Flooding effects on grassland species composition in the Azul creek basin, Argentina

2017 ◽  
Vol 39 (3) ◽  
pp. 245 ◽  
Author(s):  
Ilda Entraigas ◽  
Natalia Vercelli ◽  
Guadalupe Ares ◽  
Marcelo Varni ◽  
Sofía Zeme

From a hydrological point of view, the characteristic of the water behaviour in catchments so depressed as the Azul creek basin (centre of Buenos Aires province, Argentina) is water accumulation above the land surface. Thus, water on the ground does not have a single runoff direction, but moves in a disorderly, indefinite and unpredictable way. Considering that periodic floods are a typical disturbance of the region, the objective of this study is to analyse, under field conditions, the transformative effect of prolonged flooding on floristic composition, taking into account the different vegetation patches and their relative position over the relief, the chemical characteristics and the groundwater fluctuation, and some edaphic properties in each site. Vegetation samplings were performed during three consecutive springs, when the grassland was on different hydrological conditions due to very different rainfall precedent histories. A digital terrain model of the study area was built and a flow accumulation map was created from it. Pits were dug to describe edaphic variables and shallow wells were drilled for monitoring the groundwater characteristics. Flooding, in relation with surface and groundwater dynamics and soil characteristics, is the factor that determines and promotes the differentiation among sites that are relatively close, contiguous and even topographically in almost identical positions. So, some patches of vegetation get their differentiation through the limiting conditions of their soils, while others receive greater influence from the hydrodynamics to which they are subject. Thus, in this study it becomes evident how certain stands are floristically homogenised or differentiated over time according to their flooding conditions and, hence, according to the area from which they receive surface and groundwater flow. Also, results corroborate the way the water regime determines the structure and heterogeneity of plant communities in such environments.

2021 ◽  
Vol 14 (4) ◽  
pp. 2186-2203
Author(s):  
Bárbara Fernanda da Cunha Tasca ◽  
Fernanda Vieira Xavier ◽  
Auberto José Barros Siqueira

Identifying urban headwaters and delimitating their Permanent Preservation Areas (PPA) before its inevitable degradation by the human occupation is essential to guarantee the long-term sustainability of the cities. However, the scarcity of tools for facilitating this purpose prevents public authorities from speeding up their control actions. As headwaters frequently occur near the beginning of first-order drainage channels, it is assumed that their location can be obtained by using numerical models of the land surface. Thus, this study aimed to evaluate and demonstrate the applicability of a Digital Terrain Model (MDT) as an auxiliary tool in the prospecting process in spring fields in the urban area of Cuiabá, MT, Brazil. The methodology consisted of extracting the drainage channels from the modeled area, making it possible to indicate locations for prospecting corresponding to the head regions of the first order channels. The results show that 62,8% of the occurrence of the headwaters were in a 300m radii from the first-order start points. However, it was not possible to issue a conclusive evaluation in 28,6% of the places due to the high level of anthropization. Nevertheless, only in 8,6% of them did not present any water emergence in the surroundings, indicating the effectiveness of this method in guiding the prospection of headwaters in field. We concluded that our procedures are worthful for cities that have detailed altimetric surveys, being especially useful in urban expansion areas, where the preventive character of headwaters conservation is essential.


2021 ◽  
Vol 12 (25) ◽  
pp. 158
Author(s):  
Pablo Aparicio-Resco ◽  
Alejandro García Álvarez-Busto ◽  
Iván Muñiz-López ◽  
Noelia Fernández-Calderón

