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Investigation:

LC-01 (Walsh / Bilsborrow / Manosalvas)

LBA Dataset ID:

LC01_TOPOGRAPHY_ECUADOR

Originator(s):

1. BILSBORROW, R.E.
2. WALSH, S.J.
      3. FRIZZELLE, B.G.

Point(s) of Contact:

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Dataset Abstract:

This data set contains topographic/geomorphological data associated with the four Intensive Study Areas (ISAs) in the northern Oriente of Ecuador that are part of the University of North Carolina's Carolina Population Center (CPC) Ecuador Projects study. Northeastern Ecuador borders the Andes and lies at headwaters of the Amazon River. This region of high biological diversity possesses major centers of endemism as well as identified biodiversity 'hot spots'. Study area boundaries were developed directly from 1:50,000 topographical maps. Point elevation features and 20-meter elevation contours were digitized from these same maps. Digital elevation models (DEMs) were derived from these elevation data and, in turn, terrain aspect and terrain slope were derived from the digital elevation models. Only boundary data were provided for the southwestern ISA. These data are presented in ARC/INFO interchange format files.

Beginning Date:

1993-01-01

Ending Date:

1993-01-01

Metadata Last Updated on:

2012-05-15

Data Status:

Archived

Access Constraints:

PUBLIC

Data Center URL:

http://daac.ornl.gov/

Distribution Contact(s):

ORNL DAAC User Services Office Oak Ridge National Laboratory Oak Ridge, Tennessee 37 (ornldaac@ornl.gov)

Access Instructions:

PUBLIC

Data Access:

IMPORTANT: The LBA-ECO Project website is no longer being supported. Links to external websites may be inactive. Final data products from the LBA project can be found at the ORNL DAAC. Please follow the fair use guidelines found in the dataset documentation when using or citing LBA data.
Datafile(s):

LBA-ECO LC-01 Topographic Data for Intensive Study Areas, Northern Ecuadorian Amazon:  http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1082

Documentation/Other Supporting Documents:

LBA-ECO LC-01 Topographic Data for Intensive Study Areas, Northern Ecuadorian Amazon:  http://daac.ornl.gov/LBA/guides/LC01_Topography_Ecuador_ISA.html

Citation Information - Other Details:

Bilsborrow, R.E., S.J. Walsh and B.G. Frizzelle. 2009. LBA-ECO LC-01 Topographic Data for Intensive Study Areas in Northern Ecuador. Data set. Available on-line [http://www.daac.ornl.gov] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A. http://dx.doi.org/10.3334/ORNLDAAC/1082

Keywords - Theme:

Parameter Topic Term Source Sensor
BOUNDARY SURVEYS HUMAN DIMENSIONS BOUNDARIES MAPS DIGITIZER
TOPOGRAPHICAL RELIEF LAND SURFACE TOPOGRAPHY TOPOGRAPHIC MAP DIGITIZER

Uncontrolled Theme Keyword(s):  BOUNDARIES, DIGITAL ELEVATION MODELS, ECUADOR, INTENSIVE STUDY AREAS (ISAS), NORTHERN ECUADORIAN AMAZON, TOPOGRAPHY

Keywords - Place (with associated coordinates):

Region
(click to view profile)
Site
(click to view profile)
North South East West
  ECUADOR 0.28890 -0.83700 -76.50170 -77.12700

Related Publication(s):

Mena CF, Bilsborrow RE, McClain ME. 2006. Socioeconomic drivers of deforestation in the Northern Ecuadorian Amazon. Environmental Management, 37, 802-815.

Messina J.P. and S.J. Walsh. 2001. 2.5D Morphogenesis: modeling landuse and landcover dynamics in the Ecuadorian Amazon. Plant Ecology 156(1):75-88.

Pan, W.K.Y., S.J. Walsh, R.E. Bilsborrow, B.G. Frizzelle, C.M. Erlien, and F. Baquero. 2004. Farm-level models of spatial patterns of land use and land cover dynamics in the Ecuadorian Amazon. Agriculture Ecosystems & Environment 101(2-3):117-134.

Walsh SJ, Evans TP, Turner II BL. 2004. Population-Environment Interactions with an Emphasis on LULC Dynamics and the Role of Technology, in Geography and Technology, edited by Brunn SD, Cutter SL and Harrington JJ, Kluwer Academic Publishers, 491-519.

Walsh SJ, Messina JP, Zonn L. Deforestation of the Ecuadorian Amazon: Characterizing Patterns and Associated Drivers of Change. 2004. in World Minds: Geographical Perspectives on 100 Problems, edited by Janelle DG, Warf B and Hansen K, Kluwer Academic Publishers, 299-304.

Data Characteristics (Entity and Attribute Overview):

Data Characteristics:

Study Area: The northern Ecuadorian Amazon.

Projection: Universal Transverse Mercator Zone 18S

Horizontal_Datum_Name: D_WGS_1984

Ellipsoid_Name: WGS_1984





Boundary data:</b>

Attribute items are in typical ARC/INFO polygon format. No additional attributes were assigned to this data set.




Point elevation features, 20-meter elevation contours, DEM, terrain aspect, and terrain slope:</b>




These data are presented in ARC/INFO interchange format files.




Point elevation data and 20-meter elevation contours are in meters above sea level.




DEM data consists of a sampled array of elevations interpolated from elevation contours and a sampled array of elevations for ground positions at a relatively normally spaced interval. The spatial resolution of this DEM is 30 meters, meaning that each raster pixel represents a 30 m by 30 m area on the ground, and each pixel has one elevation value, in meters above sea level.




