A Generic Web Service for Ad‐hoc Statistical Spatio‐Temporal Aggregation     

Mario Härtwig  Matthias Müller  Lars Bernard 《Transactions in GIS》2014,18(4):527-543

  相似文献   

Fine-resolution population mapping using OpenStreetMap points-of-interest   总被引：1，自引：0，他引：1  

Mohamed Bakillah  Steve Liang  Amin Mobasheri  Jamal Jokar Arsanjani  Alexander Zipf 《International journal of geographical information science》2014,28(9):1940-1963

Data on population at building level is required for various purposes. However, to protect privacy, government population data is aggregated. Population estimates at finer scales can be obtained through areal interpolation, a process where data from a first spatial unit system is transferred to another system. Areal interpolation can be conducted with ancillary data that guide the redistribution of population. For population estimation at the building level, common ancillary data include three-dimensional data on buildings, obtained through costly processes such as LiDAR. Meanwhile, volunteered geographic information (VGI) is emerging as a new category of data and is already used for purposes related to urban management. The objective of this paper is to present an alternative approach for building level areal interpolation that uses VGI as ancillary data. The proposed method integrates existing interpolation techniques, i.e., multi-class dasymetric mapping and interpolation by surface volume integration; data on building footprints and points-of-interest (POIs) extracted from OpenStreetMap (OSM) are used to refine population estimates at building level. A case study was conducted for the city of Hamburg and the results were compared using different types of POIs. The results suggest that VGI can be used to accurately estimate population distribution, but that further research is needed to understand how POIs can reveal population distribution patterns.  相似文献   

Does freshening of surface water enhance heterotrophic prokaryote production in the western Arctic? Empirical evidence from the Canada Basin during September 2009   总被引：1，自引：0，他引：1  

Mario?UchimiyaEmail author  Hideki?Fukuda  Shigeto?Nishino  Takashi?Kikuchi  Hiroshi?Ogawa  Toshi?Nagata 《Journal of Oceanography》2011,67(5):589-599

This study examined possible environmental factors that affect prokaryote variables in surface waters (upper 100 m of water column) in the Canada Basin, western Arctic Ocean. We collected data on prokaryote abundance and heterotrophic production ([³H]leucine incorporation) at eight stations deployed along a slope-to-offshore transect during September 2009. Prokaryote production and growth tended to increase with increasing chlorophyll a (Chl. a) and temperature and with decreasing salinity. The combination of Chl. a, temperature, and salinity accounted for a large fraction (74%) of the variability in prokaryote production, with the highest contribution made by Chl. a (r ² = 0.56), followed by salinity (r ² = 0.14) and temperature (r ² = 0.03). Similarly, the variability in prokaryote growth rate was largely accounted for by the combination of the three environmental variables (overall r ² of 0.64), with Chl. a making the largest contribution to variability (r ² = 0.33), followed by salinity (r ² = 0.27) and temperature (r ² = 0.05). These data are consistent with the notion that organic matter supply associated with freshwater inputs to surface layers can result in enhanced prokaryote production and growth in the Canada Basin. Our results provide insights into the regulation of the microbial loop in the Canada Basin where freshening has been proceeding rapidly due to increasing river discharge and sea-ice melting.  相似文献   

The origin of salinity and sulphate contamination of groundwater in the Colima State, Mexico, constrained by stable isotopes     

Axel Horst  Jürgen Mahlknecht  Miguel Angel López-Zavala  Bernhard Mayer 《Environmental Earth Sciences》2011,64(7):1931-1941

