between their causes and effects as it is to differentiate between preventive and protective measures.The damage caused by a landslide varies according to the phenomenon at the origin of the danger and can affect whole regions through, for example, flooding or rivers of mud,or very limited areas as when rock slides or falls occur.A localized event can also have widespread consequences especially if it disrupts transport links (roads, rail, and cable cars) or damages the infrastructure (important buildings, electricity grids, telecommunication networks, conduits, pipe works and reservoirs for water, gas, toxic and polluting substances).Landslides can also affect the safety of power houses and hydro power dams or cause the buildup of water behind unstable embankments thus threaten to the population and infrastructure in downstream. 

Interruptions on road


Landslides can occur slowly or rapidly. They can generally be predicted by observing areas known to be unstable and by taking into account the meteorological conditions (bad weather).
Preventive measures consist of developments and constructions intended to avoid or at least limit landslides through stabilizing work: terracing, drainage anchoring, deep injections into the soil or by the construction of retaining dikes to hold back or divert landslides, tunnels, shafts, etc. Plantation in unstable areas is also an efficient preventive measure.As regards long term security measures it is important that legislation on land development requires a systematic appraisal of the potential natural dangers. Before establishing residential areas and granting planning permission for buildings in vicinity of highways and railways, vulnerability must be taken into account.These measures will be complemented by the constant monitoring of unstable areas and by an obligation to upkeep forests and vegetation and to maintain high altitude waterways (water falls, silting basins, dikes etc.).The damaging effects of landslides will primarily be avoided or limited by taking the following preventive and protective measures:
  •       Monitoring (observatories or specialist institutes) constantly or randomly unstable                areas representing a major threat.
  •      Establishing one or several information and alarm centers to inform the authorities and      the public.
  •      Imposing building restrictions, forbidding people from staying in restricted areas and          banning traffic on certain routes (road, rail, etc.)
  •      Erecting buildings and developing infrastructures that will prevent or limit landslides            and protect the population.
  •       Planning the evacuation of populations eventually at risk.
  •      Establishing well equipped and trained disaster management and rescue teams.


Preventive measures

For undisturbed life on megacity, we have to manage the infrastructures that use for linkage to rural area. In contest of infrastructure management we have to do some risk analysis and implement the preventive measures to reduce risks of landslide and other hazards, which must have to be a part in the management of megacity.

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