Alluvial anastomosed channels : the preferred channel type on active UK rivers

Paper presented at 11th International Symposium on EcoHydraulics, 7-12 February 2016, Melbourne, Australia. Abstract: Anastomosing rivers constitute an important category of multi-channel rivers and are characterised by multiple, interconnected, coexisting channels flowing over alluvial plains. They commonly form by avulsion processes, causing the formation of new channels on the floodplain; a process primarily driven by loss of channel capacity and flow breakout linked to local in-channel deposition. This style of channel is presently rare in the UK primarily due to historic channel and floodplain engineering and management. This study examines the character of developing anastomosed channels seen on a number of active gravel-bed channels in the north of England using aerial imagery and metre scale resolution aerial LIDAR data. Aerial imagery of the study sites indicate progressive development of a well-developed wooded valley floor associated with lateral bar extension and succession across stable isolated bar units. The LIDAR data are used to create detailed digital terrain models (DEMs) of the study reaches accurately representing sub-channel planform and morphology. Topographic metrics suggest well-developed underlying morphological features, dominated by an interlinked channel network split by variable length, generally low elevation interfluves and variograms created for each site suggest a common topographic pattern associated with the study sites. The gross morphology does not reflect the classic anastomosed features described by previous research, suggesting that different processes are operating to create these channel types. It is suggested that the anastomosing networks have developed across systems that were initially active meandering and wandering in nature, evolving in line with floodplain vegetative succession to stabilise these planform types. These modes of formation suggest a different origin of these anastomosed sites compared with those previously reported with floodplain management playing a key role in system development

Automated Classification of Airborne Laser Scanning Point Clouds

Making sense of the physical world has always been at the core of mapping. Up until recently, this has always dependent on using the human eye. Using airborne lasers, it has become possible to quickly "see" more of the world in many more dimensions. The resulting enormous point clouds serve as data sources for applications far beyond the original mapping purposes ranging from flooding protection and forestry to threat mitigation. In order to process these large quantities of data, novel methods are required. In this contribution, we develop models to automatically classify ground cover and soil types. Using the logic of machine learning, we critically review the advantages of supervised and unsupervised methods. Focusing on decision trees, we improve accuracy by including beam vector components and using a genetic algorithm. We find that our approach delivers consistently high quality classifications, surpassing classical methods

High-Resolution Vertical Habitat Mapping of a Deep-Sea Cliff offshore Greenland

Recent advances in deep-sea exploration with underwater vehicles have led to the discovery of vertical environments inhabited by a diverse sessile fauna. However, despite their ecological importance, vertical habitats remain poorly characterized by conventional downward-looking survey techniques. Here we present a high-resolution 3-dimensional habitat map of a vertical cliff hosting a suspension-feeding community at the flank of an underwater glacial trough in the Greenland waters of the Labrador Sea. Using a forward-looking set-up on a Remotely Operated Vehicle (ROV), a high-resolution multibeam echosounder was used to map out the topography of the deep-sea terrain, including, for the first time, the backscatter intensity. Navigational accuracy was improved through a combination of the USBL and the DVL navigation of the ROV. Multi-scale terrain descriptors were derived and assigned to the 3D point cloud of the terrain. Following an unsupervised habitat mapping approach, the application of a K-means clustering revealed four potential habitat types, driven by geomorphology, backscatter and fine-scale features. Using groundtruthing seabed images, the ecological significance of the four habitat clusters was assessed in order to evaluate the benefit of unsupervised habitat mapping for further fine-scale ecological studies of vertical environments. This study demonstrates the importance of a priori knowledge of the terrain around habitats that are rarely explored for ecological investigations. It also emphasizes the importance of remote characterization of habitat distribution for assessing the representativeness of benthic faunal studies often constrained by time-limited sampling activities. This case study further identifies current limitations (e.g., navigation accuracy, irregular terrain acquisition difficulties) that can potentially limit the use of deep-sea terrain models for fine-scale investigations