Chemical compositions and stable isotope ratios of water and sulphate were used to characterise sources and processes responsible for elevated concentrations of sulphate and other constituents in groundwater from aquifers at Colima State along Mexico’s Pacific Coast. The δ¹⁸O and δ²H values of the groundwater were similar to those of precipitation indicating a meteoric origin, and recharge processes are relatively uniform in large parts of the study area with only slight local evaporation effects. δ³⁴S_sulphate and δ¹⁸O_sulphate analyses indicated that high sulphate concentrations of up to 1,480 mg/l are mainly due to dissolution of evaporites and volcanic exhalations. Chloride is largely related to sources other than seawater. The Marabasco sub basin is affected by anthropogenic contamination through manganese and iron ore mining activities. The obtained knowledge regarding sources and areas of contamination will be essential for the development and design of a water quality monitoring program in the study area.  相似文献   

Magnetostratigraphy and detrital apatite fission track thermochronology in syntectonic conglomerates: constraints on the exhumation of the South‐Central Pyrenees     

Elisabet Beamud  Josep Anton Muñoz  Paul G. Fitzgerald  Suzanne L. Baldwin  Miguel Garcés  Lluis Cabrera  James R. Metcalf 《Basin Research》2011,23(3):309-331

The syntectonic continental conglomerates of the South‐Central Pyrenees record the late stages of thin‐skinned transport of the South‐Pyrenean Central Units and the onset of exhumation of the Pyrenean Axial Zone (AZ) in the core of the orogen. New magnetostratigraphic data of these syntectonic continental conglomerates have established their age as Late Lutetian to Late Oligocene. The data reveal that these materials were deposited during intense periods of tectonic activity of the Pyrenean chain and not during the cessation of the deformation as considered previously. The magnetostratigraphic ages have been combined with new detrital apatite fission track (AFT) thermochronology from AZ‐derived granite cobbles within the syntectonic conglomerates. Distribution of the granitic cobbles with different AFT ages and track lengths combined with their depositional ages reveal information on the timing and rate of episodes of exhumation in the orogen. Some AFT ages are considerably older than the AFT ages of the outcropping AZ granitic massifs, indicating erosion from higher crustal levels within the massifs than presently exposed or from completely eroded plutons. Inverse thermal modelling reveals two well‐defined periods of rapid cooling in the hinterland at ca. 50–40 and ca. 30–25 Ma, with another poorly defined cooling episode at ca. 70–60 Ma. The lowest stratigraphic samples experienced postburial annealing caused by the deposition of younger syntectonic sediments during progressive burial of the south Pyrenean thrust and fold belt. Moreover, samples from the deeper stratigraphic levels also reveal postorogenic cooling during the Late Miocene as a response to the excavation of the Ebro River towards the Mediterranean Sea. Our data strongly support previous ideas about the burial of the South Pyrenean fold and thrust belt by Late Palaeogene syntectonic conglomerates and their subsequent re‐excavation and are consistent with other thermochronological data and thermal modelling from the interior part of the orogen.  相似文献   

Climate and human impact on a meromictic lake during the last 6,000 years (Montcortès Lake,Central Pyrenees,Spain)     

Juan Pablo Corella  Ana Moreno  Mario Morellón  Valentí Rull  Santiago Giralt  María Teresa Rico  Ana Pérez-Sanz  Blas Lorenzo Valero-Garcés 《Journal of Paleolimnology》2011,46(3):351-367

Sedimentological, mineralogical and compositional analyses performed on short gravity cores and long Kullenberg cores from meromictic Montcortès Lake (Pre-Pyrenean Range, NE Spain) reveal large depositional changes during the last 6,000 cal years. The limnological characteristics of this karstic lake, including its meromictic nature, relatively high surface area/depth ratio (surface area ~0.1 km²; z _max = 30 m), and steep margins, facilitated deposition and preservation of finely laminated facies, punctuated by clastic layers corresponding to turbidite events. The robust age model is based on 17 AMS ¹⁴C dates. Slope instability caused large gravitational deposits during the middle Holocene, prior to 6 ka BP, and in the late Holocene, prior to 1,600 and 1,000 cal yr BP). Relatively shallower lake conditions prevailed during the middle Holocene (6,000–3,500 cal years BP). Afterwards, deeper environments dominated, with deposition of varves containing preserved calcite laminae. Increased carbonate production and lower clastic input occurred during the Iberian-Roman Period, the Little Ice Age, and the twentieth century. Although modulated by climate variability, changes in sediment delivery to the lake reflect modifications of agricultural practices and population pressure in the watershed. Two episodes of higher clastic input to the lake have been identified: 1) 690–1460 AD, coinciding with an increase in farming activity in the area and the Medieval Climate Anomaly, and 2) 1770–1950 AD, including the last phase of the Little Ice Age and the maximum human occupation in late nineteenth and early twentieth centuries.  相似文献   

