Geotagged smartphone photos can be employed to build digital terrain models using structure from motion-multiview stereo (SfM-MVS) photogrammetry. Accelerometer, magnetometer, and gyroscope sensors integrated within consumer-grade smartphones can be used to record the orientation of images, which can be combined with location information provided by inbuilt global navigation satellite system (GNSS) sensors to geo-register the SfM-MVS model. The accuracy of these sensors is, however, highly variable. In this work, we use a 200 m-wide natural rocky cliff as a test case to evaluate the impact of consumer-grade smartphone GNSS sensor accuracy on the registration of SfM-MVS models. We built a high-resolution 3D model of the cliff, using an unmanned aerial vehicle (UAV) for image acquisition and ground control points (GCPs) located using a differential GNSS survey for georeferencing. This 3D model provides the benchmark against which terrestrial SfM-MVS photogrammetry models, built using smartphone images and registered using built-in accelerometer/gyroscope and GNSS sensors, are compared. Results show that satisfactory post-processing registrations of the smartphone models can be attained, requiring: (1) wide acquisition areas (scaling with GNSS error) and (2) the progressive removal of misaligned images, via an iterative process of model building and error estimation.

This study provides a detailed integrated analysis of the erosional processes affecting the volcanoclastic headlands of a pocket beach, of a typical Tyrrhenian volcanic island (Ventotene, south Italy). It compares the survey carried out in 2012 and the recent landslides that occurred in 2018–2020. The studied tuff cliff is characterised by steep, up to overhanging walls affected by a fracture network, which locally isolates blocks in precarious equilibrium. The stability conditions of the southern Cala Nave Bay sea cliff were evaluated by integrating a geological field survey, structural analysis of discontinuities, and a detailed topographic survey consisting of a terrestrial laser scanner (TLS) and photogrammetry data acquisition and processing, providing a three-dimensional (3D) model of the sea cliff. The 3D model of the area affected by the recent landslides was created using proximity photogrammetry, the Structure for Motion (SfM) methodology. The fracture network was represented by using high-resolution digital models and projected to realize geostructural vertical mapping of the cliff. The data acquired in 2012 were more recently compared with further surveys carried out, following rock failures that occurred in winter 2019–2020. The detachment planes and failure modalities coincide perfectly with the ones previously assessed. The applied techniques and the comparison with the recent rock failures have proven to be important in defining these conditions to address risk mitigation interventions.

This work reports the results of a study on the effects of an earth levee in flow depth and velocity reduction found by mapping the flood hazard for the baseline and Nature-Based Solution scenarios for one of the case studies of the H2020 Phusicos Project, namely, the Jorekstad site, in the town of Lillehammer (Norway). To achieve this target, the study employed various modelling procedures. These included climate, GIS, hydrological and hydraulic modelling structured in an integrated workflow. By running the FLO-2D model, the flooded areas were computed, and maximum flow depth and velocity were assessed by varying the return period with reference to different settings of the antecedent moisture conditions.

Many types of Nature-Based Solutions (NBSs) have been applied worldwide to mitigate impacts of hydro-meteorological hazards produced by anthropic activities such as grazing and agriculture. Among them, vegetated buffer strips (VBSs) and winter cover crops (WCCs) are suitable solutions for reducing runoff and soil erosion rates from cultivated fields. However, their mitigating effects depends largely on local conditions such as morphology and soil nature.This study investigated these aspects by modelling the NBS effects on soil and water dynamics in two test sites located within the Massaciuccoli agricultural plain (Vecchiano, Pisa, Central Italy) and characterised by different soil types (peaty and silty soils). The SWAT+ model has been chosen to simulate hydraulic and hydrological phenomena using high-resolution data such as digital terrain models (DTMs) from close-range photogrammetry, detailed land cover mapping, actual crop rotations, and detailed calendars of agronomic operations. We considered two types of NBSs: i) 3 m wide VBSs planted along both sides of field ditches, covering about 10% of the agricultural land, and ii) WCCs sowed after harvesting summer cash crops. Both NBSs exert their action on 30% of the experimental area. The mitigating effect was tested by comparing simulation results from NBS and control (conventional agriculture) scenarios under ongoing climatic conditions and future climate changes.Results indicated that VBSs and WCCs showed different capabilities to reduce runoff and sediment losses, and the adoption of both can enhance the mitigation effect significantly. NBSs resulted effective also in completely flat areas since slight topographic irregularities can cause local preferential flows resulting in high runoff rate and sediment losses. Furthermore, it is demonstrated how the soil variability in texture and organic matter content can affect the amount of runoff and sediment loss on a local scale. Consequently, the mitigating effects of NBS can be closely driven by the soil nature and heterogeneity. This influence is even more significant under extreme climatic conditions such as higher temperatures and more aggressive rainfall events. In these cases, NBSs can play an essential role in mitigating runoff and soil erosion phenomena on fine-textured mineral soils. In contrast, they lose much of their effectiveness on peat soils.