Tool risk reduction measures

PREVENT DAMAGES

«The benefits of prevention are not tangible; they are the disasters that did not happen.»

Kofi Annan, former UN SG

What do you find here?

Info

This section provides support, mainly for municipalities and private persons , to find out if a development area or a property might be at heavy rain flood risk, and if so, which measures can be taken in order to avoid or reduce the risk identified. Additionally, for existing settlement areas or properties already at risk of heavy rain, support is provided for finding helpful information and suitable protection measures. Moreover, regional administrations might additionally support municipalities and private persons e.g. by providing overarching information.

What is prevention, and how can it contribute to risk reduction?

Prevention measures in flood risk management are all those measures which can be taken in times without heavy rain events, in order to avoid or reduce the risk of possible damages or losses.

The focus of this section is on municipalities and on private persons, as those two actor groups are the ones with the presumably highest potential to reduce adverse consequences by protecting life, property and environment.

What can be done?

Find the basic steps and get further information:

Private persons can do a lot to protect themselves and their property from heavy rain flood damages. Houses and other buildings can be designed flood-resilient, existing houses with flood risk can be retrofitted in order to reduce future flood damages. Residents can develop a private alarm plan and ensure financial security, e.g. by taking out a flood insurance policy.

 

Step 1: Know your risks

Step 2: Prevent damages

Public municipal administrations are responsible for the development of the municipality. They are the key actors to collect available heavy rain risk information, to close information gaps, to steer flood safe housing and infrastructure development, to initiate community measures for flood protection, to initiate emergency management planning for heavy rain flooding, and to provide information to the population.

Step 1: Know your risks

Step 2: Prevent damages

Regional administrations are often responsible for providing information on higher-level issues such as e.g. floods. With regards to the rather local issue of heavy rain, some provide supporting material like informative brochures, technical guidelines and funding information to municipalities and private persons, therewith ensuring coordinated information, planning and risk reduction processes within their region.

Step 1: Know your risks

Step 2: Prevent damages

...as private person

Step 1: Know your risks

Check your location:

  • Is your property in a basin-shaped or sloped area with relevant portions of land lying above the future house or other buildings?
  • Is your planned building lying in a depth contour or adjacent to a sloped street?
  • Are there (dried up) watercourses nearby, and how do their water levels rise in or after heavy rain events?
  • Is there a relevant proportion of soil sealing or soils with reduced infiltration capacity in the neighbourhood and will the future development worsen the current situation?
  • Can water leak out of nearby sewage systems and flow to my property / future house?
  • Will my future house be connected to the sewage system?
  • Can heavy rain cause problems through overloaded roof drainage systems, yard drainage systems, or infiltration systems?

Each of these factors can contribute to heavy rain flooding.

Ask the previous land owners or current neighbours:

  • Have there been reports on previous flood events?
  • Are there frequently or longer lasting puddles, muddy areas or erosions after rain events on your property?

If so, heavy rain flooding might be an issue.

Plan the built structures: Generally, you are obliged not to worsen the flooding situation for your neighbours. Therefore, you should plan the built structures (main house, auxiliary buildings, pavements, fences and enclosures) on your property such that (i) heavy rain water can follow its natural discharge paths on the surface, from the upper flow entrances to your property to the lower flow outlets on your property, (ii) the water flow velocity on your property remains as before or better be decreased, (iii) the amount of rain water discharged to the lower flow outlets remains as before or is better being decreased e.g. by new infiltration measures.

Check web portals: EU member states have produced official flood hazard and risk maps, mainly for river flooding, but recently also for flooding from heavy rain. Other official maps might be obtained from federal portals for natural hazards or from water management adminstrations. This official information can be assessed as valid and reliable. Besides this, other products might be publicly available as well, maybe coming from academic institutions, cooperations, or technical offices. This information could be assessed as indicative. A collection of links to available web information is provided in the boxes below.

Ask your municipality: Nothing found online? Then ask your municipality: they might have general natural hazards maps, or specific heavy rain flood maps, or other plans addressing heavy rain flood issues like e.g. hazard zone plans. Otherwise they might know where such information can be obtained.