Limnogeology in Brazil’s “forgotten wilderness”: a synthesis from the large floodplain lakes of the Pantanal     

Michael M. McGlue  Aguinaldo Silva  Fabrício A. Corradini  Hiran Zani  Mark A. Trees  Geoffrey S. Ellis  Mauro Parolin  Peter W. Swarzenski  Andrew S. Cohen  Mario L. Assine 《Journal of Paleolimnology》2011,46(2):273-289

Sediment records from floodplain lakes have a large and commonly untapped potential for inferring wetland response to global change. The Brazilian Pantanal is a vast, seasonally inundated savanna floodplain system controlled by the flood pulse of the Upper Paraguay River. Little is known, however, about how floodplain lakes within the Pantanal act as sedimentary basins, or what influence hydroclimatic variables exert on limnogeological processes. This knowledge gap was addressed through an actualistic analysis of three large, shallow (<5 m) floodplain lakes in the western Pantanal: Lagoa Gaíva, Lagoa Mandioré and Baia Vermelha. The lakes are dilute (CO₃ ²⁻ > Si⁴⁺ > Ca²⁺), mildly alkaline, freshwater systems, the chemistries and morphometrics of which evolve with seasonal flooding. Lake sills are bathymetric shoals marked by siliciclastic fans and marsh vegetation. Flows at the sills likely undergo seasonal reversals with the changing stage of the Upper Paraguay River. Deposition in deeper waters, typically encountered in proximity to margin-coincident topography, is dominated by reduced silty-clays with abundant siliceous microfossils and organic matter. Stable isotopes of carbon and nitrogen, plus hydrogen index measured on bulk organic matter, suggest that contributions from algae (including cyanobacteria) and other C₃-vegetation dominate in these environments. The presence of lotic sponge spicules, together with patterns of terrigenous sand deposition and geochemical indicators of productivity, points to the importance of the flood pulse for sediment and nutrient delivery to the lakes. Flood-pulse plumes, waves and bioturbation likewise affect the continuity of sedimentation. Short-lived radioisotopes indicate rates of 0.11–0.24 cm year⁻¹ at sites of uninterrupted deposition. A conceptual facies model, developed from insights gained from modern seasonal processes, can be used to predict limnogeological change when the lakes become isolated on the floodplain or during intervals associated with a strengthened flood pulse. Amplification of the seasonal cycle over longer time scales suggests carbonate, sandy lowstand fan and terrestrial organic matter deposition during arid periods, whereas deposition of lotic sponges, mixed aquatic organic matter, and highstand deltas characterizes wet intervals. The results hold substantial value for interpreting paleolimnological records from floodplain lakes linked to large tropical rivers with annual flooding cycles.  相似文献   

Vegetation changes in the southern Pyrenean flank during the last millennium in relation to climate and human activities: the Montcortès lacustrine record     

Valentí Rull  Penélope González-Sampériz  Juan Pablo Corella  Mario Morellón  Santiago Giralt 《Journal of Paleolimnology》2011,46(3):387-404

