Historical Imagery Research Articles

Groundwater controls on biogeomorphic succession and river channel morphodynamics

Biogeomorphic succession describes feedbacks between vegetation succession and fluvial processes that, at the decadal timescale, lead to a transition from bare river-deposited sediment to fully developed riparian forest. Where the rate of stabilization by biogeomorphic succession is greater than the rate of ecological disturbance by fluvial processes, a river is likely to evolve into less dynamic states. While river research has frequently considered the physical dimensions of morphodynamics, less is known about physical controls on succession rates, and how these impact stream morphodynamics. Here we test the hypothesis that groundwater dynamics influence morphodynamics via the rate of biogeomorphic succession. We applied historic imagery analysis in combination with dendroecological methods for willows growing on young gravelly fluvial landforms along a steep groundwater-depth gradient. We determined the following: floodplain morphodynamics and plant encroachment at the decadal scale, pioneer willow growth rates, and their relationships to hydrological variables. Willow growth rates were correlated with moisture availability (groundwater, discharge, and precipitation variability) in the downwelling reach, while little correlation was found in the upwelling reach. After a reduction in ecological disturbance frequency, data suggest that where groundwater is upwelling, biogeomorphic succession is fast, the engineering effect of vegetation is quickly established, and hence channel stability increased and active channel width reduces. Where groundwater is downwelling, deeper and more variable, biogeomorphic succession is slower, the engineering effect is reduced, and a wider active width is maintained. Thus, groundwater is an important control on biogeomorphic feedbacks intensity and, through the stabilizing effect of vegetation, may drive long-term river channel morphodynamics.

Factors related to building loss due to wildfires in the conterminous United States.

Wildfire is globally an important ecological disturbance affecting biochemical cycles and vegetation composition, but also puts people and their homes at risk. Suppressing wildfires has detrimental ecological effects and can promote larger and more intense wildfires when fuels accumulate, which increases the threat to buildings in the wildland-urban interface (WUI). Yet, when wildfires occur, typically only a small proportion of the buildings within the fire perimeter are lost, and the question is what determines which buildings burn. Our goal was to examine which factors are related to building loss when a wildfire occurs throughout the United States. We were particularly interested in the relative roles of vegetation, topography, and the spatial arrangement of buildings, and how their respective roles vary among ecoregions. We analyzed all fires that occurred within the conterminous United States from 2000 to 2010 and digitized which buildings were lost and which survived according to Google Earth historical imagery. We modeled the occurrence as well as the percentage of buildings lost within clusters using logistic and linear regression. Overall, variables related to topography and the spatial arrangement of buildings were more frequently present in the best 20 regression models than vegetation-related variables. In other words, specific locations in the landscape have a higher fire risk, and certain development patterns can exacerbate that risk. Fire policies and prevention efforts focused on vegetation management are important, but insufficient to solve current wildfire problems. Furthermore, the factors associated with building loss varied considerably among ecoregions suggesting that fire policy applied uniformly across the United States will not work equally well in all regions and that efforts to adapt communities to wildfires must be regionally tailored.

Change in woody cover at representative sites in the Kruger National Park, South Africa, based on historical imagery.

BackgroundThe coexistence of woody vegetation and grass is a key characteristic of savanna ecological balance. Gains in woody vegetation at the expense of grass can lead to changes in grazer and browser carrying capacities on the savannas. This study examined long-term change in woody cover at four study sites representative of the geology and rainfall in the Kruger National Park, South Africa. Scanned 1940/1942, 1968, and 1977 high spatial resolution (0.44–1.35 m) panchromatic aerial photographs were used, supplemented by 5 and 10 m resolution 1998 and 2012 panchromatic and red band grey scale digital SPOT images. The imagery datasets of the respective study sites were georeferenced to the UTM projection. Woody cover on the imagery was enhanced using texture analysis, and mapped by unsupervised classification of the texture images using the K-means clustering algorithm. Change in woody cover was mapped using Boolean addition Geographic Information System overlay analysis.ResultsThe results indicated 29 and 40 % reductions in woody cover for the southern granites and southern basalts sites, respectively. The northern granites and northern basalts sites, on the other hand, had gains in woody cover over the analysis period. The location context-specific factors of fire frequency and elephant density, and not rainfall fluctuations, explained most of the change in woody cover.ConclusionsThe results point to the need for location context-specific management of fire and elephant concentrations. The changes in woody cover are likely to have effects on the grazer and browser carrying capacities of the savannas in the Kruger National Park.

