Coastal river deltas are densely populated areas and hotspots of vulnerability. The delta's ecological, social, and economic components are vulnerable to a wide variety of natural and anthropogenic threats. Sea level rise, climate variability, and rapid socio-economic development exert pressure on the already highly dynamic regions. To protect river deltas and their components, it is necessary to assess the degree of vulnerability so that mitigation efforts can be recommended to stakeholders and policy makers. Many such vulnerability assessments have been undertaken for river deltas. However, as vulnerability and related terms, such as resilience, coping-, and adaptive capacity only entered geosciences in the past decades, these terms are often used ambiguously. This makes it hard to compare existing studies, which not only interpret the related terms differently, but also consider completely different threats to deltas and their components, at different spatial and temporal scales. A comprehensive overview of studies addressing vulnerability of river deltas is missing. This paper presents a review, based on a consolidated set of definitions of vulnerability and related concepts in the context of coastal river deltas. All studies reviewed were categorized depending on their focus on either the ecologic, social, or economic component of river deltas, and were classified according to their spatial scale, temporal resolution, and numerous other research characteristics. Clear trends on dominant research foci in the field of river delta vulnerability could be extracted. Additionally, based on the findings presented here, recommendations for future assessments considering existing research gaps, are formulated.
