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TwitterThe top 200 locations where reported collisions occurred at intersections have been identified. The crash cluster analysis methodology for the top intersection clusters uses a fixed meter search distance of 25 meters (82 ft.) to merge crash clusters together. This analysis was based on crashes where a police officer specified one of the following junction types: Four way intersection, T-intersection, Y-intersection, five point or more. Furthermore, the methodology uses the Equivalent Property Damage Only (EPDO) weighting to rank the clusters. EPDO is based any type of injury crash (including fatal, incapacitating, non-incapacitating and possible) having a weighting of 21 compared to a property damage only crash (which has weighting of 1). The clusters were reviewed in descending EPDO order until 200 locations were obtained. The clustering analysis used crashes from the three year period from 2017-2019. The area encompassing the crash cluster may cover a larger area than just the intersection so it is critical to view these spatially.
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TwitterThe top locations where reported collisions occurred at intersections have been identified. The crash cluster analysis methodology for the top intersection clusters uses a fixed meter search distance of 25 meters (82 ft.) to merge crash clusters together. This analysis was based on crashes where a police officer specified one of the following junction types: Four way intersection, T-intersection, Y-intersection, five point or more. Furthermore, the methodology uses the Equivalent Property Damage Only (EPDO) weighting to rank the clusters. EPDO is based any type of injury crash (including fatal, incapacitating, non-incapacitating and possible) having a weighting of 21 compared to a property damage only crash (which has weighting of 1). The clustering analysis used crashes from the three year period from 2019-2021. The area encompassing the crash cluster may cover a larger area than just the intersection so it is critical to view these spatially.
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TwitterThis course will introduce you to two of these tools: the Hot Spot Analysis (Getis-Ord Gi*) tool and the Cluster and Outlier Analysis (Anselin Local Moran's I) tool. These tools provide you with more control over your analysis. You can also use these tools to refine your analysis so that it better meets your needs.GoalsAnalyze data using the Hot Spot Analysis (Getis-Ord Gi*) tool.Analyze data using the Cluster and Outlier Analysis (Anselin Local Moran's I) tool.
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TwitterDataset for the textbook Computational Methods and GIS Applications in Social Science (3rd Edition), 2023 Fahui Wang, Lingbo Liu Main Book Citation: Wang, F., & Liu, L. (2023). Computational Methods and GIS Applications in Social Science (3rd ed.). CRC Press. https://doi.org/10.1201/9781003292302 KNIME Lab Manual Citation: Liu, L., & Wang, F. (2023). Computational Methods and GIS Applications in Social Science - Lab Manual. CRC Press. https://doi.org/10.1201/9781003304357 KNIME Hub Dataset and Workflow for Computational Methods and GIS Applications in Social Science-Lab Manual Update Log If Python package not found in Package Management, use ArcGIS Pro's Python Command Prompt to install them, e.g., conda install -c conda-forge python-igraph leidenalg NetworkCommDetPro in CMGIS-V3-Tools was updated on July 10,2024 Add spatial adjacency table into Florida on June 29,2024 The dataset and tool for ABM Crime Simulation were updated on August 3, 2023, The toolkits in CMGIS-V3-Tools was updated on August 3rd,2023. Report Issues on GitHub https://github.com/UrbanGISer/Computational-Methods-and-GIS-Applications-in-Social-Science