O crescimento das cidades médias brasileiras tem promovido o desenvolvimento de distintos problemas ambientais em seus sistemas hidrogeomorfológicos, exigindo a sistematização de estudos que permitam ...a avaliação dos efeitos das intervenções antrópicas nas formas e processos geomorfológicos. Nessa perspectiva, o presente estudo teve como objetivo avaliar as mudanças morfológicas induzidas pelas atividades antrópicas na bacia hidrográfica do Córrego da Água Quente, situada em setor de expansão urbana de São Carlos, cidade de médio porte do centro-leste do estado de São Paulo. O estudo foi conduzido pelos princípios da Antropogeomorfologia e da cartografia geomorfológica de detalhe. Com base nesses pressupostos teórico-metodológicos, realizou-se o mapeamento de cenários representativos da morfologia pré-perturbação antrópica e da morfologia antropogênica, e de geoindicadores que denotam à dinâmica de feições geomórficas de detalhe numa série histórica de 48 anos. As mudanças morfológicas decorrentes dos usos urbanos e rurais promoveram o aumento nos parâmetros extensão e quantidade dos geoindicadores de origem denudativa, indicando a intensificação da erosão linear e a degradação dos solos nos segmentos de vertentes. A concomitante ampliação da sinuosidade do curso d’água principal evidencia os efeitos indiretos da interferência antrópica na dinâmica fluvial. A diversidade paisagística identificada no eixo de expansão de cidade média evidencia a possibilidade da formulação de modelos de planejamento físico-territorial adequados às características ambientais dos sistemas hidrogeomorfológicos em estágio de perturbação ativa.
Developing countries face more impacts due to natural hazards because of rapid urbanization, natural resources overexploitation, and lack of territorial management. Mexico City is one of the most ...populated metropolitan areas of the world and in addition, due to its geophysical dynamics and increasing vulnerability, is frequently impacted by natural disasters. Every year, various natural hazards affect Iztapalapa district, the most densely populated political-administrative unit in Mexico, and represent a high risk for approximately two million inhabitants. We used various geomorphic analyses to develop a feasible methodology to reduce the disaster risk in Iztapalapa district. In order to understand the general geomorphic dynamic of Iztapalapa district, we defined three geomorphological regions: the lacustrine plain, the volcanic piedmont, and the mountain area. Afterwards, we developed a geomorphological mapping based on LiDAR and aerial photographs to obtain thirty landforms divided into endogenic and exogenic landforms, both erosional and depositional, at 1:20,000 scale. Based on these maps, we described four geomorphological hazard zonation for floods, subsidence, soil fractures, and rockfalls in Iztapalapa district. The higher occurrence of subsidence, soil fractures and floods are in the palustrine plains, while rockfalls are associated with volcanic slopes. This study provides important input for local and regional stakeholders on territorial and risk management. Moreover, this practical methodology can be applied in other countries to facilitate disaster risk assessments.
•Developing countries face more economic losses due to natural disasters.•We studied Iztapalapa, the most densely populated district in Mexico.•Geomorphological mapping determined thirty endogenic and exogenic landforms.•Flood, subsidence, soil cracks and rockfalls were geomorphically assessed.•Practical methodology for geomorphological hazards mapping on dense urban areas.
Geomorphological mapping is a well-established method for examining earth surface processes and landscape evolution in a range of environmental contexts. In glacial research, it provides crucial data ...for a wide range of process-oriented studies and palaeoglaciological reconstructions; in the latter case providing an essential geomorphological framework for establishing glacial chronologies. In recent decades, there have been significant developments in remote sensing and Geographical Information Systems (GIS), with a plethora of high-quality remotely-sensed datasets now (often freely) available. Most recently, the emergence of unmanned aerial vehicle (UAV) technology has allowed sub-decimetre scale aerial images and Digital Elevation Models (DEMs) to be obtained. Traditional field mapping methods still have an important role in glacial geomorphology, particularly in cirque glacier, valley glacier and icefield/ice-cap outlet settings. Field mapping is also used in ice sheet settings, but often takes the form of necessarily highly-selective ground-truthing of remote mapping. Given the increasing abundance of datasets and methods available for mapping, effective approaches are necessary to enable assimilation of data and ensure robustness. This paper provides a review and assessment of the various glacial geomorphological methods and datasets currently available, with a focus on their applicability in particular glacial settings. We distinguish two overarching ‘work streams’ that recognise the different approaches typically used in mapping landforms produced by ice masses of different sizes: (i) mapping of ice sheet geomorphological imprints using a combined remote sensing approach, with some field checking (where feasible); and (ii) mapping of alpine and plateau-style ice mass (cirque glacier, valley glacier, icefield and ice-cap) geomorphological imprints using remote sensing and considerable field mapping. Key challenges to accurate and robust geomorphological mapping are highlighted, often necessitating compromises and pragmatic solutions. The importance of combining multiple datasets and/or mapping approaches is emphasised, akin to multi-proxy approaches used in many Earth Science disciplines. Based on our review, we provide idealised frameworks and general recommendations to ensure best practice in future studies and aid in accuracy assessment, comparison, and integration of geomorphological data. These will be of particular value where geomorphological data are incorporated in large compilations and subsequently used for palaeoglaciological reconstructions. Finally, we stress that robust interpretations of glacial landforms and landscapes invariably requires additional chronological and/or sedimentological evidence, and that such data should ideally be collected as part of a holistic assessment of the overall glacier system.
