Terrain Configurations Research Articles

Alleviating urban pluvial floods via dual-use water plazas orchestrated by predictive algorithms

Old urban areas, characterized by complex land use and inadequate infrastructure, exhibit high vulnerability to precipitation extremes. The integration of dual-use public infrastructure stands at the forefront of planning initiatives to enhance urban flood resilience. This study introduces a pioneering Smart Water Plaza (SWP) system, orchestrated by predictive algorithms, to mitigate pluvial floods. A high-risk old neighborhood (4.5 km2) in Changsha, China, is selected as a case for empirical analysis. Two types of SWPs—in-situ detention, and runoff-receiving units—are initially established based on spatial mapping and potential analysis. The core feature of the SWP system is a multi-horizon 2D-1D model predictive control (MPC), which directly verifies the suitability of terrain configurations and evaluates temporal efficiency. The study plots the performance curves of the SWPs under various design rainfalls and demonstrates flood dynamics using an actual torrential event. The findings indicate that SWPs’ resilience contribution index for the stormwater system ranges from 9 % to 38 %. Furthermore, SWPs covering only 5 % of the site lead to an obvious decrease in flooded areas, with reductions ranging from 46 % to 48 %. These outcomes highlight the disaster mitigation potential inherent in multifunctional public spaces for Sponge City transformation and urban renewal efforts.

Self-AdaptIve LOcal Relief Enhancer (SAILORE): A New Filter to Improve Local Relief Model Performances According to Local Topography

The use of Light Detection and Ranging (LiDAR) is becoming more and more common in different landscape exploration domains such as archaeology or geomorphology. In order to allow the detection of features of interest, visualization filters have to be applied to the raw Digital Elevation Model (DEM), to enhance small relief variations. Several filters have been proposed for this purpose, such as Sky View Factor, Slope, negative and positive Openness, or Local Relief Model (LRM). The efficiency of each of these methods is strongly dependent on the input parameters chosen in regard of the topography of the investigated area. The LRM has proved to be one of the most efficient, but it has to be parameterized in order to be adapted to the natural slopes characterizing the investigated area. Generally, this setting has a single value, chosen as the best compromise between optimal values for each relief configuration. As LiDAR is mainly used in wide areas, a large distribution of natural slopes is often encountered. The aim of this paper is to propose a Self AdaptIve LOcal Relief Enhancer (SAILORE) based on the Local Relief Model approach. The filtering effect is adapted to the local slope, allowing the detection at the same time of low-frequency relief variation on flat areas, as well as the identification of high-frequency relief variation in the presence of steep slopes. First, the interest of this self-adaptive approach is presented, and the principle of the method, compared to the classical LRM method, is described. This new tool is then applied to a LiDAR dataset characterized by various terrain configurations in order to test its performance and compare it with the classical LRM. The results of this test show that SAILORE significantly increases the detection capability while simplifying it.

Energy Efficiency of a Quadruped Robot with Neuro-Inspired Control in Complex Environments

This paper proposes an analysis of the energy efficiency of a small quadruped robotic structure, designed based on the MIT Mini Cheetah, controlled using a central pattern generator based on the FitzHugh–Nagumo neuron. The robot’s performance evaluated on structurally complex terrain in a dynamic simulation environment is compared with other robotic structures on wheels and with hybrid architectures. The energy cost involved in carrying out an assigned task involving the need to traverse uneven terrain is calculated as a relevant index to be taken into account. In particular, simple control strategies impacting the leg trajectories are taken into account as the main factors affecting the energy efficiency in different terrain configurations. The adaptation of the leg trajectories is evaluated depending on the terrain characteristics, improving the locomotion performance.

Visualizations of the Doblar Accumulation Basin Based on the UAV Survey

Abstract. Our research is based on a large case study of Unmanned Aerial Vehicle (UAV) surveys, modelling and visualizations of the Doblar accumulation basin. The various approaches for UAV surveying of large, demanding terrain configurations, and the benefits of surveying products used as a basis for other interdisciplinary hydrological and environmental services were researched. The demanding mountainous terrain, the steep slopes and deep and narrow streams required detailed pre-planning of the survey, including the pre-survey terrain overview. The accumulation basin was emptied merely for a short period; thus, the survey was performed in unfavourable weather conditions, which included coldness, snowfall and wind. Point clouds were generated and georeferenced from the 4377 recorded photos. The dense point cloud contained approximately 222 million points in the medium setting and more than a billion in the high setting. A 3D model was built from the data. This became the basis for numerous further analyses and for the presentation using cartographic principles: a digital elevation model with a resolution of 10 cm, an orthophoto with a resolution of 10 cm, a 3D model draped with orthophoto, contour lines with a 1 m interval, topographic profiles, calculations of volumes at different water levels, a flythrough, augmented reality and a video simulation of the water level changes. The model can also serve as a basis for hydraulic and environmental analysis and simulations or used for analyses of the accumulation and deposition of river material compared with previous and future surveys.