Coseismic and postseismic displacements from the 1978 Mw 7.3 Tabas-e-Golshan earthquake in eastern Iran

We use optical image correlation of historical aerial photographs, and modern satellite images to investigate the 1978 Mw 7.3 Tabas-e-Golshan thrust earthquake in eastern Iran. Correlation of images between 1974 and 1991 reveals a near-surface shortening component of ∼2.9 m across the margin of the Tabas fold, which is a combination of coseismic and postseismic deformation. Correlation of images between 1991 and 2013 shows a further ∼0.3 m of postseismic shortening. Using six pre-earthquake aerial photographs acquired in 1956 and stereo SPOT-6 imagery from 2013, we also generate pre- and post-earthquake digital elevation models (DEMs) for one of the main fold segments. Differencing of the two DEMs reveals a height change of ∼4.7 m. Elastic dislocation modelling of the 1974–2013 displacement field requires 7 m slip on a 50° dipping fault, extending from a depth of 0.1 km to 6 km at its base (the majority of slip, ∼6.5 m, occurred prior to 1991). Our results, combined with previous InSAR observations, indicate time-decaying shallow postseismic afterslip. It is likely that most of the afterslip occurred prior to 1991. The slip appears to dissipate in the near surface, and is accommodated as a narrow band of flexural slip on bedding planes. Comparison of the fault slip model with terrace heights measured from the SPOT-6 DEM suggests that the Tabas fold system may exhibit characteristic slip behaviour. Such behaviour would require a magnitude Mw 7.3 earthquake every ∼3500 years, based on the previously estimated shortening rate of ∼1.0 mm/yr. This study highlights the usefulness of historical imagery in investigating past earthquakes, thus providing new information about historical faulting in continental regions.

Unmanned aerial vehicles for the assessment and monitoring of environmental contamination: An example from coal ash spills

Unmanned aerial vehicles (UAVs) offer new opportunities to monitor pollution and provide valuable information to support remediation. Their low-cost, ease of use, and rapid deployment capability make them ideal for environmental emergency response. Here we present a UAV-based study of the third largest coal ash spill in the United States. Coal ash from coal combustion is a toxic industrial waste material present worldwide. Typically stored in settling ponds in close proximity to waterways, coal ash poses significant risk to the environment and drinking water supplies from both chronic contamination of surface and ground water and catastrophic pond failure. We sought to provide an independent estimate of the volume of coal ash and contaminated water lost during the rupture of the primary coal ash pond at the Dan River Steam Station in Eden, NC, USA and to demonstrate the feasibility of using UAVs to rapidly respond to and measure the volume of spills from ponds or containers that are open to the air. Using structure-from-motion (SfM) imagery analysis techniques, we reconstructed the 3D structure of the pond bottom after the spill, used historical imagery to estimate the pre-spill waterline, and calculated the volume of material lost. We estimated a loss of 66,245 ± 5678 m3 of ash and contaminated water. The technique used here allows rapid response to environmental emergencies and quantification of their impacts at low cost, and these capabilities will make UAVs a central tool in environmental planning, monitoring, and disaster response.

ESTIMATION OF STAND HEIGHT AND FOREST VOLUME USING HIGH RESOLUTION STEREO PHOTOGRAPHY AND FOREST TYPE MAP

Abstract. Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m3/ha) using normalized digital surface model (nDSM) from high resolution stereo photography (25cm resolution) and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM) was created by photogrammetric methods(aerial triangulation, digital image matching). Then, digital terrain model (DTM) was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.). Two independent variables from nDSM were used to estimate forest stand volume: crown density (%) and stand height (m). First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri’s ArcGIS and the USDA Forest Service’s FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s–present) will be produced using this stand volume estimation method and a historical imagery archive.