<p class="VARKeywords">The virtual reconstruction of a site is the mirror in which the archaeological research process is reflected, with all its uncertainties and certainties, generating a space for reflection on the lost materiality while the vestige itself is reconfigured into a didactic and social resource. Here we present the result of the three-dimensional (3D) reconstruction of the archaeological structures preserved in the Peñón de Raíces, in Castrillón (Asturias), which correspond to the ruins of the castle of Gauzón, a famous fortification of the Asturian kings in which La Cruz de la Victoria was made in 908.</p><p>The article begins with an introduction and a first part (Section 2) dedicated to the explanation of the site itself from an archaeological and historical point of view. We believe that this analysis should be the basis of any scientific virtual reconstruction. The virtual reconstruction presented here is dated to the 9-10th centuries and corresponds to the fortification built in the time of the Asturian kings. We offer a detailed analysis of the morphological and architectural components that have been documented in this defensive settlement in the light of archaeological research, and that provide the main foundations for the infographic reconstruction.</p><p>In the second part of the article (Section 3), we analyse the specific sources of historical and archaeological information that support the reconstruction and serve as a reference for it. The historical-archaeological sources used for the representation, for example, of the walls and the palaeoenvironmental environment, are detailed. Likewise, we comment on the process of discussion of the different hypotheses that, finally, lead to the presented result. It is important to note that without this discussion process it is not possible to produce a sound and solid proposal over time.</p><p>In the third part (Section 4), we show the result of the virtual reconstruction with a series of images. To obtain the virtual reconstruction presented in this article, the Blender Geographic Information System (GIS) addon has been used, which allows us to have a digital terrain model (DTM) on our 3D desktop easily so that we can begin to carry out the work from it. The archaeological planimetries were arranged on it and, based on all this information, the modelling process began. In the first place, basic modelling of volumes was carried out that served to raise the first sketches and, on them, to continue discussing the reconstructive hypotheses. Little by little the geometry of the virtual reconstruction was detailed and the castle took shape. The next step was to carry out texturing in a photorealistic way, for which it was decided to use Substance Painter software. We continued with the texturing and addition of details of the surrounding terrain using particle systems, which has been one of the most complex phases to carry out given the level of realism that we set ourselves as a goal. Later, other types of minor details were added: objects, characters and animals, which help to better understand the context. Finally, the final renderings are carried out and their post-processing is developed in Adobe Photoshop, for which matte painting techniques were used that merge 3D images with photographs and digital drawing.</p><p>Our interest was to carry out scientific graphic work, for which we have emphasized the importance of using the scale depicting historical/archaeological evidence for virtual reconstructions, a tool that allows us to ensure the principles of authenticity and scientific transparency of any virtual reconstruction (Aparicio et al., 2016). In this case, thanks to this tool, it is clear that the highest level of evidence is found in the castle itself excavated in the acropolis, while the town and the surrounding palisade clearly show a lower level of evidence. We hope that subsequent excavations in this area will allow us to review the reconstruction and thus also reflect a higher level of evidence in this area.</p><p>We believe that the work presented here constitutes a good example of the use of virtual scientific reconstruction for the development and consolidation of new hypotheses not only reconstructive but also interpretive of an archaeological site. Furthermore, the result presented here demonstrates the power of this graphic resource for the dissemination of historical-archaeological knowledge, a fundamental objective when carrying out any scientific work.</p><p><strong>Highlights:</strong></p><ul><li><p>Reconstrucción infográfica de una de las principales fortificaciones del reino de Asturias (s. VIII-X), a partir de la evidencia material documentada en las campañas de excavación arqueológica realizadas en el yacimiento.</p></li><li><p>Desarrollo de hipótesis reconstructivas de arquitectura militar altomedieval arruinada mediante la interpretación de vestigios arqueológicos aplicando un enfoque multidisciplinar.</p></li><li><p>Ejemplo de uso de la escala de evidencia histórico-arqueológica y de las unidades reconstructivas (UR) como instrumentos que permiten garantizar los principios de autenticidad y transparencia científica.</p></li></ul>


2020 ◽  
Author(s):  
Daniele Fabrizio Bignami ◽  
Leonardo Stucchi ◽  
Daniele Bocchiola ◽  
Christian Zecchin ◽  
Davide Del Curto ◽  
...  

&lt;p&gt;Keeping ISA Modern is a project of Fondazione Politecnico di Milano and other partners aimed at planning the conservation of some of the buildings (Schools) of the University of Arts (ISA) of Cuba, built over a former country club, designed by eminent architects of the time (Vittorio Garatti, Roberto Gottardi and Ricardo Porro), and bestowed with the status of UNESCO World Heritage in 2003.&lt;/p&gt;&lt;p&gt;Most of the Schools are currently unusable, also due to damages caused by frequent floods from the surrounding Rio Quib&amp;#249; river, and they need urgent restoration if they are to be used. Personnel of Politecnico di Milano carried out a field survey on the Rio Quib&amp;#249; during 2019, and also based upon information from the Cuban National Institute of Hydraulic Resources (INRH) they studied established flood risk for ISA.&lt;/p&gt;&lt;p&gt;Here, we built a high-resolution digital terrain model (DTM) of the park where Schools are located, using laser scanner data, and previously georeferenced points. Using field measurements taken in June 2019 we were able to assess geometry (included bridges), slope and roughness coefficients of the main channel of the Quib&amp;#249; river, influence of the sea level. Then using as input critical discharge data provided by INRH we evaluated flood area and flood volume for 4 representative return periods (5, 20, 50, 100 years).&lt;/p&gt;&lt;p&gt;The most impacted building is the School of Ballet, located within a narrow meander of Rio Quib&amp;#249;, immediately upstream of a narrow bridge, clogging largely during floods, only 1 km far from the sea, and with drainage system unable to discharge storm water.&lt;/p&gt;&lt;p&gt;Given the high required cost, a partially collapsed wall originally partially protecting the School of Ballet was not rebuilt, and we are now exploring flood mitigation strategy which are cheaper, and feasible from the point of view of compatibility with the historical and architectural value of the building.&lt;/p&gt;


