Abstract.A 5-class intensity scale for wave storms in the Catalan coast is presented. This has been done by analysing a storm data set which comprises 5 buoys during the period 1988/2008. The obtained classification improves the former proposal of Mendoza and Jiménez (2008) by better resolving spatial and temporal variability in wave storms in the area. The obtained classification reflects the increase in wave storm properties as the storm category increases. Because the selected classification parameter was the energy content which implicitly contains H s and storm duration, this variable was used to define class limits; class I storms (24-250 m 2 h), class II storms (251-500 m 2 h), class III (501-700 m 2 h), class IV storms (701-1200 m 2 h) and class V storms (>1200 m 2 h). The energy content variable was also used as proxy for induced hazards; the observed increase in energy content for higher classes reflected a significant increase in the intensity of the potential hazards. Lastly, the dominant synoptic situation for wave storms along the Catalan coast was the presence of a Mediterranean cyclone although a direct correspondence on cyclone's intensity over the western Mediterranean with wave energy content was not found.

Against the background of potentially substantial sea-level rise, one important question is to what extent are coastal societies able to adapt? This question is often answered in the negative by referring to sinking islands and submerged megacities. Although these risks are real, the picture is incomplete because it lacks consideration of adaptation. This Perspective explores societies' abilities to adapt to twenty-first-century sea-level rise by integrating perspectives from coastal engineering, economics, finance and social sciences, and provides a comparative analysis of a set of cases that vary in terms of technological limits, economic and financial barriers to adaptation and social conflicts.

A simple formula to calculate the settling velocity of natural sediment particles for grain sizes between 0.063 and 1 mm is presented. The formula has been derived from the previous work of Dietrich, and it predicts the dimensionless settling velocity W * as a function of a dimensionless fluid-sediment parameter S * , provided the sediment shape factor and roundness are known. In case no information on shape and roundness factors is available, this paper recommends using the formula with a shape factor of 0.7 and a roundness value of 3.5 for naturally worn particles. The formula is tested against several independent data sets, and its performance is compared to other existing simple settling velocity formulas. For fine sediments with nominal diameters d N between 0.063 and 0.25 mm, for which sediment suspension in natural conditions is most likely to occur, the proposed formula is shown to perform the best in terms of standard error of the estimation.

Aeolian dune dimensions and migration rates are analysed along the Ceará coast, north‐east Brazil. Dunes that are currently mobile along the Ceará coast are composed of barchans and sand sheets. The results show that barchans maintain an equilibrium form, which can be characterized by values of dimensionless shape parameters H/W and W/L, where H is the dune height, W is the wing‐to‐wing width and L is the dune length. Dunes are highly mobile, with average migration rates of 17·5 m year−1 for barchans and 10 m year−1 for sand sheets. The calculated migration rates were found to depend strongly on dune dimensions for both barchans and sand sheets, i.e. the larger the dune is, the lower the migration rate will be. This size dependence was associated with the existence of a representative common transport rate along the dune fields, which induces a different dune migration rate dependent on dune size. Finally, from the observed dune evolution, an aggregated scale aeolian sediment transport was inferred. This bulk transport rate, of the order of 90–100 m3 m−1 year−1, is only valid for a timescale of years to decades, which is the timescale used in dune evolution analysis.

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