Terrain Modification Research Articles

Hydrodynamic effects and water environment improvement of topographic reconstruction in shallow lakes

This paper focuses on a typical shallow lake, Lake Changdanghu, which is subject to frequent hydrodynamic disturbances and suspended sediment deposition, resulting in reduced water clarity and the degradation of the grass-type ecosystem. Using a combination of long-term systematic observations and numerical simulations, the impact of terrain modification on the hydrodynamic characteristics of Lake Changdanghu and its resulting environmental improvements are systematically analyzed. The results indicate that there is a significant correlation between the wind wave intensity, suspended solids concentration of the water, and water clarity. The artificial shoal project effectively reduces the local wind wave intensity, increases the water area of the weak waves, and alters the flow structure and transport path of the lake. The wave reduction effect of the artificial shoal significantly improves the transparency of the local water, especially under high wind wave conditions, with a 60% increase in the sheltered area, significantly improving the physical habitat environment. Additionally, the flow resistance and guidance roles of the artificial shoal concentrate the impact of the poor water quality of the inflow in a local area, reducing its adverse effects on the main body of the lake. Our research demonstrates that for shallow lakes, the water transparency can be improved, the physical habitat conditions for aquatic vegetation can be enhanced, and grass-type ecosystems can be gradually restored through artificial intervention and vegetation recovery projects by reducing the wave energy, flow resistance, and guidance through the construction of artificial shoals. This approach achieves long-term maintenance of eutrophication control and water quality improvement in shallow lakes.

Local Controls on Near‐Surface Glacier Cooling Under Warm Atmospheric Conditions

AbstractThe near‐surface boundary layer can mediate the response of mountain glaciers to external climate, cooling the overlying air and promoting a density‐driven glacier wind. The fundamental processes are conceptually well understood, though the magnitudes of cooling and presence of glacier winds are poorly quantified in space and time, increasing the forcing uncertainty for melt models. We utilize a new data set of on‐glacier meteorological measurements on three neighboring glaciers in the Swiss Alps to explore their distinct response to regional climate under the extreme 2022 summer. We find that synoptic wind origins and local terrain modifications, not only glacier size, play an important role in the ability of a glacier to cool the near‐surface air. Warm air intrusions from valley or synoptically‐driven winds onto the glacier can occur between ∼19% and 64% of the time and contribute between 3% and 81% of the total sensible heat flux to the surface during warm afternoon hours, depending on the fetch of the glacier flowline and its susceptibility to boundary layer erosion. In the context of extreme summer warmth, indicative of future conditions, the boundary layer cooling (up to 6.5°C cooler than its surroundings) and resultant katabatic wind flow are highly heterogeneous between the study glaciers, highlighting the complex and likely non‐linear response of glaciers to an uncertain future.

Ancient agricultural terrace walls control floods and regulate the distribution of Asphodelus ramosus geophytes in the Israeli arid Negev

Ancient stone terrace walls aimed at harvesting water runoff and facilitating crop production are widespread across the drylands of the Middle East and beyond. In addition to retaining the scarce water resource, the terrace walls also conserve soil and thicken its profile along ephemeral stream channels (wadis) by decreasing fluvial connectivity and mitigating erosional processes. In this study, we created hydrological models for three wadis with ancient stone terrace walls in the arid northern Negev of Israel, where the predominant geophyte species is Asphodelus ramosus L. A two-dimensional (2D) rain-on-grid (RoG) approach with a resolution of 2 m was used to simulate the rain events with return periods of 10, 20, 50, and 99 % (10-y, 5-y, 2-y, and yearly, respectively) based on the Intensity-Duration-Frequency rain curves for the region. To evaluate the effect of stone terrace walls on fluvial hydrology and geomorphology, the ground level was artificially elevated by 20 cm at the wall locations in a digital terrain model (DTM), using the built-in HEC-RAS 2D terrain modification tool. Our results showed that the terraced wadis have a high capacity to mitigate runoff loss, but a lesser capacity to delay the peak flow. Yet, for all rainstorm return periods, peak flow mitigation was positively related to the number of terrace walls along the stream channel. Field surveys in two of the studied wadis demonstrated that the A. ramosus clones were found in proximity to the stone terrace walls, presumably due to the greater soil–water content there. The results thus suggest that the terrace walls provide improved habitat conditions for these geophytes, supporting their growth and regulating their distribution along the wadi beds.

