Klimaatrobuust waterbeheer Friese zandgronden : Resultaten modelberekeningen en praktijkproeven watervasthoudende maatregelen

Samenvatting

The Dutch climate is changing; winters are becoming wetter and summers are becoming drier. How can water management at regional level respond to the increasing drought in the growing season? Model calculations were used to study the effect of water retention measures at regional level on agriculture and nature in the eastern sandy area of Friesland. In addition, the effectiveness of water retention measures was evaluated in field experiments on seven dairy farms. Model results showed that in the current climate, the increase in wet damage was larger than the decrease in drought damage following regional water retention measures, resulting in a slight net increase in total damage. For the future Dutch climate (Gh-2050), both wet and drought damage increased compared to the current reference situation, with drought damage increasing relatively more than wet damage. In contrast to measures on a regional scale, water measures taken on farm scale in field experiments reduced drought damage to a larger extent than the increase in wet damage. Farm-scale measures therefore appear to be more effective than regional measures. Results also showed that the more farmers implement water retention measures, the better they will succeed in structurally raising the low groundwater level in the summer. It is expected that a large-scale approach to water conservation will pay off, if its implementation is locally tailored. The low-lying peat and bog parts (watershed areas) are the limiting factor for water retention due to the extra wetting occurring in this areas. For these soils it is important to combine different tasks: water storage, stream restoration, nature development, water storage and lower greenhouse gas emissions by reducing peat oxidation. Robust and future-oriented water management requires choices regarding the low parts of the sandy area.