Historical Topographic Maps Research Articles

Estimation of the thickness of anthropogenic deposits in historical urban centres: An interdisciplinary methodology applied to Rome (Italy)

In historical urban centres, the superimposition of excavation and deposition activities over time has resulted in an irregular spatial distribution of anthropogenic deposits, which may reach considerable thicknesses. The detection of those thicknesses requires extensive investigations. Broad borehole and geophysical campaigns cost time and money, consequently at the urban-planning level, it is usual to shift to an estimation of thicknesses, which may be performed through map-algebra operations, that is, by subtracting from the modelled ground surface the elevation of the anthropogenic-deposit basal surface. The latter is implemented through the interpolation of point elevation data, which are generally provided by borehole logs. Despite the development of advanced spatial interpolation methodologies, previous modelling results in the literature show that if the process is affected by insufficient input data, it produces imprecise interpolation outputs. This paper reports an interdisciplinary methodology aiming at enhancing elevation datasets, in order to obtain more accurate digital elevation models. The increase in number and spatial distribution of input points is achieved through past-landscape analyses mainly based on elevation data given by borehole logs, available archaeological reports and historical topographic maps, these being generally available for historical urban centres. The methodology was tested in an urban sector of Rome, where significant activities have been performed for millennia particularly during the Roman Age. A reliable model of the basal surface of the anthrostrata led to a better estimation of the spatial distribution of such deposits and, in addition, revealed the original topographic surface, as modified by human activities.

Detection and Geometrical Characterization of a Buried Landfill Site by Integrating Land Use Historical Analysis, Digital Photogrammetry and Airborne Lidar Data

Abandoned quarries are frequently used as sites of illegal dumping of solid urban waste. These sites often occur nearby or within urban areas so that their detection may turn out to be quite difficult from the surface. This study focuses on the detection and geometrical characterization of a hidden landfill site located along the coastline of the Campi Flegrei, near Naples, Italy. Our approach is based on the analysis of historical topographic maps and aerial photographs, coupled with quantitative comparison of multitemporal digital elevation models obtained by digital photogrammetry and lidar techniques. The comparative analysis of topographic maps and aerial photos clearly shows modifications of the landscape associated with the urban development and quarrying activity, as well as the later filling of the quarry. The change detection analysis reveals that remarkable elevation changes occurred in the study area between 1956 and 2008. The average thickness of the landfill deposits is ca. 8 m, whereas the average volume is ca. 100,000 m3. The results of this work confirm the suitability of the used methodological approach that combines both qualitative and quantitative techniques for the detection of buried landfill sites. The geometric characterization of a landfill represents a fitting starting point for the further planning of geophysical site surveys and direct investigations aimed at the assessment of environmental hazards.

A review of recent advances in scanned topographic map processing

Abstract Historical topographic maps carry huge information of this planet over a very long period. Geographic information extraction from topographic map (TM) is helpful for understanding the environmental changes and other geography related research fields. However, both quality and quantity of TM bring big challenges in efficient interpretation. Numerous studies have been focused on extracting geographic information from scanned topographic maps (STM). In this work, we will review lots of studies on STM processing in the past a few decades. Most of the discussing approaches are grouped into two categories which are segmentation and vectorization. Segmentation is the foundation for information extraction from STM and the segmenting results directly influence the subsequent procedures. Vectorization component contains four main geographic elements including contour line, road, text and symbols. This work reviews amount of published articles in these research areas and gives brief introduces about those previous studies as well as analysis and comments. Our goal is to show the exist ideas in STM processing and provide some general knowledge on methods and patterns which are employed in those studies. Most important, through the overview of existing approaches, new thoughts and ideas about STM processing are expected.