We report vegetation changes of the last millennium inferred from palynological analysis of a sediment core from Lake Montcortès, situated at ~1,000 m elevation in the southern pre-Pyrenean flank. The record begins in the Middle Ages (~AD 800) and ends around AD1920, with an average resolution of ~30 years. The reconstructed vegetation sequence is complex and shows the influence of both climate and humans in shaping the landscape. Pre-feudal times were characterized by the presence of well-developed conifer forests, which were intensely burned at the beginning of feudal times (AD 1000) and were replaced by cereal (rye) and hemp cultivation, as well as meadows and pastures. In the thirteenth century, a relatively short period of warming, likely corresponding to the Medieval Warm Period, was inferred from the presence of a low Mediterranean scrub community that is today restricted to <800 m elevation. This community disappeared during Little Ice Age cooling in the fifteenth century, coinciding with a decline in human activities around the lake. Forest recovery began around AD 1500, at the beginning of the Modern period, coinciding with wetter climate. Forests, however, declined again during the seventeenth century, coinciding with maximum olive and hemp cultivation. This situation was reversed in post-Modern times (nineteenth century), characterized by an intense agricultural crisis and a significant decline in population that favored forest re-expansion. Correlations with nearby Estanya Lake, situated about 350 m below, provide a regional picture of environmental change. Besides some climate forcing evident in both sequences, human activities seem to have been the main drivers of landscape and vegetation change in the southern Pyrenean flank, in agreement with conclusions from other studies in high-mountain environments.  相似文献   

Improvement of the JRC Calculation Using Different Parameters Obtained Through a New Survey Method Applied to Rock Discontinuities     

Pedro Alameda-Hernández  Jorge Jiménez-Perálvarez  José A. Palenzuela  Rachid El Hamdouni  Clemente Irigaray  Miguel A. Cabrerizo  José Chacón 《Rock Mechanics and Rock Engineering》2014,47(6):2047-2060

This paper presents a new, fast and economical method for digitizing a rock surface profile to determine its joint roughness coefficient (JRC) value (Barton and Choubey, Rock Mech Rock Eng 10:1–54, 1977) using a set of existing parameters, the appropriateness of which has been tested. The new procedure was applied to four rock road cuts in the Alpujarra area of Granada province (Andalusia, Spain), supported by 117 digitized profiles. The method avoids any personal subjectivity bias. The usual subjectivity in the visualization and assessment of the JRC value is estimated here by a survey test answered by 90 trained users. The survey test consisted of a set of JRC visual comparisons of 12 roughness profiles, selected from the 117 profiles surveyed during the field research in the Alpujarra region, with the Barton typical profiles. The results of the survey clearly show systematic inaccuracies in the traditional procedure that are reduced if the advice presented in the conclusions of this paper is taken in account when performing the visual estimation.  相似文献   

A GIS method for landslide inventory and susceptibility mapping in the Río El Estado watershed,Pico de Orizaba volcano,México     

Gabriel Legorreta Paulín  Marcus Bursik  José Lugo Hubp  Luis Mario Paredes Mejía  Fernando Aceves Quesada 《Natural Hazards》2014,71(1):229-241

In volcanic terrains, dormant stratovolcanoes are very common and can trigger landslides and debris flows continually along stream systems, thereby affecting human settlements and economic activities. It is important to assess their potential impact and damage through the use of landslide inventory maps and landslide models. In Mexico, numerous geographic information systems (GIS)-based applications have been used to represent and assess slope stability. However, there is no practical and standardized landslide mapping methodology under a GIS. This work provides an overview of the ongoing research project from the Institute of Geography at the National Autonomous University of Mexico that seeks to conduct a multi-temporal landslide inventory and produce a landslide susceptibility map by using GIS. The Río El Estado watershed on the southwestern flank of Pico de Orizaba volcano, the highest mountain in Mexico, is selected as a study area. The geologic and geomorphologic factors in combination with high seasonal precipitation, high degree of weathering, and steep slopes predispose the study area to landslides. The method encompasses two main levels of analysis to assess landslide susceptibility. First, the project aims to derive a landslide inventory map from a representative sample of landslides using aerial orthophotographs and field work. Next, the landslide susceptibility is modelled by using multiple logistic regression implemented in a GIS platform. The technique and its implementation of each level in a GISs-based technology is presented and discussed.  相似文献