The IJkdijk is a facility in the Netherlands to test dikes and to develop sensor network technologies for early warning systems. Furthermore, the sensor network will be able to detect many water-related environmental factors that affect the health of humans such as pollution and biological changes. Disasters on rivers and coastal waters are also detected. In studies of dike stability, about eighty dikes will be destroyed and establish, ultimately, a relation between the sensor readings and the future of the dike. Hence the (in Dutch) good-sounding name IJkdijk: dijk=dike and ijk is from the Dutch word ijken=to calibrate (models). Clearly the most urgent goal here is to forecast dike failures. In contrast to popular belief, most disasters with dikes occur because they are too wet and not because they are too low. Another major source of dike failures are streams of water flowing through the dike, ultimately destroying, through erosion, the dike from the inside. A detection system for these failure mechanisms might be cheaper and safer than the alternative: over-dimensioning by adding more clay. As dike improvements are very costly, e.g. 500 euros per meter, there is ample financial room to pay for the sensor system. The IJkdijk will also increase the geophysical understanding of dike behavior. A better understanding of dikes, expressed in a sensor-based early warning system in dikes, prevents unnecessary and costly over-dimensioning. That is good news for the owners of millions of kilometers of dikes that exist nowadays and the developers of millions of kilometers of dikes that will be constructed in the future.
Driving forces
Dike innovations are no luxury. With the expected climate changes, the land subsidence, the increased economic value of the low-lying areas as a result of economic prosperity, and the declining acceptance of calamities by the general public, many countries of world need to invest substantially in flood protection to keep the risk of flooding at an acceptable level. Especially developing countries seek new lands for housing and industry which are frequently found close(r) to rivers. Here building dikes is equivalent to economic growth. As investments in dikes are in the same order of magnitude as investments in economic development, developing countries will benefit most from smarter, cheaper and safer dikes. Developments in communication and sensor technology have advanced so far that it seems possible to utilize this new technology to effectively support the management and monitoring of flood protection works in an economically efficient manner. This seems to open up ways to offer cheaper and better alternatives for the traditional methods of embankment monitoring, maintenance and improvement. However, most of the recently developed sensor technology still needs to be tested under field circumstances, to prove its applicability and suitability. Recently, prototypes of dike conditioning systems have been constructed that aim at maintaining the dikes continuously in optimum shape. Inline with jargon from the sensor communities we call such systems actuators.
Design goals
In many cases, protection against flooding is not only determined by the height of the embankments, but merely by the strength of the embankments. Most of the weak spots in the embankments collapse because of a lack of strength with regard to stability or internal erosion rather than be flooded. The key to a better utilization of the existing embankments and thereby reduction of the flood risks is to find ways to determine the very processes which undermine the strength of embankments with a high degree of certainty. The system must ultimately be able to sense weaknesses in tens of thousands of kilometers of embankments. Determining failure processes of embankments is still a research field in development. It is clear that the strength of embankments depends on a large number of parameters which are hard to determine. Calculation methods for embankment strengths are available, but there seems to be a significant uncertainty, or gap, between the calculated strengths and the actual ones. Because of the huge investments involved and the increasing costs of maintenance and management for the regional water boards this is a very unsatisfactory situation. Systematic experiments are needed to calibrate the models. This enables the design of correctly sized embankments. Furthermore, a primary design goal are models, when fed by real time data from sensors in dikes, calculate the short and long time future of the embankment system. Most importantly they can report if immediate safety issues are at stake.
IJkdijk consortium The IJkdijk (‘Calibration dike’ (or embankment, levee)) is an initiative of the research institutes TNO ICT and Deltares, the Dutch national water board research foundation STOWA (Stichting Toegepast Onderzoek Waterschappen), regional development agencies NOM (Investerings- en Ontwikkelingsmaatschappij voor Noord-Nederland) and IDL. The plan emerged to build test embankments to enable the systematic testing of various types of new sensor, actuator and communication technologies, both during construction and the entire lifetime of an embankment. The embankments and the corresponding data infrastructure are set up in such a way that ensures that any future technologies can be tested. Furthermore, the IJkdijk is an open innovation environment where companies have been invited to join the experiments. About 50 companies are enlisted now.
IJkdijk results The IJkdijk enables to overstress embankments to failure using diverse and realistic methods in a controlled and reproducible manner. This will provide knowledge of:
sensor, actuator and communication technology for embankment monitoring; enhanced geophysical knowledge of failure mechanisms and computer models that forecast these failure mechanisms; the practical and economical feasibility of systems tested for use in large-scale applications; technologies for large scale sensor, actuator and communication technology that support GEOSS technologies; Thus, the IJkdijk project provides valuable insights and practical technologies for organizations dealing with water management, e.g. regional water boards and the national department of public works – everywhere in the world.
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