Analysis Of Aerial Photographs Research Articles

Spatial probability distribution of future volcanic eruptions at El Hierro Island (Canary Islands, Spain)

The 2011 submarine eruption that took place in the proximity of El Hierro Island (Canary Islands, Spain) has raised the need to identify the most likely future emission zones even on volcanoes characterized by low frequency activity. Here, we propose a probabilistic method to build the susceptibility map of El Hierro, i.e. the spatial distribution of vent opening for future eruptions, based on the probabilistic analysis of volcano-structural data of the Island collected through new fieldwork measurements, bathymetric information, as well as analysis of geological maps, orthophotos and aerial photographs. These data have been divided into different datasets and converted into separate and weighted probability density functions, which were included in a non-homogeneous Poisson process to produce the volcanic susceptibility map. The most likely area to host new eruptions in El Hierro is in the south-western part of the West rift. High probability locations are also found in the Northeast and South rifts, and along the submarine parts of the rifts. This map represents the first effort to deal with the volcanic hazard at El Hierro and can be a support tool for decision makers in land planning, emergency measures and civil defense actions.

Land use history of a floodplain area during the last 200 years in the Upper-Tisza region (Hungary)

Research into landscape history makes it possible to follow landscape changes in the past and support landscape management, conservation and restoration programs. Floodplain habitats are lost, isolated and fragmented on account of land use. Nowadays, these habitats are threatened by modifications in the natural water regime, as well as agricultural and forestry practices. Floodplains have great importance because they provide a transition between aquatic habitats and terrestrial biotopes. Our analysis of aerial photographs and topographical maps revealed that the major predicted changes in the study area are related to agricultural abandonment and afforestation. The comparison of land cover maps from 1784 to 2005 showed intensification of agriculture with land cover conversions from arable land and orchards to grasslands, marshes and woodlands. The land use types that are mostly responsible for the fragmentation of the landscape are arable land, economic plantations and orchards. We found that fragmentation was greater after 1956. This was caused by socioeconomic changes and showed that the habitats of floodplains have changed intensively during the last 200 years. Knowledge of this last 200 years of history contributes to a more careful and wiser management of the region through biodiversity protection and environmental development.

A GIS-based approach for gully erosion susceptibility modelling: a test in Sicily, Italy

The aim of this study is to analyze the susceptibility conditions to gully erosion phenomena in the Magazzolo River basin and to test a method that allows for driving the factors selection. The study area is one of the largest (225 km2) watershed of southern Sicily and it is mostly characterized by gentle slopes carved into clayey and evaporitic sediments, except for the northern sector where carbonatic rocks give rise to steep slopes. In order to obtain a quantitative evaluation of gully erosion susceptibility, statistical relationships between the spatial distributions of gullies affecting the area and a set of twelve environmental variables were analyzed. Stereoscopic analysis of aerial photographs dated 2000, and field surveys carried out in 2006, allowed us to map about a thousand landforms produced by linear water erosion processes, classifiable as ephemeral and permanent gullies. The linear density of the gullies, computed on each of the factors classes, was assumed as the function expressing the susceptibility level of the latter. A 40-m digital elevation model (DEM) prepared from 1:10,000-scale topographic maps was used to compute the values of nine topographic attributes (primary: slope, aspect, plan curvature, profile curvature, general curvature, tangential curvature; secondary: stream power index; topographic wetness index; LS-USLE factor); from available thematic maps and field checks three other physical attributes (lithology, soil texture, land use) were derived. For each of these variables, a 40-m grid layer was generated, reclassifying the topographic variables according to their standard deviation values. In order to evaluate the controlling role of the selected predictive variables, one-variable susceptibility models, based on the spatial relationships between each single factor and gullies, were produced and submitted to a validation procedure. The latter was carried out by evaluating the predictive performance of models trained on one half of the landform archive and tested on the other. Large differences of accuracy were verified by computing geometric indexes of the validation curves (prediction and success rate curves; ROC curves) drawn for each one-variable model; in particular, soil texture, general curvature and aspect demonstrated a weak or a null influence on the spatial distribution of gullies within the studied area, while, on the contrary, tangential curvature, stream power index and plan curvature showed high predictive skills. Hence, predictive models were produced on a multi-variable basis, by variously combining the one-variable models. The validation of the multi-variables models, which generally indicated quite satisfactory results, were used as a sensitivity analysis tool to evaluate differences in the prediction results produced by changing the set of combined physical attributes. The sensitivity analysis pointed out that by increasing the number of combined environmental variables, an improvement of the susceptibility assessment is produced; this is true with the exception of adding to the multi-variables models a variable, as slope aspect, not correlated to the target variable. The addition of this attribute produces effects on the validation curves that are not distinguishable from noise and, as a consequence, the slope aspect was excluded from the final multi-variables model used to draw the gully erosion susceptibility map of the Magazzolo River basin. In conclusion, the research showed that the validation of one-variable models can be used as a tool for selecting factors to be combined to prepare the best performing multi-variables gully erosion susceptibility model.