Historical glacier outlines from digitized topographic maps of the Swiss Alps

Abstract. Since the end of the Little Ice Age around 1850, the total glacier area of the central European Alps has considerably decreased. In order to understand the changes in glacier coverage at various scales and to model past and future streamflow accurately, long-term and large-scale datasets of glacier outlines are needed. To fill the gap between the morphologically reconstructed glacier outlines from the moraine extent corresponding to the time period around 1850 and the first complete dataset of glacier areas in the Swiss Alps from aerial photographs in 1973, glacier areas from 80 sheets of a historical topographic map (the Siegfried map) were manually digitized for the publication years 1878–1918 (further called first period, with most sheets being published around 1900) and 1917–1944 (further called second period, with most sheets being published around 1935). The accuracy of the digitized glacier areas was then assessed through a two-step validation process: the data were (1) visually and (2) quantitatively compared to glacier area datasets of the years 1850, 1973, 2003, and 2010, which were derived from different sources, at the large scale, basin scale, and locally. The validation showed that at least 70 % of the digitized glaciers were comparable to the outlines from the other datasets and were therefore plausible. Furthermore, the inaccuracy of the manual digitization was found to be less than 5 %. The presented datasets of glacier outlines for the first and second periods are a valuable source of information for long-term glacier mass balance or hydrological modelling in glacierized basins. The uncertainty of the historical topographic maps should be considered during the interpretation of the results. The datasets can be downloaded from the FreiDok plus data repository (https://freidok.uni-freiburg.de/data/15008, https://doi.org/10.6094/UNIFR/15008).

Analyses of Archival Cartographic Materials for Geomorphological Changes of River Channel

In Lithuania, the old archival topographic maps of locations of small and medium scale and 1 : 10,000 scale contour photo plans were created on the basis of aerial images. The material of these scales provides documented records on the condition of the objects in the location and the landscape at the moment of aerial photography. Those maps can be used to restore the accurate topographic image of the terrain and buildings in 1945–1951 and in later years and perform the necessary topographic, photogrammetric, and geodetic measurements of the parameters of objects, to identify the location of objects and changes. This information is necessary for a variety of disputed property issues and for building farmhouses in reserves, in areas of forestry land parcels, and for assessment of changes in the landscape. Studies of landscape changes are needed for the assessment of renaturalization processes. This paper presents the geodetic method used for geomorphological changes at the channel of River Žalesa during the period 1942–2017, based on the collected archival cartographic materials: historical topographic maps from archive of the Lithuanian State Company Land Fund, Land Information System, and land management projects and orthophoto maps from Lithuanian spatial information portal and free open‐access Sentinel‐1 satellite data from the Copernicus Open Access Hub.

Hagiotoponimi na istarskim gradinama

Mjesna imena odraz su izgleda prostora, gospodarstva, povijesnog razvitka te društvenih odnosa. Ona govore o slojevitosti naseljavanja određenog teritorija. Tijekom brončanog i željeznog doba u Istri, osim pećina, glavni oblik naselja bile su gradine kojih je kartirano oko 450, od kojih čak 85 ili 19 % nose svetačka imena. Na temelju terenskih istraživanja te korištenja podataka s povijesnih i suvremenih topografskih karata napravljen je detaljni razmještaj toponima i analiza njihove rasprostranjenosti s obzirom na dva fizička prostora, more i kopno, i dva jezična prostora, hrvatski i talijanski. Crkvice ili njihovi ostatci, ili samo toponimi sa svetačkim imenom, pokazuju kontinuitet života na određenom mjestu, kao i sigurnost koju su jamčile unutar svojih zidova. Najučestaliji hagiotoponim jest Sveta Marija i sve njezine inačice (Sveta Marina).

Modeling the Economic Value of Blue Carbon in Delaware Estuary Wetlands: Historic Estimates and Future Projections

Coastal wetlands sequester large amounts of carbon in their soils, effectively removing carbon dioxide from the atmosphere and acting as a carbon sink. In this paper, we estimate the economic value of carbon sequestered by wetlands in the Delaware Estuary. We estimate the value of the current stock of wetlands, the value of the historic loss of wetlands, and under a range of different scenarios the expected future loss. We use historical topographic maps and Land Cover inventories of the Delaware Estuary to measure the acreage of tidal wetlands in nine distinct time periods from 1778 to 2011. Using these data, we estimate an annual rate of wetland loss of 1.03 km2. Coupling observed land cover change with exogenous factors including sea-level rise, population pressure, and channel dredging, we estimate changes in tidal wetland area under a range of future scenarios for our expected future economic loss estimates.

