Real-time monitoring of civil infrastructure provides valuable information to assess the health and condition of the associated systems. This paper presents the recently developed shape acceleration array (SAA) and local system identification (SI) technique, which constitute a major step toward long-term effective health monitoring and analysis of soil and soil-structure systems. The SAA is based on triaxial micro-electro-mechanical system (MEMS) sensors to measure in situ deformation (angles relative to gravity) and dynamic accelerations up to a depth of one hundred meters. This paper provides an assessment of this array's performance for geotechnical instrumentation applications by reviewing the recorded field data from a bridge replacement site and a full-scale levee test facility. The SI technique capitalizes on the abundance of static and dynamic measurements from the SAA. The geotechnical properties and constitutive response of soil contained within a locally instrumented zone are analyzed and identified independently of adjacent soil strata.

Internal erosion is the cause of significant damage in dams and river embankments in many countries. In the last 20 years, the use of fiber-optic distributed temperature sensing (DTS) has proved to be an effective tool for the detection and quantification of leakages and internal erosion in dams. This work investigates the effectiveness of DTS for levee monitoring and focuses on the early detection of backward erosion piping. The latter is a failure mechanism that affects the foundation layer of structures resting on sandy soils. The paper presents data from a piping test performed on a large-scale experimental levee equipped with a DTS system together with a large number of accompanying sensors. With the help of numerical modeling, the effect of seepage and backward erosion piping on the pore pressure and temperature field is analyzed, eventually bringing the identification of the processes that promote the onset of thermal anomalies.

Backward erosion piping poses a severe threat for embankments founded on sandy deposits. The physical mechanism by which a pipe progresses upstream beneath the embankment is conceptually understood, and assessments indicate high failure probabilities in the Netherlands. Rising sea levels and economic growth increase the risk of flooding, and the need for remediation measures. Conventional measures have undesired side effects, in terms of costs, maintenance, space requirements and sustainability. The coarse sand barrier (CSB) is a novel nature-based solution lacking these side effects. The CSB is a trench filled with coarse sand that is placed below the downstream toe of the embankment, which prevents the pipe from progressing upstream. The effectiveness of the CSB is based on its higher resistance against erosion and its effect on groundwater flow. This paper presents experimental work that was conducted to test the feasibility of a CSB for application at a pilot site in the Netherlands. This involved experiments with seepage lengths of 0·34, 1·34 and 15 m, using different barrier materials and background sands. A conceptual model is presented for the physical mechanism of pipe formation in the presence of a barrier. As the resistance of the barrier can be characterised by a local scale-independent strength criterion, laboratory results are applicable for design practice.

In regions with a temperate climate, a well-maintained grass sod on a clay layer is considered a reliable protection for dams and dikes. In the Living Lab Hedwige-Prosperpolder, on the left bank of the Scheldt river straddling the border between Belgium and the Netherlands, a series of 27 overflow tests with a purpose-built overflow generator has been executed to determine the strength of the protective layer against erosion at various conditions. The goal of this paper is to inform on the executed test program and the initial results. From the results, it was concluded that in general, a high-quality grass cover on the landside dike slope can withstand high overflow discharges well for 12 to 30 h, without severe erosion damage. Anomalies, such as the presence of animal burrows, reed vegetation, and already present deformations can strongly reduce the resistance of the cover layer and may lead to failure within a couple of hours.

During the July 2021 Flood, the main flood defences along the River Meuse in the Netherlands performed well and did not breach. This paper provides an overview and description of the reported incidents related to flood defences, including a few breaches in minor flood defences. The incidents include overflow of embankments, sand boils, internal erosion at structures, and damage to a large weir and an outflow structure. Also, two local flood defences breached: an emergency embankment at Horn and an embankment in Roermond. During the event, the media reported on a dike breach at Meerssen/Bunde, however, after further investigation, it appeared that the concentrated outflow there was fuelled from a forgotten buried culvert.

Coastal flood managers seek to anticipate future flood risk and as a result consider the adaptation of flood defences. Instead of crest heightening, dikes can be adapted to include hydrodynamic reducing vegetated foreshores to form a nature‐based hybrid flood defence, for instance; at managed realignments. In this study we investigated the potential of vegetated revetments as a natural continuous connection between the realigned dike and restored foreshore. We applied the historic grass sod transplantation technique with the aim to improve our understanding of the strength of a transplanted sod revetment. In Living Lab Hedwige‐Prosperpolder, dikes were available for in‐situ experiments during managed realignment preparations. We transplanted grass sods and studied erosion resistance after one growth season. Our results show transplanted sod vegetation continued to grow and started to attach to the clay layer. While erosion occurred under extreme wave impact and overflow, the sod pulling method revealed individual sod strength. In conclusion, sod transplantation is a good technique to source local material for green realigned dike revetments. A vegetated dike revetment can hereby create a natural continuous connection between the realigned dike and foreshore, which benefits flood protection as well as flora and fauna.