How to read and use flood maps: flood maps usually display one or more of the following information: hazard or risk areas, flow paths, flooded areas, water depths, flow velocities. If you can identify your property, then you can assess whether a heavy rain risk is assigned to it or not.

READ MORE

In Germany information is sometimes offered on national level, but also frequently offered on the federal state level, and sometimes even on the municipal level. Therefore the link list below contains a selection of examples which are – from the RAINMAN perspective – considered as current good-practice.
If you want to know your risk, you might find information on federal state level regarding flood forecast information, early warning, topographical information, guidance for assessing and mapping of heavy rain risks. The heavy rain hazard and risk maps are often available on the municipal level.

The tool ASSESSMENT and MAPPING provides further information on how to assess and display your hazard and risks.

Step 2: Prevent damages

Private persons can effectively protect themselves and their property from heavy rain flood damages. Houses and other buildings on the property can be built in places or designed such that

  • ideally no heavy rain water flows to the building,
  • ideally no heavy rain water can enter the building, or
  • flood-affected building parts are used in a way that entering water causes no damage.

Already existing houses with possible heavy rain flood risk can be retrofitted by technical measures in order to reduce or eliminate future damages, e.g.

  • flood barriers can be installed to prevent water from entering the building
  • the use of flood-affected building parts can be changed in a way that entering water will cause no damage in the future

Moreover, natural measures like new retention areas or soil infiltration measures can be established on the property in order to reduce the water flowing on the surface.

Finally, preparation measures can be established, e.g. residents can develop a private alarm plan and ensure financial security, e.g. by taking out a flood insurance policy.

Experts like insurance companies, architect, flood protection systems planners / traders, municipality advisory services might be available in your area to support you in assessing your risks and finding appropriate measures.

READ MORE

In Germany information is sometimes offered on national level, but also frequently offered on the federal state level, and sometimes even on the municipal level. Therefore the link list below contains a selection of examples which are – from the RAINMAN perspective – considered as current good-practice.
If you want to prevent damages, natural hazard information is often found on federal state levels, the same applies to general guidelines for private protection or municipal measures. In some cases, city websites also contain heavy rain information for prevention.

Riskreductiuonmeasures

The RAINMAN-Toolbox provides a comprehensive overview over possible measures: Browse through our CATALOGUE OF 100 RISK REDUCTION MEASURES

...as municipality

Step 1: Know your risks

Meteorological characteristics: Check with the hydrographical services of your region the precipitation characteristics of the area in question. If there is high annual precipitation, a high probability of heavy rain events, or experience with past floodings from heavy rain, then you might have an issue.

Location characteristics:

Ask yourself or an experienced local expert the following questions:

  • Is the area basin-shaped or sloped with relevant portions of land lying above the future development area?
  • Are there (dried up) watercourses nearby, and how do water levels rise in or after heavy rain events?
  • Is there a relevant proportion of soil sealing or soils with reduced infiltration capacity in the area and will the land development worsen the current situation in the area itself or in neighbouring areas?

Each of these factors can contribute to heavy rain flooding.

Ask the current land owners or current neighbours in the area:

  • Have there been reports on previous flood events?
  • Are there frequently or longer lasting puddles, muddy areas or erosions after rain events?

If so, heavy rain flooding might be an issue.

Get information: Ask your higher authority (e.g. regional administration) for spatial planning for regional spatial plans or regional development plans in which heavy rain risk is accounted for. Ask your higher authority (e.g. regional administration) for water management for available heavy rain hazard mapping information.

How to use the information: Local planning instruments should take the regionally available information into account, such that future infrastructures and buildings can be placed and designed resilient against heavy rain floods. If possible, official building regulations could additionally request future house owners to build in a flood resilient manner. Additionally, the local planning should be designed such that the already existing risks for existing infrastructures and buildings do not increase.

How to assess / quantify heavy rain hazards: Usually, water management experts can provide heavy rain hazard information, based upon computer simulation results. Results like flow paths or flooded areas, water depths, and flow velocities can provide the necessary information for municipality planning and protection measures. See also the RAINMAN mapping tool for further information to this subject.