Reconstructing the evolution of a deep seated rockslide (Marzell) and its response to glacial retreat based on historic and remote sensing data

In this study a combination of different topographic data from historic topographic maps and remote sensing is used to reconstruct and monitor the behaviour of the high alpine ice contact rockslide system Marzell and its response to glacial debuttressing in the Eastern Alps. Topographic data from archives (historical topographic maps, national glacier inventories, aerial images, orthoimages and ALS data) and data from monitoring campaigns (geodetic measurements, terrestrial laser scanning and UAV imaging campaigns) are processed to georeferenced images and/or elevation data, respectively. The data from different data sources is compiled and analysed with the aim to i) reconstruct the extent, thickness and volume changes of the glacier since 1893 and ii) to analyse the rockslide deformation evolution by extracting information about the displacement direction, dip angle, velocity and partial failure of rockslide slabs since 1951. The rockslide is compound of different rockslide slabs which move downwards as rigid blocks along basal shear zones. The analyses and interpretation of the data suggest a rotational type of rockslide failure mechanisms. The rockslide activity correlates with the ice volume loss at the adjacent part of the glacier. In the period between 1971 and 1997 the annual average rockslide activity was about 0.05m/a and the annual average ice thickness loss was 0.1m/a. Since the end of the last century the annual average ice thickness loss increased dramatically to 5m/a. In that period the rockslide activity accelerated. The highest rockslide activity (up to 1.5m/a) was observed in the 2000s when half of the slope toe was exposed because of glacier retreat. Since 2010 a deceleration of the rockslide can be observed. In the vicinity of the rockslide the glacier almost disappeared and lost 99.88% of its ice volume between 1893 and 2014. The geomorphological and geological information gathered about the rockslide evolution and the glacier retreat form the base for further rockslide analyses and allow to study and model the influence from glacial debuttressing.

Typy morfogenetyczne wsi w środkowej Polsce

Historico-geographical analysis of the layouts of villages in central Poland made it possible to distinguish the morphogenetic types of rural settlements characteristic of the specified historical periods. On the basis of the historical topographic maps, it is also possible to describe the features of spatial distribution of the morphogenetic types of villages for the investigated area. Central Poland presents a very diversified morphogenetic picture of villages, which results from a great number of complex historical and socio-economic processes, as well as from varied geographical conditions. Four main historical periods were distinguished, during which the following characteristic morphogenetic types of villages were established: 1. irregular medieval villages which did not undergo regulation in the Middle Ages; 2. regular medieval villages located on German Law; 3. newer settlements founded in the Modern Period (e.g. manorial layouts and villages connected with the so-called oleder settlement and Frederician colonization); 4. villages formed in the process of regulation and parcellation in 19th c. The villages form Early Middle Ages developed in an evolutionary way, were not regulated, and adapted well to the local topographic position. Among the villages with irregular habitats from this period the following types can be singled out: road villages, little green villages (small oval) and circular villages; cross-road villages and multi-road villages. The land was divided into numerous small fields, irregular in shape. The layout of fields in these villages takes the form of blocks, block-strips and irregular small fields. Two distinct processes were taking place in the Middle Ages: foundation of the new villages on the so-called in cruda radice , and regulation of the villages already existing according to the German law. These villages were built mostly on the Church land of the cloisters and bishops, as well as on land belonging at that time to the Duke. The generally accepted types of villages founded on the German law are: large regular street villages and regular green villages (with oval or rectangular square). Regular field patterns in those villages were organized in the open-field patternadapted to the three-field rotation system. Within the group of villages of later origin, established between the 16th c. and the 1th half of 19th c., the following types were distinguished: manors and marshy row villages (the so-called oleder or Frederician colonies and other colonies – the so-called forest settlements). In Modern Period one can identify mostly the manor-peasant village with a complex of manor buildings and peasant homesteads. Manor and peasant fields intermingled and were cultivated by means of the three-field system. Rarely can one observe manor villages which included only the manor complex with crofters’ small holdings and where fields were consolidated into large blocks. In the 18th c. planned villages were built again, which was connected with the Frederician and the so-called oleder colonization. Marshy row villages located on clearings can be distinguished, which represented a different spatial pattern with regard to the economic functions of their population. Agricultural colonies were mostly regular street villages, densely built-up. The pattern of the fields took the form of regular, schematic, broad stripes, belonging to separate owners. The 19th c. marks the turning point in the development of the forms of rural settlement. The ancient spatial settings of villages have changed mostly in connection with the transformation of the socio-economic life of the countryside, in particular the enfranchisement of peasants, the parcellation of manors and field consolidation, the disappearance of the threefield rotation system, and the introduction of new techniques of cultivation. In the manor- peasant village one can observe the process of separation of manor and peasant land. In the context of parceling-out it is possible to distinguish row villages with fields in the form of ownership stripes, perpendicular to the road and dispersed settlement with block system of fields. The irregular layouts of villages from the Middle Ages were formed mostly in the peripheries of central Poland, in the valleys of the Warta, Bzura and Pilica rivers. Compact settlement regions of regular villages, founded during the medieval colonization, have been identified in the area of former ecclesiastical or royal estates where proprietors were interested in location of villages based on the German law. Manors developed mainly inside the villages, and they did not form separate settlement units and morphogenetic zones. Forest colonies and marshy row villages appear as small enclaves throughout the whole investigated area, especially in the central part of region, because they were mostly founded on clearings, areas not cultivated before, on poor soils and in forests.