The relief is formed by the conjunction of processes that can be influenced to a greater or lesser extent by the morphostructure or morphosculpture, both of which act in the formation of the ...landscape. This work aims to, through the analysis of relief formation, provide subsidies for the studies of the run-off and the groundwater in an area of carbonate rocks in the north of Minas Gerais. The geomorphological landscape of this area is strongly influenced by morphostructural factors. Such influence is observed in the rectilinear drainage pattern of some rivers, in the presence of structural valleys, in abrupt changes in the direction of drainage net, and in scarps aligned in the same direction of joints and faults present in the area. Such structural influence is quite clear in the southern and central portions of the study area, being less significant in the northern portion, which has a much higher concentration of sinkholes than what was observed in the other areas. Considering a systemic perspective of the processes and dynamics that act on the surface and underground, this work presents these results of the formation of the geomorphological landscape so that such analysis helps in understanding the dynamics of groundwater in this area, as well as the relationship between surface waters and underground.
Despite advances in data collection and analytical software, mapping of glacial geomorphology is still largely achieved through manual techniques. Manual mapping is a relatively slow, inefficient and ...potentially subjective process, particularly given the extensive spatial coverage of remotely sensed datasets. Thus, glacial geomorphic mapping would benefit from semi-automated techniques able to map large areas quickly and efficiently. Here, we develop novel semi-automated techniques for mapping glacial geomorphology, based on lidar derived data collected from Breiðamerkurjökull, Iceland using Object Based Image Analysis (OBIA). The landforms classified were moraines, eskers, flutes/drumlins, and glacio-fluvial outwash. Several land surface parameters (LSPs) were calculated during image segmentation and analysis, representing the characteristics of the landforms of interest. The segmentation and classification routines were developed in Matlab, whereas most attempts so far have used specialised OBIA software. Our techniques utilised exploratory data analysis, where statistical groupings within the data define different landform types. Accuracy was assessed against a reference map derived using traditional manual mapping techniques. Landforms were classified to an overall accuracy of 77%. Our semi-automated mapping techniques should, with further algorithm development, be applicable using other datasets commonly used in palaeo-glaciology such as radar derived elevation data and swath bathymetry.
•Object Based Image Analysis for the classification of glacial landforms•Techniques based on widely available software•Overall accuracy of 77%•Results suggest that semi-automated techniques can be used for mapping glacial geomorphology.
The management of Mediterranean Agroecosystems is crucial to prevent or mitigate sediment-related threats like soil erosion, water quality issues, and reservoir sedimentation. Hence, the ...identification of type, extent, and location of sediment sources and sinks, in relation to geological and landscape features, is a key prerequisite for identifying erosion hot spot areas and assessing sediment dynamics at catchment scale. This study was carried out in the upper Val d'Arda catchment (Northern Apennines, Italy). We applied geomorphological field mapping together with multi-temporal photointerpretation, GIS-based hydrological modelling, terrain analysis and photogrammetry. Our approach was aimed at exploring the main landscape features, as well as identifying the variety of processes influencing sediment dynamics. In this poorly studied area, we identified a high heterogeneity in terms of type and extent of sediment sources and related processes. Landslides are the most common processes contributing to the sediment yield. Their morphogenesis, extent and location are controlled mainly by lithology and topography. Large ancient earthflows have been the most important geomorphic factor in shaping the landscape, strongly influencing the surficial drainage pattern and the morphological evolution of the main fluvial systems. Upland rill-interrill erosion is another main sediment source, particularly on arable lands. Piping and gullying locally contribute to the development of badlands, and have a high potential for soil loss and sediment production. Finally, fluvial processes significantly contribute to the sediment yield with several active fluvial erosion scarps and bank erosion source areas. Alluvial sediments are locally stored in transient landforms such as bars or more permanent sinks such as floodplains or river terraces. Our study shows that an integrated methodology based on fieldwork, geomorphological mapping, GIS applications and proximal sensing methods is an effective approach to characterize complex geomorphic systems in the Northern Apennines.