Which external factors can change the risk? Generally, climate change effects will change the meteorological precipitation characteristics, but also changes in the location characteristics like earthworks (e.g. dams, underpasses), land use changes (e.g. from forest to farmland), soil sealing processes (e.g. new streets, new buildings), disadvantageous agricultural uses (crops, soil cultivation practices) can aggravate heavy rain risks. Anticipatory planning could account for future consequences from expected changes.

READ MORE

In Germany information is sometimes offered on national level, but also frequently offered on the federal state level, and sometimes even on the municipal level. Therefore the link list below contains a selection of examples which are – from the RAINMAN perspective – considered as current good-practice.
If you want to know your risk, you might find information on federal state level regarding flood forecast information, early warning, topographical information, guidance for assessing and mapping of heavy rain risks. The heavy rain hazard and risk maps are often available on the municipal level.

Let the RAINMAN experineces guide you…

Please find further information on the experiences and lessons-learned in heavy rain risk assessment and mapping in different pilot regions in tool ASSESSMENT AND MAPPING.

Different studies and guideline were developed within RAINMAN. E.g.

  • Instruction Manual on Sound Hydrodynamic Modelling of Heavy Rain Surface Flow for Technical Experts and Administrations and
  • Technical Report “Structural Effects in Hydrodynamic Surface Flow Modelling for Heavy Rain Risk Assessment Using Different Software”
    University of Innsbruck, Unit of Hydraulic Engineering; Environment Agency Austria, Surface Waters Team; Federal Office of Upper Austria, Flood Protection Group
  • Guideline on Model-based urban flood provision,
    Graz University of Technology, Institute of Urban Water Management and Landscape Water Engineering, Office of the Styrian Government, Department 14 Water Management, Resources and Sustainability 

You can find more in our Downloads page.

The tool ASSESSMENT and MAPPING provides further information on how to assess and display your hazard and risks.

Step 2: Prevent damages

Municipal administrations are responsible for the development of the municipality. They can steer a flood safe housing and infrastructure development, and initiate community measures for better flood protection.

  • Local land use planning measures can be used to e.g. keep hazardous areas free of building and infrastructure developments, or to adapt the land use such that heavy rain events cannot cause damages to valuable assets.
  • Legal measures like e.g. official requirements for new buildings can be used to enforce constructions which ensure that heavy rain events cannot cause damages.
  • Natural measures like e.g. creation of natural heavy rain retention areas or adaptation of agricultural practices can help to keep heavy rain water and eroded soils away from vulnerable buildings and infrastructures
  • Technical measures like e.g. flood barriers or elevated floors can help to make buildings or infrastructures resilient against heavy rain events, or to reduce possible damages
  • Other measures like e.g. awareness raising activities can help to make citizens aware of possible heavy rain risks, and can encourage them to take self-protection measures

By involving other experts and stakeholders like e.g. sewage system experts, emergency response teams, responsible persons for traffic or social issues, forest owners or farmers, future property owners, planners, a comprehensive coordination of future development can take place and an integrated concept for heavy rain mitigation measures can be achieved.

READ MORE

In Germany information is sometimes offered on national level, but also frequently offered on the federal state level, and sometimes even on the municipal level. Therefore the link list below contains a selection of examples which are – from the RAINMAN perspective – considered as current good-practice.
If you want to prevent damages, natural hazard information is often found on federal state levels, the same applies to general guidelines for private protection or municipal measures. In some cases, city websites also contain heavy rain information for prevention.

Get some insights on how other countries, which were not involved in RAINMAN, are approaching prevention of damages from heavy rain:

Belgium:

The Netherlands:

United Kingdom:

Let the RAINMAN experience guide you…

The Tool RISK REDUCTION MEASURES provides many approaches to reducing the risks of a heavy rain event. Hereby, different strategies for risk reduction should be combined while taking different fields of action into account. E.g.

Communication of risks and thereby raising awareness are also important precautionary components of an integrated heavy rain risk management.