Forest cover mask from historical topographic maps based on image processing

This study aimed to obtain accurate binary forest masks which might be directly used in analysis of land cover changes over large areas. A sequence of image processing operations was conceived, parameterized and tested using various topographic maps from mountain areas in Poland and Switzerland. First, the input maps were filtered and binarized by thresholding in Hue‐Saturation‐Value colour space. The second step consisted of a set of morphological image analysis procedures leading to final forest masks. The forest masks were then assessed and compared to manual forest boundary vectorization. The Polish topographical map published in the 1930s showed low accuracy which could be attributed to methods of cartographic presentation used and degradation of original colour prints. For maps published in the 1970s, the automated forest extraction performed very well, with accuracy exceeding 97%, comparable to accuracies of manual vectorization of the same maps performed by nontrained operators. With this method, we obtained a forest cover mask for the entire area of the Polish Carpathians, easily readable in any Geographic Information System software.

Long-Term Geomorphic Changes in the Coastal Profile of Lingding Bay in the Pearl River Estuary and the Response to Tides Since 1906

Lingding Bay in the Pearl River Estuary, located on the north coast of the South China Sea, experiences frequent storm surges caused by typhoons. The geomorphic features of the Pearl River Estuary have changed tremendously due to natural processes and human activities over the last century, and these changes have led to changes in the hydrodynamic environment, such as a reduced capacity for holding tides in the coastal zone. In this paper, the relation between geomorphic features and the capacity for holding tides is analyzed. In order to ascertain how historical landform change affects this capacity, we study the spatial morphology change of Lingding Bay in the Pearl River Estuary (since 1906) through the analysis of historical topographic maps and nautical charts. The shape index and fractal dimension were introduced as indicators to reflect coastline changes that have affected the tides. The tidal dissipation rate and tidal influx were found to describe a bay’s capacity to hold tides. The results show that, since 1906, the tidal influx and the tidal dissipation rate have decreased by about 14.11% and 23%, respectively, in the study area. We suppose that these changes could be attributed to geomorphic changes, primarily changes brought about by land reclamation projects.

