Strength of grass covers on dikes

Wave overtopping, in which a wave washes over the crest of a dike and damages its inner slope, is one of the many mechanisms that is found to be responsible for dike failures. As these dikes are generally covered with grass, insight into the erosion resistance of these grass covers against wave overtopping is desired. To assess the performance...

Prediction method for grass erosion on levees by wave overtopping: Linking models to experiments

Large areas of the world are protected by flood defence systems. A common part of flood defence systems is a levee with grass cover, with the primary function to protect hinterland against floods. Waveovertopping might lead to erosion of the grass cover, followed by erosion of the inner slope and potentially levee breaching. The wave overtopping...

Designing with elephant grass based bioplastic

The company Vibers makes bioplastic from elephant grass, which has a positive effect on the environment. The crop grows perfectly on the Dutch soils, so the material is locally attuned. There are low fertilizer and pesticide requirements, which makes the crop relatively environmentally friendly (Lewandowski, Clifton-Brown, Scurlock & Huisman...

Strength of grass covers on dikes

Wave overtopping is responsible for many dike failures, dike breaches and severe flooding. The erosion resistance of dikes to overtopping waves is determined by the strength of the grass cover. Therefore, a thorough understanding of the erosion resistance of grass covers is desired to enable a good and effective dike management. In the existing...

Assessment on the effect of flood defences asset management maturity to cost and performance

Maturity model has proven to be helpful for an organization to identify its current capability, strength, and weaknesses through maturity levels. These levels are used to rank the various dimension or process of an organization. However, maturity levels only describe a general description of organization capability. The effect of different...

Translating Management Maturity Levels to Flood Defences Asset Cost and Performance: Using Dynamic Bayesian Networks

Maturity model is widely known as an assessment tool to understand an organization management capabilities and identifying potential improvement. The model demonstrates informative results towards the organization management maturity but hard to acknowledge the influence of potential improvement towards the organization’s asset performance....

Grass revetment reinforcements: A study into the effectiveness of measures applied during critical conditions.

Reinforcement measures are applied by water boards during critical conditions in an ultimate attempt to prevent flooding. However, the effect of these measures on the reduction in flood risk or failure probability of the flood defence is often unknown. This research focusses on the effectiveness of grass revetment reinforcement measures applied...

Strength of the grass sod on dikes during wave overtopping

There is a shift in the approach for designing coastal structures. In the past, dikes were designed on the probability of exceedance of an incoming wave during storm conditions. In the near future, the design criteria will be the probability of flooding of the hinterland. In order to determine this flooding probability, the strength of the dike...

Clean grass: Development of a pretreatment machine for grass pressing

In this project a grass refinery process line is designed for producing grass fibers and juice that are suitable for cardboard, fuel pellets and animal feed production. A washing machine is designed for an essential processing step, cleaning the grass.

The development of a grass collection system for the Skil Urban Trimmer

This master thesis covers the development of a grass collection system and grass catcher for Skil Urban Trimmer. The number of people that live in an urban environment is rapidly increasing. A result of this urbanization is the growing demand for products that are specialized for urban needs. This demand has driven Skil to launch the urban...

Vulnerability of structural transitions in flood defences: Erosion of grass covers due to wave overtopping

Hardly any flood defence system is a continuous dike system, since it is often interrupted by non-water retaining structures, as for example stairs, buildings, roads, fences and trees. Also larger hydraulic structures as floodgates and sluices are sometimes situated in the dike alignment. The transition between these different objects and the...

Wave impact on grass covered outer slopes

Against the background of enhanced hydraulic loads due to climate change there will be a need for improvement of the flood defence system in the Netherlands in the future. These days there is a growing interest in grass as a dike cover because it is a cheap and a sustainable dike protection. Yet at the moment there is a hiatus in the knowledge...

Wave overtopping: Impact of water jets on grassed inner slope transitions

The safety of a large part of the Netherlands depends on sea dikes. Due to climate change, a sea level rise is predicted. Together with stronger storms and more wave attack, wave overtopping on the current dikes will increase. As a response, crest levels of the dikes need to be raised in order to meet the present regulations for wave overtopping...

Reinforced grass on inner dike slopes

This thesis shows a set of equations that define the micro-stability and macro-stability of reinforced grass revetments with geosynthetics on inner dike slope during an overtopping event. At micro-stability level, it has been analyzed that the equilibrium in a soil particle using the criterion of incipient motion of soil particle. The forces in...

Erosion processes on dike slopes

Erosion processes are divided in two parts, whereas first process is detachment process and second process is transport of detached soil. The main function of grass cover is to avoid detachment. Therefore certain strength is necessary to execute this assignment. Resistance of grass covers are affected by several parameters. The influencing...

Coastal erosion project, Diani beach, Kenya

Master project report. Since the seventies, the establishment of hotels and other facilities has increased the pressure on the Kenyan coast. During the last decade, hotel managers and residents in Diani Beach have been experiencing problems with erosion. The only measures taken to address the problem are individually built seawalls to protect...