Water management
Adapting to climate change requires a different approach to water management. This is due to the increase in heat and drought periods, when more water is needed for irrigation and cooling, as well as the higher risk of flooding due to heavy rainfall.
Heavy rainfall must be diverted and stored, and the stored water must be made available for irrigation and cooling. ‘Sponge city’ is the term used to discuss this concept, which is already being tested in several pilot projects in Switzerland.
WATER MANAGEMENT IN THE CITY
Some measures for improved water management are listed below:
Unsealing sealed surfaces (asphalt, concrete, paving stones): Rainwater can seep into the ground, relieving the pressure on the sewage system and reducing the risk of flooding. In addition, this replenishes the groundwater and allows the planting of more green spaces.
Green spaces: They store water and thereby help to protect against flooding.
Retention basins or underground detention systems (such as infiltration trenches): Retention basins store rainwater, which can be used to irrigate green infrastructure during dry periods. Infiltration trenches, on the other hand, collect rainwater, temporarily store it, and allow it to slowly infiltrate into the soil in a controlled manner.
Collecting channels or deflector walls: These enable a controlled runoff of rainwater where surfaces are sealed.
SPONGE CITY PILOT PROJECT IN ZURICH
The Turbinenplatz features unsealed, landscaped surfaces and a sunken infiltration basin to ensure that rainwater is retained and can seep into the ground during heavy rainfall. Light-coloured surfaces, a large stock of trees, fountains and water channels contribute to a comfortable microclimate. The project has improved the site’s attractiveness and promoted biodiversity. Photo: Ulrike Kastrup, focusTerra
RETHINKING AGRICULTURE
Traditional agriculture (intensive arable crops with irrigation) in a new combination with a decentralised water reservoir and livestock farming. Collage: ralphsonderegger.ch
WATER MANAGEMENT IN AGRICULTURE AND INDUSTRY
Current systems and uses of water also need to be adapted in agriculture. It is to be expected that dry periods in summer will lead to increased demand for irrigation. Seasonal water availability is changing as well, firstly due to the disappearance of glaciers, which previously held back water until spring, and secondly due to changes in precipitation (quantity, duration, timing and form). The consequences include periods of drought and floods.
Possible measures include the cultivation of drought- and heat-resistant crops or varieties, a more efficient use of water and the creation of infrastructure to store and supply water. It is equally important that water-saving technologies are developed and promoted in trade and industry.
WATER MANAGEMENT IN THE HOME AND GARDEN
There are also measures that we can implement at home to counteract increasing water scarcity. By the way, the average person in Switzerland consumes 120 litres of drinking water per day, but only drinks 1 litre.
The cutaway of a detached house presents labeled tips for household water management. Outdoors, a downpipe feeds a rain barrel used to water the garden; paths and beds are de‑paved to let water infiltrate and support biodiversity. Upstairs, the bathroom shows a shower (prefer over a bath) with advice to turn off water while soaping; low‑flow faucets and showerheads are highlighted; the toilet features a dual‑flush button. Downstairs, the kitchen note says to heat only as much water as needed; an efficient dishwasher should run on eco programs; in the utility room, efficient washing machines are recommended and hand‑washing minimized. Another callout suggests biodegradable soaps and reusing greywater for toilets and irrigation. The overall message: reduce consumption, reuse suitable water streams, and prevent leaks.
Exhibits
Water cycle on sealed and unsealed surfaces
Thanks to evaporation and infiltration, unsealed surfaces prevent rainwater runoff, which otherwise occurs even in small precipitation events and strains the capacity of sewage systems and bodies of water.
Surface runoff is responsible for approx. 50 % of flood damage in Switzerland water (FOEN, pers. comm.). 62 % of buildings are at risk from surface runoff. That amounts to around 1.3 million buildings with a replacement value of 2 300 billion CHF (die Mobiliar, 2023).
Graphics: FOEN (modif.)