Lime treated soil erodibility investigated by EFA erosion testing

Erosion is susceptible to reduce the overall stability of a structure under hydraulic and static loads, but also can lead to the development of a fast breach. In parallel, dikes and levees builders and designers have not so many ways to improve initial properties of materials available on site, for the construction or restoration of hydraulic embankments. In this context, soil treatment with lime is a relevant procedure that is reported to improve the mechanical properties and erosion behavior of silty and clayey soils. This study focuses on the changes induced by lime treatment on the erosion resistance of a silty soil, and the evolution of relevant erosion parameters with curing time. EFA (Erosion Function Apparatus) tests on a silty soil from Marche-les-Dames (Belgium) were performed on the native soil, and after 2.5 % lime addition at several curing times (1, 7 and 28 days). After 1 day curing time, a slight increase in the soil erosion resistance is recorded, whereas after seven days submitted to a water flow velocity above 3 m/s, the soil passes from a medium to a low erodibility level. After 28 days, the soil has a very low erodibility for the same water velocity

Restoration of intertidal habitats by the managed realignment of coastal defences, UK

Abstract In the United Kingdom, coastal defence has been the primary driver of intertidal habitat restoration. Rising sea levels, coupled with the high cost of maintaining coastal defences, have led coastal managers to look for more cost effective and sustainable methods of coastal protection. Managed realignment, the landward retreat of coastal defences and subsequent tidal inundation of formally reclaimed land, has since the early 1990's, been increasingly used to fulfil these requirements. Results from several managed realignment schemes have shown that with fairly minimal pretreatment and management, by allowing tidal ingress through a simple relatively small breach, the landward realignment of coastal defences will quickly produce intertidal mudflats on low-lying agricultural land which are colonised by invertebrates and, given the appropriate elevation, saltmarsh plants. What is unclear, however, is the time scale needed to produce intertidal habitats that are equivalent to reference conditions or if equivalency can indeed ever be reached. To date, most research effort has concentrated on monitoring the biological and physical development of realignment sites. This paper presents the results of a survey of saltmarshes that have developed on formally reclaimed land as a result an accidental breach in the embankment. These marshes are used as analogues for managed realignment and may give an indication of the future trajectories of current saltmarsh creation efforts

Supporting dune management by quantitative estimation of evapotranspiration

Abstract Research was conducted in the nature reserve De Westhoek (B) in order to estimate the hydrological impact of shrub removal in favour of the recolonisation and development of herbaceous vegetation types in the dune slacks. Dune slacks are one of the most rare ecotopes in Europe. Therefore, the evapotranspiration of herbaceous and shrub vegetation types was estimated based on experimentally obtained data and modelling. Analysis of the experimentally obtained stomatal resistance values revealed that there was no difference in the minimal stomatal resistance values (in absence of any stress) between herbs and shrubs. Stomatal resistance was modelled based as a function of climatic variables. Maximal rooting depth was similar in both vegetation types, and was maximal 60cm. For both vegetation types more than 60% of the roots were found in the upper 15cm. The mean leaf-area-index (LAI) of herbaceous and shrub vegetations is respectively 2.11±0.34 and 3.27±0.20 m 2 .m -2 . Evapotranspiration of both vegetation types was modelled with a multi-layer dynamic vegetation model FORUG and seasonal evapotranspiration amounted roughly 200 and 550mm for the herbaceous and shrub vegetation types respectively. Although these estimates can be somewhat refined, from these results it can be concluded that shrub removal, and the replacement of this vegetation type by a herbaceous vegetation type, will not result in a lowering of the groundwater table. This knowledge can help managing hydrologically disturbed dune ecosystems

The importance of seed bank knowledge for the restoration of coastal plant communities -a case study of salt marshes and dune slacks at the Belgian coast

Abstract Knowledge on seed bank density and species composition is crucial for predicting the probability that target species will establish in the plant community on a restored site. A general overview of data available for plant species occurring in coastal plant communities showed that information on seed persistence is up to now very limited. The available data suggest that restoration of coastal plant communities cannot rely on the seed bank, except for annual species of salt marshes, and that the seed bank is to a large extent composed of species of nutrient rich habitats. This was confirmed by two case studies in dune slacks and salt marshes on the Belgian coast. Seed density in dune slacks was found to be relatively high, but the seed bank contained almost exclusively seeds of species of nutrient rich habitats, resulting in a very low similarity ratio between seed bank and vegetation. Germination from the seed bank would rather hamper the establishment of target species because competitive pressure imposed by fast growing species of nutrient rich habitats would increase. In salt marshes, the similarity between seed bank and vegetation was higher, because there is a higher contribution of typical salt marsh species in the seed bank, although not all target species are equally represented. To allow predictions of future species composition on restored sites, seed bank studies should be an essential part of each coastal restoration project

Energy efficient plasma processing of industrial wastes

The paper presents the results of thermodynamic modeling of the process of joint plasma treatment of non-combustible and combustible industrial wastes. The compositions of water-salt-organic compositions based on these wastes and regimes providing their energy-efficient joint treatment in air plasma have been determined