GoKawiilFor centuries, the Netherlands were mainly dredged by hand, supplemented by animal power, wind power and tidal power. Could it be done again?
The dredging industry has been the backbone of the Dutch economy for centuries. If canals, harbours and rivers would not be maintained for a few years, the whole country would literally grind to a halt.
Today, dredging happens with oil powered ships, which burn up to 3,000 litres of fuel per hour. However, in earlier times, the Dutch waterways were dredged mostly by hand, using simple but ingenious tools.
Manual dredging was heavy labour, especially when waterways became deeper. Therefore, it was supplemented by animal power, wind power and tidal power. However, in some parts of the Netherlands, people chose a different strategy: they designed a new type of cargo ship that could sail in shallow waterways.
35 million m³ of mud
Siltation is a serious problem in the Netherlands, which lies in the delta area of various rivers that supply large amounts of silt and clay particles. At the same time, navigable waterways are essential to maintain transportation and trade — the country is home to the largest port in Europe, Rotterdam.
Each year, some 30 to 35 million m³ of mud are dredged out for the maintenance of the Dutch waterways. Approximately 75% comes from salty waters. In the port of Rotterdam alone, 20 million m³ of mud is collected each year.
The demand for dredging continues to increase. Both inland ships and seagoing vessels continue to get bigger, requiring ever deeper and wider waterways. A “modal shift” policy, in which cargo transport moves from the road to the water in order to improve sustainability and reduce congestion, also leads to more and larger ships, and thus to more dredging.
Although most of the mud is dumped into the sea, each year 3.5 to 5 million m³ of contaminated sediments must be landfilled. Then there is the dependency on fossil fuels. A typical suction hopper dredger has a pumping power of 2,500 kW and removes 100 m³ of sediments per minute. The largest dredgers have 30,000 kW engines and 6,000 kW of pumping power. At full power, these ships consume 3,000 litres of oil per hour.
Dredging a Country by Hand
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