Historical analysis and visualization of the retreat of Findelengletscher, Switzerland, 1859–2010

Since the end of the Little Ice Age around 1850, glaciers in Europe have strongly retreated. Thanks to early topographic surveys in Switzerland, accurate maps are available, which enable us to trace glacier changes back in time. The earliest map for all of Switzerland that is usable for a detailed analysis is the Dufour map from around 1850 with subsequent topographic maps on a ~20year interval. Despite the large public and scientific interest in glacier changes through time, this historic dataset has not yet been fully utilized for topographic change assessment or visualization of historic glacier extents. In this study, we use eleven historical topographic maps and more recent digital datasets for the region of Zermatt to analyze geometric changes (length, area and volume) of Findelengletscher as well as for creating animations of glacier evolution through time for use in public communication. All maps were georeferenced, the contour lines digitized, and digital elevation models (DEMs) created and co-registered. Additional digital data like the SRTM X-band DEM and high resolution laser scanning data were used to extend the analysis until 2010. Moreover, one independent DEM from aerial photogrammetry was used for comparison. During the period 1859–2010, Findelengletscher lost 3.5km of its length (6.9km in 2010), 4.42±0.13km2 of its area (15.05±0.45km2 in 2010) and 1.32±0.52km3 of its volume. The average rate of thickness loss is 0.45±0.042myr−1 for the 151years period. Four periods with high thickness change from −0.56m±0.28yr−1 (1859–1881), −0.40±0.08myr−1 (1937–1965), −0.90±0.31myr−1 (1995–2000) and −1.18±0.02myr−1 (2000–2005) have been identified. Small positive thickness changes were found for the periods 1890–1909 (+0.09±0.46myr−1) and 1988–1995 (+0.05±0.24myr−1). During its retreat with intermittent periods of advance, the glacier separated into three parts. The above changes are demonstrated through an animation (available from the supplementary material), which has been created to inform the general public.

Automatic delineation of built-up area at urban block level from topographic maps

To comprehensively study and better understand urban dynamic processes — such as densification, growth and sprawl, or shrinkage — spatio-temporal databases that allow to track changes of geographic objects like buildings and urban blocks are essential. While comprehensive databases exist for contemporary data, they usually lack a historic dimension. The manual constitution of historic geographic data, be it based on historic maps or aerial images, is a time consuming and laborious process, however. Therefore, we present an approach to semi-automatically extract this data from binary topographic maps with regard to built-up areas at urban block level. The suitability of topographic maps for historic urban analysis has been proven in previous research. To overcome the challenges that are inherent in scanned topographic maps in regard to digital image interpretation we designed a modular process. Among others, these challenges include fused and (multi-)fragmented map objects caused by the overlap of competing content layers in one single binary map. After a preliminary separation of individual map object layers from the map content, the process follows a two-stage top-down approach. At first, the map is organized into street blocks, which after that are re-delineated in regard to built-up area. In doing so, we achieve correctness values ranging from 0.97 to 0.93 for three study sites in Germany. With an increasing number of projects that provide historic topographic maps as georeferenced digital data, our process represents a promising approach to efficiently prepare these historic data for integration into a spatio-temporal database with minimal user intervention.

The Influence of the Online Availability of USGS Topographic Maps on Weeding Decisions in Academic Libraries

ABSTRACTThis study looked at the degree to which the online availability of U.S. Geological Survey historical topographic maps affects academic libraries' decisions to withdraw the print versions of those maps. Other factors in making the decisions, such as usage, user preferences, support of academic programs, user discovery, shelving location, and printing options, were also investigated. Results show that while in 40% of the cases the online USGS historical topographic maps influenced the decision to weed, the need for space was the overwhelming driver of print USGS topographic map collection weeding within the past ten years.