Looking at the Big Picture: Using Spatial Statistical Analyses to Study Indigenous Settlement Patterns in the North-Western Dominican Republic

After several field campaigns between 2007 and 2018 in the northwestern region of the Dominican Republic, more than 300 archaeological sites have been registered and revisited. While several of these sites were identified through the scatter of surface material culture, others show terrain modifications in the form of anthropogenic mounds and levelled areas. Researchers have gathered valuable information regarding these features’ functionality and construction processes through large-scale excavations in archaeological sites with anthropogenic mounds, paleoenvironmental studies and remote sensing analyses. These anthropogenic mounds represent a long-term process of formation and were used for a variety of purposes ranging from agricultural to ritual activities. While excavations and small-scale remote sensing can provide a myriad of data to improve our understanding of these archaeological sites, a regional perspective is needed to map the relationship among archaeological sites with and without terrain modifications, to better understand the Indigenous cultural patterns in their regional environment. In this regard, the primary objective of this paper is to explore to what extent these archaeological sites were related to the environment and each other. This was achieved by correlating archaeological data with a set of archaeologically recognized important environmental variables using advanced spatial statistics. The results provide important insights to understand the underlying pattern of archaeological sites in this region and its relationship with the environmental setting.

Fish Pain and Human Sport in Victorian Britain

Abstract: Victorian Britons were interested in encounters between humans and fish for many reasons: fishing for sport as opposed to food gathering was expanding rapidly in popularity; fishing was practiced by many different people in many ways around the world; and fish populations were visibly suffering from pollution, overfishing, and terrain modification. This article analyzes the changing meanings of these encounters through addressing the beliefs about fish pain held by Victorian anglers. These beliefs were intertwined with ideas about race, food, civilization, and class. Elite British anglers increasingly understood their relationship with fish and their own capacity to feel pain (and to judge others' pain) as a justification of their place as the managers and stewards of all fisheries, not just those in Britain.

Fish Pain and Human Sport in Victorian Britain

Abstract: Victorian Britons were interested in encounters between humans and fish for many reasons: fishing for sport as opposed to food gathering was expanding rapidly in popularity; fishing was practiced by many different people in many ways around the world; and fish populations were visibly suffering from pollution, overfishing, and terrain modification. This article analyzes the changing meanings of these encounters through addressing the beliefs about fish pain held by Victorian anglers. These beliefs were intertwined with ideas about race, food, civilization, and class. Elite British anglers increasingly understood their relationship with fish and their own capacity to feel pain (and to judge others' pain) as a justification of their place as the managers and stewards of all fisheries, not just those in Britain.

FaDebrisFOAM validation using field data surveyed in Crucecita (Chile) alluvial fan for the event of 13th May 2017

The openFOAM solver faDebrisFOAM was recently developed to simulate debris flows with the finite area method. This new solver includes, among other capabilities, a variable density for the solid-liquid mixture, erosion and deposition processes, and a terrain modification algorithm. To test the performance of this new solver, we simulate the debris flow event that occurred in the Crucecita alluvial fan on the 13th May 2017 in the Atacama Desert, Chile. Thanks to pre- and post-event topographies, we have an accurate measure of the morphological changes that took place. Comparing the field data and our numerical model results shows that faDebrisFOAM can reproduce the main flooded, eroded, and deposited areas. Once the model is calibrated, we study the behavior of the terrain modification algorithm. Finally, we discuss the advantages of using this model to reproduce erosion and deposition processes together with changing rheologies for a debris flow event.