Slip Rate on the Wellington Fault, New Zealand, during the Late Quaternary: Evidence for Variable Slip during the Holocene

We investigate fault‐offset fluvial terraces at two sites along the Hutt River, near Wellington, New Zealand, to determine horizontal slip rates for the southern part of the Wellington fault for the last ∼100 ka. Using photogrammetric analysis of historic aerial photos, we measured the original displacements of terrace risers at Emerald Hill, which have been modified by urban development. Fourteen sediment samples from this site and from another location, Dry Creek, were analyzed using Optically Stimulated Luminescence (OSL) methods, yielding ages of between ∼10 ka and ∼100 ka. From our displacement‐age relations, we estimate an average slip rate of ![Graphic][1] (2 σ ) during the last ∼100 ka. However, slip on the Wellington fault has not been steady throughout this time. During the Holocene, there was a phase of heightened ground rupture activity between ∼10 and 8 ka, when an incremental dextral displacement of ∼32 m accrued. This was followed by a period of relative quiescence between ∼8 and 4.5 ka, with ∼5 m of displacement during this time. Another period of heightened activity followed, resulting in a further ∼20 m of slip during the last ≤4.5 ka. Our inference of variable slip during the Holocene accords with independent evidence from paleoseismological studies at other sites along the Wellington fault. Slip on the Wellington fault, and its variability through time, may be influenced by activity on neighboring faults. Online Material: Part I: Optically stimulated luminescence (OSL) dating: Technical report and results. Part 2: Stratigraphic logs. [1]: /embed/inline-graphic-1.gif

The Northwestern Mediterranean Coast of Tunisia: Wave Processes, Shoreline Stability and Management Implications

The 10-km long coastline of the Tabarka–Berkoukech on the northwestern Mediterranean coast of Tunisian is characterized by marked morphological features, including embayments, long extensions, headlands, pocket beaches, sand dunes and sea-cliffs. The undulated nature of this coastline has permit sand, originated from three rivers, to confine between headlands, embayments, pocket beaches and the downdrift leeside of Tabarka Harbor breakwaters. Wave-related coastal processes simulated by STWAVE model together with the analysis of aerial photographs are jointly combined to evaluate degree of stability of this coastline. Analysis of aerial photographs dated 1963 and 2001 (38 years) using the Digital Shoreline Analysis System document significant beach changes in the sandy beaches. Maximum accretion occurs downdrift of Tabarak Port (3.8 meter/year), followed eastward by a minor erosion of −1.5 meter/year at El Morjene beach. The morphological characteristics of this coastline exhibit a wide range of beach dynamics resulted from interactions of waves, shoreline orientation and sediment supply. Pattern of longshore sediment transport direction has been deduced from the interplay between incident waves versus average shoreline orientation (angle of incidence). Results indicate that the W and NW waves are responsible for the generation of the sediment transport to the east throughout the year. This transport process is also accompanied with a net westerly reversals induced from the N and NE waves. Such wave reversibility, in general, generates a long-term equilibrium between the opposing east and westward sand movement within the coastline, yielding to an effective zero net littoral drift with a minimum sand loss resulting in stable beaches. Collectively, results obtained are jointly discussed in the context of sustainable management of this coastline.