•First synoptic geomorphological characterization of the upper Val d'Arda•Litho-morphological features promote strongly heterogeneous geomorphic systems.•Complex and polygenic geomorphic systems interact intensively with human activities.•Landslides are major sediment sources and influence channel network configuration.•Soil erosion, bank erosion and mass movements severely impact the agroecosystem.
We introduce a novel method for classification and mapping of landform elements from a DEM based on the principle of pattern recognition rather than differential geometry. At the core of the method ...is the concept of geomorphon (geomorphologic phonotypes) — a simple ternary pattern that serves as an archetype of a particular terrain morphology. A finite number of 498 geomorphons constitute a comprehensive and exhaustive set of all possible morphological terrain types including standard elements of landscape, as well as unfamiliar forms rarely found in natural terrestrial surfaces. A single scan of a DEM assigns an appropriate geomorphon to every cell in the raster using a procedure that self-adapts to identify the most suitable spatial scale at each location. As a result, the method classifies landform elements at a range of different spatial scales with unprecedented computational efficiency. A general purpose geomorphometric map — an interpreted map of topography — is obtained by generalizing allgeomorphons to a small number of the most common landform elements. Due to the robustness and high computational efficiency of the method high resolution geomorphometric maps having continental and even global extents can be generated from giga-cell DEMs. Such maps are a valuable new resource for both manual and automated geomorphometric analyses. In order to demonstrate a practical application of this new method, a 30m cell−1 geomorphometric map of the entire country of Poland is generated and the features and potential usage of this map are briefly discussed. The computer implementation of the method is outlined. The code is available in the public domain.
Land-surface quantitative analysis based on digital elevation model (DEM) has been applied for improving the geomorphological mapping of piedmont alluvial fans. Indeed, these fans are frequently ...along a mountain front, where a series of coalescing fans may eventually occur. The margins of adjacent fans are rather difficult to map, thus preventing accurate and meaningful quantification of fan morphometric properties such as fan area, length, and slope. These morphometric properties are essential for informing on the influence of climatic conditions and tectonic factors on the fan-building processes. Therefore, in this paper, we propose a quantitative digital mapping approach along a stretch of about 50 km in the southern front of the Anti-Lebanon Mountains. Here, the Geomorphological Map of Syria at 1:1,000,000 scale (1963) reported at least nine piedmont alluvial fans, but these were poorly characterized in terms of geomorphometric characteristics and construction processes. Adopting the 1-arcsec SRTMv3 DEM, we propose a four-step workflow to analyse the feeding catchments morphology and fan morphometry. In this manner, the identification and geomorphological mapping of coalescent piedmont fans as well as the recognition of the main construction process have been improved. The proposed approach can support geomorphological investigations of wide and inaccessible areas—especially where arid and semi-arid climate conditions prevail—as well as where socio-political issues may prevent effective field work.
•Land-surface quantitative analysis is suitable for geomorphological mapping and characterization of piedmont alluvial fans.•Recognition of the construction processes of the alluvial fan is challenging for a remotely-desk study.•Fluvial fans (FFs) are wider, with longer axis, gentle slope, and extended feeding catchment.•Alluvial fans (AFs) are smaller, with shorter axis, steeper slope, and small feeding catchment.
So far, the longest known unroofed cave in Slovenia has been found on the Slavinski ravnik, southwest of Postojna. From its position on the surface, its shape, and its containing sediments, we can ...infer its spatial and temporal development, as well as the processes and evolution of the contact karst in its hinterland. The corrosional plain Slavinski ravnik is a small area of the Dinaric Karst in Slovenia, located at the contact between impermeable flysch and karstified carbonate rocks, where many contact karst features formed. Due to erosion, multi-phase regional tectonic uplift, and sedimentation, a paragenetic cave system, active and relict blind valleys have formed. During the geomorphological mapping, elements were examined and drawn using ESRI ArcMap and Golden Software Surfer, and the stages of their formation were observed. During the survey, the active cave system Markov spodmol and Vodna jama v Lozi, the relict unroofed cave Brezstropa jama v Lozi, Biščevci blind valley, Sajevško polje blind valley, Ivačevci blind valley, and Sajevško polje sediment accumulation were studied. The changing hydrological regime, the allogenic sediments, the distribution of active and relict ponors, and the placement of active and relict elements of these contact karst forms, show different stages of formation and subsequent development of the northern border of Slavinski ravnik. The geomorphological map of these contact karst features and their following studies give us an insight into the morphogenesis of the southern karst periphery of the Postojna Basin as an exceptional - relatively small but highly variable Slovenian contact karst site.
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