Is anthropogenic land subsidence a possible driver of riverine flood-hazard dynamics? A case study in Ravenna, Italy

ABSTRACTWe investigate possible changes in flood hazard over a 77-km2 area around the city of Ravenna. The subsidence rate in the area, naturally a few mm year−1, increased dramatically after World War II because of groundwater and natural gas extraction, exceeding 110 mm year−1 and resulting in cumulative drops larger than 1.5 m. The Montone–Ronco river system flows in the southern portion of the area, which is protected against frequent flooding by levees. We performed two-dimensional simulations of inundation events associated with levee breaching by considering four different terrain configurations: current topography and a reconstruction of ground elevations before anthropogenic land subsidence, both neglecting and representing the main linear infrastructures (e.g. roads, artificial channels). Results show that flood-hazard changes due to anthropogenic land subsidence (e.g. significant changes in computed water depth and velocity) are observed over less than 10% of the study area and are definitely less important than those resulting from construction of the linear infrastructures.

Adaptive scattered data fitting by extension of local approximations to hierarchical splines

We introduce an adaptive scattered data fitting scheme as extension of local least squares approximations to hierarchical spline spaces. To efficiently deal with non-trivial data configurations, the local solutions are described in terms of (variable degree) polynomial approximations according not only to the number of data points locally available, but also to the smallest singular value of the local collocation matrices. These local approximations are subsequently combined without the need of additional computations with the construction of hierarchical quasi-interpolants described in terms of truncated hierarchical B-splines. A selection of numerical experiments shows the effectivity of our approach for the approximation of real scattered data sets describing different terrain configurations.

Multi-criteria evaluation of topographic correction methods

Abstract In the last decades, several topographic correction methods (TOC) have been proposed, but there is not an agreement on the best method. Furthermore, different evaluation criteria have been used in the past, and there is not any simple and objective evaluation procedure to measure the quality of the correction. Consequently, a multi-criteria analysis of widely used topographic correction methods is required that evaluates their performance over different sensors, terrain and temporal configurations. In this work, ten TOC methods were assessed using seven different evaluation strategies. The analysis was carried out for three SPOT5 images acquired over a mountainous area of northern Spain. The images had different acquisition dates and solar angles, so as to evaluate performance under varying illumination conditions. The results obtained showed that Statistic-Empirical method, C-Correction and Sun-Canopy-Sensor + C performed the best, and differences were minor when favorable illumination conditions were considered. For the seven tested evaluation strategies, interquartile range reduction of land covers or the comparison of sunlit and shaded slopes gave very similar results, whereas there were greater contrasts among other criteria.

Case Study of Three High-Performing Contract Loggers with Distinct Harvest Systems: Are They Thriving, Striving, or Just Surviving?

Abstract This article focuses on the narrow margins faced by contract loggers under various harvest systems in the forest products supply chain of the northeastern United States. Contract logging firms conduct a majority of the harvesting across the various forest cover types of the region—from spruce-fir to white pine to northern hardwoods—supplying sawlogs, pulpwood, chipwood, and firewood to various markets. Over the past few decades, performance expectations have increased owing to the expansion of harvesting regulations, including best management practices, and the adoption of forest and logger certification programs. These rising expectations have corresponded with increasing logging costs, resulting in narrowing margins for contract loggers. Using results from a recent logger case study, we examine operating margins for three harvest systems under varying terrain, harvest levels, and systems configurations. Results suggest that across all harvest systems, there is a fine line between just making a living (striving), succeeding and growing (thriving), and only partially covering costs while losing equity to uncompensated depreciation (surviving).

Suitability of airborne laser scanning for the assessment of forest protection effect against rockfall

Rockfall simulation models are now able to quantify the protective effect of forest with the integration of rock impacts on trees. Those models require spatially explicit forest characteristics which are costly to acquire in operational conditions. The present study compares rockfall simulation results obtained with different forest input data sources: field data with different levels of spatial detail and two methods based on airborne Lidar data. Three different forest stands are tested with several virtual terrain configurations. When rockfall energies are below 200 kJ, the forest protection effect is significant. For higher energies, it also exists but it is minor compared to the effects of topography and rock volume. For all forest input data sources, the estimated rockfall intensity is within −13 and 16 % of the reference value, whereas the frequency is generally overestimated. Both Lidar methods yield a satisfactory forest protection effect evaluation, but single tree detection tends to underestimate it. Improvements are possible regarding the spatial heterogeneity of stem density and the diameter distribution by tree species.