GPR and aerial imageries to identify the recent historical course of the Obra River and spatial extent of Obrzańskie Lake, altered by hydro-technical works

Ground penetrating radar (GPR) measurements have been conducted to retrace the natural course of the Obra River and changes of spatial extent of Obrzanskie Lake (western Poland). The Obra River valley was subjected to intensive anthropogenic transformation. Three artificial canals were constructed here in the beginning of the nineteenth century. The GPR surveys were done using a georadar MALA ProEx equipped with 250 MHz antenna. The measurement was verified by coring and analyses of historical maps, aerial photographs, and satellite images. The research has shown that there are at least three elongated depressions preserved in the modern land surface near the village of Solec, situated in the middle course of the valley. Several structures suggesting functioning of a multi-channel pattern in the past have been detected inside and in the vicinity of the depressions. Filling the channels with silts and peats might have been the effect of flow deceleration caused by the construction of the Obra Canals. Moreover, situation of two of the retraced depressions suggests that the landforms might be the remains of a river bed disappearing in wetlands. Further studies including groundwater flux measurements in the area between the depressions are needed to confirm such hypothesis. Furthermore, the study allowed retracing the spatial extent of Obrzanskie Lake. The sediment structures detected by the GPR measurements and calibrated with coring were interpreted to be the traces of the lake shoreline. The interpretation was supported by the findings inferred from aerial and satellite images. It was shown that Obrzanskie Lake had had at least three islands and had been directly connected with a network of braided channels before the anthropogenic intervention. The spatial extent of the lake was significantly altered by the construction of the North Obra Canal. Disconnecting the lake from the Canal resulted in more than 50 % decrease of the lake surface.

Changes in dunefield geomorphology and vegetation cover as a response to local and regional climate variations

Miot da Silva, G., Hesp, P., Keim, B., Martinho, C.T. and Ferligoj, Y., 2013. Changes in dunefield geomorphology and vegetation cover as a response to local and regional climate variations. In: Conley, D.C., Masselink, G., Russell, P.E. and O'Hare, T.J. (eds.)Published analyses of aerial photographs show a marked increase in vegetation cover of coastal transgressive dunefields along the Southern Brazilian Holocene Barrier around the late 1970s. This phenomenon is reflecting an increase in precipitation and a decrease in aeolian sediment transport. These climatic changes are associated with recurring high intensity El Niño events related to the 1976/1977 regime shift of the Pacific Decadal Oscillation (PDO).

高津川河口の砂州変形と航路埋塞の数値シミュレーション

Masuda port is located in both sides of the mouth of Takatsu River, the access channel of which passes behind a river-mouth bar. This study intends to develop a tool for examination of countermeasures against channel infilling which is very linked with deformation of river-mouth bar. First, the relation between the sand bar deformation and channel infilling has been examined for the river mouth area of Takatsu River through analysis of aerial photos, current and wave data, bathymetric survey data, and so on. As the results, two dominant processes of flushing sand bar due to flood and reformation of sand bar by waves are confirmed. Also, numerical simulations for the two dominant processes have been conducted and the reproducibility of the model has been examined.

Testing Geographical Methodology and Tools for the Study of Territories Damaged by Earthquakes. The Case of L’Aquila and Other Localities Three Years after the April 6th 2009 Event

In this paper, we discuss a geographical methodology supported by specific geo-technologies which we are testing for the study of territories damaged by the L’Aquila earthquake of 6 April 2009 and which can be used in similar situations. Subsequently, we provide an overview of the current situation and make a comparison between some aerial photographs obtained from an overflight in March 2012 and some photos made during our first field study in February 2010, in order to show the work undertaken or not during this period and to substantiate any considerations regarding the choices adopted and the necessary future planning. Moreover, we provide an example of the added value provided by the analysis of aerial photographs in both visible and thermal light for recognizing the provisional non-painted metal roofing of buildings in a post-earthquake urban area. In fact this technique can be useful for the rapid identification of damaged buildings and zones with provisional covering. In the present paper, we focus attention on L’Aquila town centre which provides a significant example of a “City of Stone” almost “minus” the presence of people.

Analyse des changements d’occupation du sol de trois sites de la région naturelle de l’Orléanais de 1949 à 2006

A diachronic analysis of aerial photographs of three sites in Orleanais natural region (not including state forests) show that landscapes have become increasingly complex over the last fifty years in the vicinity of cities. Changes in use mainly concern forest expansion which occurs to the detriment of open environments and hedges, particularly in rural areas. This expansion, involving mostly deciduous species, has retained the contour of forests that already existed in the 19th century. The use of aerial photographs furthermore high- lights the different silvicultural practices applied in 1949 illustrating how heavily wood was relied on as a source of energy.

