One satau parameter in determining the elevation of coastal vulnerability index
or slope. The importance of information on coastal elevation data relating
to estimate inundation area face rising sea levels. by knowing the
elevation information of an area it can be estimated well and the wide range of land
to be inundated due to sea level rise looks at each particular hike,
locations to determine areas prone to inundation.
There are many ways in the present elevation of the earth's surface in the form
Digital. One way to present the earth's surface with storage
limited capacity is a Digital Elevation Model (DEM). DEM is
one model to describe the shape of the earth surface topography that can
visualized in 3D (three dimensional). There are many ways to obtain
DEM data, interferometry SAR (Synthetic Aperture Radar) is one of the algorithms
to make a relatively new DEM data. SAR image data or a radar image
used in the process of interferometry can be obtained from satellite or airplane rides,
apart from the radar DEM can also be obtained from the ASTER image. In this training DEM data
which will be used for the GDEM (Global Digital Elevation Model) derived from satellite
ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer). GDEM
have ketilitian (spatial resolution) are pretty good that is 30 meters, while
coverage area is nearly the entire surface of the earth is covered in the data GDEM. data
GDEM can be downloaded (download) for free on the internet through the website, which issued the data format is TIF (Tag Image
Format) which can be opened directly diperangkat GIS software, making it easier for
needs further analysis

In general, the process of downloading the data, there are three main stages to be passed,
the registration as a member, select the desired area, the latter is
download the data. in detail here are the steps in the process
download data:
A. Type the website address into the address bar
browser, in which case we are using Mozilla Firefox, then press enter

2. If your computer is connected to the internet it will show a web page
as follows:

3. Click on register & modification to register  then you will fit in
form filling of personal data

4. Fill the form in accordance with his orders, which marked with an asterisk (*) is
sign a required field command  After filling the form is complete click the menu button
Next  if the registration is successful then you will return to the main page and
means that the registration was successful, and your user name will be printed on the left
top right corner

5. Then click the Search menu to start your search DEM data  you will go
to map the following page

6. With the help of a computer mouse to enlarge the area you want
download  in this case we will enlarge the area tangerang

7. Before the download of data you must first choose a location where
Just that you will donwload  Select tiles directly select menu and then click the menu 
Start  then the cursor will change shape like a plus sign (plus) next 
Click the area you want, in this case we choose the Tangerang

8. Once you selected the location  Next  then click menu then the data will
display and ready for dowload

9. Once the data is in the download is performed  Click Next to enter the menu
agreement page  Select purpose choose the menu Climate (as needed
you)   Agree then click menu then you will go to the download page