2015 ◽  
Vol 11 (1) ◽  
Author(s):  
Luiz Gilberto Bertotti ◽  
Mauricio Camargo Filho ◽  
Marcos Aurélio Pelegrina ◽  
Marquiana Freitas Vilas Boas Gomes ◽  
Bruno Henrique Costa Toledo ◽  
...  

2015 ◽  
Vol 3 (2) ◽  
pp. 8-11
Author(s):  
Mária Mrázová ◽  

Digital terrain model is applicable for many possibilities related to aerial works by use of photogrammetry or laser scanning of the earth’s surface. For the purpose of this research we consider just laser scanning used for work in difficult mountain terrain. The terrain of the Slovak Republic has many high hills and it signifies more complex flight planning, as laser scanning is usually flown in lower heights than photogrammetry. Moreover, as lower height is above terrain than the overlap between subsequent LIDAR strips is also lower. This situation can also lead towards the negative value in extreme instances. This paper also describes the most effective way for flight planning during laser scanning of mountain terrain by comparison of two different technologies from operational and economical point of view.


Author(s):  
Ioan Voina ◽  
Maricel Palamariu ◽  
Iohan Neuner ◽  
Tudor Salagean ◽  
Dumitru Onose ◽  
...  

With the development of specialized software applications it was possible to approach and resolve complex problems concerning automating and process optimization for which are being used field data. Computerized representation of the shape and dimensions of the Earth requires a detailed mathematical modeling, known as "digital terrain model". The paper aims to present the digital terrain model of Vulcan mining, Hunedoara County, Romania. Modeling consists of a set of mathematical equations that define in detail the surface of Earth and has an approximate surface rigorously and mathematical, that calculated the land area. Therefore, the digital terrain model means a digital representation of the earth's surface through a mathematical model that approximates the land surface modeling, which can be used in various civil and industrial applications in. To achieve the digital terrain model of data recorded using linear and nonlinear interpolation method based on point survey which highlights the natural surface studied. Given the complexity of this work it is absolutely necessary to know in detail of all topographic elements of work area, without the actions to be undertaken to project and manipulate would not be possible. To achieve digital terrain model, within a specialized software were set appropriate parameters required to achieve this case study. After performing all steps we obtained digital terrain model of Vulcan Mine. Digital terrain model is the complex product, which has characteristics that are equivalent to the specialists that use satellite images and information stored in a digital model, this is easier to use.


2019 ◽  
Vol 16 (1) ◽  
pp. 89-97
Author(s):  
Stanisław Rudowski ◽  
Radosław Wróblewski ◽  
Janusz Dworniczak ◽  
Kazimierz Szefler ◽  
Benedykt Hac ◽  
...  

Abstract The purpose of the paper is to present the potentialities of current non-invasive methods for bottom surveys, including cartometric presentation of its relief and structure in both marine and inland reservoirs. The paper presents examples of results obtained in the Maritime Institute in Gdańsk during surveys carried out at the bottom of seas, lakes and rivers with the use of the same apparatus: primarily, a multibeam echosounder (MBES) to obtain a digital terrain model (DTM); a side-scan sonar (SSS) to obtain a general image of the nature of the bottom (its “roughness”); and seismic profiling (sub-bottom profiler, sediment echo sounder [SES]) to recognise the structure of the bottom. The obtained results constitute a necessary basis for carrying out further specialist surveys (non-invasive or invasive) when needed. Current bottom survey options that use MBES, SSS and SES may be treated as subaqueous equivalents of the subaerial potentialities of a land surface survey using LiDaR and GPR (Ground Penetration Radar).