Aspect is the downslope direction of the maximum rate of change on a hillside. It is derived from a digital elevation model (DEM). Each pixel is attributed with a value that represents the compass direction, in degress clockwise from 0 at north, in which the hillside faces. The raster resolution of the data set is based on the resolution of the source DEM, in this case, 30 meters.




For a raster terrain data set, slope is the rate of maximum change in the elevation values from the surrounding eight pixels, through the pixel of interest. It is derived from a digital elevation model (DEM). For terrain slope, the pixels are attributed with the slope rate of change in degrees. The range of slope values is 0 to 90, where 0 indicates perfectly flat terrain, and 90 indicates a vertical wall. The raster resolution of the data set is based on the resolution of the source DEM, in this case, 30 meters.

Data Application and Derivation:


Typical application of data:



ISA boundary data: Purposes include delineation of the ISA on maps, reference for the clipping of larger data sets, and as a physical limit for selected analyses.



Contour vectors data: The elevation contours are used, in conjunction with point elevations, to create a raster digital elevation model (DEM).



Point elevations: Point elevations can be used to derive a DEM. However, potential users should be aware point elevations should not be used alone to create a digital elevation model, as the accuracy would be very poor.



Elevation contours: The elevation contours are used, in conjunction with point elevations, to create a raster digital elevation model (DEM).



Digital elevation models: The DEM can be used for any analyses that require an elevational component, for example to calculate slope or potential wetness index values, or for simple three-dimensional representation of the ISA.



Terrain aspect: The aspect data can be used for any analyses that require a directional terrain component, or for simple three-dimensional representation of the ISA.



Terrain slope: The slope data can be used for any analyses that require a terrain component that represents rate of change.



Derivation of data:



ISA boundaries:


Four 1:50,000 topographic maps were identified as the larger area containing the ISA. The ISA extent was selected to be the full north-south extent, and lie centered between the east and west extents of the four topos. The coordinates were recorded as follows. The latitude coordinates were taken from the four corners of the four-topo group. The longitude coordinates were recorded as the coordinates lying at the central east-west point on each topo map. These four coordinates were recorded in latitude/longitude. The latitude/longitude coordinates were converted to UTM, Zone 18 South coordinates. The four UTM coordinates were used to generate a boundary polygon for the ISA.



Contour vectors:


Elevation contours were digitized from topographic maps, and attributed. The two contour coverages were edge-matched and appended.



DEMs:


The elevation contour data and the point elevation data were used to generate the DEM in ARC/INFO. The TOPOGRID command was used. The contour data were the primary basis for the interpolation, with the point elevations enhancing the quality of the interpolation. A ISA subset of the 1:50,000 hydrography data was also inputted to make the DEM hydrologically correct. A 60-meter margin was applied to the process to allow TOPOGRID to more accurately interpolate the pixels on the boundaries of the ISA. A tolerance of 10 was applied to the process to assist in the smoothing of the surface and the removal of sinks in the drainage enforcement process. This value was chosen as half of the contour interval.



Terrain aspect:


The directional aspect values assigned to the pixels in the data set were generated with the ASPECT algorithm in ARC/INFO, which calculates the direction of greatest elevational change based on surrounding pixels. Aspect values are derived solely from DEM data.



Terrain slope data:


The SLOPE command in ARC/INFO was used to derive terrain slope. For each pixel, SLOPE takes the values of the eight surrounding pixels, fits a plane to the 3x3 pixel array, and calculates the rate of maximum elevational change along the slope. That rate value is assigned to the central pixel. Slope values are derived solely from the DEM data.

Quality Assessment (Data Quality Attribute Accuracy Report):

Quality Assessment:

Data usage guidance:


Boundaries: There are no usage constraints.


Contour vectors: There are no use constraints. However, potential users should be aware of possible ramifications of using the contours to create a DEM of too fine a resolution, given the interval of the contours. Horizontal accuracy is assumed to be within the NMAS standards for a map of this scale.


DEMs: There are no use constraints. However, potential users should be aware that the resolution of this data set makes it inappropriate for any analyses where the scale of analysis is finer than 30 meters. An accuracy assessment of the elevation values has not been performed.


Point elevations: Attribution was based on the elevations assigned to points on the source map. There is 100% agreement for attribution between each digitized point and its source point. Accuracy of the attribution is dependent solely on the accuracy of the data source.


Terrain aspect: An accuracy assessment of the aspect values has not been performed.


Terrain slope: An accuracy assessment of the slope values has not been performed.

Process Description:

Data Acquisition Materials and Methods:

Data for ISA boundaries, contour vectors, DEMs and point elevations were all derived from 1: 50,000 topographic maps. Maps for the sites were published in 1993 and obtained from the Instituto Geografico Militar de Ecuador (IGM) in 1999. Names of individual maps used in generating the data for each ISA are listed below. NISA: General Farfan, Nueva Loja EISA: Pacayacu, Shushufindi SISA: La Joya de los Sachas, San Francisco de Orellana



Terrain aspect: Aspect data are derived from DEMs. The DEMs were developed by interpolating elevation contours and point elevations digitized from 1:50,000 scale source maps.



Terrain slope: The ISA DEMs were used to generate the slope surface. The SLOPE command in ARC/INFO was used. For each pixel, SLOPE takes the values of the eight surrounding pixels, fits a plane to the 3x3 pixel array, and calculates the rate of maximum elevational change along the slope. That rate value is assigned to the central pixel.

References:

None cited.

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