Application of virtual earth in 3D terrain modeling to visual analysis of large-scale geological disasters in mountainous areas

Sudden large-scale geological disasters can be triggered in mountainous areas by events such as earthquakes, rainfall, volcanic eruptions, or human activity, leading to serious loss of life and property. Generating digital elevation model (DEM) for such geological disasters allows the rapid identification of affected areas, which is essential for emergency response and hazard mitigation. The main aim of this study is to propose a low-cost and efficient method based on virtual earth to generate a three-dimensional (3D) DEM. Based on the terrain model, numerical simulations can be conducted and the results integrated with virtual earth to perform 3D visualization and visual analysis. The method proposed in this study may solve some limitations existing in other more traditional methods. For example, historical topographic maps exist mostly in paper format, which is not conducive to spatial analysis, while interpretation of remote-sensing images generally requires professional knowledge at a high cost. The emergence of the virtual earth platform of Google Earth (GE) provides new possibilities for generating terrain models. Terrain information can be extracted efficiently and freely from GE using an application programming interface (API) and then used to generate DEM. In this paper, the Donghekou landslide-debris flow triggered by the 2008 Wenchuan earthquake was selected as a case study. 3D visualization of the temporal-spatial dynamic process of a natural disaster was carried out by combination of the numerical results and GE imaging. The comparison of the study case with field survey data proves the validity of the proposed method as it describes the real terrain shape and determines the slide distance accurately, although the elevation error may be large. The free and easy-to-use method proposed here can provide an intuitive basis for hazard assessment and rapid responses to geological disasters.

Cosmogenic 10Be constraints on Little Ice Age glacial advances in the eastern Tian Shan, China

Presumed Little Ice Age (LIA) glacial advances, represented by a set of fresh, sharp-crested, boulder covered and compact moraines a few hundred meters downstream from modern glaciers, have been widely recognized in the Central Asian highlands. However, few studies have constrained the formation ages of these moraines. We report 31 10Be exposure ages from presumed LIA moraines in six glacial valleys in the Urumqi River headwater area and the Haxilegen Pass area of the eastern Tian Shan, China. Our results reveal that the maximum LIA glacial extent occurred mainly around 430 ± 100 yr, a cold and wet period as indicated by proxy data from ice cores, tree rings, and lake sediments in Central Asia. We also dated a later glacial advance to 270 ± 55 yr. However, 10Be exposure ages on several presumed LIA moraines in front of small, thin glaciers are widely scattered and much older than the globally recognized timing of the LIA. Historical topographic maps indicate that most glaciers were more extensive in the early 1960s, and two of our 10Be sample sites were located close to the ice front at that time. Boulders transported by these small and thin glaciers may be reworked from deposits originally formed prior to the LIA glacial advances, producing apparently old and widely scattered exposure ages due to varied nuclide inheritance. Other published ages indicated an earlier LIA advance around 790 ± 300 yr in the easternmost Tian Shan, but in our study area the more extensive advance around 430 ± 100 yr likely reworked or covered deposits from this earlier event.

Broad scale forest cover reconstruction from historical topographic maps

Land cover change is one of the major contributors to global change, but long-term, broad-scale, detailed and spatially explicit assessments of land cover change are largely missing, although the availability of historical maps in digital formats is increasing. The problem often lies in efficiency of analyses of historical maps for large areas. Our goal was to assess different methods to reconstruct land cover and land use from historical maps to identify a time-efficient and reliable method for broad-scale land cover change analysis. We compared two independent forest cover reconstruction methods: first, regular point sampling, and second, wall-to-wall mapping, and tested both methods for the Polish Carpathians (20,000 km2) for the 1860s, 1930s and 1970s. We compared the two methods in terms of their reliability for forest change analysis, relative to sampling error, point location and landscape context including local forest cover, area of the spatial reference unit and forest edge-to-core ratio. Our results showed that the point-based analysis overestimated forest cover in comparison to wall-to-wall mapping by 1–3%, depending on the mapping period. The reasons for the differences were mainly the backdating approach and map generalisation rather than the point grid position or sampling error. When we compared forest cover trajectories over time, we found that the point-based reconstruction captured forest cover dynamics with a comparable accuracy to the wall-to-wall mapping. More broadly, our assessment showed that historical maps can provide valuable data on long-term land cover trends, and that point-based sampling can be an efficient and accurate way to assess forest area and change trends. We suggest that our point-based approach could allow land cover mapping across much of Europe starting in the 1800s. Our findings are important because they suggest that land cover change, a key component of global change, can be assessed over large areas much further back in time than it is commonly done. This would allow to truly understand path dependencies, land use legacies, and historical drivers of land cover change.