Following the website of Fahui Wang : http://faculty.lsu.edu/fahui Contents Chapter 1. Getting Started with ArcGIS: Data Management and Basic Spatial Analysis Tools Case Study 1: Mapping and Analyzing Population Density Pattern in Baton Rouge, Louisiana Chapter 2. Measuring Distance and Travel Time and Analyzing Distance Decay Behavior Case Study 2A: Estimating Drive Time and Transit Time in Baton Rouge, Louisiana Case Study 2B: Analyzing Distance Decay Behavior for Hospitalization in Florida Chapter 3. Spatial Smoothing and Spatial Interpolation Case Study 3A: Mapping Place Names in Guangxi, China Case Study 3B: Area-Based Interpolations of Population in Baton Rouge, Louisiana Case Study 3C: Detecting Spatiotemporal Crime Hotspots in Baton Rouge, Louisiana Chapter 4. Delineating Functional Regions and Applications in Health Geography Case Study 4A: Defining Service Areas of Acute Hospitals in Baton Rouge, Louisiana Case Study 4B: Automated Delineation of Hospital Service Areas in Florida Chapter 5. GIS-Based Measures of Spatial Accessibility and Application in Examining Healthcare Disparity Case Study 5: Measuring Accessibility of Primary Care Physicians in Baton Rouge Chapter 6. Function Fittings by Regressions and Application in Analyzing Urban Density Patterns Case Study 6: Analyzing Population Density Patterns in Chicago Urban Area >Chapter 7. Principal Components, Factor and Cluster Analyses and Application in Social Area Analysis Case Study 7: Social Area Analysis in Beijing Chapter 8. Spatial Statistics and Applications in Cultural and Crime Geography Case Study 8A: Spatial Distribution and Clusters of Place Names in Yunnan, China Case Study 8B: Detecting Colocation Between Crime Incidents and Facilities Case Study 8C: Spatial Cluster and Regression Analyses of Homicide Patterns in Chicago Chapter 9. Regionalization Methods and Application in Analysis of Cancer Data Case Study 9: Constructing Geographical Areas for Mapping Cancer Rates in Louisiana Chapter 10. System of Linear Equations and Application of Garin-Lowry in Simulating Urban Population and Employment Patterns Case Study 10: Simulating Population and Service Employment Distributions in a Hypothetical City Chapter 11. Linear and Quadratic Programming and Applications in Examining Wasteful Commuting and Allocating Healthcare Providers Case Study 11A: Measuring Wasteful Commuting in Columbus, Ohio Case Study 11B: Location-Allocation Analysis of Hospitals in Rural China Chapter 12. Monte Carlo Method and Applications in Urban Population and Traffic Simulations Case Study 12A. Examining Zonal Effect on Urban Population Density Functions in Chicago by Monte Carlo Simulation Case Study 12B: Monte Carlo-Based Traffic Simulation in Baton Rouge, Louisiana Chapter 13. Agent-Based Model and Application in Crime Simulation Case Study 13: Agent-Based Crime Simulation in Baton Rouge, Louisiana Chapter 14. Spatiotemporal Big Data Analytics and Application in Urban Studies Case Study 14A: Exploring Taxi Trajectory in ArcGIS Case Study 14B: Identifying High Traffic Corridors and Destinations in Shanghai Dataset File Structure 1 BatonRouge Census.gdb BR.gdb 2A BatonRouge BR_Road.gdb Hosp_Address.csv TransitNetworkTemplate.xml BR_GTFS Google API Pro.tbx 2B Florida FL_HSA.gdb R_ArcGIS_Tools.tbx (RegressionR) 3A China_GX GX.gdb 3B BatonRouge BR.gdb 3C BatonRouge BRcrime R_ArcGIS_Tools.tbx (STKDE) 4A BatonRouge BRRoad.gdb 4B Florida FL_HSA.gdb HSA Delineation Pro.tbx Huff Model Pro.tbx FLplgnAdjAppend.csv 5 BRMSA BRMSA.gdb Accessibility Pro.tbx 6 Chicago ChiUrArea.gdb R_ArcGIS_Tools.tbx (RegressionR) 7 Beijing BJSA.gdb bjattr.csv R_ArcGIS_Tools.tbx (PCAandFA, BasicClustering) 8A Yunnan YN.gdb R_ArcGIS_Tools.tbx (SaTScanR) 8B Jiangsu JS.gdb 8C Chicago ChiCity.gdb cityattr.csv ...
