Sand instead of stone to combat coastal erosion

For the first time, a Swedish municipality has placed large amounts of sand on its beaches as a way of combating coastal erosion. This would probably never have happened if it wasn’t for Hans Hanson, Professor of Water Resources Engineering at LTH, who has been “nagging the municipal leaders and the Government for the past 25 years”.

Hans Hansson

Hans Hanson by the pier that Ystad municipality has named after him.

Since the summer, Ystad Sandskog has contained 80 000 cubic metres of fine, white sand. The method is still controversial in Sweden. According to Hans Hanson, the problem is that our gut reaction sets us thinking along the wrong lines.

“When the sea hollows out the shoreline, homeowners and municipalities dump stones on the beach to save their own section of coast. The coast stays, but the sand disappears, and instead, their neighbours suffer more severe erosion”, he explains, giving the example of the Öresund coast:
“Just look at Landskrona or Höganäs, or along Löderups Strandbad on the south coast of Skåne. Sandy beaches have disappeared along long stretches of coast because people have put out boulders.”

If enough sand is dumped to keep in line with rising sea levels, the dunes behind also grow thanks to the wind. This reduces the risk of erosion and floods.

The sand deposition procedure will be repeated in Ystad once every three years. SEK 10 million has been earmarked for each of the further two replenishments until 2020. That is when the current permit from the Environmental Court runs out. The sand is collected from the sea off Sandhammaren at a depth of 15 metres.

Ystad local government commissioner Kristina Bendz thinks it is a good investment.

“Our sandy beaches are estimated to generate SEK 50 million a year. This includes everything from ice cream sales to accommodation at the beach hotel.”

The method is more common in other countries, especially in tourist areas.

Way back in 1984, Hans Hanson developed calculation models for the US Army. This led to sand being deposited on Miami Beach in Florida every year from the late 1980s. Every dollar invested is estimated to pay back 1 800 times the amount.

However, money in the municipality’s tourism coffers is not the most important motive for the sand dumping, stresses Hans Hanson. In Ystad, erosion is primarily a natural phenomenon resulting from shifts in wind direction, but global warming is causing sea levels to rise more rapidly and erosion is becoming more common.

“Globally, sea levels are now rising by over 4mm a year. This is double the rate of the 1950s. For every centimetre, the sea recedes by a metre”, says Hans Hanson.

It is necessary to find a range of measures that don’t just cost money, but that can produce economic benefits such as tourism or protection of property, such as on the southern edge of the flat Falsterbonäset peninsula, where there are plans to deposit sand.

This summer, Ystad municipality recognised Hans Hanson’s many years of work for the municipality’s beaches by naming one of the piers in Ystad Sandskog the “Professor Hans Hanson Pier”

“I’m extremely proud. It’s not every day you get a pier named after you”, says Hans Hanson with a smile.

Text: Kristina Lindgärde

Photo: Käthe Hanson