Dredging transforms the seafloor and enhances functional diversity in urban seascapes

Landscape modification alters the condition of ecosystems and the complexity of terrain, with consequences for animal assemblages and ecosystem functioning. In coastal seascapes, dredging is routine practice for extracting sediments and maintaining navigation channels worldwide. Dredging modifies processes and assemblages by favouring species with wide trophic niches, diverse habitat requirements and tolerances to dredge-related eutrophication and sedimentation. Dredging also transforms the three-dimensional features of the seafloor, but the functional consequences of these terrain changes remain unclear. We investigated the effects of terrain modification on the functional diversity of fish assemblages in natural and dredged estuaries to examine whether dredging programs could be optimised to minimise impacts on ecological functioning. Fish assemblages were surveyed with baited remote underwater video stations and variation in functional niche space was described using species traits to calculate metrics that index functional diversity. Terrain variation was quantified with nine complementary surface metrics including depth, aspect, curvature, slope and roughness extracted from sonar-derived bathymetry maps. Functional diversity was, surprisingly, higher in dredged estuaries, which supported more generalist species with wider functional niches, and from lower trophic levels, than natural estuaries. These positive effects of dredging on functional diversity were, however, spatially restricted and were linked to both the area and orientation of terrain modification. Functional diversity was highest in urban estuaries where dredged channels were small (i.e. <1% of the estuary), and where channel slopes were orientated towards the poles (i.e. 171–189°), promoting both terrain variation and light penetration in urban estuaries. Our findings highlight previously unrecognised functional consequences of terrain modification that can easily be incorporated into dredging programs. We demonstrate that restricting the spatial extent of dredging operations and the orientation of dredged channel slopes, wherever this is practical, could help to limit impacts on ecosystem functioning and productivity in urban seascapes.

Palaeoflood level reconstructions in a lowland setting from urban archaeological stratigraphy, Rhine river delta, the Netherlands

Reconstructing water levels reached during past floods contributes to fluvial system understanding and flood risk assessments. For methodological restrictions, this type of research is usually conducted in confined valley settings. In this study, we expand upon that geomorphological context by reconstructing extreme flood levels in a lowland delta setting. We used the archaeological stratigraphy of medieval river cities in the Rhine delta to determine water levels for the largest historic flood in the year 1374. We obtained minimum estimates by identifying thin fluvial deposits interbedded with anthropogenic layers, and further constrained peak flood levels using fourteenth-century raised ground layers directly overlying these deposits. First, we tested the proposed method for extracting flood levels from urban archaeological stratigraphy in the city of Arnhem. Then, we complemented those results with archaeological and historical data in other cities to arrive at a complete overview for the Rhine delta. This overview shows that the 1374 flood levels exceed the highest levels in the instrumental record along the northern distributary (IJssel river), but not along the western distributaries in the central delta (Nederrijn and Waal rivers). This pattern is explained by changes in the discharge division over the different river branches and by the rise of embankments since late medieval times, which considerably decreased the flooded area. Thus, this study demonstrates not only the potential of palaeoflood reconstructions in lowland floodplain settings, but also the pitfalls, resulting from spatially complex flooding patterns and anthropogenic terrain modifications.

Onshore convection associated with the easterly wave over the South China Sea: A case study

A heavy rainfall event associated with a low-level shear line, a mid-level easterly wave, and a marine boundary layer jet occurred from 17 to 18 July 2017 along the coastal area of South China. The shear line was found associated with a low-level disturbance on the northwestern edge of the Luzon Island, while the easterly wave exerted significant influences on its maintenance and development over the South China Sea (SCS). Using the Global Forecast System (GFS) analysis and numerical simulations, the mechanism for the disturbance development is investigated. Along with its development, the disturbance extended upwards to the mid-level easterly wave and established an eastward-tilting structure under the effect of the vertical wind shear. When it approached the coast of South China, the height of the disturbance was lowered down due to the intensified divergence above it, and a slanting updraft was formed. A quasi-closed circulation within the easterly wave helped to protect the moist air inside and was favorable for sustained convection. The westward component of the divergent flow, which was induced by the downdraft below the easterly wave, converged in the disturbance that proved to be the primary mechanism for the disturbance development, while the cold core formed in the downdraft intensified the local baroclinicity and contributed to convection development. Although the simulation reproduced the disturbance evolution, it failed to reproduce the vertically tilting structure of the disturbance. In addition, the convection intensity in the simulation was overestimated due to the wet biases in the low troposphere. Sensitivity experiments showed that the disturbance moved faster and more westwards, when it was weakened through terrain modification, which led to stronger boundary layer jet and heavier precipitation.

