Bart Schultz
This time I am deviating from this due to an article in de Volkskrant from Saturday, March 7, 2026, under the title Ditch by ditch, water is being wiped off the map. According to this article, thousands of ditches disappear in the Netherlands every year, partly because they are illegally filled in, primarily by farmers. To be honest, I was shocked by this article, because I had not expected that something like this could occur in the Netherlands, where good water management plays such an essential role. Therefore, this time, a contribution prompted by an actual topic.
For years, I gave lectures on Land and Water Development to international students at UNESCO-IHE in Delft. These students typically worked for organizations, such as the Water Authorities in the Netherland, or agencies like Rijkswaterstaat. During the first lecture, I always asked them:
"Why do we actually install irrigation or drainage systems?"
The question usually seemed to surprise them, and often there was no direct answer. When I explained to them that in rural areas it was primarily to improve crop growth, or in urban areas primarily to be able to live and work, it provided some clarification.
Especially in the low-lying parts of the Netherlands, our ancestors have made many efforts over the centuries to manage water as effectively as possible during wet and dry periods and to protect the people against flooding. This has resulted in landscapes where good management, operation and maintenance, as well as anticipating future developments, are of the utmost importance. An international saying therefore goes:
"God created the world and the Dutch created the Netherlands."
The water management systems in the low-lying part of the Netherlands are primarily based on water level management and the discharge of excess water. In addition, there are water supply facilities in various areas, which have become more important in recent decades due to the increase in dry periods.
When considering drainage in the polders of the Netherlands, of the parcels in the rural areas, the water flows via trenches, subsurface drainage, or directly into the parcel ditches. From the parcel ditches, it flows into the submain canals, and from the submain canals via main canals or directly to discharge sluices or pumping stations. The discharged or pumped-out water is typically collected in collecting and transport systems, through which it is transported to the sea, rivers, or the IJsselmeer. The ditches therefore form an essential link in the process of draining and discharge of excess precipitation.
In urban areas, excess rainwater from paved surfaces - buildings, streets, and squares - flows via a combined or separate sewer system into urban open water, and from there - either directly or via rural areas - out of the polder into the collecting and transport system. From unpaved surfaces - gardens, green strips, public gardens, and parks - the excess water flows via the subsurface or drains to urban open water.
As I described earlier in Development of urban areas in polders, until the 1970s, when urban areas were developed in polders, the land was typically raised to a certain level above the preferred water level in the adjacent collecting and transport system. Later on, raising the land to a certain level above the water level in the polder was generally deemed sufficient.
Ditches can serve various functions. Examples include parcel ditches for the direct discharge of parcels or for discharge of excess water from trenches or subsurface drains; road ditches for discharge of excess water from roads; and seepage ditches for discharging seepage water entering through dikes and for ensuring the stability of the dikes. Thus, in rural areas, parcel ditches are an important link in the system for maintaining the desired groundwater level within the parcels, as well as for discharge of excess water into the main watercourses in the polders. In urban areas, this role is fulfilled by urban open water.
In rural areas, the maintenance of ditches rests largely with the farmers and landowners, and partly with the Water Authorities and Road Authorities. For centuries, we have had inspections, during which the Water Authority would go around in autumn to check whether the ditches had been cleaned by those responsible. If this was not the case, the person concerned was ordered to do so within a short period. If it still was not done, the Water Authority would have it done, but the bill went to the person who should have done it. I have always assumed that this was still the case, so I was quite surprised that you can apparently fill in ditches with impunity.
Water management, and certainly the role that ditches play in it, is of essential importance to the Netherlands. Let us therefore hope that the centuries-old practice of management, operation and maintenance will be fully restored, because otherwise the problems of flooding will only increase. It is then not due to climate change, as is often said, but to our own inability to manage matters properly.