Naturbanización y patrones urbanos en los parques nacionales de Andalucía

Texto resumen.

CO2 Exchanges within Zones of Rapid Conversion from Permafrost Plateau to Bog and Fen Land Cover Types

Variability of midday net ecosystem CO2 exchange (NEE) and respiration was measured using a transect of closed system chambers spanning transitions from channel fen, permafrost plateau, and ombrotrophic flat bog land cover types during the spring melt season (26 April—6 June 2008). The primary objective was to compare fluxes from different land cover types and topographic variability within zones adjacent to and including rapid permafrost thaw. During this period, the bog was the greatest net source of CO2 to the atmosphere, followed by plateau, and fen. NEE was slightly positive (indicating CO2 loss to the atmosphere) during the snowmelt period (average = 0.009 ± 0.004 mg CO2 m-2 s-1), and increased to 0.025 ± 0.012 mg CO2 m-2 s—1, on average, possibly due to soil thaw and increased microbial activity within two days of completely snow-free conditions. Near surface soil temperature and depth to the water table were the most significant controls of soil and ground cover CO2 fluxes within chambers at all sites (p < 0.05). Analysis of historical aerial photographs and satellite imagery of the area from 1947 to 2008 indicates that plateaus are converting more rapidly into bogs than fen, where 73% of plateau areas (since 1970) that thawed had become bogs (as opposed to 27% conversion into fen). Future research requires establishment of a full ecosystem or land cover greenhouse gas and soil nutrient exchange/transfer program, including CO2 and water fluxes as well as dissolved organic and inorganic C, and CH4 losses from the soil. These results contribute to a better understanding of northern soil and ground-cover carbon exchanges as greater areas of permafrost plateaus collapse and form bogs.

The effects of fire on woody plant encroachment are exacerbated by succession of trees of decreased palatability

Abstract The ingression of woody plants into the grassy layer of savannas and grasslands has become a global concern. The increase of woody plants has been primarily attributed over grazing, fire and more recently to the increase of atmospheric CO2. We used long-term observations and analyses to assess changes in woody vegetation in Ithala Game Reserve (IGR), South Africa. Textural analysis of aerial photographs was used to detect changes in woody vegetation, from 1943 to 2007 in Ithala Game Reserve (IGR), South Africa. Daily rainfall data from 1905 to 2009 were used in a time-series analysis to determine if rainfall patterns have changed. The time-series analysis showed that the low magnitude (0–10 mm) rainfall events decreased from 1916 to 2009 and high magnitude rainfall events increased (10–20 and >20 mm). The mean annual rainfall increased from ∼700 to ∼850 mm from the 1930s to the 2000s. This change in rainfall was a key factor in the increase in woody vegetation from 1943 to 2009. We also used field data from the same reserve collected over 30 years to assess the increases in tree cover. Tree cover and density increased significantly by 32.5% and 657.9 indiv ha−1 respectively, over 64 years. Before the proclamation of IGR in 1972, increases in woody vegetation from 1943 were non-significant. After the proclamation of IGR, herbivore population numbers and spatial distribution influenced the accumulation of grassy biomass required to fuel fires. In areas with reduced fuel loads, the consequential suppression of fire accelerated the rate of woody plant invasion into savannas. The increase in woody vegetation coincided with a decrease in palatable (e.g. Acacia gerrardii and Acacia davyi) and an increase in unpalatable woody plants. The avoidance of the unpalatable trees (e.g. Euclea and Searsia species) by large mammalian herbivores has allowed these trees to increase in density relatively unhindered.

