Drought and water distribution
Water availability during drought
Prolonged droughts and heat waves are becoming increasingly common. When there is no rain and the water evaporates, we have less and less water in our ditches. We can then draw water from the IJsselmeer and Markermeer lakes. But if there is no rain in the rest of Europe either and the IJsselmeer is no longer being sufficiently replenished with water via the Rhine and the IJssel, we will have to distribute the available surface water.
Distribution of available water
The available water will then first be allocated to matters of great importance, such as maintaining our dikes, supplying drinking water, and power plants. Other matters, such as crop irrigation, shipping, and recreation, will be given lower priority. Below you can see which facilities and activities belong to which category. Category 1 has the highest priority and category 4 the lowest.
Determined nationally, implemented regionally
We refer to this (national) prioritization as the displacement series. It indicates which issues take precedence over others in water distribution. Categories 3 and 4 have subsequently been elaborated regionally by the provinces and water boards in the Water Distribution Strategy.
The HHNK Water Distribution Strategy was adopted by our general board on February 28, 2024.
Web viewer for water level monitoring during drought
The animation below shows how water is distributed when less water is available/comes in.
Even during dry periods, we try to provide farmers with as much water as possible for as long as possible. We first take measures that lead to water savings, such as limiting lock movements and closing fish passages. However, if the drought persists, it may be necessary to prohibit the extraction of surface water for irrigation. This particularly affects the agricultural sector.
When setting withdrawal bans, the focus is on minimizing social and economic damage. This means that low-yield agricultural crops will be the first to be affected by withdrawal bans. Crops that have a higher yield per hectare, known as 'capital-intensive crops', can in principle be supplied with water for longer. To determine the order in which crops are subject to withdrawal bans, we use the NSO classification from Wageningen University & Research (WUR) as an objective source for crop yield per hectare.
The use of surface water for irrigation will be phased out in three steps in the event of increasing scarcity:
- Low yield, income per hectare less than €2,000;
- Average yield, revenue per hectare between €2,000 and €10,000 per hectare;
- High-yield, or capital-intensive, crops, yielding more than €10,000 per hectare.
Withdrawal prohibitions
On Texel, a ban on water extraction applies throughout the year. This is due to the vulnerability of the area and because no water supply is possible here.
There are also areas where, due to the brown rot bacterium, you are not allowed to use surface water for growing starch and consumption potatoes and tomatoes. This is important for vegetable gardens where tomatoes and potatoes are grown. Based on research, the Netherlands Food and Consumer Product Safety Authority (NVWA) determines the areas where these extraction bans are in force on an annual basis. These areas can be found on theNVWA website.
Tightening of agreements on water distribution
Following the dry summer of 2018, Rijkswaterstaat, all provinces, and the water boards around the IJsselmeer region, in consultation with key users of fresh water, such as agriculture and industry, have made new agreements on water distribution. The old distribution system was no longer adequate. The most important changes are:
- Stop maintaining the water level in less vulnerable areas earlier;
- Stop flushing earlier to prevent salt intrusion;
- Stop water consumption by agriculture and greenhouse horticulture sooner;
- Stop using urban water sooner.
Exception for capital-intensive crops
For certain capital-intensive crops, a limited amount of water is available for as long as possible. Because water supply is lower than demand during this phase, an Advisory Committee on Agriculture has established a ranking system for water distribution based on yield per hectare.
During the dry season, HHNK may also adjust this ranking if necessary, on the advice of the Agricultural Advisory Committee. The criterion is that large-scale socio-economic damage can be prevented with minimal and temporary irrigation. This advisory committee consists of representatives from LTO Noord, KAVB, NFO Kring Noord, NAJK, NAV, Glastuinbouw NL Noord-Holland NL , ANV Water, Land en Dijken, and NMV Noord-Holland.
Level maintenance
It may happen that capital-intensive crops are watered while at the same time the water level in the area concerned is no longer maintained. In that case, no water may be extracted from the water system around the plot. In this case, water users may extract water from areas where the water level is still being maintained, with the exception of dike ditches, high water zones, or urban areas. This may involve traveling distances. It is then particularly important to be alert to water quality. This is because there is no longer any flushing to prevent salinization. There is insufficient water available for this. If this becomes an issue, you will find a map on the above web viewer showing where you can extract water.
Although the scope for action is limited, this approach makes the best possible use of the water available at that moment. In practice, this will mean that small amounts of water will be available for certain crops for a few days, thereby reducing or, in the ideal case, preventing as much economic and social damage as possible.
Measures concerning water distribution
The displacement series comes into effect when there is an imminent water shortage. From that moment on, as precipitation deficits increase, measures are taken in sequence to distribute the available water fairly. The total measures and their sequence are shown in the table below.
