Water irrigation needs radical change

Water irrigation needs radical change

Have you ever been thinking about water usage in cities? I personally have met some of the irrigation systems that are poorly maintained. Leakage in water distribution can be as much as 40%. Also there are many futilities in water distribution, like over-irrigation in football stadiums, golf courses or planting trees in cities.

Trees are, however, a central element of green city quarters and streets. They have a high ecological and aesthetic significance, especially for the quality of life in densely populated cities. Urban trees are also exposed to extreme conditions at their location. These are, for example, a high degree of sealing of the soil, high soil compaction, a climate in the city with higher temperatures influenced by the heat from surrounding buildings.

As a consequence of climate change, a tendency towards more and longer dry periods is expected. Urban trees in particular, in their already extreme locations, will therefore be increasingly stressed by changing climatic conditions in the future, making them more susceptible to pests. All in all, this increases the risk that the trees will be weakened in their vitality or even have to be felled and will therefore no longer be able to fulfil their important function in the city. Persistent drought must be directly countered in tree control and daily tree management. Even during relatively short dry periods, newly planted trees will be affected if they do not receive additional water and must be removed. Trees in the ripening or aging phase will survive short-term drought longer, but must also be watered. The city of Bonn, for example, has planted 350 new trees due to the dry summers of 2018 and 2019 at a cost of between 2500 and 4200 euros per tree (site restoration, two years of care and four years of irrigation).

Knowledge of each individual tree location is the basis for an optimal irrigation scheme. However, it is not practical to actually monitor each tree individually. If the data of the existing tree sites are available, different model sites can be defined, which behave in the same or a similar way as the whole set of trees in a city. If these model sites are equipped with appropriate sensor technology that reflects the actual demand, it is possible to draw conclusions about the comparable sites. The irrigation is then based on these same model locations.