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This dataset and code are presented to explain a manuscript entitled "Leveraging temporal changes of spatial accessibility measurements for better policy implications: a case study of electric vehicle (EV) charging stations in Seoul, South Korea", which is published in International Journal of Geographical Information Science. To run this code properly, all shapefile(*.shp) should be stored in a relative path folder (./data).
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TwitterThis data set describes Neighborhood Clusters that have been used for community planning and related purposes in the District of Columbia for many years. It does not represent boundaries of District of Columbia neighborhoods. Cluster boundaries were established in the early 2000s based on the professional judgment of the staff of the Office of Planning as reasonably descriptive units of the City for planning purposes. Once created, these boundaries have been maintained unchanged to facilitate comparisons over time, and have been used by many city agencies and outside analysts for this purpose. (The exception is that 7 “additional” areas were added to fill the gaps in the original dataset, which omitted areas without significant neighborhood character such as Rock Creek Park, the National Mall, and the Naval Observatory.) The District of Columbia does not have official neighborhood boundaries. The Office of Planning provides a separate data layer containing Neighborhood Labels that it uses to place neighborhood names on its maps. No formal set of standards describes which neighborhoods are included in that dataset.Whereas neighborhood boundaries can be subjective and fluid over time, these Neighborhood Clusters represent a stable set of boundaries that can be used to describe conditions within the District of Columbia over time.
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TwitterThe top locations where reported collisions occurred between bicyclists and motor vehicles have been identified. The crash cluster analysis methodology for the top bicyclist clusters uses a fixed meter search distance of 100 meters (328 ft.) to merge crash clusters together. Located crashes between motor vehicles and bicyclists were identified by using the non-motorist type code within the CDS database (which may yield different results from using most harmful event, first harmful event, or sequence of events data fields). Furthermore, the methodology uses the Equivalent Property Damage Only (EPDO) weighting to rank the clusters. However, because of the relatively small number of reported bicyclists crashes in the crash data file, the clustering analysis used crashes from the ten year period from 2010-2019. Additionally, due to the larger geographic area encompassed by the bicyclist crash clusters, it was difficult to name them so they were left unnamed but can be viewed spatially.
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TwitterThe top locations where reported collisions occurred between bicyclists and motor vehicles have been identified. The crash cluster analysis methodology for the top bicycle clusters uses a fixed meter search distance of 100 meters (328 ft.) to merge crash clusters together. Located crashes between motor vehicles and bicyclists were identified by using the non-motorist type code as well as first harmful events and most harmful events within the CDS database. Furthermore, the methodology uses the Equivalent Property Damage Only (EPDO) weighting to rank the clusters. EPDO is based any type of injury crash (including fatal, incapacitating, non-incapacitating and possible) having a weighting of 21 compared to a property damage only crash (which has weighting of 1). However, because of the relatively small number of reported bicycle crashes in the crash data file, the clustering analysis used crashes from the ten year period from 2008-2017. Additionally, due to the larger geographic area encompassed by the bicycle crash clusters, it was difficult to name them so they were left unnamed but can be viewed spatially.
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TwitterThe top locations where reported collisions occurred between pedestrians and motor vehicles have been identified. The crash cluster analysis methodology for the top pedestrian clusters uses a fixed meter search distance of 100 meters (328 ft.) to merge crash clusters together. Located crashes between motor vehicles and pedestrians were identified by using the non-motorist type code as well as first harmful events and most harmful events within the CDS database. Furthermore, the methodology uses the Equivalent Property Damage Only (EPDO) weighting to rank the clusters. EPDO is based any type of injury crash (including fatal, incapacitating, non-incapacitating and possible) having a weighting of 21 compared to a property damage only crash (which has weighting of 1). However, because of the relatively small number of reported pedestrian crashes in the crash data file, the clustering analysis used crashes from the ten year period from 2010-2019. Additionally, due to the larger geographic area encompassed by the pedestrian crash clusters, it was difficult to name them so they were left unnamed but can be viewed spatially.
