Potential sensitivity of fen plant species to salinity

Het is te verwachten dat laagveen plantensoorten verschillend kunnen reageren als gevolg van een blootstelling aan zout. In dit rapport worden verschillende typen informatie vergeleken, waaronder verspreidingsdata, indicatiegetallen en experimentele data. Een aantal soorten (13–18% van totaal aantal soorten, vooral wijdverspreide soorten) tolereren brakke condities, terwijl 41 andere (minder wijdverspreide) soorten mogelijk gevoelig zijn voor chlorideconcentraties boven 100 à 200 mg/L, maar er blijven onzekerheden. Verspreidingsdata geven een beperkt inzicht in de tolerantiegrenzen, maar gevoeligheid hangt niet altijd samen met verspreiding. Daarnaast kan de blootstelling in de wortelzone verschillen van het zoutgehalte in het oppervlaktewater. Experimentele gegevens zouden meer inzicht kunnen bieden, maar op dit moment is er weinig informatie beschikbaar van experimenteel onderzoek naar wilde plantensoorten

Praktijktoets Waterwijzer Landbouw in pilotgebieden de Raam en Vecht

In het kader van het kennisprogramma Lumbricus is voor twee gebieden op de zandgronden een praktijktoets uitgevoerd voor de Waterwijzer Landbouw. Geconcludeerd is dat het mogelijk is met de Waterwijzer Landbouw om uitgesplist droogte en natschade voor gras en mais te berekenen. De studie heeft laten zien dat Waterwijzer Landbouw – zeker na uitbreiding voor andere gewassen en de bedrijfsvoering – een goed instrument is en onmisbaar is bij het doorrekenen van klimaatscenario’s, het bepalen van effecten op gewasopbrengsten en voor het klimaatrobuust inrichten van gebieden. Zo kan straks met behulp van de Waterwijzer Landbouw ook de meest geschikte gewassen voor specieke gebieden bepaald worden

Balancing supply and demand of fresh water under increasing drought and salinisation in the Netherlands

The latest climate impact assessments show that climate change will cause an increasing mismatch between demand and supply of fresh water in many densely populated deltas around the world. Recent studies for the Netherlands show that the current water supply strategy is not climate proof in the long-run. Therefore, a future ‘climate proof’ fresh water supply is national priority on the Dutch water policy agend

Deltafact: hergebruik van effluent

Deze Deltafact gaat in op het hergebruiken van effluent als zoetwaterbron. Effluent kan onder andere ingezet worden als irrigatiewater en als proceswater voor de industrie

Effects of root mat buoyancy and heterogeneity on floating fen hydrology

Floating fen ecosystems are home to several protected habitats and species. Their development and conservation require specialattention regarding water management. Although they are known to be heterogeneous and partially buoyant, their root mats aresimulated in hydrological models as homogeneous, static systems. The objective of this study is to quantify root matheterogeneity and buoyancy and to assess their effects on groundwater flow and transport, and to determine if these factors needto be taken into account in modelling.We conducted field measurements of root mat heterogeneity and buoyancy in the ‘Nieuwkoopse Plassen’, the Netherlands. Wefound that hydraulic conductivity varied over four orders of magnitude and negatively correlated with degree of decomposition,resulting in a zonation of high conductivity near the surface and low conductivity in the deeper layers. Also, we found that theroot mat moved vertically with the surface water. It became more buoyant with higher temperatures, but less buoyant withincreasing groundwater levels relative to the surface.We implemented the findings in a semi-steady state hydrological model of a floating fen to compare the effects with otherparameters. The profound heterogeneity had a limited effect on the water budget, but a clear effect on the flow lines and thusshould be taken into account when modelling transport processes in floating fens. Although buoyancy affected the relativegroundwater level near the root mat edge, it did not affect the water budget or the flow lines and may therefore be neglected inwater budget modelling

Effects of salinity on growth of plant species from terrestrializing fens

Terrestrializing lowland fens may be temporarily exposed to elevated surface water salinity, which may have serious consequences for nature conservation. We investigated the response of five fresh water fen plant species to elevated salinity.In a controlled greenhouse experiment, these species were exposed to salt concentrations up to 3000mg C

Increasing Water System Robustness in the Netherlands : Potential of Cross-Sectoral Water Reuse

Water reuse has the potential to substantially reduce the demand on groundwater and surface water. This study presents a method to evaluate the potential of water reuse schemes in a regional context and demonstrates how water reuse propagates through the water system and potentially reduces pressure on groundwater resources. The use of Sankey diagram visualisation provides a valuable tool to explore and evaluate regional application of water reuse, its potential to reduce groundwater and surface water demand, and the possible synergies and trade-offs between sectors. The approach is demonstrated for the Dutch anthropogenic water system in the current situation and for a future scenario with increased water demand and reduced water availability due to climate change. Four types of water reuse are evaluated by theoretically upscaling local or regional water reuse schemes based on local reuse examples currently in operation in the Netherlands or Flanders: municipal and industrial wastewater effluent reuse for irrigation, effluent reuse for industrial applications, and reuse for groundwater replenishment. In all cases, water reuse has the potential to significantly reduce groundwater extraction volume, and thus to alleviate the pressure on the groundwater system. The water-quantity based analysis is placed in the context of water quality demands, health and safety aspects, technological requirements, regulations, public perception, and its net impact on the environment. This integrative context is essential for a successful implementation of water reuse in practice