Special issue  

The transition zone between land and water is difficult to map due to shallow water depth and often challenging environmental conditions. Airborne topobathymetric lidar is capable of providing both topographic and bathymetric elevation information, resulting in a seamless coverage of the land–water transition zone. We present the processing and performance of topobathymetric lidar data along with a geomorphometric and morphological classification of landforms in a high-energy tidal environment.

The authors apply an object-based geomorphometric procedure to define the runoff contribution areas. The results enabled us to identify the contribution area related to the different runoff components activated during the storm events through an advanced hydro-chemical analysis. This kind of approach could be useful applied to similar, rainfall-dominated, forested and no-karst Mediterranean catchments.

During the creation and geomorphometric analysis of a landslide inventory, I stumbled across an issue: while the majority of the landslides are developed along the direction of material flow and have a larger length than width, there are situations where the landslides have a larger width than length. For distinguishing these long and wide landslides, I devised an algorithm that used the geometric processing of the bounding box and the geomorphometric analysis of a digital elevation model.

Application of digital terrain analysis (DTA), which is typically a modeling process involving workflow building, relies heavily on DTA domain knowledge. However, the DTA knowledge has not been formalized well to be available for inference in automatic tools. We propose a case-based methodology to solve this problem. This methodology can also be applied to other domains of geographical modeling with a similar situation.

We study detectability of changes in water surface areas on orthophotomaps. We use unmanned aerial vehicles to acquire visible light photographs. We offer a new method for detecting changes in water surface areas and river stages. The approach is based on the application of the Student's t test, in asymptotic and bootstrapped versions. We test our approach on aerial photos taken during 3-year observational campaign. We detect transitions between all characteristic river stages using drone data.

Geomorphometry, the science of quantitative terrain characterization, has traditionally focused on the investigation of terrestrial landscapes. More recently, a suite of geomorphometric techniques have been applied to characterize the seafloor. The dynamic, four-dimensional nature of the marine environment and differences in data collection methods cause issues for geomorphometry that are specific to marine applications. This article offers the first review of marine geomorphometry to date.

We design and implement a theoretical experiment to show that, under low-flow conditions, observed streamflow discrepancies between early and late summer can be attributed to different flow velocities in the river network. By developing an analytic solution to represent flow along a given river network, we emphasize the dependence of streamflow amplitude and time delay on the geomorphology of the network. We also simulate using a realistic river network to highlight the effects of scale.

Future sea level rise is inevitable. We investigate the effects of 2 m sea level rise on the island of Gotland, Sweden. In a multi-criteria analysis we analyze the quantity of infrastructure that will be inundated, and the effect of saltwater intrusion in wells. Almost 100 km² (3 %) of Gotland's land area will be inundated. Important touristic and nature values will be strongest affected. Well salinization will greatly increase. Administrative planning is needed to prepare for changes.

This paper presents a novel approach that provides evidence of environmental conditions during the formation of a cave inferred from measuring the geometry of the cave surface. We focused on winding channels with associated cave landforms carved high up in the cave ceiling inaccessible to direct inspection by speleologists. This was possible by coupling 3-D laser scanning of the cave and analyzing the cave morphology by the tools used in 3-D computer graphics and digital terrain analysis.

To investigate the present-day morphology of the 2006 Guinsaugon landslide scar and potential failure that may occur, analysis of a 5 m resolution IfSAR-derived DTM was conducted using Coltop3D and Matterocking software to produce a structurally controlled landslide hazard map for Southern Leyte, Philippines. This type of simulated hazard maps would be useful for disaster prevention and to facilitate disaster risk reduction efforts for landslide-susceptible areas in the country.