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Twitter[Metadata] 2010 Census Urbanized Areas and Urban Clusters. Source: US Census Bureau.
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TwitterBoundary designating the Cluster Commercial Development District within the City of Lynchburg.
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Cluster service area GIS data.
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For a series of studies on the ecosystem service values of chaparral in Southern California, we developed a raster data layer providing an ecological unit classification of the Southern California landscape. This raster dataset is at a 30 meter pixel resolution and partitions the landscape into 37 different ecological unit types. This dataset was derived through a GIS-based cluster analysis of 10 different physiographic variables, namely soil suborder type, terrain geomorphon type, flow accumulation, slope, solar irradiation, annual precipitation, annual minimum temperature, actual evapotranspiration, and climatic water deficit. This partitioning was based on physiographic variables rather than vegetation types because of the wish to have the ecological units reflect biophysical characteristics rather than the historical land use patterns that may influence vegetation. The cluster analysis was performed across a set of 10,000 points randomly placed on a GIS layer stack for the 10 variables. These random points were grouped into 37 discrete clusters using an algorithm called partitioning around medoids. This assignment of points to clusters was then used to train a random forest classifier, which in turn was run across the GIS stack to produce the output raster layer.
This dataset is described in the following book chapter publication:
Underwood, Emma C., Allan D. Hollander, Patrick R. Huber, and Charlie Schrader-Patton. 2018. “Mapping the Value of National Forest Landscapes for Ecosystem Service Provision.” In Valuing Chaparral, 245–70. Springer Series on Environmental Management. Springer, Cham. https://doi.org/10.1007/978-3-319-68303-4_9.
Methods Summary of Methods for Developing Ecological Units in Southern California
Allan Hollander and Emma Underwood, University of California Davis.
1) Compiling GIS layers. These data were compiled from a variety of sources and resolutions (Table 1) for the southern California study area (see Methods_figure_1.png for the study area). The original resolution of these raster layers ran from 10 meters to 270 meters, and resampling was conducted so all analyses were performed at a 30 meter raster resolution. We decided not to include vegetation in the data stack as the aim was to capture biophysical characteristics and vegetation will reflect current landscape history and land use patterns (e.g. fire history, type conversion from shrubland, or agricultural use). Lakes and reservoirs were omitted from the subsequent analysis. Data compiled:
a) Soil suborders. This was a discretely-classified raster layer with 22 soil suborder classes included in the southern California region. This was derived from the gridded Soil Survey Geographic Database (gSSURGO, available at http://www.nrcs.usda.gov/wps/portal/nrcs/detail/soils/survey/geo/?cid=nrcs142p2_053628). This product is a rasterization at a 10-meter resolution of the county-scale SSURGO data published by the USDA Natural Resources Conservation Service.
b) Terrain geomorphons. This raster layer derives from a DEM surface and classifies the landscape into 10 discrete landform types, examples being ridges, slopes, hollows, and valleys. The algorithm for geomorphon classification uses a pattern recognition approach based on line of sight analysis (Jasiewisc and Stepinski 2013). This layer was created from a 30 meter DEM in GRASS 7.0.0, using the extension r.geomorphon (https://grass.osgeo.org/grass70/manuals/addons/r.geomorphon.html).
c) Annualized solar irradiation. This layer uses the r.sun model available in GRASS 7.0.0 (https://grass.osgeo.org/grass70/manuals/r.sun.html) which calculates direct, diffuse, and reflected solar irradiation for a given day, location, topography, and atmospheric conditions. This layer was created from a 30 meter DEM and assumes clear-sky conditions. To estimate the total annual irradiation, the model was run for every 15th day and these values were integrated over the year.