Changes in Glacier Volume in the North Bank of the Bangong Co Basin from 1968 to 2007 Based on Historical Topographic Maps, SRTM, and ASTER Stereo Images

Heterogeneous mass wastage has been found across the northwestern Tibet Plateau, and both slight positive and negative average mass budgets were observed using different data sets during the past decades. The north bank of the Bangong Co Basin partly covers the Western Kunlun Mountains and Karakoram Mountains. The assessment of glacier mass budget in this region over a long period is of particular interest to understanding the regional diversity of the mass changes of glaciers. Changes in glacier mass in the area of concern were assessed by differentiation of digital elevation models (DEMs) from the earliest available topographic maps, the Shuttle Radar Terrain Mission (SRTM), and the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) stereo images. Results show that glaciers in this basin have in general experienced a decelerated mass loss but with regional differences. Glaciers were found to have lost a volume of 4.45 ± 0.63 km3 from 1968 to 2007, corresponding to -0.18 ± 0.03 m a-1 water equivalent (w.e.) in the north bank of the Bangong Co Basin. Loss of glacier mass in this region from 1999 to 2007 was 0.11 ± 0.12 m w.e. a-1, which was approximately half the loss that occurred from 1968 to 1999 (-0.20 ± 0.01 m w.e. a-1). From 1968 to 1999, higher mass losses were found in the north with smaller losses in the south, while from 1999 to 2007 there was more loss of mass in the southeast and a somewhat balanced mass budget in the northeast.

Back-extrapolating a land use regression model for estimating past exposures to traffic-related air pollution.

Land use regression (LUR) models rely on air pollutant measurements for their development, and are therefore limited to recent periods where such measurements are available. Here we propose an approach to overcome this gap and calculate LUR models several decades before measurements were available. We first developed a LUR model for NOx using annual averages of NOx at all available air quality monitoring sites in Israel between 1991 and 2011 with time as one of the independent variables. We then reconstructed historical spatial data (e.g., road network) from historical topographic maps to apply the model's prediction to each year from 1961 to 2011. The model's predictions were then validated against independent estimates about the national annual NOx emissions from on-road vehicles in a top-down approach. The model's cross validated R2 was 0.74, and the correlation between the model's annual averages and the national annual NOx emissions between 1965 and 2011 was 0.75. Information about the road network and population are persistent predictors in many LUR models. The use of available historical data about these predictors to resolve the spatial variability of air pollutants together with complementary national estimates on the change in pollution levels over time enable historical reconstruction of exposures.

Geospatial Resources for the Geology Community: The USGS National Map

Geospatial data are a key component of investigating, interpreting, and communicating the geological sciences. Locating geospatial data can be time-consuming, which detracts from time spent on a study because these data are not obviously placed in central locations or are served from many disparate databases. The National Map of the US Geological Survey is a publicly available resource for accessing the geospatial base map data needs of the geological community from a central location. The National Map data are available through a viewer and download platform providing access to eight primary data themes, plus the US Topo and scanned historical topographic maps. The eight themes are elevation, orthoimagery, hydrography, geographic names, boundaries, transportation, structures, and land cover, and they are being offered for download as predefined tiles in formats supported by leading geographic information system software. Data tiles are periodically refreshed to capture the most current content and are an efficient method for disseminating and receiving geospatial information. Elevation data, for example, are offered as a download from the National Map as 1° × 1° tiles for the 10- and 30- m products and as 15′ × 15′ tiles for the higher-resolution 3-m product. Vector data sets with smaller file sizes are offered at several tile sizes and formats. Partial tiles are not a download option—any prestaged data that intersect the requesting bounding box will be, in their entirety, part of the download order. While there are many options for accessing geospatial data via the Web, the National Map represents authoritative sources of data that are documented and can be referenced for citation and inclusion in scientific publications. Therefore, National Map products and services should be part of a geologist’s first stop for geospatial information and data.