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    L 2 B Terrain Data and Other Helpful GIS Datasets

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    Ivon Camelo
    This document discusses terrain data and other helpful GIS datasets for use in hydrologic modeling. It identifies terrain data as a required dataset and lists the National Hydrography Dataset (NHD), gage locations, reservoir locations, land use, soil, and other locations as helpful datasets. It provides information on acquiring, preparing, and using terrain data and the NHD within a hydrologic model, including details on mosaicking, projecting, modifying, extracting, and processing the terrain data and integrating the NHD streams and watershed boundaries.

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    L 2 B Terrain Data and Other Helpful GIS Datasets

    Uploaded by

    Ivon Camelo
    25 views14 pages
    This document discusses terrain data and other helpful GIS datasets for use in hydrologic modeling. It identifies terrain data as a required dataset and lists the National Hydrography Dataset (NHD), gage locations, reservoir locations, land use, soil, and other locations as helpful datasets. It provides information on acquiring, preparing, and using terrain data and the NHD within a hydrologic model, including details on mosaicking, projecting, modifying, extracting, and processing the terrain data and integrating the NHD streams and watershed boundaries.

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    L+2+b+Terrain+Data+and+Other+Helpful+GIS+Datasets

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    This document discusses terrain data and other helpful GIS datasets for use in hydrologic modeling. It identifies terrain data as a required dataset and lists the National Hydrography Dataset (NHD), gage locations, reservoir locations, land use, soil, and other locations as helpful datasets. It provides information on acquiring, preparing, and using terrain data and the NHD within a hydrologic model, including details on mosaicking, projecting, modifying, extracting, and processing the terrain data and integrating the NHD streams and watershed boundaries.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    25 views14 pages

    L 2 B Terrain Data and Other Helpful GIS Datasets

    Uploaded by

    Ivon Camelo
    This document discusses terrain data and other helpful GIS datasets for use in hydrologic modeling. It identifies terrain data as a required dataset and lists the National Hydrography Dataset (NHD), gage locations, reservoir locations, land use, soil, and other locations as helpful datasets. It provides information on acquiring, preparing, and using terrain data and the NHD within a hydrologic model, including details on mosaicking, projecting, modifying, extracting, and processing the terrain data and integrating the NHD streams and watershed boundaries.

    Copyright:

    © All Rights Reserved
    Download as PPTX, PDF, TXT or read online from Scribd
    Download as pptx, pdf, or txt
    of 14

    Terrain Data and other Helpful GIS Datasets

    1
    Hydrologic Engineering Center
    GIS Datasets
    Required Datasets
    • Terrain data

    Helpful GIS Datasets


    • NHD (published streams and
    watersheds)
    • Gage locations
    • Reservoir locations
    • Landuse
    • Soil
    • Locations for linking to other models

    Hydrologic Engineering Center 2


    GIS Datasets
    • Add GIS Datasets (shapefiles) to the
    Basin Model Map using the Map
    Layers Editor
    • GIS datasets should be in the same
    projection as the basin model
    • Use the Draw Properties Editor to
    edit the display properties

    Hydrologic Engineering Center 3


    National Elevation Dataset (NED)
    • A raster product assembled by the U.S.
    Geological Survey
    • Provide national elevation data in a seamless
    form with a consistent datum, elevation unit,
    and projection
    • Resolution
    – Nationally 1 arc-second (approx 30
    meters) and 1/3 arc-second (approx 10
    meters) are available (1/9 arc-second
    limited)
    • Coordinate System Info
    – Elevation values are in meters and are
    referenced to the North American Vertical
    Datum of 1988
    – Data distributed in geographic
    coordinates with units of decimal degrees
    and in conformance with the North
    American Datum of 1983
    • Data are distributed through the National Map
    Viewer, http://ned.usgs.gov

    Hydrologic Engineering Center 4


    Preparing the Terrain Dataset for Automated
    Delineation
    1) Mosaic terrain tiles into one continuous terrain tile
    2) Project the terrain dataset
    3) Make sure the vertical units are the same as the horizontal units
    (determined by the projection)
    4) Clip/Extract the terrain dataset
    5) Check and remove missing values
    6) Resample to a larger cell size or convert the grid to an integer grid if
    appropriate. Keep the terrain file size below 200 mb for most
    applications.
    https://www.hec.usace.army.mil/confluence/hmsdocs/hmsguides/gis-tutorials-and-
    guides/preparing-terrain-data-for-hec-hms-using-arcmap
    https://www.hec.usace.army.mil/confluence/hmsdocs/hmsguides/gis-tutorials-and-
    guides/preparing-terrain-data-for-hec-hms-using-qgis
    Hydrologic Engineering Center 5
    Mosaic Terrain Tiles

    Hydrologic Engineering Center 6


    Project the Terrain Dataset

    Hydrologic Engineering Center 7


    Modify the Vertical Units

    Hydrologic Engineering Center 8


    Buffer Watershed Boundary
    • Use an existing watershed boundary and
    buffer before extracting the terrain data
    • Or use a bounding box

    Hydrologic Engineering Center 9


    Clip/Extract the Terrain Dataset

    446 MB
    Terrain File

    26 MB Terrain File

    Hydrologic Engineering Center 10


    Check and Remove Missing Data

    Fill in NoData cells with average


    value from neighboring cells

    Con(IsNull ("dem"), 1, 200)


    Use this statement to identify
    no data cells; no data cells will
    have a value of 1, cells with a
    valid value will have a value of
    200

    Con(IsNull(“dem”), FocalStatistics(‘dem’, NbrRectangle(3,3), “Mean”), “dem”)


    Use this statement to fill in no data cells with the average of neighboring cells

    Hydrologic Engineering Center 11


    Modify the Terrain Dataset
    • If the file size exceeds 200 MB after Extracting by Mask, then
    consider resampling to a larger grid cell size or converting to an
    integer grid
    • After modifying the terrain, us the Burn Streams and Build
    Walls tools to enforce the correct drainage

    Hydrologic Engineering Center 12


    National Hydrography Dataset (NHD)
    NHD contains digital spatial data for
    surface water http://nhd.usgs.gov/index.html

    The data is contained in a geodatabase


    that has two feature datasets, one with
    water bodies and the other containing
    basin boundaries
    Surface water obtained from topo maps
    (1:100k and 1:24k)
    NRCS developing basin boundaries –
    Watershed Boundary Dataset

    Hydrologic Engineering Center 13


    National Hydrography Dataset (NHD)
    • NHD files can be downloaded
    from The National Map
    Downloader
    • Project the Stream and Watershed
    GIS layers
    • Edit/Clip the datasets for the
    watershed
    • Use these layers to burn streams /
    build walls

    Hydrologic Engineering Center 14

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