LiDARによる山岳地形における風速鉛直プロファイル分析

Wind turbines are often constructed in mountainous region in Japan, because mountainous region is account for more than 70 percent of land in Japan. In complex terrains, wind characteristics depend heavily on wind direction with strong locality. Especially the vertical wind profiles are complicated in the complex terrain. So It is necessary to measure the wide-ranging wind conditions from a low altitude to a high altitude. However, wide-ranging wind measurements are difficult for conventional equipment such as meteorological mast. Then, remote sensing devices such as Light Detection and Ranging (LiDAR) are counted on for wind measurements in complex terrain. In this paper, we investigated the effects of terrain configurations on vertical wind speed profiles by wind measurements using LiDAR in mountainous terrain, and we also investigated LiDAR measurements validity by comparison among vertical profiles from three LiDARs that have different wind measurements mechanism. The trends of vertical wind speed profiles from different LiDARs are similar and the wind profiles are different by wind directions (NNW and SE). NNW wind is the flow that do not over a ridge of the mountain and SE wind is the flow that over the ridge. The NNW wind profile is uniform, and the SE wind profile is separated flow. By using LiDAR, it is able to research condition of flow in mountainous terrain such as separated flow.

Automatic Orthorectification of High-Resolution Optical Satellite Images Using Vector Roads

This paper presents a completely automatic processing chain for orthorectification of optical pushbroom sensors. The procedure is robust and works without manual intervention from raw satellite image to orthoimage. It is modularly divided in four main steps: metadata extraction, automatic ground control point (GCP) extraction, geometric modeling, and orthorectification. The GCP extraction step uses georeferenced vector roads as a reference and produces a file with a list of points and their accuracy estimation. The physical geometric model is based on collinearity equations and works with sensor-corrected (level 1) optical satellite images. It models the sensor position and attitude with second-order piecewise polynomials depending on the acquisition time. The exterior orientation parameters are estimated in a least squares adjustment, employing random sample consensus and robust estimation algorithms for the removal of erroneous points and fine-tuning of the results. The images are finally orthorectified using a digital elevation model and positioned in a national coordinate system. The usability of the method is presented by testing three RapidEye images of regions with different terrain configurations. Several tests were carried out to verify the efficiency of the procedure and to make it more robust. Using the geometric model, subpixel accuracy on independent check points was achieved, and positional accuracy of orthoimages was around one pixel. The proposed procedure is general and can be easily adapted to various sensors.

The role of forest cover and valley geometry in cold‐air pool evolution

AbstractThis study utilizes a version of the Advanced Regional Prediction System (ARPS) with a canopy submodel (ARPS‐CANOPY) to evaluate the sensitivity of cold‐air pool evolution to forest canopy density and valley geometry and elucidate the underlying processes. Numerical experiments are conducted with forest canopy structures spanning from bare ground to dense canopies and terrain configurations ranging from small, shallow valleys to broad, deep valleys. In a set of experiments in which forest canopy density is varied, the minimum potential temperature in the cold‐air pool is found to be as much as 15 K warmer with a dense canopy than with no canopy. Analysis of the thermodynamic budget reveals weaker cooling rates in the dense canopy case than the sparse canopy case, with differences in cooling rates persisting through the duration of the simulation. An additional experiment in which cooling of canopy elements and the influence of the canopy on the ground radiation budget are neglected highlights the important role the canopy plays in limiting radiative loss from the ground surface along the sidewall and valley floor. In experiments in which valley geometry is varied, the cold‐air pool is found to be strongest in a medium valley (10 km wide, 187.5 m deep) and weakest in a small valley (2 km wide, 37.5 m deep). Analysis of along‐slope buoyancy suggests that downslope flow‐driven cooling in a medium valley is more efficient than in a large valley (30 km wide, 500 m deep).

Development of an integrated system for air pollutant dispersion modelling

A complex expert system for air pollutant dispersion modeling (ScalEx) is currently being developed at Faculty of Technology and Metallurgy in Belgrade. The project goal is to develop a powerful software system as an engineering toolbox for modelling air pollutant dispersion under various conditions and terrain configurations. ScalEx is planned to be an integrated software system of the new generation, putting together an expert system, advanced database technologies, hypermedia, conventional numeric routines and neural networks.