ESTIMATION OF STAND HEIGHT AND FOREST VOLUME USING HIGH RESOLUTION STEREO PHOTOGRAPHY AND FOREST TYPE MAP

Traditional field methods for measuring tree heights are often too costly and time consuming. An alternative remote sensing approach is to measure tree heights from digital stereo photographs which is more practical for forest managers and less expensive than LiDAR or synthetic aperture radar. This work proposes an estimation of stand height and forest volume(m<sup>3</sup>/ha) using normalized digital surface model (nDSM) from high resolution stereo photography (25cm resolution) and forest type map. The study area was located in Mt. Maehwa model forest in Hong Chun-Gun, South Korea. The forest type map has four attributes such as major species, age class, DBH class and crown density class by stand. Overlapping aerial photos were taken in September 2013 and digital surface model (DSM) was created by photogrammetric methods(aerial triangulation, digital image matching). Then, digital terrain model (DTM) was created by filtering DSM and subtracted DTM from DSM pixel by pixel, resulting in nDSM which represents object heights (buildings, trees, etc.). Two independent variables from nDSM were used to estimate forest stand volume: crown density (%) and stand height (m). First, crown density was calculated using canopy segmentation method considering live crown ratio. Next, stand height was produced by averaging individual tree heights in a stand using Esri’s ArcGIS and the USDA Forest Service’s FUSION software. Finally, stand volume was estimated and mapped using aerial photo stand volume equations by species which have two independent variables, crown density and stand height. South Korea has a historical imagery archive which can show forest change in 40 years of successful forest rehabilitation. For a future study, forest volume change map (1970s–present) will be produced using this stand volume estimation method and a historical imagery archive.

Assessing Field-Specific Risk of Soybean Sudden Death Syndrome Using Satellite Imagery in Iowa.

Moderate resolution imaging spectroradiometer (MODIS) satellite imagery from 2004 to 2013 were used to assess the field-specific risks of soybean sudden death syndrome (SDS) caused by Fusarium virguliforme in Iowa. Fields with a high frequency of significant decrease (>10%) of the normalized difference vegetation index (NDVI) observed in late July to middle August on historical imagery were hypothetically considered as high SDS risk. These high-risk fields had higher slopes and shorter distances to flowlines, e.g., creeks and drainages, particularly in the Des Moines lobe. Field data in 2014 showed a significantly higher SDS level in the high-risk fields than fields selected without considering NDVI information. On average, low-risk fields had 10 times lower F. virguliforme soil density, determined by quantitative polymerase chain reaction, compared with other surveyed fields. Ordinal logistic regression identified positive correlations between SDS and slope, June NDVI, and May maximum temperature, but high June maximum temperature hindered SDS. A modeled SDS risk map showed a clear trend of potential disease occurrences across Iowa. Landsat imagery was analyzed similarly, to discuss the ability to utilize higher spatial resolution data. The results demonstrated the great potential of both MODIS and Landsat imagery for SDS field-specific risk assessment.

REMOTELY-SENSED GLACIER CHANGE ESTIMATION: A CASE STUDY AT LINDBLAD COVE, ANTARCTIC PENINSULA

This study builds on existing literature of glacier change estimation in polar regions and is a continuation of efforts aimed at unlocking the information encapsulated in archival aerial photography of Antarctic Peninsula glaciers. Historical aerial imagery acquired in 1957 over three marine-terminating glaciers at Lindblad Cove on the West Coast of Trinity Peninsula is processed to extract digital elevation models (DEMs) which are subsequently compared to DEMs generated from present day (2014) WorldView-2 satellite stereo-imagery. The new WorldView-2 images offer unprecedented sub-metre resolution of the Antarctic Peninsula and are explored here to facilitate improved registration and higher accuracy analysis of glacier changes. Unlike many studies, which focus on glacier fronts or only restricted regions of glaciers, this paper presents a complete coverage of elevation changes across the glacier surfaces for two of the studied glaciers. The study utilises a robust least squares matching technique to ensure precise registration of the archival and modern DEMs, which is applied due to lack of existing ground control in this remote region. This case study reveals that, while many glaciers in polar regions are reported as experiencing significant mass loss, some glaciers are stable or even demonstrate mass gain. All three glaciers reported here demonstrated overall mean increases in surface elevation, indicative of positive mass balance ranging from 0.6 to 5.8 metre water equivalent between 1957 and 2014.

Frozen debris lobe morphology and movement: an overview of eight dynamic features, southern Brooks Range, Alaska

