SO503, Spring 2008

Hydrosheds Lab

http://gisdata.usgs.net/website/HydroSHEDS/viewer.php

We have the following data sets for Africa, SE Asia, and Australia on the J:\so503 directory.  Download them to your local hard disk before attempting to open them.

• 30second void filled BIL (to open, select the file the BIL extension)

• 30 sec river network

• 30 sec drainage basins

Download a 250 m MODIS image to go with the data. (remember that the image file needs to have a JPG extension, that you have to remove the .TXT extension that Internet Explorer helpfully adds to your world file, and that you need to get the world file with the same resolution as you JPEG file);

Answer the following questions:

• Can you display the entire data sets?  Why or why not?

• What is the distribution of stream size, and drainage basin size?  Note that the data bases have an added field with the log of the size.  Which produces the better histogram?  Which of the streams and drainage basins are "important", and where are the less important ones located?

• If you want to display the entire data set, what can you do with the two databases to make the display faster?