Warmer summers, autumns sunnier and drier winters. Sounds like a dream? Rather a nightmare. The recent lack of snow and rain and warmer summers, with increased evaporation has led to a record Swedish groundwater which also affects the drinking water.
Gotland desalinated seawater
Geological survey, SGU, assess groundwater levels in the southeastern parts of the country as “extremely low”. The shortage is most acute in the major groundwater reservoirs, ie reservoirs in sand and eskers that the majority of municipalities taking their water from.
– The basis of the problem is poor groundwater recharge. It began during the hot summer of 2014 and has worsened due to the dry autumn and winter, says Ingrid Gudmundsson, information officer at the National knowledge center for climate adaptation at SMHI.
It’s worst on Öland and Gotland where there is no equivalent to a year’s rainfall. To solve the water supply began Mörbylånga on Öland in February to drive trucks with drinking water from the mainland. In addition, it has recently inaugurated a water supply from the mainland. Gotland has instead chosen to focus on desalination of seawater and is currently building a plant that will clean Baltic Sea water using reverse osmosis.
Precipitation and evaporation control
Groundwater formed mainly during the cold months because almost all the precipitation in summer is taken up by plants or evaporates. That is why the groundwater may be low even if the ground looks green and lush out. Thus, it is not a single substantial rainfall to replenish the groundwater reservoirs.
– To the reservoirs should be filled require a lot of rain over a long period and there are no indications that they would have time to be replenished during the summer, says Ingrid Gudmundsson.
on the contrary, a substantial summer rains and even exacerbate the situation. Because of the large volumes of lacking the capacity to take care of the water. To avoid problems with bacteria and parasites in groundwater revenue thus forced municipalities sometimes releasing untreated water in lakes and seas.
Looking forward 50-100 years in time it does not look much brighter. Global warming rather indicates increased evaporation, which means that today’s water shortage is just the beginning of what is to come. In southern Sweden, calculated groundwater recharge reduced by 20 percent by the turn of the century.
– According to climate models, we see that rainfall in Sweden will increase in the future, but it applies especially to the north and winter. Southeast Sweden, however, will experience increased drought problems in the future. Maybe we will not get as big a problem as in, for example, California, but the basic problem of climate change is.
People are using more water than what is supplied
Kenneth M Persson professor of water resources engineering at Lund University. He points out that the water table varies naturally from year to year and that the designation deficiency is linked to that we humans use more groundwater than is supplied.
– There will not automatically deficiency that the levels vary. If the terminals is greater than the supply for a long time, however, groundwater levels to drop permanently, something that has already happened around the Mediterranean and in big cities like Beijing and Mexico City, he said.
However, there are solutions for the seeking. These include methods to increase the amount of rainwater that reaches down into the groundwater.
– We can not influence how much it rains, but we can influence the amount of rain that reaches the reservoirs. To have less impervious surfaces in urban areas means that more rain can infiltrate, as well as ponds, delay reservoirs and wetlands which give it the opportunity and time to reach down to the ground.
Another technique is to desalinate water from the sea, something as is already done on the island. The technology, which is common in water-poor countries, has been accused of being expensive and resource intensive. Also released the residual product, a concentrated salt solution, usually directly into the sea where it can do great harm to flora and fauna if not managed properly.
Another option is to use treated wastewater for irrigation and infiltration.
– Swedish treatment plants do a fine job, but no one wants to deal with treated wastewater preferring to retrieve other waters if it is to be used for washing or cleaning. However, it is quite possible to disinfect the wastewater and use it for things that do not require the highest quality drinking water.
Like the location?
He mentions a variety of other methods, such as drip irrigation of crops, the use of brackish water to salt-tolerant plants and the use of recirculating water. In Malmö, for example, a company that developed a shower where 85 percent of the water is reused. Thus hand shower water to five showers instead of one.
– A final and boring method is like state, save and wait for the rain to replenish groundwater reservoirs.
Type: Izabella Rosengren, a freelance writer on behalf of forskning.se
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