Understanding levee failures can be significantly improved by analysing historical failures, experiments and performance observations. Individual efforts have been undertaken to document flood defence failures but no systematically gathered large scale, open access dataset is currently available for thorough scientific research. Here, we introduce an efficiently structured, global database, called International Levee Performance Database (ILPD), which aims to become a valuable knowledge platform in the field of levee safety. It comprises information on levee characteristics, failure mechanisms, geotechnical investigations and breach processes for more than 1500 cases (October 2019). We provide a macro-scale analysis of the available data, aiming to provide insights on levee behaviour based on historical records. We outline common failure mechanisms of which external erosion is identified as the most frequent for levees. As an example, we investigate flood events occurred in Germany (2002, 2013) and examine breach characteristics of hundreds of failures. It is found that initial failure mechanisms have an influence on breach characteristics and that failures due to instability and internal erosion are less frequent but lead to larger breaches. Moreover, a relation between the return period and the expected breach density during a flood event is identified. These insights could complement flood risk assessments.

Levees are critical systems in safeguarding an area against catastrophic flooding events with potential fatalities and economic losses. Current monitoring methods of levees highly rely on expert judgement, resulting in infrequent and subjective assessments of their status. Satellite radar imaging, in particular using interferometry (InSAR), holds a large potential to monitor the condition of levees with millimetre‐level precision, anywhere on the planet. However, for levee management, the usability of the technique requires significant radar expert knowledge. Here, we provide a comprehensive overview of the state of the art in using time‐series InSAR for systematic levee deformation monitoring. We explore its use to complement existing approaches for assessing levee deformation and failure investigations in a fast, systematic, and cost‐effective way. The applicability of imaging radar satellites is discussed, supported by case studies on levee monitoring in the Netherlands. We elaborate on the technical aspects with respect to levee monitoring using SAR technology, such as estimating deformation in different directions, satellite characteristics, precision, and reliability. We conclude that InSAR is becoming an operational deformation monitoring system, which allows for the detection, tracking, and analysis of irregularities on levee sections with increased efficiency and quality, thus contributing to improved risk management.

Levees are critical in providing protection against catastrophic flood events, and thus require continuous monitoring. Current levee inspection methods rely on limited information obtained by visual inspection, resulting in infrequent, localized, mostly qualitative and subjective assessments. This hampers the timely detection of problematic locations and the assessment of levee safety in general. Satellite radar interferometry yields weekly observations of levee conditions with high precision which complement current inspection methods. Here we show that levees are susceptible to short-term swelling and shrinkage associated with meteorological conditions, and assess how deformations can be related to the geohydrological properties and the safety of the levee. Our findings allow to understand the sub-seasonal behaviour of the levee in greater detail and to predict swelling and shrinkage due to variation of the loading conditions. This will improve the detection of anomalous levee responses which contributes to the development of reliable early warning methods using continuous deformation monitoring.

It is undisputed that in view of climate change, the thousands of kilometers of dikes in the Netherlands are one of the country’s most critical flood protection infrastructures. The Dutch coastal and river dikes are designed to withstand rising sea levels, storm surges, as well as extreme peak river discharges. In addition to these hydraulic loads, however, dikes are also affected by land subsidence processes that cause local to regional reductions in crest elevation, potentially compromising flood safety. This study aims to develop a spatial model that red-flags dike sections susceptible to subsidence, thereby supporting national and regional authorities in prioritizing monitoring programs and reinforcement strategies. A detailed 3D geological understanding of the natural subsurface underneath the dikes is conducted, as soil type governs spatial patterns of subsidence. To explain spatial variability in subsidence rates, observed surface deformations derived from Interferometric Synthetic Aperture Radar (InSAR) are integrated with a 3D geological subsurface model and Cone Penetration Test data. Results demonstrate a clear correlation between the presence of shallow peat and clay beds underneath dikes and increased subsidence rates, whilst sandy subsurface corresponds to more stable behavior. This integrated spatial analysis provides a robust basis for a red-flag model, contributing to proactive risk management of the Netherlands’ most vital infrastructures in the light of climate change.