Katabatic Flows and Their Relation to the Formation of Convective Clouds—Idealized Case Studies

AbstractThe formation of a convective cloud system as a result of a katabatic-induced surface cold front at the eastern Andes Mountains of South America was investigated in a numerical model study. The occurrence of this cloud system is hypothesized to be a consequence of converging cold-air drainage from slopes and valleys resulting from the concave shape of the terrain. Simplified terrain configurations were applied to three different atmospheric experiments to determine the influence of the terrain and the ambient stratification on the underlying processes. The simulation demonstrated the occurrence of a convective cloud, but not in every simulation. The initial stable stratification experiment did not initiate convective activity. Further analysis of the development of the convective cells confirmed the terrain’s impact, but it also showed a dependence on atmospheric conditions. The katabatic flows and the surface fluxes from which they are induced are sensitive to the ambient stratification, which was seen when only a weak cold front developed in response to a decrease in the surface inversion and the downslope velocity. On the basis of specific characteristics of katabatic flows and the heat-exchange budget, the presence of these flows and their significance as the driving force behind the cloud-formation process were confirmed.

Genetic Algorithm Aided Antenna Placement in 3D and Parameter Determination Considering Electromagnetic Field Pollution Constraints

This paper presents genetic algorithm based method for antenna placement in 3D space and parameter determination satisfying environmental electromagnetic field pollution constraints. The main goal is to find out antenna parameters (power, position in 3D, azimuth and elevation) in the area of interest so that electromagnetic field satisfies minimal electromagnetic field strength for service availability and, at the same time, be below prescribed limit in restricted subareas (people populated areas). The proposed method is validated with two real world antenna types and with seven different terrain configurations (various restricted areas). Besides finding the most optimal antenna parameters, the method finds “almost” optimal solutions which give certain freedom to choose alternative antenna position if optimal is not available. The investigation described here is extension of previous 2D research.

Coupling groundwater and land surface processes: Idealized simulations to identify effects of terrain and subsurface heterogeneity on land surface energy fluxes

This work investigates the role of terrain and subsurface heterogeneity on the interactions between groundwater dynamics and land surface energy fluxes using idealized simulations. A three‐dimensional variably saturated groundwater code (ParFlow) coupled to a land surface model (Common Land Model) is used to account for both vertical and lateral water and pressure movement. This creates a fully integrated approach, coupling overland and subsurface flow while having an explicit representation of the water table and all land surface processes forced by atmospheric data. Because the water table is explicitly represented in these simulations, regions with stronger interaction between water table depth and the land surface energy balance (known as critical zones) can be identified. This study uses simple terrain and geologic configurations to demonstrate the importance of lateral surface and subsurface flows in determining land surface heat and moisture fluxes. Strong correlations are found between the land surface fluxes and water table depth across all cases, including terrain shape, subsurface heterogeneity, vegetation type, and climatological region. Results show that different land forms and subsurface heterogeneities produce very different water table dynamics and land surface flux responses to atmospheric forcing. Subsurface formation and properties have the greatest effect on the coupling between the water table and surface heat and moisture fluxes. Changes in landform and land surface slope also have an effect on these interactions by influencing the fraction of rainfall contributing to overland flow versus infiltration. This directly affects the extent of the critical zone with highest coupling strength along the hillside. Vegetative land cover, as seen in these simulations, has a large effect on the energy balance at the land surface but a small effect on streamflow and water table dynamics and thus a limited impact on the land surface‐subsurface interactions. Although climate forcing has a direct effect on water table dynamics and feedbacks to the land surface, in this study it does not overcome that of subsurface heterogeneity and terrain.

The Impact of Different Terrain Configurations on the Formation and Dynamics of Katabatic Flows: Idealised Case Studies

Impacts of different terrain configurations on the general behaviour of idealised katabatic flows are investigated in a numerical model study. Various simplified terrain models are applied to unveil modifications of the dynamics of nocturnal cold drainage of air as a result of predefined topographical structures. The generated idealised terrain models encompass all major topographical elements of an area in the tropical eastern Andes of southern Ecuador and northern Peru, and the adjacent Amazon. The idealised simulations corroborate that (i) katabatic flows develop over topographical elements (slopes and valleys), that (ii) confluence of katabatic flows in a lowland basin with a concave terrainline occur, and (iii) a complex drainage flow system regime directed into such a basin can sustain the confluence despite varying slope angles and slope distances.