d) Flow accumulation. This layer is another product of 30 meter DEM data and measures the upslope area in pixel count that conceivably drains into a given pixel. This was calculated using the accumulation option in the GRASS 7.0.0 command r.watershed (https://grass.osgeo.org/grass70/manuals/r.watershed.html)
e) Slope. This was derived from 30 meter DEM data using the GRASS 7.0.0 command r.slope.aspect, and is measured in degrees.
f) Annual precipitation. This layer came from the 2014 Basin Characterization Model (BCM) for California (Flint et al. 2013) and gives the average annual precipitation between 1981 and 2010 at a 270-meter resolution.
g) Annual minimum temperature. This layer also came from BCM (Flint et al. 2013) and gives the average annual minimum temperature between 1981 and 2010 at a 270-meter resolution. Minimum temperature was included in the set of climate variables to represent montane winter conditions.
h) Climatic water deficit. This layer also came from the BCM (Flint et al. 2013) and gives the average climatic water deficit between 1981 and 2010 at a 270-meter resolution. The two evapotranspiration variables (climatic water deficit and actual evapotranspiration) are included in this set because they are strong drivers of vegetation distribution (Stephenson 1998).
i) Actual evapotranspiration. This layer also came from the BCM (Flint et al. 2013) and gives the average actual evapotranspiration between 1981 and 2010 at a 270-meter resolution.
Table 1. Summary of GIS data stack
LAYER
ORIGINAL SOURCE
ORIGINAL RESOLUTION
THEME
Soil suborders
gSSURGO
10 meters
Soil type
Terrain geomorphons
Digital elevation model
30 meters
Geomorphometry
Solar irradiation
Digital elevation model
30 meters
Energy balance
Flow accumulation
Digital elevation model
30 meters
Geomorphometry
Slope
Digital elevation model
30 meters
Geomorphometry
Annual precipitation
Basin Characterization Model
270 meters
Climate
Annual min temperature
Basin Characterization Model
270 meters
Climate
Climatic water deficit
Basin Characterization Model
270 meters
Climate
Actual evapotranspiration
Basin Characterization Model
270 meters
Climate
2) Generating 10,000 random points. A mask was imposed to limit analyses to the 35,158 square study area and 10,000 random points were generated to create a data table of the values of each GIS layer at each of the random points. This data table was the basis for sorting the random points into a limited number of clustered types. The first step in doing this is calculating in multivariate space the distance with respect to these environmental variables each random point is from every other point, in other words creating a dissimilarity matrix.
3) Assigning weights to variables. Because the 9 environmental variables use completely different metrics and are a combination of numerical and categorical types, calculating an environmental distance between any two of these random points requires some weighting to be assigned to each of the environmental variables to sum up their relative distances. A subanalysis to determine these weightings used a subset of the study area, the Santa Clara River watershed. Since these ecological units are intended to summarize a diverse set of ecological services, we chose three different proxy variables from the GIS data available for this area to represent biomass, hydrological response, and biodiversity. These proxies included mean annual MODIS Enhanced Vegetation Index (EVI) value for biomass, recharge for hydrological response, and habitat type in the California Wildlife Habitat Relations (CWHR) classification for biodiversity.
The MODIS EVI data was derived by averaging over the 2000-2014 period the maximum EVI value in a single year. The MODIS index used was MOD13Q1 (https://lpdaac.usgs.gov/dataset_discovery/modis/modis_products_table/mod13q1) at a 250 meter resolution, available at 16-day intervals.
The hydrological recharge data were extracted from the 2014 Basin Characterization Model (Flint et al. 2013) at 270 meter resolution.
The CWHR habitat type came from the 2015 FRAP vegetation layer (FVEG15_1, from http://frap.fire.ca.gov/data/frapgisdata-sw-fveg_download), available at a 30 meter resolution.
a) We used random forest regression and classification (Hastie et al. 2009) to determine a ranking of importance values of these predictor variables using random forest regression for EVI and recharge and random forest classification for the habitat type. These were calculated using the randomForest package in R (Liaw and Wiener 2002).
b) We then averaged these three sets of importance values to create an overall set of weightings to enter into the dissimilarity matrix (Table 2).