2021 ◽  
Vol 10 (5) ◽  
pp. 285
Author(s):  
Sergio Iván Jiménez-Jiménez ◽  
Waldo Ojeda-Bustamante ◽  
Mariana Marcial-Pablo ◽  
Juan Enciso

Digital terrain model (DTM) generation is essential to recreating terrain morphology once the external elements are removed. Traditional survey methods are still used to collect accurate geographic data on the land surface. Given the emergence of unmanned aerial vehicles (UAVs) equipped with low-cost digital cameras and better photogrammetric methods for digital mapping, efficient approaches are necessary to allow rapid land surveys with high accuracy. This paper provides a review, complemented with the authors’ experience, regarding the UAV photogrammetric process and field survey parameters for DTM generation using popular commercial photogrammetric software to process images obtained with fixed-wing or multicopter UAVs. We analyzed the quality and accuracy of the DTMs based on four categories: (i) the UAV system (UAV platforms and camera); (ii) flight planning and image acquisition (flight altitude, image overlap, UAV speed, orientation of the flight line, camera configuration, and georeferencing); (iii) photogrammetric DTM generation (software, image alignment, dense point cloud generation, and ground filtering); (iv) geomorphology and land use/cover. For flat terrain, UAV photogrammetry provided a horizontal root mean square error (RMSE) between 1 to 3 × the ground sample distance (GSD) and a vertical RMSE between 1 to 4.5 × GSD, and, for complex topography, a horizontal RMSE between 1 to 7 × GSD and a vertical RMSE between 1.5 to 5 × GSD. Finally, we stress that UAV photogrammetry can provide DTMs with high accuracy when the photogrammetric process variables are optimized.


2015 ◽  
pp. 26-37
Author(s):  
V. B. Golub ◽  
V. V. Bondareva ◽  
A. N. Sorokin ◽  
L. F. Nikolaychuk

Plant communities with reed domination (Phragmites australis agg.) occupy the large areas in the Lower Volga Valley and especially in the river delta. We have set the task to reveal the diversity of these communities in the Lower Volga Valley. For this purpose, we applied the database that is registered in the Global Index of Vegetation-Plot Databases (GIVD) under the EU-RU–002 index (http://www.givd.info/) and includes 14871 relevés made during the period from 1924 to 2013. Communities with the dominance of reed were defined as such, if the coverage of this plant was more than 50 %. We have found 375 such relevés in the database. At first, one basal community, 3 associations and 3 subassociations with domination of Phragmites australis agg. were distinguished in the Lower Volga Valley. All processing and analysis of relevés were performed using the software package JUICE 7.0. (Tichý, 2002). The «Cocktail» method was applied to establish the sociological groups that indicate environmental conditions (Bruelheide, 2000). The expert system for selection from the database of relevés by means of these groups was created. It is allowed us to ascribe relevés to earlier distinguished associations, subassociations and basal community. 171 relevés have been identified by the expert system and they were assigned to association, subassociation or the basal community. 204 relevés were not referred to any association, subassociation or the basal community. We wanted to answer the question: are there among these 204 relevés, which could be interpreted as the new syntaxa, giving them the proper ecological characteristics? For this purpose, the cluster analysis of 204 relevés has been carried out. The optimal level of clustering was determined by calculating the index of “crispness of classification” (Botta-Dukát et al., 2005). The greatest “crispness of classification” was reached at allocation of 13 clusters. Consideration of the floristic composition of allocated groups had shown that 11 of them were the transitional plant communities among the earlier established syntaxa. Only two clusters were differed in rather original structure that we could explain by the influence of environment factors. We have identified them as new associations Rubio tataricae-Phragmitetum australis and Cynancho acuti-Phragmitetum australis. All associations with the dominance of Phragmites australis agg. distinguished in the Lower Volga Valley were included in the alliance Phragmition communis Koch 1926, order Phragmitetalia communis Koch 1926. In literary sources from the ecological point of view these syntaxa are defined as the wetland communities, which are closely linked to water bodies (Šumberová et al., 2011; Ermakov, 2012). However, in many cases this definition does not correspond to the ecology of plant communities with the dominance of reed in the lower reaches of the Volga River. Ecotops of these communities are flooded for up to 2–3 months in a year and then they dry out. In the autumn, the ground water level can drop to a depth of one meter (Golub et al., 2011). The plant satellites of the reed here are often mesophytic plants such as Rubus caesius, Calamagrostis epigeios, Phalaris arundinacea, Rubia tatarica, Althaea officinalis, and Rumex stenophyllus. Therefore, the inclusion of phytocoenosises with domination of the reed in the lower reaches of the Volga River in the alliance Phragmition communis is rather relative. A correct placement of these plant communities in the system of vegetation syntaxa of the arid areas can be made only if it is based on original data obtained from much bigger territory than the Lower Volga Valley. In future geobotanical studies, it is desirable to divide the aggregation of Phragmites australis agg. into smaller species taxa.


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