Suggestions for solutions to desiccation in the Netherlands
All things considered, desiccation is a relatively simple problem in technical terms. The causes are known: there is a structural shortage of water of the right composition at the right time in the right place. And we know what has to be done to solve the problem. In many cases, what it amounts to is that we need to reverse the consequences of things done in the past. Generally, that means retaining precipitation for longer by allowing higher surface water levels, by slowing down withdrawal from an area or by reducing groundwater extraction so that upward seepage increases again.In areas with a predominantly peaty soil, that is not so simple. More intensive draining means that some of the organic material has been oxidised and lost. As a result, the original situation cannot be restored.
Technical measures
The technical measures that contribute to the recovery of the hydrological situation include:
- filling in and/or making ditches shallower so that withdrawal from an area is cut back;
- introducing small dams, pushing up surface water levels and retaining water from the area for longer;
- allowing brooks to meander again, slowing down withdrawal;
- converting dark coniferous forest into deciduous forest, cutting back considerably on evaporation in the winter and increasing groundwater replenishment;
- disconnecting the guttering of houses from the sewers to that more precipitation infiltrates into the soil;
- building housing without crawl space so that less stringent requirements are needed with respect to the drainage head when preparing the ground for construction;
- cutting down on groundwater extraction and/or moving it to less vulnerable sites or deeper aquiferous layers;
- digging away the surface soil so that seepage water can reach roots again.
Difficulties for agriculture
In addition to the positive impact on nature, there can also be rewetting damage to agriculture. The wetter conditions and the resulting fall in the soil temperature in the spring mean that the growth of agricultural crops is slower to get going. The earth is also weaker so that work with heavy equipment becomes more problematic.
In principle, then, measures should be implemented in such a way as to avoid rewetting damage. In some cases, win-win situations are a possibility, for example by making improvements in the water supply for agriculture. Where this is unsuccessful or impossible, financial compensation may be given for rewetting damage. However, experience has shown that hardly any use is made of the possibility of compensation for rewetting damage (DLG, 2001).
Choosing between nature and agriculture
If no feasible compromise is possible between nature and agriculture, a spatial-planning decision will be required. The functions must be segregated rather than intertwined.
- Or the requirements for the quality of the natural area will have to be relaxed in favour of agriculture. In the most extreme cases, the area in question will lose its nature function (with compensation elsewhere).
- Alternatively, the farm will have to be moved elsewhere.