Abstract. Frozen debris lobes (FDLs) are elongated, lobate permafrost features that mostly move through shear in zones near their bases. We present a comprehensive overview of eight FDLs within the Dalton Highway corridor (southern Brooks Range, Alaska), including their catchment geology and rock strengths, lobe soil characteristics, surface movement measurements collected between 2012 and 2015, and analysis of historic and modern imagery from 1955 to 2014. Field mapping and rock strength data indicate that the metasedimentary and metavolcanic bedrock forming the majority of the lobe catchments has very low to medium strength and is heavily fractured, thus easily contributing to FDL formation. The eight investigated FDLs consist of platy rocks typical of their catchments, organic debris, and an ice-poor soil matrix; massive ice, however, is present within FDLs as infiltration ice, concentrated within cracks open to the surface. Exposure of infiltration ice in retrogressive thaw slumps (RTSs) and associated debris flows leads to increased movement and various stages of destabilization, resulting in morphological differences among the lobes. Analysis of historic imagery indicates that movement of the eight investigated FDLs has been asynchronous over the study period, and since 1955, there has been an overall increase in movement rates of the investigated FDLs. The formation of surface features, such as cracks, scarps, and RTSs, suggests that the increased movement rates correlate to general instability, and even at their current distances, FDLs are impacting infrastructure through increased sediment mobilization. FDL-A is the largest of the investigated FDLs. As of August 2015, FDL-A was 39.2 m from the toe of the Dalton Highway embankment. Based on its current distance and rate of movement, we predict that FDL-A will reach the Dalton Highway alignment by 2023.

Change detection of cotton root rot infection over 10-year intervals using airborne multispectral imagery

Cotton root rot is a very serious and destructive disease of cotton grown in the southwestern United States. Accurate information regarding its spatial and temporal distribution within fields is important for effective management of the disease. The objectives of this study were to examine the consistency and variation of cotton root rot infections within cotton fields over 10-year intervals using airborne multispectral imagery and to assess the feasibility to use historical imagery to create prescription maps for site-specific management of the disease. Airborne multispectral images collected from a 102-ha cotton field in 2001 and 2011 and from a 97-ha field in 2002 and 2012 in south Texas were used in this study. The images were rectified and resampled to the same pixel size between the two years for each field. The normalized difference vegetation index (NDVI) images were generated and unsupervised classification was then used to classify the NDVI images into root rot-infected and non-infected zones. Change detection analysis was performed to detect the consistency and change in root rot infection between the two growing seasons for each field. Results indicate that the spatial patterns of the disease were similar between the two seasons, though variations existed for each field. To account for the potential expansion and temporal variation of the disease, buffer zones around the infected areas were created. The buffered maps between the two years agreed well. The results from this study demonstrate that classification maps derived from historical images in conjunction with appropriate buffer zones can be used as prescription maps for site-specific fungicide application to control cotton root rot.

Response of a temperate alpine valley glacier to climate change at the decadal scale

Glacier advance and recession are considered key indicators of climate change. Understanding the relationship between climatic variations and glacial responses is crucial. Here, we apply archival digital photogrammetry to reconstruct the decadal scale glacial history of an unmonitored Alpine valley glacier, the Haut Glacier d'Arolla, Switzerland, and we use the data generated to explore the linkages between glacier recession and climate forcing. High precision digital elevation models were derived. They show continual recession of the glacier since 1967, associated with long‐term climatic amelioration but only a weak reaction to shorter‐term climatic deterioration. Glacier surface velocity estimates obtained using surface particle tracking showed that, unlike for most Swiss glaciers during the late 1970s and early 1980s, ice mass flux from the accumulation zone was too low to compensate for the effects of glacier thinning and subsequent snout recession, especially during the rapid warming that occurred through the 1980s. The results emphasise the dangers of inferring glacier response to climate forcing from measurements of the terminus position only and the importance of using remote sensing methods as an alternative, especially where historical imagery is available.

Wetland loss patterns and inundation-productivity relationships prognosticate widespread salt for southern New England.

Tidal salt marsh is a key defense against, yet is especially vulnerable to, the effects of accelerated sea level rise. To determine whether salt marshes in southern New England will be stable given increasing inundation over the coming decades, we examined current loss patterns, inundation-productivity feedbacks, and sustaining processes. A multi-decadal analysis of salt marsh aerial extent using historic imagery and maps revealed that salt marsh vegetation loss is both widespread, and accelerating, with vegetation loss rates over the past four decades summing to 17.3%. Seaward retreat of the marsh edge, widening and headward expansion of tidal channel networks, loss of marsh islands, and the development and enlargement of interior depressions found on the marsh platform contributed to vegetation loss. Inundation due to sea level rise is strongly suggested as a primary driver: vegetation loss rates were significantly negatively correlated with marsh elevation (r2=0.96; p=0.0038), with marshes situated below mean high water (MHW) experiencing greater declines than marshes sitting well above MHW. Growth experiments with Spartina alterniflora, the Atlantic salt marsh ecosystem dominant, across a range of elevations and inundation regimes further established that greater inundation decreases belowground biomass production of Spartina alterniflora and thus negatively impacts organic matter accumulation. These results suggest that southern New England salt marshes are already experiencing deterioration and fragmentation in response to sea level rise, and may not be stable as tidal flooding increases in the future.

