satellite data processing using qgis and nays2d flood...
TRANSCRIPT
Satellite Data Processing using QGISand Nays2D Flood Calculation
Released: October 2013Modified: November 2013
Division of River Engineering Research,Civil Engineering Research Institute for Cold Region
README FIRST
• This document shows how to perform a flooding calculation in Nays2D Flood.
• Basically, you should follow Chapter 2 of the “Nays2D Flood Examples”, however, there are several steps where you need to make another choices according to this file.
2Download URL: http://i‐ric.org/en/downloads#cat_7
README FIRST
• In the following pages when you see titles like: “Nays2D Flood Examples p.XX”, you have to set or select the options like shown in this document.
• Before you start Section 1 of Chapter 2, first you need to process SRTM data for topographic data preparation, however, the process is described in Section 1 of Chapter 3.
3
Workflow in this document
• Retrieving and converting SRTM data (p.37‐, Sect.1, Chap.3)
• Creating the calculation grid (p.9‐, Sect.1, Chap.2)• Setting the calculation conditions (p.16‐, Sect.2, Chap.2)• Making a simulation (p.29‐, Sect.3, Chap.2)• Visualizing the calculation results (p.30‐, Sect.4, Chap.2)
4
After the preparation of tpo data…
Do this first
Nays2D Flood Textbook p.47
5
For calculation in Northern part of Indonesia, you should choose appropriate SRS. Here we should use WGS84/UTM zone 46N SRS, EPSG:32646 or ID:3130.
Nays2D Flood Textbook p.51
8
Double click the application“xyz2tpo.exe”
Prompt window will appear.Input the file name you have just exported like:srtm_56_11_clip
File conversion may take several seconds.
Nays2D Flood Textbook p.51
9
“srtm_56_11_clip.tpo” file is exported
NOTE: This application “xyz2tpo.exe” simply adds the first line of the tpo file which indicates total number of data points and also modifies the file extension “.xyz” to “.tpo”.Or, if you prefer, you can rename the file as “srtm_56_11_clip.tpo”, manually count the number of lines using text editors and add the first line to the .tpo file. Textbook pages 51‐52 explain this procedure.
Nays2D Flood Textbook p.10
10
Right click the Elevation
In elevation color setting window, set max as 25 and min as ‐5
In custom color map window, check the left box and set the value as 10