Hamburg‘s Online, Real-time Heavy Rain Map
Hamburg has created an online, real-time heavy rain map that provides residents with information on rainfall in an intuitive and transparent manner.
Extremes of weather describe the range of possible weather and climate conditions that a location can expect to encounter. These events can be expressed in a variety of ways including the probability of occurrence of rare events such as heavy rainstorms.
Rainfall can have three separate extreme values: duration of rainfall, the intensity of rainfall, and the accumulation of rainfall. Extreme rainfall can happen under a few different weather conditions, for example, extreme rainfall can occur while hurricanes and tropical storms are making landfall or moving slowly over land. When rain falls continuously over the same area for a long period of time, significant floods can result.
However, all of this information is difficult to communicate to the general public.
Hamburg’s online heavy rain map
Hamburg has created an online heavy rain map that provides residents with information on rainfall in an intuitive and transparent manner. The tool lets users see how much precipitation has actually occurred, making it easier for people to classify and compare rainfall. The heavy rain is divided into 12 levels – from moderate to extreme. The color representation in the index ranges from green to yellow, orange to red and to violet. Very rarely is the threshold for heavy rain reached with 90% of all rain in Germany not considered to be heavy.
The online tool shows in real-time whether, where, and to what extent it is raining in Hamburg and the metropolitan region. For this purpose, radar data from the German Weather Service and rain data from Hamburg Wasser’s own measuring points are combined. The information is assigned to fields with a size of 500×500 meters on a map of the metropolitan region, totalling around 24,000 fields. This gives a very precise picture of the current rainfall on a particular site. The online map is updated every 5 minutes and users can set the time period up to a maximum of 3 days back. The fields are coloured according to the amount of rain: light rain in shades of blue and heavy rain from green to violet. When zooming in, rain levels and heavy rain indices are also displayed as a value.
Hamburg becoming a sponge city
This information enables Hamburg residents to become sensitive to the effects of climate change and encourages property owners to become aware of green infrastructure solutions to heavy rainfall events, such as permeable car parks. The city itself is also preparing to become a ‘sponge city’ with the aim of relieving the sewage system by temporarily storing the rainwater and then slowly releasing it again by unsealing areas, creating more green roofs or turning parks, squares or streets into temporary water storage areas.
Conclusion
Online, real-time maps can inform the public of climatic extremes and raise awareness of adaptation solutions.