Riskreductiuonmeasures

The RAINMAN-Toolbox provides a comprehensive overview over possible measures: Browse through our CATALOGUE OF 100 RISK REDUCTION MEASURES

...as regional administration

Step 1: Know your risks

Regional administrations are often responsible for providing regional information on higher-level issues such as e.g. floods. Heavy rain flooding is addressed in the EU Floods Directive, and in its actual second implementation cycle, the Member States are encouraged to include pluvial flooding into their risk assessment, mapping and plan of measures. As the considerations of this source of flooding has started around 2015, in 2019 only few national / regional approaches are available, and several methods for risk assessment and mapping can be found in different Member States. RAINMAN provides a collection of available administrative approaches, own experimental studies, and experiences and guidelines for numerical simulations of pluvial flooding.

READ MORE

In Germany information is sometimes offered on national level, but also frequently offered on the federal state level, and sometimes even on the municipal level. Therefore the link list below contains a selection of examples which are – from the RAINMAN perspective – considered as current good-practice.
If you want to know your risk, you might find information on federal state level regarding flood forecast information, early warning, topographical information, guidance for assessing and mapping of heavy rain risks. The heavy rain hazard and risk maps are often available on the municipal level.

Let the RAINMAN experineces guide you…

Please find further information on the experiences and lessons-learned in heavy rain risk assessment and mapping in different pilot regions in tool ASSESSMENT AND MAPPING.

Different studies and guideline were developed within RAINMAN. E.g.

  • Instruction Manual on Sound Hydrodynamic Modelling of Heavy Rain Surface Flow for Technical Experts and Administrations and
  • Technical Report “Structural Effects in Hydrodynamic Surface Flow Modelling for Heavy Rain Risk Assessment Using Different Software”
    University of Innsbruck, Unit of Hydraulic Engineering; Environment Agency Austria, Surface Waters Team; Federal Office of Upper Austria, Flood Protection Group
  • Guideline on Model-based urban flood provision,
    Graz University of Technology, Institute of Urban Water Management and Landscape Water Engineering, Office of the Styrian Government, Department 14 Water Management, Resources and Sustainability 

You can find more in our Downloads page.

The tool ASSESSMENT and MAPPING provides further information on how to assess and display your hazard and risks.

Step 2: Prevent damages

Compared to fluvial flooding, heavy rain flood risk is rather a local issue. However, considering climate change effects and the progressing land consumption and soil sealing, regional planning and risk mitigation measures for enhanced soil infiltration and distributed retention will gain increasing attention. Furthermore, integrative planning with several stakeholders will gain importance for the crosscutting subject of heavy rain.

READ MORE

In Germany information is sometimes offered on national level, but also frequently offered on the federal state level, and sometimes even on the municipal level. Therefore the link list below contains a selection of examples which are – from the RAINMAN perspective – considered as current good-practice.
If you want to prevent damages, natural hazard information is often found on federal state levels, the same applies to general guidelines for private protection or municipal measures. In some cases, city websites also contain heavy rain information for prevention.

Let the RAINMAN experience guide you…

The Tool RISK REDUCTION MEASURES provides many approaches to reducing the risks of a heavy rain event. Hereby, different strategies for risk reduction should be combined while taking different fields of action into account. E.g.

Communication of risks and thereby raising awareness are also important precautionary components of an integrated heavy rain risk management.

Riskreductiuonmeasures

The RAINMAN-Toolbox provides a comprehensive overview over possible measures: Browse through our CATALOGUE OF 100 RISK REDUCTION MEASURES

OUR STORIES

Heavy Rain Adapted House Design is nothing new: effective prevention by local architect in the late sixties - Example from Lower Austria

Look at the old houses in our hilly landscape in Lower Austria: the local architects in the past already knew how to plan heavy rain safe houses: barrier-free openings on those sides of the house where the terrain is descending; no low-lying openings on sides of the house where the terrain is ascending. The house on the pictures is about 50 years old and was planned by a local building master. This is simply best practice! (Dr. Yvonne Spira, Environmental Agency Austria)