Generative Design in Minecraft (GDMC), Settlement Generation Competition

This paper introduces the settlement generation competition for Minecraft, the first part of the Generative Design in Minecraft challenge. The settlement generation competition is about creating Artificial Intelligence (AI) agents that can produce functional, aesthetically appealing and believable settlements adapted to a given Minecraft map - ideally at a level that can compete with human created designs. The aim of the competition is to advance procedural content generation for games, especially in overcoming the challenges of adaptive and holistic PCG. The paper introduces the technical details of the challenge, but mostly focuses on what challenges this competition provides and why they are scientifically relevant.Comment: 10 pages, 5 figures, Part of the Foundations of Digital Games 2018 proceedings, as part of the workshop on Procedural Content Generatio

The physics of wind-blown sand and dust

The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This article presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.Comment: 72 journal pagers, 49 figure

Simulo Tempestas : a simulation tool for hydrological modelling

Man’s existence has clearly interfered with nature. Ever since man appeared on the face of our planet, the landscape was adapted to make it a more habitable environment. Although early humans transformed land to accommodate their dwellings and livestock, land was changed only to a certain extent. However, modern man has altered his surroundings beyond recognition through the building of road networks, sprawling cities, industrial zones, so on and so forth. This project studies the natural flow of water over the terrain through the use of a simulation tool, with particular focus on the Maltese Islands. Such a tool would help engineers plan better the assignment of construction zones as it allows proper analysis of the effects of land development on the flow of storm water before making any commitment that would change the landscape irreversibly. Different weather scenarios, based either on past statistics or completely fictitious ones, could be fed to the tool and its effects studied in the quest of finding the best solutions to avoid man-made catastrophes.peer-reviewe

The Impact Of Rock-Climbing Disturbance On Cliff Communities Of The Linville Gorge Wilderness Area

Cliff communities are dominated by stress-tolerant, often cryptic communities whose abundance is controlled by harsh abiotic conditions. These taxa vary in their requirement for soil, water, sunlight and ability to withstand disturbance. To assess the impact of climbing and habitat variability, cliffs at Table Rock and Hawksbill Mountain in western North Carolina were surveyed. I observed 42 lichen, 21 bryophyte, and 22 vascular plant species. Climbed plots were less diverse and species rich than their unclimbed counterparts. Climbing impacts cliffs by holding back ecological succession to the pioneer stage, with abundant crustose lichens, while removing larger, later successional stage lichens. Since cliff vegetation varies by site due to differences in surface heterogeneity, each potential climbing area should be surveyed, especially for cryptic species, before management decisions are made. We built 3D models of cliffs using Structure-from-Motion techniques to quantify surface heterogeneity. Two focal statistics at larger neighborhood cell sizes were weakly correlated with field measures of heterogeneity. Vascular plant richness and diversity were correlated with few measures of remotely modeled surface heterogeneity. The methodology developed in this study will help lay the ground-work for remotely quantifying structural variability on cliff faces and hence increased consistency among cliff ecology researchers

Simulations of snow distribution and hydrology in a mountain basin

We applied a version of the Regional Hydro‐Ecologic Simulation System (RHESSys) that implements snow redistribution, elevation partitioning, and wind‐driven sublimation to Loch Vale Watershed (LVWS), an alpine‐subalpine Rocky Mountain catchment where snow accumulation and ablation dominate the hydrologic cycle. We compared simulated discharge to measured discharge and the simulated snow distribution to photogrammetrically rectified aerial (remotely sensed) images. Snow redistribution was governed by a topographic similarity index. We subdivided each hillslope into elevation bands that had homogeneous climate extrapolated from observed climate. We created a distributed wind speed field that was used in conjunction with daily measured wind speeds to estimate sublimation. Modeling snow redistribution was critical to estimating the timing and magnitude of discharge. Incorporating elevation partitioning improved estimated timing of discharge but did not improve patterns of snow cover since wind was the dominant controller of areal snow patterns. Simulating wind‐driven sublimation was necessary to predict moisture losses