The influence of seafloor terrain on fish and fisheries: A global synthesis

AbstractThe structure of seafloor terrain affects the distribution and diversity of animals in all seascapes. Effects of terrain on fish assemblages have been reported from most ecosystems, but it is unclear whether bathymetric effects vary among seascapes or change in response to seafloor modification by humans. We reviewed the global literature linking seafloor terrain to fish species and assemblages (96 studies) and determined that relief (e.g. depth), complexity (e.g. roughness), feature classes (e.g. substrate types) and morphology (e.g. curvature), have widespread effects on fish assemblages. Research on the ecological consequences of terrain have focused on coral reefs, rocky reefs, continental shelves and the deep sea (n ≥ 20 studies), but are rarely tested in estuaries (n = 7). Fish associate with a variety of terrain attributes, and assemblages change with variation in the depth and aspect of bathymetric features in reef and shelf seascapes, and in the deep sea. Fish from different seascapes also respond to distinct metrics, with fluctuations in slope of slope (coral reefs), rugosity (rocky reefs) and slope (continental shelves, deep sea) each linked to changes in assemblage composition. Terrain simplification from coastal urbanization (e.g. dredging) and resource extraction (e.g. trawling) can reduce fish diversity and abundance, but assemblages can also recover inside effective marine reserves. The consequences of these terrain changes for fish and fisheries are, however, rarely measured in most seascapes. The key challenge now is to examine how terrain modification and conservation combine to alter fish distributions and fisheries productivity across diverse coastal seascapes.

Seasonal hydrochemical dynamics of surface water in the Limbang River, Northern Borneo—evaluating for spatial and temporal trends

Limbang River Basin (LRB), an equatorial tropical river basin which witnesses the effect of climate change and terrain modification, is hydro-statistically characterized in the present research. In order to characterize the seasonal dynamics of hydrochemical characteristics of surface water, a total of 72 surface water samples were collected from 24 locations in the Limbang River and its tributaries for three different sampling periods (November 2016 (S1), March 2017 (S2), and September 2017 (S3)). Physical parameters (pH, electrical conductivity (EC), total dissolved solids (TDS), dissolved oxygen (DO), turbidity), nutrients (sulfate, nitrate, ammonia, phosphate), major ions (Ca, Mg, Na, K, Cl, HCO3), and trace metals (Co, Ni, Cd, Fe, Mn, Pb, Zn, Cu) were analyzed using standard procedures and the results were statistically processed through Pearson correlation and factor analysis. Gibbs diagram, Piper plot, partial pressure of carbon dioxide, and saturation index of carbonate minerals were also employed to determine the geochemical characteristics and dominant processes operating in the river basin. Higher mean EC value of 129.28 μS/cm in S3 and higher mean pH (6.77) in S1 were observed. The results show spatial and temporal variations in analyzed parameters but are within tolerable limits of the Malaysian water quality and WHO standards. A decreasing order of HCO3- > Cl- > Na+ > Mg2+ > Ca2+ > K+ was noted in the mean concentration of major ions, whereas the mean concentration of trace metals follows the order of Fe > Ni > Pb > Mn > Zn > Co > Cu > Cd. Higher mean concentration of HCO3 (47.09 mg/L) in S2 and higher mean concentration of Fe (1.77 mg/L) in S1 were observed. The Pearson correlation test (r ≥ ± 0.70) shows varying relationships among the parameters and is different in three sampling periods. Piper diagram revealed two distinct chemical facies such as mixed Ca2+-Mg2+-Cl- and Ca2+-Mg2+-HCO3- irrespective of seasons. At the same time, Gibbs plots indicated dominant control of precipitation (rainfall) with an influence of mineral dissolution over the surface water chemistry. An increasing trend of log pCO2 values from upstream to downstream shows the direct recharge of rainwater with lower log pCO2 values in the upstream side and mixed water with higher log pCO2 in the downstream side. The saturation index indicates the under-saturated state of the carbonate minerals in the order of SIMagnesite > SICalcite > SIAragonite > SIDolomite and suggesting the effect of dilution through monsoon rainfall. Factor analysis revealed the dominance of high sediment load in response to severe rainfall, weathering, leaching and dissolution of bed rocks, hydrolysis of organic nitrogen through decomposition of microorganisms, and the aerobic decomposition of organic nitrogenous matter and atmospheric fallout as the major contributors of surface water geochemistry.