Table 2. Weightings for each variable to reflect their relative importance to the ecological units
VARIABLE NAME
WEIGHT
Precipitation
1.00
Annual minimum temperature
0.600
Slope
0.507
Climatic water deficit
0.413
Annualized solar radiation
0.404
Soil suborder
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Significant clusters for age appropriate vaccination in Ethiopia using 2016 EDHS data (n = 4083).
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Abstract: The process of siting municipal solid waste landfills in Greece faces significant challenges due to land resource limitations, the country’s mountainous and water-permeable terrain, and strong public opposition. This study introduces a novel methodology for optimizing landfill sites on Lemnos Island in the North Aegean Sea using a Fuzzy Spatial Multiple Criteria Analysis (FSMCA) approach. By combining Fuzzy Sets Theory, Geographic Information Systems (GIS), the Analytic Hierarchy Process (AHP), G-Statistics for Spatial Autocorrelation, and Fuzzy C-Mean for Spatial Clustering, this methodology addresses the uncertainties and complexities inherent in landfill siting. The decision problem is structured hierarchically into five levels to manage multiple criteria effectively. Criteria weights are determined using AHP, with discrete criteria graded according to Greek and EU guidelines, and continuous criteria evaluated through Fuzzy Sets Theory. The region's suitability is assessed using Multiple Criteria Analysis, revealing that 10.2% of Lemnos Island is appropriate for landfill placement. Sensitivity analysis confirms the robustness of the methodology to changes in criteria weights. Case study demonstrate the practical application and benefits of FSMCA in real-world scenario, underscoring its potential to improve sustainable waste management practices and inform policy-making.
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BackgroundAchieving spatial equity in healthcare and older adult care services is critical for ensuring fair and effective service access among aging populations. In rapidly urbanizing cities like Wuhan, the spatial distribution of facilities directly influences accessibility and integration outcomes. While existing research has primarily focused on service demand, the spatial distribution of medical and older adult care institutions which is a key factor for achieving effective integration remains underexplored.MethodThe current study classifies medical and older adult care institutions into four categories and employs multiple spatial analysis methods such as Ripley’s K-function (K), the geographical concentration index (G), the imbalance index (S), and kernel density analysis using Geographic Information System (GIS) to examine their spatial distribution in Wuhan. The spatial characteristics, distribution patterns, and interrelationships among these institutions are examined in the context of Wuhan, China. These spatial analysis methods are employed to assess disparities in the geographic distribution of institutions, highlighting spatial inequity between urban and peripheral areas.Results(1) Ripley’s K-analysis reveals significant spatial clustering across all four institution categories, with observed K-values exceeding expected thresholds and high confidence levels.(2) The geographical concentration index G0= 27.73, with G values surpassing this threshold for all four categories, indicates a pronounced spatial concentration.(3) The imbalance index (S > 0) indicates considerable disparities in the spatial distribution of resources across all categories.(4) Kernel density analysis identifies a strong concentration of institutions in central urban areas, highlighting notable urban–rural disparities in service accessibility.ConclusionThe results reveal significant spatial clustering and disparities in the distribution of older adult care institutions, highlighting challenges in equitable resource allocation and urban planning. Ultimately limiting the accessibility, availability and equity of services for the older adult population. To address these disparities, policymakers should prioritize spatial equity in planning decisions, ensuring balanced service distribution that supports healthy aging objectives and the goals of “Healthy China 2030. Such effort are essential to improving system efficiency and enhancing the quality of life for China’s aging population, both in Wuhan and across the nation.
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Top 10 circulation paths (according to the number of circulation paths).