Psychoanalysis, Fantasy, Postcoloniality: Turkish Nationalism and Historiography in Post-Ottoman Turkey

In this article, I investigate the surge of scholarly interest in Ottoman minorities since 1980s - a surge that acts in defense of a national culture. What distinguishes the nationalist-cum-Ottomanist historiography of the Turkish historians under study here is the heavy emphasis on notions of tolerance and multiculturalism with direct reference to the imperial era of 15th and 17th centuries. This emerging discourse has been striving to rebut the Orientalist stigmas attributed to Turkish-Ottoman culture and civilization—such as barbaric, despotic and authoritarian—and construct its own tolerant and multicultural historical imagery. Drawing upon the urgent lessons of postcolonial experience, theory and history, I analyze the pitfalls of uncritically clinging to such an imaginary. The emergence of this new Turkish-Ottoman imaginary and its discourse of a Turkish nativism and Occidentalism that emphasizes minority rights, tolerance and the harmonious coexistence of a plurality remains an under-explored territory for postcolonial criticism. The analysis of nostalgic Ottoman literature can illuminate how the ‘Occident/Western’ and ‘Oriental/Derivative’ (i.e. the Ottoman and Turkish) formations of the national imaginary are constructed, remembered and contested in the contemporary global order.

Application of Ground Penetrating Radar for Identification of Washover Deposits and Other Stratigraphic Features: Assateague Island, MD

A combination of ground penetrating radar (GPR) data, core data, and aerial photographs were analyzed to better understand the evolution of two portions of Assateague Island, Maryland. The focus of the study was to investigate the applicability of using GPR data to image washover deposits in the stratigraphic record. High amplitude reflections observed in two shore-perpendicular GPR profiles were correlated to shallow (<1 m) lithologic contacts observed in sediment cores. At these contacts, deposits consisting primarily of quartz sand overlie sediments with organic matter that include degraded plant root or stem material. The underlying organic matter likely represents the vegetated portion of the barrier island that was buried by washover fans deposited during hurricanes Irene (2011) and Sandy (2012), as indicated in high-resolution aerial photographs. The GPR data were able to delineate the washover deposits from the underlying stratigraphic unit; however, the radar data did not resolve finer structures necessary to definitively differentiate washover facies from other sand-rich deposits (e.g., flood-tide deltas and dunes). Other GPR profiles contain reflections that likely correlate to geomorphic features like tidal channels and vegetated zones observed in historical aerial imagery. Burial of these features by overwash fluxes were observed in the aerial imagery and thus the resulting radar sequence is largely interpreted as washover deposits. Deeper, channel-like features that have been infilled were also observed in shore-parallel profiles and these features coincide with scour channels observed in the 1966 aerial photography. Additional sedimentological data are required to determine what role overwash played in the in-filling of these features.

Encroachments in floodways of the Mississippi River and Tributaries Project

The Mississippi River and Tributaries (MR&T) Project aims to protect the land within the lower Mississippi Valley from floods and to assure the navigability of the channel. One of the main flood risk mitigation features comprised in this project are floodways, or flood bypass channels, which divert excess flows in order to lower critical stages in the river. However, encroachments, i.e., buildings and other structures constructed within the floodways, can jeopardize their proper functioning and therefore compromise the functioning of the entire system. The presence of encroachments and resistance to flooding them delayed activation of the Birds Point-New Madrid Floodway in the flood of 2011. However, there has been no prior comprehensive study of encroachments on this and the West Atchafalaya floodways, the two largest in the MR&T system. Using historical maps and aerial imagery, we systematically measured the number, type, and spatial distribution of encroachments in the two floodways since the late 1960s. Encroachments in the Birds Point-New Madrid Floodway decreased by half, while the number of encroachments in the West Atchafalaya Floodway tripled, mainly concentrated along highways, such that they create linear bands of higher hydraulic resistance. The presence of encroachments clearly discourages use of the floodways from their designed purpose, but we are not aware of any studies that have analyzed whether the presence of these structures would measurably affect flow hydraulics through the floodways.