LiDAR-derived high-resolution palaeo-DEM construction workflow and application to the early medieval Lower Rhine valley and upper delta

Reconstruction of past topography in palaeo-DEMs serves various geomorphological analyses. Constructing a palaeo-DEM by stripping young elements from a LiDAR DEM can provide results for large study areas at high resolution. However, such a ‘top-down’ approach is more suited to recent periods and geomorphologically static parts of the landscape than to geomorphologically dynamic areas and periods farther back in time. Here, we explore this approach by reconstructing the early medieval (circa 800CE) topography of the Lower Rhine river valley and upper delta in Germany and the Netherlands. The large (4500km2) study area contains abundant anthropogenic terrain modification and stretches across geomorphologically active as well as inactive zones. We first removed all anthropogenic relief elements from the LiDAR DEM, using separate procedures for linear and non-linear elements. These steps were sufficient to obtain the palaeotopography of the inactive zone, characterized by inherited natural relief. Then, we reconstructed the topography and bathymetry in the fluvially-reworked active zone by incorporating geological and historical geographical information. We present and evaluate zonal averages of elevation differences between the modern and past valley floor topography in this densely populated area with complex land-use history, which allows us to approximate total anthropogenic volumetric change. Further comparisons with the modern LiDAR DEM elucidate changes in floodplain negative-relief connectivity, showing the potential importance of investing in palaeo-DEMs when assessing past river flooding. Our palaeo-DEM construction workflow is deployable at diverse spatial scales and widely applicable to other lowland areas, because of its top-down and generic nature. The relative importance of different workflow aspects depends on the time period that is targeted. Beyond a target age of 10–15ka, valley floors that are too large in area are to be considered geomorphologically dynamic and the top-down approach to palaeo-DEM construction is no longer advisable.

Local terrain modification method considering physical feature constraints for vector elements

ABSTRACT Many studies have been focused on rendering 2D vector elements on 3D terrain, and a series of algorithms have been proposed. Most of these algorithms struggle to provide a seamless overlay between vector elements and an irregular terrain surface. Despite their importance, the physical characteristics of vector elements are often ignored, which distorts the surface of vector elements. For example, if vector elements that represent roads and rivers are simply overlaid on terrain, the phenomena of uneven surfaces and rivers going uphill may occur because of elevation fluctuation. To correct these deficiencies, terrain should be modified according to the physical characteristics of vectors. We propose a local terrain modification method: First, the elevation of terrain covered by vector elements is recalculated according to vectors’ physical characteristics. Second, the multigrid method is used to realize a smooth transition between the modified terrain and its surrounding area. Finally, by setting different transition ranges and comparing the visualization effects, rules are given for the selection of a suitable range. After modification, the terrain conforms to vectors’ physical characteristics, and the overall relief is undamaged. The proposed method was applied to a CPU–GPU parallel heterogeneous model and demonstrated a high level of performance.

Vegetation development in a stormwater management system designed to enhance ecological qualities

Urban green areas can provide ecosystem services such as biodiversity conservation, recreational and educational services, and local climate regulation including stormwater management. Implementation of sustainable urban drainage systems (SUDS) allows for development of designs targeting desired habitats or species groups. This study investigated short-term changes in a plant community following implementation of a SUDS designed to enhance nature quality of a 4.8 ha urban grassland in Lynge, Denmark. Dry basins allowed for water detention with construction entailing terrain modifications, seeding of target species and changes to water dynamics, resulting in four treatments differing in soil conditions and water regimes. Plant species richness and composition were documented before (2012) and two years after (2015 and 2016) implementation of the SUDS. A floral resources index was composed to assess the quality of the flora as foraging resource for four groups of bees. Plant species richness, alpha- and beta-diversity as well as frequency of target plant species significantly increased after SUDS construction, as did floral resources for bees. Increased alpha diversity was primarily seen in areas around dry basins, while the increase in overall beta-diversity related to a shift in plant community composition within dry basins. The SUDS construction also changed dominance relationships among plant groups as forb cover increased at the expense of grasses, and cover of seeded and post-construction naturally colonising species increased. Two years after construction this study confirms potentials of SUDS to enhance ecological value of urban grasslands, when targets for ecological enhancement are integrated in the SUDS design.