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TwitterSee MetadataZOAM-2020-0002, Prime Agricultural Soils and Cluster Subdivision was adopted in June 2024, with an effective date of March 12, 2025, resulted in the amendment ordinances and revised regulations to improved cluster developments and use of prime agricultural soils in the Rural AR-1 and AR-2 Zoning Districts of the Rural Policy Area. The design of clustered residential development will be improved by incorporating natural features, protecting and conserving agriculturally productive prime agriculture soils, allowing for equine and rural economy uses, and further implementing the policies of the Loudoun County 2019 General Plan with respect to clustered residential development in order to guide all future cluster subdivision applications in the Rural North (AR-1) and Rural South (AR-2) Zoning Districts of the Rural Policy Area.As part of the ZOAM's approval, 15 soil types were identified as Prime Farmland Soils. They include the following soils types; 3A, 13B, 17B, 23B, 28B, 31B, 43B, 45B, 55B, 71B, 76B, 90B, 93B, 94B, 95B. All of these soil types are also currently identified as Prime Soils in the current Interpretive Guide to the use of Soils Maps; Loudoun County, VA, which further describes the soil mapping units within the Loudoun County Soils layer. The Interpretive Guide also identifies 3 other soil types as Prime Farmland Soils (17C, 70B, 70C) but for the purpose of this adopted ZOAM are not considered part of the new Prime Farmland Soils (Cluster Subdivision Option).This map shows, in small scale, a subset of the information contained on the individual detailed soil maps for Loudoun County by identifying the soil types that are considered Prime Farmland Soils (Cluster Subdivision Option). Because of its small scale and general soil descriptions, it is not suitable for planning small areas or specific sites, but it does present a general picture of soils in the County, and can show large areas generally suited to a particular kind of agriculture or other special land use. For more detailed and specific soils information, please refer to the detailed soils maps and other information available from the County Soil Scientist. Digital data consists of mapping units of the various soil types found in Loudoun County, Virginia. The data were collected by digitizing manuscript maps derived from USDA soil maps and supplemented by both field work and geological data. Field work for the soil survey was first conducted between 1947 and 1952. Soils were originally shown at the scale of 1:15840 and then redrafted by the County soil scientist to 1:12000; the data were redrafted a final time to fit Loudoun County's base map standard of 1:2400. Although the current data rely heavily on the original soil survey, there have been extensive field checks and alterations to the soil map based on current soil concepts and land use. The data are updated as field site inspections or interpretation changes occur.
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TwitterSummary of Methods for Developing Ecological Units in Southern California
Allan Hollander and Emma Underwood, University of California Davis.
1) Compiling GIS layers. These data were compiled from a variety of sources and resolutions (Table 1) for the southern California study area (see Methods_figure_1.png for the study area). The original resolution of these raster layers ran from 10 meters to 270 meters, and resampling was conducted so all analyses were performed at a 30 meter raster resolution. We decided not to include vegetation in the data stack as the aim was to capture biophysical characteristics and vegetation will reflect current landscape history and land use patterns (e.g. fire history, type conversion from shrubland, or agricultural use). Lakes and reservoirs were omitted from the subsequent analysis. Data compiled:
a) Soil suborders. This was a discretely-classified raster layer with 22 soil suborder classes included in the southern California region. This was derived ...
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TwitterThe top 200 locations where reported collisions occurred at intersections have been identified. The crash cluster analysis methodology for the top intersection clusters uses a fixed meter search distance of 25 meters (82 ft.) to merge crash clusters together. This analysis was based on crashes where a police officer specified one of the following junction types: Four way intersection, T-intersection, Y-intersection, five point or more. Furthermore, the methodology uses the Equivalent Property Damage Only (EPDO) weighting to rank the clusters. EPDO is based any type of injury crash (including fatal, incapacitating, non-incapacitating and possible) having a weighting of 21 compared to a property damage only crash (which has weighting of 1). The clusters were reviewed in descending EPDO order until 200 locations were obtained. The clustering analysis used crashes from the three year period from 2017-2019. The area encompassing the crash cluster may cover a larger area than just the intersection so it is critical to view these spatially.