Assessing the long-term impact of urbanization on run-off using a remote-sensing-supported hydrological model

Land use/land cover (LULC) change in Dongguan, a city belonging to the Pearl River Delta metropolitan area, and its impact on the run-off of this city since the rapid urbanization period starting in 1979 are analysed in this article. Historic remote-sensing imagery (acquired in 1979, 1989, 2000, 2006, and 2013) was processed by the Support Vector Machine (SVM) method to obtain LULC data, and a long-term hydrologic impact assessment (L-THIA) model was applied to evaluate the long-term effects of LULC changes on surface run-off. The results show the urbanized area in Dongguan has increased more than 52% from 1979 to 2013 and the percentages of annual surface run-off depth and annual surface run-off coefficient are 58% and 5.83%, respectively. The increase in annual surface run-off is related to urbanization, and the centre area of the city has experienced the largest increase in annual surface run-off. The 32 towns’ local indicators of spatial association show centre towns are hot spots of increases in annual surface run-off in Dongguan city.

The Death of the Agama Lizard: The Historical Significances of a Multi-authored Rock-art Site in the Northern Cape (South Africa)

The ethnographic data of the Bleek-Lloyd archive pertaining to the ǀXam Bushmen (San) of the Karoo have been marshalled to great effect in developing understandings of Bushman rock art throughout southern Africa, with implications for archaeological interpretations of hunter-gatherer rock arts worldwide. Rock art from their homelands, however, has received comparatively little attention, and obvious historical content—which would tie the art to the socio-cultural milieu of the Bleek-Lloyd informants—has occasioned relatively little comment. This paper returns to one site (the Strandberg) known to have been a prominent feature in the cultural landscape of the ǀXam to explore the historical imagery present there, examining the ways in which this art demonstrates the ongoing vitality of certain aspects of ǀXam life in the face of the dramatic socio-cultural changes experienced by these groups from the nineteenth to early twentieth centuries. The paper investigates the range of potential authors for the art, and looks at the context of its production within the expansion of global markets, violent interactions and shifting subsistence options that characterized the late nineteenth-century Northern Cape.

Evolution of the Unzen Volcano and the Shimabara Peninsula (Japan) during the last 60 years: The role of the 1990-1995 eruption in modifying the landscape

The Unzen Volcano, located at the centre of the Shimabara Peninsula is a stratovolcano that has left scars both in the landscapes and the lives of local inhabitants. After almost two centuries of slumber, the Unzen erupted during the period 1990-1995, producing numerous dome-collapses pyroclastic flows that engulfed a large part of the structure. Using a dataset retrieved by structure-from-motion from historical imagery, the present contribution provides an insight on the landscape trajectory of the volcano between the period 1947 and 2013, using the lenses of geomorphology and biogeography. The results have shown that the volcano has been evolving in two different manners since the eruption. The summit area of the volcano still holds a large amount of material (pyroclasts of 50 m depth have been measured from the 1998 imagery). This area has seen a return of the vegetation, which contrasts with the foot of the volcano, trapped in a concrete coffin, limiting the return of vegetation and living the wounds of the eruption open. Finally, at the exit of the Mizunashigawa, the impacts of the eruption have spread to the shore, with a linear expansion over the sea of almost 500 m. In Conclusion, this contribution shows that it isn’t much the volcanic eruption that modified the landscape over long periods of time, but the human infrastructure that stops some part of the landscape to evolve.

The relative impacts of vegetation, topography and spatial arrangement on building loss to wildfires in case studies of California and Colorado

Wildfires destroy thousands of buildings every year in the wildland urban interface. However, fire typically only destroys a fraction of the buildings within a given fire perimeter, suggesting more could be done to mitigate risk if we understood how to configure residential landscapes so that both people and buildings could survive fire. Our goal was to understand the relative importance of vegetation, topography and spatial arrangement of buildings on building loss, within the fire’s landscape context. We analyzed two fires: one in San Diego, CA and another in Boulder, CO. We analyzed Google Earth historical imagery to digitize buildings exposed to the fires, a geographic information system to measure some of the explanatory variables, and FRAGSTATS to quantify landscape metrics. Using logistic regression we conducted an exhaustive model search to select the best models. The type of variables that were important varied across communities. We found complex spatial effects and no single model explained building loss everywhere, but topography and the spatial arrangement of buildings explained most of the variability in building losses. Vegetation connectivity was more important than vegetation type. Location and spatial arrangement of buildings affect which buildings burn in a wildfire, which is important for urban planning, building siting, landscape design of future development, and to target fire prevention, fuel reduction, and homeowner education efforts in existing communities. Landscape context of buildings and communities is an important aspect of building loss, and if taken into consideration, could help communities adapt to fire.