Phragmites australis L. , a widespread vegetation in riparian zones such as rivers and canals, is extensively studied for its ecological benefits such as nutrient removal and hydraulic retention. However, its direct contribution to bank stability through root reinforcement, a key factor for its use in soil bioengineering techniques, has received limited attention. This study investigated the root reinforcement provided by P. australis and its root traits at a soil bioengineering test site on a canal bank in the Province of North-Holland in the Netherlands. Direct measurements of root-soil composite strength were performed using a corkscrew extraction technique at two distinct distances from the canal. Concurrently, root distribution parameters, including Root Area Ratio (RAR) and Root Length Density (RLD), were quantified from extracted soil plugs. Root reinforcement was also indirectly estimated using biomechanical models, incorporating measured root tensile strength and root distribution parameters as inputs. A total of 12 excavations, each 0.25 m 2 , were conducted for comprehensive root trait analysis at both locations. Direct measurements revealed substantial root reinforcement (max 36 kPa; avg 6–19 kPa). RAR showed effective stabilization values between 0.03 and 0.65 %, peaking at 0.65 % in the area close to canal. Root systems were dominated by fine roots (<0.5 mm diameter), comprising >80 % of total root length and creating dense reinforcing networks. Corkscrew measurements yielded conservative values. Modeled estimates significantly exceeded these field measurements, which is consistent with conventional shear testing. The extensive root surface area (>3.9 m 2 m −2 ) further demonstrates the species' soil-binding capacity, with higher values occurring in hydrologically favorable zones. While the ecological implications of using this widespread species must be contextually considered, its pronounced mechanical reinforcement makes it a highly effective biotechnical tool, particularly in managed environments like canals. • Measured root reinforcement and root area ratio were higher closer to the water body. • Root reinforcement increased soil shear strength significantly, adding an average of 6–19 kPa. • Corkscrew measurements yielded conservative estimates compared to model estimates. • Majority of root length was concentrated in the <0.5 mm diameter class.

In tropical mountains, extreme hydrometeorological hazards have the potential to produce significant geomorphic changes that influence flood hazard dynamics. Although considerable research has been devoted to the geomorphic response of catchments to flood in temperate areas, comparatively little attention has been paid to the geomorphic and hydrological impacts of hurricanes in tropical mountainous areas. It is thus crucial to identify and quantify the differential response of catchments to these events and to integrate those changes into the corresponding flood hazard analyses. In this study, we address three key research questions: (1) What are the geomorphic impacts triggered by hurricanes in mountainous regions at the river reach scale? (2) To what extent do neighboring catchments differ in their response to hurricanes? (3) How do hurricane-induced geomorphic changes influence flood hazard dynamics? For that, we investigate the geomorphic response and flood hazard of two catchments in the Sierra de las Minas (Guatemala), Pasabien and Jones, by analyzing their response to cascading events triggered by Hurricane Mitch in 1998 and Hurricanes Eta and Iota in 2020. We use an integrated approach that combines UAV and satellite-based remote sensing analyses, field-based evidence and physically based modeling to analyze landform and flood extent changes after the events. The overall results indicate that hurricanes have the capacity to impact flood hazard dynamics as they play a key role in landscape evolution, and that the storm characteristics, together with physiographic characteristics of the catchment, condition their differential geomorphic impact . These results have strong implications for disaster risk reduction, especially in the light of the ongoing urbanization process and the increasing frequency of hydrometeorological extreme in tropical mountains. • Hurricanes Eta-Iota triggered divergent geomorphic responses and flood hazards in adjacent catchments. • Catchment physiography controls landslide susceptibility and post-hurricane channel response. • Hurricanes Eta-Iota mobilized vast coarse sediment, driving river widening, avulsion, and floodplain change. • An integrated multi-method approach reconstructs cascading hazards in data-scarce tropical mountain regions.

Oceanic islands at mid to high latitudes are usually encircled by sea cliffs and other rock coast landforms. In contrast, islands in low latitudes are usually fringed by coral reefs that dissipate wave energy. Norfolk Island is a volcanic island (~3 Ma) near the centre of an extensive marine shelf, close to the southern limit to reef growth in the Pacific Ocean. This study describes the cliffs that encircle Norfolk Island and the geomorphology of offshore sea stacks, hanging valleys, boulder beaches, shore platforms and offshore platforms, using a combination of remote-sensing and field survey. Much of the steep basaltic coast is deeply weathered and landslides are common. Hanging valleys imply that marine erosion rates generally outpace long-term fluvial and other subaerial erosion rates. Talus slopes produced by cliff collapse are rare, suggesting that cliff-erosion debris is being removed faster than it is generated. The only section of the coastline where this is not the case is the southern coast, where aeolianite dunes and small patch reefs have developed within sandy embayments that are protected by a calcarenite rim. Contemporary coastal landforms indicate highly effective marine erosion typical of a reef-less eroding remnant volcano. However, the shelf surrounding Norfolk Island appears too wide to have been eroded entirely within the 2–3 million years since it was formed, implying that there may be other volcanic, tectonic or geophysical processes contributing to the long-term evolution of Norfolk Island. • Norfolk Island comprises a rocky, predominantly erosional, coastline. • Marine erosion outpaces subaerial erosion in all but the southern coastline segment. • Norfolk Island is more similar to reef-less volcanoes than reef-encircled volcanoes. • The anomalously-wide marine shelf implies more complex evolution than adjacent hotspot chains.