Numerical Evaluation of Wind Flow over Complex Terrain: Review

This paper reviews the current state of the art in the numerical evaluation of wind flow over different types of topographies. Numerical simulations differing from one another by the type of numerical formulation followed, the turbulence model used, the type of boundary conditions applied, the type of grids adopted, and the type of terrain considered are summarized. A comparative study among numerical and experimental (both wind tunnel and field) existing works establishing the modifications of wind flow over hills, escarpments, valleys, and other complex terrain configurations demonstrates generally good predictions on the upstream but problematic predictions on the downstream areas of the complex terrain. Comparisons are also made with provisions of the current wind standards as well as with speed-up values calculated using guidelines derived from theoretical models.

Wolves, elk, willows, and trophic cascades in the upper Gallatin Range of Southwestern Montana, USA

We summarized the status of wolves ( Canis lupus), elk ( Cervis elaphus), and woody browse conditions during the 20th century for the upper Gallatin elk winter range in southwestern Montana, USA. During this period, wolves were present until about the mid-1920s, absent for seven decades, and then returned to the basin in 1996. A chronosequence of photographs, historical reports, and studies indicated willows ( Salix spp.) along streams became heavily browsed and eventually suppressed following the removal of wolves, apparently due to unimpeded browsing by elk. However, after wolf establishment in 1996, browsing intensity on willows lessened in some areas and we hypothesized that, at both a landscape and fine scale, browsing pressure reflects terrain configurations influencing predation risk (nonlethal effects), in conjunction with lower elk densities (lethal effects). We measured browsing intensity and heights of Booth willow ( S. boothii) along 3000 m reaches of the Gallatin River and a tributary to examine the potential influence of wolf/elk interactions upon willow growth. Where the Gallatin Valley is relatively narrow (high predation risk), willows began releasing in 1999 and by 2002 were relatively tall (150–250 cm). In contrast, willow heights along a wider portion of the Gallatin Valley, along the open landscape of the tributary, and an upland site (all low predation risk) generally remained low (<80 cm). We identified terrain and other features that may contribute to the perceived risk of wolf predation, by elk for a given site. Although alternative mechanisms are discussed, changes in willow communities over time following wolf removal and their subsequent reintroduction were consistent with a top-down trophic cascade model involving nonlethal and possibly lethal effects. If similar top-down effects upon vegetation hold true in other regions of North America and other parts of the world where wolves have been extirpated, wolf recovery may represent a management option for helping to restore riparian plant communities and conserve biodiversity.

A knowledge-based approach to the statistical mapping of climate

The demand for spatial climate data in digital form has risen dramatically in recent years. In response to this need, a variety of statistical techniques have been used to facilitate the pro- duction of GIS-compatible climate maps. However, observational data are often too sparse and unrepresentative to directly support the creation of high-quality climate maps and data sets that truly represent the current state of knowledge. An effective approach is to use the wealth of expert knowl- edge on the spatial patterns of climate and their relationships with geographic features, termed 'geospatial climatology', to help enhance, control, and parameterize a statistical technique. Described here is a dynamic knowledge-based framework that allows for the effective accumulation, application, and refinement of climatic knowledge, as expressed in a statistical regression model known as PRISM (parameter-elevation regressions on independent slopes model). The ultimate goal is to develop an expert system capable of reproducing the process a knowledgeable climatologist would use to create high-quality climate maps, with the added benefits of consistency and repeata- bility. However, knowledge must first be accumulated and evaluated through an ongoing process of model application; development of knowledge prototypes, parameters and parameter settings; test- ing; evaluation; and modification. This paper describes the current state of a knowledge-based framework for climate mapping and presents specific algorithms from PRISM to demonstrate how this framework is applied and refined to accommodate difficult climate mapping situations. A weighted climate-elevation regression function acknowledges the dominant influence of elevation on climate. Climate stations are assigned weights that account for other climatically important factors besides elevation. Aspect and topographic exposure, which affect climate at a variety of scales, from hill slope to windward and leeward sides of mountain ranges, are simulated by dividing the terrain into topographic facets. A coastal proximity measure is used to account for sharp climatic gradients near coastlines. A 2-layer model structure divides the atmosphere into a lower boundary layer and an upper free atmosphere layer, allowing the simulation of temperature inversions, as well as mid-slope precipitation maxima. The effectiveness of various terrain configurations at producing orographic precipitation enhancement is also estimated. Climate mapping examples are presented.