Water harvesting techniques based on terrain modification enhance vegetation survival in dryland restoration

To successfully restore drylands, where the scarcity of water is one of the main limiting factors for plant survival, water inputs should be enhanced as much as possible. A specific type of water harvesting that concentrates runoff generated in bare areas upslope (runoff source areas) in a planting area downslope (runoff sink area) is an effective technique that, unlike traditional restoration, does not entail much over-cost. The objective of this study was to analyze the effectiveness of terrain modification techniques, aimed at water harvesting, on a degraded hillslope at a quarry restoration site in an arid area (Almeria, southeast Spain). Two different terrain modifications, to harvest surface runoff and increase soil water retention, were applied at two different hillslope sectors: a) micro-catchments were constructed on the upper section of the hillslope, where the slope gradient was high and b) narrow terracing was done in the middle part of the hillslope, which was characterized by moderate slope gradients. An additional sector, not subjected to terrain modification treatment, was used as a control, and was set in the lower part of the hillslope where the slope gradient was the lowest. A similar planting system was adopted for all experimental treatments; planting was done in 12 fertility island patches. Within each patch 12 different autochthonous plant species were planted in a staggered pattern with 80 cm separation. All plant species, which were from a nursery, were planted within a 1 L container made from organic fibers and containing compost from plant residues enriched with zeolites. To determine the microtopographical modifications required in the analysis of the optimal water harvesting strategy, a digital elevation model, with 0.2 m spatial resolution, was created from the data generated using a terrestrial laser scanner. Runoff flow direction and contribution areas, as well as a set of topographical attributes strongly related to the terrain water retention capacity (wetness index, slope gradient, aspect, USLE LSF factor, etc.), were calculated. Results indicated that micro-catchments had the highest plant survival rates and vegetation coverage values because they were the terrain treatment areas with the largest capacity to retain run-on from contributing areas. The areas without terrain modification (control areas) showed the highest plant mortality.

Analyzing complex wake-terrain interactions and its implications on wind-farm performance.

Rotating wind turbine blades generate complex wakes involving vortices (helical tip-vortex, root-vortex etc.).These wakes are regions of high velocity deficits and high turbulence intensities and they tend to degrade the performance of down-stream turbines. Hence, a conservative inter-turbine distance of up-to 10 times turbine diameter (10D) is sometimes used in wind-farm layout (particularly in cases of flat terrain). This ensures that wake-effects will not reduce the overall wind-farm performance, but this leads to larger land footprint for establishing a wind-farm. In-case of complex-terrain, within a short distance (say 10D) itself, the nearby terrain can rise in altitude and be high enough to influence the wake dynamics. This wake-terrain interaction can happen either (a) indirectly, through an interaction of wake (both near tip vortex and far wake large-scale vortex) with terrain induced turbulence (especially, smaller eddies generated by small ridges within the terrain) or (b) directly, by obstructing the wake-region partially or fully in its flow-path. Hence, enhanced understanding of wake- development due to wake-terrain interaction will help in wind farm design. To this end the current study involves: (1) understanding the numerics for successful simulation of vortices, (2) understanding fundamental vortex-terrain interaction mechanism through studies devoted to interaction of a single vortex with different terrains, (3) relating influence of vortex-terrain interactions to performance of a wind-farm by studying a multi-turbine wind-farm layout under different terrains. The results on interaction of terrain and vortex has shown a much faster decay of vortex for complex terrain compared to a flatter-terrain. The potential reasons identified explaining the observation are (a) formation of secondary vortices in flow and its interaction with the primary vortex and (b) enhanced vorticity diffusion due to increased terrain-induced turbulence. The implications of this vortex-terrain interactions on wind-farm performance is observed by comparing two LES simulations of a multi-turbine wind-farm layout (in real actual complex terrain and a made-up flat terrain scenario) with the observed annual power data at the actual wind-farm. The comparison reveals drop in power production due to terrain and wake effects for flatter terrain case. The insights from this study can serve as a step towards enhancing wake-dissipation through either artificial obstruction or artificial terrain modifications.

