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Climate change

Torrential rain

RISKS DESCRIPTION

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One of the effects of climate change is an increase in extreme episodes of torrential rain. Torrential rain is an extremely strong and violent rainfall episode, normally associated with a storm accompanied with lightning and hail, which is short in duration and limited to a particular area. This rain causes flooding, especially if it coincides with relief that favours an increase in the volume of water accumulated in a small area.

A change in the rainfall pattern is expected in coming years. And this would not only result in a risk of torrential rain at a given moment, but also in the risk of drought in intermediate periods and in the impossibility of the water from these torrential rainfall episodes being “available” water.

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The Meteorological Service of Catalonia (SMC) determines extremely abundant precipitation to be in excess of 100 mm in 24 hours.
More than 40% of the municipalities in Catalonia present a high or very high risk of flooding, the majority of which are on the coast. According to various studies, 219 episodes of flooding were registered in Catalonia from 1981 to 2010, 71% of which in the coastal regions. 11% caused serious damage, resulting in partial or complete destruction of infrastructure (catastrophic), and 53% caused major damage (extraordinary). The majority of these episodes were registered in autumn (48%) and summer (32%). Within the complex meteorology of the Mediterranean climate, the frequency and peak flows of torrential rainfall episodes in Catalonia, which have a magnitude corresponding to return periods of 50 to 100 years, could significantly increase.
These phenomena have been exacerbated by the considerable increase in the number of urbanised and impermeable zones built in floodable areas in the last 50 years, resulting in significant damage to urban centres, seafront promenades and numerous infrastructure elements throughout Catalonia.

 

 

HEALH EFFECTS

The most visible effects caused by this phenomenon are deaths by drowning and physical injury due to impacts and falls.

The psychological damage that may be caused by the loss of tangible assets, aside from the financial consequences, both personally and collectively, should not be forgotten either.

OBJECTIVE

General

  • Reduce the effects of torrential rain and increase the resilience of the populations.

Specific

  • Increase the permeable land of the inhabited environment and avoid the use of non-permeable solutions and measures in paving projects in order to prevent runoffs (nature-based solutions, soft solutions).
  • Incorporate the risk of flooding into urban planning and management within the framework of climate change.
  • Reconsider the environment in terms of the new climate paradigm.
  • Develop a flood risk management plan that takes into account the effects of torrential rain, focussing on prevention, protection, preparation and communication.

PROPOSALS AND RECOMMENDATIONS

  • Environmental restoration of areas along the banks of rivers and streams (including those located in urban areas). Enforce the law preventing the construction of extremely vulnerable housing and buildings (hospitals, fire stations, schools, police stations) in floodable areas with a return period of less than 100 years.
  • Apply the determinations and recommendations stemming from the zoning of the water system, in accordance with the various return periods and associated risks, in urban planning.
  • Avoid the construction of residences on the ground floors and semi-basement levels of buildings.
  • In the case of the construction of basement floors for other uses, resistant construction solutions should be specified with a corresponding maintenance plan to prevent flooding.
  • Incorporate plants and trees into earth retention systems in order to reduce the risk of land erosion.
  • Increase the number of tree-covered areas.
  • Ecologically recover riverside woodland.
  • Define controlled flooding zones to reduce the effects of overflowing rivers.
  • Generally keep municipal open spaces in good condition due to the key role they play in the lamination, retention and flow of water and the protection of land during episodes of torrential rain.
  • Maintain the drainage capacity of the beds of rivers and streams.
  • Apply permeable paving solutions to prevent runoffs.
  • Increase the size of sewers and the number of scuppers.
  • Construction of underground tanks, retention reservoirs, roof gardens.
  • Sustainable drainage systems (SUDS), replacement of impermeable areas with areas with gravel, permeable paving, absorbing wells, plant life areas.
  • Maintenance plan for the cleaning of scuppers, above all in autumn and summer.
  • Emergency and communication plan.
  • Changes in the layout of certain infrastructure.
  • Changes in the type of asphalt.
  • Tanks to retain rainwater (storm tanks).
  • Separative sewers.
  • Naturalise the environment of urban stretches of rivers and streams.
  • Identification of infrastructure, buildings and specific facilities that may be affected by flooding, landslides, etc.
  • Conservation of natural spaces using the corresponding urban development techniques.
  • Limited access to and signage of rock shelters, caves, fords and other areas where there may be significant flooding.

REFERENCE EXPERIENCES

LEGISLATION

STUDIES AND TECHNICAL DOCUMENTATION

More information about addressing the Public Health Service: entornurbasalut@diba.cat

Date of last update:
dc., 12 de maig 2021 05:05:07 +0000