Sea level rise and drought threaten Dutch farmers and drinking water supplies
As drought increases salt levels in the Netherlands' soil and surface water, rising sea levels are expected to intensify the problem in the coming decades, according to a report sent to the Dutch parliament by the minister of Infrastructure and Water Management. Farmers who use ditch water to irrigate their crops and drinking water companies are expected to face negative consequences, RTL reports.
According to projections in the report, sea levels in the Netherlands will rise by about half a meter by 2070. That increase will make it more difficult to quickly drain excess water from the IJsselmeer into the Wadden Sea because the existing sluices and pumps will not have enough capacity.
"With high discharge from the IJssel and heavy rainfall, the water level in the IJsselmeer will more often exceed the agreed level. That can lead to flooding in surrounding areas," the report states.
The report also expects problems with water discharge at the sea locks in IJmuiden and the Krammersluizen if the current pumps remain in use. That could cause flooding around the Amsterdam-Rhine Canal.
Sea levels in the Netherlands are currently rising by 2 to 3 millimeters a year. Most of that rise is attributed to melting ice caps and glaciers, as well as the expansion of warmer water, which takes up more volume than colder water.
At the same time, the Netherlands is becoming drier. Fresh surface water and groundwater levels in ditches, streams and rivers are falling. As freshwater levels decline, salt water can enter the soil through upward pressure and move farther inland through rivers when there is less fresh water near sluices.
The result is an excess of salt water and a shortage of fresh water, which is essential for drinking water production and agriculture.
The changing conditions are also putting pressure on the Delta Works, which were built after floods devastated Zeeland and parts of South Holland and North Brabant in 1953. The storm surge barriers, including the Maeslantkering and Oosterscheldekering, were not designed for rising sea levels.
The Oosterscheldekering currently closes when a water level of 3 meters above NAP is expected. That happens only a few times a year, during major storms. If sea levels rise by half a meter or more, the barrier will have to close and reopen much more frequently, increasing wear on its components.
"If the water level rises by half a meter or more, then that barrier will have to close much more often and open again. Due to that, components will wear out much faster," Deltacommissaris Co Verdaas, who is responsible for the National Delta Programme, which protects the Netherlands from flooding, told RTL.
"The barrier itself can last 200 years, but if the gates open and close more often, components will have to be replaced much earlier, and more major maintenance will be needed," Verdaas said. "But as the sea level rises, the period in which you can carry out that maintenance also becomes much shorter. Eventually, that will only be possible in the summer."
One option would be to raise the threshold at which the barrier closes, from 3 meters above NAP to, for example, 4 meters. That would require the dikes behind the barrier to be strengthened and raised to absorb the initial impact.
"And to build a stronger, more stable dike, you also need more space. That is particularly difficult in the Randstad. You will have to make choices," Verdaas said, describing the required investment as "many billions."
"How much money you spend to keep the Netherlands dry is up to The Hague. How much risk do you want to take? And do you accept that people might get wet feet once, or do you want to prevent that at all costs?" he said.
Verdaas said action is unavoidable. "We once settled in a swamp. We have arranged it so well so far that people sometimes forget where we live. With climate change, you cannot escape measures," he told RTL.
According to the report, rising sea levels will also increase salinization, a process in which salt levels in the soil and groundwater rise. Water boards will not be able to stop the process, even by deploying additional pumps.
Salinization is particularly challenging for drinking water companies, which will have more difficulty providing fresh water, and for farmers who use ditch water to irrigate their crops.
Verdaas described the issue as a matter of distribution rather than an inherent shortage of fresh water. The Netherlands has enough fresh water, he said, but does not yet manage it effectively enough.
"Our entire system is geared toward quickly draining water to the sea. If you retain precipitation better, you get a long way. But we do not always do that now, because it has disadvantages. It can cause wet cellars and the saturated land of growers is harder to work," Verdaas said.
Verdaas said farmers should consider ways to retain fresh water during the wet season. They may also need to choose crops that can tolerate salt water. In Groningen province, experiments are already underway with potato varieties that can grow in saline soil.
However, Verdaas emphasized that there is no universal solution.
"For a farmer who has a successor, it may be worth investing in a drainage system. But for a farmer who stops in 10 years, that is different," he said.
