Image: Dr. Oscar van Dam, RPS
In the dry hot summer of 2003 a peat dyke in the village of Wilnis near Amsterdam collapsed. Because of the resultant flooding, over 1,500 people were evacuated and there was an estimated economic damage of several million Euros.
The Water Boards in the Netherlands – responsible for the inspection and maintenance of dykes – needed to know why the collapse had occurred and how similar catastrophes could be prevented in the future. This resulted in the research programme ‘Professionalising Inspection of Dykes’.
RPS was one of the first consulting companies to assist the Water Boards in the uniform description – based on visual inspection – of damage to dykes. Over the years several GIS-based mobile-applications were developed and training programmes for inspectors were designed and introduced. The tools included a website with photographs of all possible types of damage to dykes (http://digigids.hetwaterschapshuis.nl/). These activities helped establish our strong reputation in this important sector.
Last year, the Netherlands national Foundation for Applied Water Research (Stowa) asked RPS, in collaboration with consultants Infram and BZ, to collate and summarize almost a decade of studies on the management and visual inspection of the country’s dykes. The resulting manual was recently distributed to over 250 dyke inspectors and dyke managers at the annual symposium on dyke inspection – which took place in Arnhem.
The first section of the manual describes what an inspector might encounter on several types of dykes, what threats might arise from various degrees of damage and which counter-measures can be deployed. The information hierarchy in the manual starts with the outer, protective surface of a dyke – whether this is – for example – stone, asphalt or grass. All possible damage – such as fissures, holes or small landslips – is subsequently described in detail. The manual is produced in a handy format with plastic coated paper to facilitate outdoor use in all weathers. The second section focuses on non-visual inspection techniques – such as highly sensitive movement sensors or infrared aerial photographs – that can help dyke managers evaluate the structural status of a dyke. The manual is part of a series, which also includes a manual for organising and managing the inspections of dykes.
Together with its partners, RPS has produced a state of the art reference document that is likely to be used by all dyke inspectors in the Netherlands.