Recently natural hazards like earthquakes, landslides, subsidence, glacier bursts and flash floods have severely impacted Himalayan cities, including Joshimath, Uttarakhand. In January 2023, significant ground cracks were observed, leading to the evacuation of nearly 800 buildings. This study investigates the underlying causes of ground failure and building damage through various geotechnical and geophysical tests at 12 sites in Joshimath, including plate load test, dynamic cone penetration test, field direct shear test, multi-channel analysis of surface waves and horizontal-to-vertical spectral ratio. Soil samples are analyzed for natural moisture content and grain size distribution. There is large heterogeneity in the test results which are highly variable. The field tests indicate the soil fabric of Joshimath is a complex mixture of boulders, gravels and soil. Internal erosion in such soils causes the instability of the whole fabric and results in the readjustment of the boulders resulting in subsidence. Internal erosion, driven by subsurface drainage from rainwater, ice melting and wastewater discharge, destabilizes the soil matrix and causes subsidence. It has also been observed that even at greater depths, no clear uniform strata is present and similar heterogeneous strata extend. Lower shear strength and bearing capacity are observed at several sites, potentially contributing to building damage. The study emphasizes that individual test results alone may not adequately capture site conditions. Instead, a combination of multiple test results is essential for a comprehensive assessment. Based on the test results, a vulnerability map of the area is presented.

Land subsidence in the city of New Orleans (USA) and its surroundings increases flood risk, and may cause damage to buildings and infrastructure and loss of protective coastal wetlands. To make New Orleans more resilient to future flooding, a new approach for groundwater and subsidence management is needed. As a first step in developing such an approach, high-quality and high-resolution subsurface and groundwater information was collected and synthesized to better understand and quantify shallow land subsidence in New Orleans. Based on the collected field data, it was found that especially the low-lying areas north and south of the Metairie-Gentilly (MG) Ridge are most vulnerable to further subsidence; north of the MG Ridge, subsidence is mainly caused by peat oxidation and south of the MG Ridge mainly by peat compaction. At present, peat has compacted similar to 31% on average, with a range of 9-62%, leaving significant potential for further subsidence due to peat compaction. Phreatic groundwater levels drop to similar to 150 cm below surface levels during dry periods and increase to similar to 50 cm below surface during wet periods, on average. Present phreatic groundwater levels are mostly controlled by leaking subsurface pipes. Shallow groundwater in the northern part of New Orleans is threatened by salinization resulting from a reversal of groundwater flow following past subsidence, which may increase in the future due to sea-level rise and continued subsidence. The hydrogeologic information provided here is needed to effectively design tailor-made measures to limit urban flooding and continued subsidence in the city of New Orleans.

The vulnerability studies of human infrastructure in high-mountain areas influenced by geomorphological hazards in a changing climate are a rather young research field. Especially in high-alpine regions vulnerability maps are often not available, particularly regarding hiking trails or climbing routes. In this paper we present a heuristic approach to create vulnerability maps for Alpine trails and routes in the Grossglockner-Pasterze area (47 degrees 05'N, 12 degrees 42'E), an high-mountain area ranging from about 2000-3798 m a.s.l.. Therefore, the hazard potential that arises from gravitational mass-movements (rock falls, debris falls, other denudative processes) has been modelled in a two step approach. In the first step, the potential source areas were detected using a Digital Elevation Model combined with different further sources of information such as a geological map and orthophotos. Based on the estimation of the volume of the mobilizable substrate - which largely depends on the active layer thickness of permafrost - the second step was carried out by calculating transport paths and dispersal of the downward-moving material. The process model is based on a mass-conserving multiple direction flow propagation algorithm. Both disposition and process model were set up for the current environmental conditions (2010) and for a future scenario (2030) that is driven by a moderate regional climate scenario. Based on the assessment of these processes, susceptibility maps were generated. In a final step, vulnerability maps were created by combining the susceptibility maps with the alpine infrastructure. Considering the length of the trails, 5.5 % are classified in higher hazard classes in 2030 compared to 2010. The presented maps display all known major vulnerable trail and route sections in the study area properly. Furthermore, the evaluation of the maps by local and regional authority experts showed satisfactory results. However, future adaptions of both models - disposition as well as process model - are desirable, especially by the inclusion of better input data based on more empirical information on the processes.