Convective Initiation near the Andes in Subtropical South America

Abstract Satellite radar and radiometer data indicate that subtropical South America has some of the deepest and most extreme convective storms on Earth. This study uses the full 15-yr TRMM Precipitation Radar dataset in conjunction with high-resolution simulations from the Weather Research and Forecasting Model to better understand the physical factors that control the climatology of high-impact weather in subtropical South America. The occurrence of intense storms with an extreme horizontal dimension is generally associated with lee cyclogenesis and a strengthening South American low-level jet (SALLJ) in the La Plata basin. The orography of the Andes is critical, and model sensitivity calculations removing and/or reducing various topographic features indicate the orographic control on the initiation of convection and its upscale growth into mesoscale convective systems (MCSs). Reduced Andes experiments show more widespread convective initiation, weaker average storm intensity, and more rapid propagation of the MCS to the east (reminiscent of the MCS life cycle downstream of lower mountains such as the Rockies). With reduced Andes, lee cyclogenesis and SALLJ winds are weaker, while they are stronger in increased Andes runs. The presence of the Sierras de Córdoba (secondary mountain range east of the Andes in Argentina) focuses convective initiation and results in more intense storms in experiments with higher Andes. Average CAPE and CIN values for each terrain modification simulation show that reduced Andes runs had lower CIN and CAPE, while increased Andes runs had both stronger CAPE and CIN. From this research, a conceptual model for convective storm environments leading to convective initiation has been developed for subtropical South America.

Sistemas de información geográfico y la preservación del patrimonio natural y cultural: la exploración de La Mosquitia hondureña

En Mayo del 2012, después de más de un año de investigación y planeación, un grupo dirigido por el cinematógrafo Steve Elkins con el respaldo de Bill Benenson, y Garry Spire, realizó el primer mapeo exploratorio de la Mosquitia Hondureña utilizando tecnología LiDAR abordo un avión bimotor Cessna 337. La tecnología Li- DAR, que es un acrónimo en Inglés para Light Detection and Ranging, es también conocida como Radar Óptico o Radar Laser y utiliza pulsos laser para generar mapas tridimensionales de la superficie terrestre. En general, equipos LiDAR actuales permiten detectar múltiples retornos para cada pulso emitido a medida que estos se propagan a través de aberturas en las coronas de los árboles y demás vegetación hasta el terreno debajo de ella. A través de filtros morfológicos es posible clasificar los retornos como provenientes de vegetación o del suelo, lo que permite separar los retornos del suelo revelando lo que el bosque oculta. La Mosquita provee las condiciones más difíciles para probar las capacidades de la tecnología LiDAR.La planeación, recolección, procesamiento y análisis preliminar de los datos LIDAR fue efectuada por técnicos del centro de investigación de ciencias e ingeniería de sistemas de Geopercepción de la Universidad de Houston y el Centro Nacional para el Mapeo Laser Aéreo de la Fundación Nacional para la Ciencia. El mapeo se enfocó en varias aéreas dentro de una extensión de jungla de aproximadamente 1000 km² en el departamento de Gracias a Dios. Los planes de vuelo y el equipo fueron configurados para lograr la máxima penetración a través de la vegetación. Emitiendo más de 20 pulsos/m² y obteniendo aproximadamente 31 retornos/m² de los cuales solo 1 o 2 corresponden al suelo. Los modelos digitales de elevación de terreno revelan debajo de la espesa vegetación una exuberante topografía y una muy compleja hidrografía. Mas interesante, muestran una extensa modificación antropogénica del terreno, en lo que parece ser restos arqueológicos.Revista Ciencias Espaciales, Volumen 8, Número 1 Primavera, 2015; 260-276

STUDY ON THE SEDIMENT TRANSPORT PROCESSES IN CAM RANH BAY USING MIKE 21/3 FM COUPLE MODEL

In this paper, MIKE 21/3 FM COUPLE software was applied to assess the impact of wind, wave, current, tides in South-West monsoon on sediment transport and bottom terrain modification in Cam Ranh bay. The results show that: In South-West monsoon, the impact of wave and current is minor. Tide is dominant factor effecting sediment spread. In the flood tide phases, tide increases the penetration of sea water and sediment from open sea into the lagoons and vice versa during ebb tide phases, hence, sediment accumulation and bottom terrain modification is not much.