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River Survey File (*.riv)

Overview

The River Survey File (*.riv) contains transverse data (x and y coordinates of left/right banks) and cross-section data (distance from left bank and riverbed elevation).

River Survey Files should be ASCII files. :numref:`image_riv_structure` and Figure 6‑1 show the structure and concept, respectively.

  • Break points of input data (for example, cross-section identification number and x-coordinate value) are identified by "space", "tab" or "enter" characters. When break points are properly identified, iRIC automatically recognizes the data. Please note that cross-section identification number must be a real number.

  • Rows after the "#survey" row are recognized as cross-section data.

    • Each row contains data for one cross-section.
    • Data row: (Cross-section identification number) (x-coordinate value of the left bank) (y-coordinate value of the left bank) (x-coordinate value of the right bank) (y-coordinate value of the right bank)
  • Rows after the "#x-section" row are recognized as cross-section data (consisting of the "header line" and "data lines").

    • Header line: (Cross-section identification number) (No. of coordinates) (Index 1) (Index 2) (Index 3) (Index 4)

    Indexes 1 to 4 specify points on a cross-sectional coordinate system by sequential integer numbers. (The top is 1.) Data prior to Index 1 and after Index 4 are discarded. The point specified by Index 1 is set as the left bank and the point specified by Index 4 is set as the right bank. The points specified by Indexes 2 and 3 are to be the division points (or nodes) of the automatically created grid. The Center Point of the river is set at the point midway between Indexes 2 and 3.

    You can omit Index data. In such case, all the coordinate cross-section data are read and the first point of the coordinate cross-section data is set as the left bank and the last point is set as the right bank. The Center Point of the river is set at the mid-point between the left and right banks.

    When Index data are not set for every cross-section data, the index data of all cross-sections are ignored.

    • Data line: (Distance from left bank) (Riverbed elevation) Continue to create rows of data until there are as many rows as there are cross-sections.

    Each row describes up to five sets of combinations of (Distance from left bank) and (Riverbed elevation) data.

images/riv_structure.png

Structure of River Survey File

images/riv_concept.png

Concept of River Survey File data

:numref:`image_riv_concept` shows the concept of the River Survey File data. iRIC does not display the four dots (data of Indexes 1 to 4).

The coordinates in the cross-sectional direction displayed in the [Cross-section] window have been converted as follows; note that they are different from [Distance from left bank] in the cross-section data of the River Survey File.

  • The coordinates of the Center Point of the river have been calculated from the longitudinal data and the cross-section data.
  • The distance from the Center Point along the cross-sectional line has been calculated.

Scheduled driver longitudinal/cross-section data creation guideline and cross-sectional River Survey Data

The Ministry of Land, Infrastructure, Transport and Tourism () publishes guidelines for creating the scheduled river longitudinal/cross-section data

*http://www.mlit.go.jp/river/shishin_guideline/kasen/gis/pdf_docs/juoudan/guideline0805.pdf*

:numref:`table_riv_survey_data_guideline` shows how to convert the Guideline data items to the River Survey Data items.

Relationship between the River Survey Data items and the Guideline data
River Survey Data item How to convert the guideline data (surveyed cross-sectional numerical data) to River Survey Data items
Coordinates of left/right banks Specify the coordinates of the left/right bank distance posts.
Cross-section data
Specify the distance of the cross-sectional coordinate data for the distance from the left bank.
Specify the elevation of the cross-sectional coordinate data.
Index data
Set as follows:
Index 1: Number that corresponds to the left bank distance post
Index 2: Number that corresponds to the left bank shoreline post
Index 3: Number that corresponds to the right bank shoreline post
Index 4: Number that corresponds to the right bank distance post
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