Impacts of a half century of sea‐level rise and development on an endangered mammal

AbstractThe extraordinary growth of human populations and development in coastal areas over the last half century has eliminated and degraded coastal habitats and threatened the persistence of associated wildlife. Moreover, human‐induced sea‐level rise (SLR) is projected to further eliminate and alter the same coastal ecosystems, especially low‐lying regions. Whereas habitat loss and wildlife population declines from development are well documented, contemporary SLR has not yet been implicated in declines of coastal faunal populations. In addition, the projection of severe synergistic impacts from the combination of development and SLR is well described, yet the scientific literature offers little empirical evidence of the influence of these forces on coastal wildlife. Analysis of aerial photographs from 1959 to 2006 provided evidence of a 64% net loss of the endangered Lower Keys marsh rabbit's (Sylvilagus palustris hefneri; LKMR) habitat, the majority due to SLR (&gt;48%). Furthermore, there was a strong negative relationship between the proportion of development per island and the amount of new habitat formed. Islands with modest development (less than 8% of land area) saw formation of new areas of marsh vegetation suitable for rabbits, whereas islands with 8% or more of their lands developed between 1959 and 2006 saw little to no addition of LKMR habitat. Only 8% of habitat loss was directly due to conversion to impervious surfaces, indicating that the greatest threats from development were indirect, including blocking of the inland migration of habitat triggered by SLR. Our results were consistent with an ongoing squeeze of coastal ecosystems between rising seas and development as a threat to LKMR habitat, which raises concern for a wide variety of coastal species. Our results provide evidence that SLR has become a contemporary conservation concern, one that is exacerbated by development, and expected to increase in magnitude as ocean waters continue to rise.

Changes of river bed pattern of a lowland river: effect of natural processes or anthropogenic intervention?

GPR and aerial surveys were conducted to study changes of channel pattern in the lower course of the Obra River (western Poland). The river is an example of an intensive anthropogenic transformation, however, the origin of the river pattern changes in its lower course is not obvious. The GPR measurements were done using a georadar MALÅ ProEx equipped with a shielded 250-MHz antenna. A 3D analysis of the GPR data supported with lithologic information indicated traces of a multi‐channel pattern. A variable orientation of sediment layering within channel bars and differences in channels depth and width pointed to changes of direction of the river bed migration. Analysis of aerial photographs and a satellite image indicated that only a few of the channels inferred from GPR could be discerned. The reason could be the more than 1 m thick fine sands layer covering all the alluvial structures. Analysis of historical maps from the eighteenth and the nineteenth centuries showed that 250 years ago the Obra was a meandering river. The maps illustrate also several meander cutoffs and decreased wetlands surface. The following transformations of the river bed pattern were discerned: 1. From braided to meandering channel pattern which could be a natural process caused by climatic and sediment transport rate changes that was also observed in case of other lowland rivers. 2. From meandering to sinuous pattern with channel islands and then to sinuous with oxbow lakes. However, further research is needed to study reasons and timing of the observed changes.

Multi-temporal archaeological analyses of alluvial landscapes using the photogrammetric restitution of historical flights: a case study of Medellin (Badajoz, Spain)

One of the main challenges affecting the archaeological study of alluvial landscapes is the intensity of change these environments experience over time. Quick and dramatic alterations in geomorphological dynamics and land exploitation determine the visibility and conservation of the archaeological record. This study proposes an approach to the problem of studying these evolving environments based on the analysis and treatment of a series aerial photographs taken between the 1950s and the present day. This paper is particularly interested in looking at the process of photogrammetric restitution and in validating and comparing the digital terrain models and orthoimages produced. The quantitative analysis and visual interpretation of these results can provide valuable information about the transformation of landscapes and factors affecting surface evidence. The intended final result is to develop the ability to map the most problematic or best preserved areas. Nevertheless, it is considered in terms of a relative measure of change magnitude, rather than trying to provide absolute figures.

Precursors and triggers of an alpine rockslide in Japan: the 2004 partial collapse during a snow-melting period

The Aresawa rockslide in the Japanese Alps encountered a deep, partial collapse during an early snow-melting period in May 2004, followed by further progressive movement of the headscarp area. This paper reconstructs the pre-failure topography of the Aresawa rockslide based on the analysis of aerial photographs taken in multiple periods, and analyzes the factors controlling the threshold for the 2004 collapse. At least seven months before the collapse, new tension cracks emerged about 25 m behind the headscarp as a result of downslope movement of an unstable rock slab 5–10 × 105 m3 in volume, accompanied by the development of a slip plane below a pre-existing shallow trough (sackung feature). The collapse finally occurred when progressive weakening of the rock mass was combined with water infiltration into the ground during rapid snow melting.

Spatial Analysis of High Resolution Aerial Photographs to Analyze the Spread of Mountain Pine Beetle Infestations

Mountain pine beetle (Dendroctonus Ponderosae) infestations in Western Canada have reached alarming proportions. The spread of attacks has significantly impacted pine tree stocks, the forest ecosystem in general and the overall socio-economic condition of residents in communities that depend on the forest industry. The ability to track these attacks and anticipate their trajectories will allow forest managers to target intervention measures and improve mitigation efforts. Spatial analysis methods are well suited to characterize the dynamics of the mountain pine beetle attacks. This study implemented a multi-scale spatiotemporal analysis to describe the patterns of three consecutive attack years (2000-2002) for a 19 km2 study site in British Columbia, Canada. In the first stage, baseline complete spatial randomness (CSR) was examined using average nearest neighbour analysis and quadrat counts on infestation data extracted from 19 cm resolution black and white aerial photographs. In the second stage, global and local Moran’s I spatial autocorrelation statistics, Getis-Ord General G global high/low clustering and Getis-Ord G_i^* test statistic techniques were used to evaluate the spread patterns over time. The results show a significant clustering of attack sites in the first two years, with considerable changes in the attack spread in the third year. These changes were independent of the two levels of spatial resolution used. Knowledge about infestation patterns can be used to anticipate needed social and environmental assistance for affected communities. Further, the information can aid overall sustainable forestry management.

An Approach to Mapping Forest Growth Stages in Queensland, Australia through Integration of ALOS PALSAR and Landsat Sensor Data

Whilst extensive clearance of forests in the eastern Australian Brigalow Belt Bioregion (BBB) has occurred since European settlement, appropriate management of those that are regenerating can facilitate restoration of biomass (carbon) and biodiversity to levels typical of relatively undisturbed or remnant formations. However, maps of forests are different stages of regeneration are needed to facilitate restoration planning, including prevention of further re-clearing. Focusing on the Tara Downs subregion of the BBB and on forests with brigalow (Acacia harpophylla) as a component, this research establishes a method for differentiating and mapping early, intermediate and remnant growth stages from Japan Aerospace Exploration Agency (JAXA) Advanced Land Observing Satellite (ALOS) Phased-Array L-band Synthetic Aperture Radar (PALSAR) Fine Beam Dual (FBD) L-band HH- and HV-polarisation backscatter and Landsat-derived Foliage Projective Cover (FPC). Using inventory data collected from 74 plots, located in the Tara Downs subregion, forests were assigned to one of three regrowth stages based on their height and cover relative to that of undisturbed stands. The image data were then segmented into objects with each assigned to a growth stage by comparing the distributions of L-band HV and HH polarisation backscatter and FPC to that of reference distributions using a z-test. Comparison with independent assessments of growth stage, based on time-series analysis of aerial photography and SPOT images, established an overall accuracy of &gt; 70%, with this increasing to 90% when intermediate regrowth was excluded and only early-stage regrowth and remnant classes were considered. The proposed method can be adapted to respond to amendments to user-definitions of growth stage and, as regional mosaics of ALOS PALSAR and Landsat FPC are available for Queensland, has application across the state.

Analysis of a Deep-Seated Landslide in Permafrost, Richardson Highway, South-Central Alaska

A portion of the Richardson Highway near Glennallen, Alaska, is threatened by slope movement in an area where the highway travels along a bluff overlooking the Copper River. Analysis of aerial photographs indicates that portions of the bluff have experienced an average of 1.5 m of retreat per year since 1979, and gully erosion has completely obliterated portions of the pre-1965 highway alignment. The subsurface consists of a 1.5-m-thick surficial silt layer underlain by frozen, ice-rich clayey soils with an average annual temperature of −0.56°C. At 16 m below the ground surface, the soils become ice-poor and coarser grained. In situ measurements, soil creep tests, and slope stability analysis indicate that the ice-rich clayey soils are experiencing movement, with creep velocities of up to 2.5 cm per year. This deep-seated creep results in fracturing of the near-surface soil layer that is manifested at the surface by cracks, scarps, and back-tilted blocks. Groundwater perched above the permafrost table and seeping toward the bluff face facilitates the rapid retreat of the bluff edge through the formation of gullies.