2 simple questions when working with ArcGis10?

[pedroribas]

Hey guys,

I'm still learning how to use the ArcGis software, so I have these two questions.

First is that I want to take a GPS generated Google Earth placemark made by me and send it to my shape file in ArcGis, how do I do it?

Second, this shape file of mine is a drainage network, I would like to cut it down from where the placemark will be placed so I can calculate the watershed, what are the procedures for calculating the watershed?

Appreciate the help,

thanks

placemark 23º51'12'' latitude south (south of brazil)
              49º57'28'' longitude west

The river I'm studying is the one in light blue in the attached file named 'bacia gerada2'

if anyone could take a look it would be wonderful!!!

[boonejardot]

Yeah, First, I dont know about taking Google placemark and inserting it---- It really just seems a matter of copying the lat long converting that to decimal degrees and creating an XY event layer in arcmap.

as for the watershed:

This is a multipart step. 
Download the DEM from USGS seamless viewer.  its part of the USGS.gov website.  Download the study area you are working with.
Project the DEM.  Open up the spatial analysis tools in the toolbox, open hydrology.  (Im doing this off memory so...)
Chances are there are errors in the DEM called SINKS. Okay from memory it goes something like this.
  Run flow direction.
Then run Fill Sinks(just search for it) on the flow direction.
Run flow accumulation.
Then run the watershed tool. 

If you dont project the DEM, your results will be meaningless and incorrect.. If you can figure out how to do the steps I have written, you just might have it in you to get the job done.  Good luck.



If you are working on an area that the DEM is not readily available, I am not sure how you will get it.  Many times the foreign countries other than the US charge for the DEM. Good luck again.

[MarkBoucher]

First is that I want to take a GPS generated Google Earth placemark made by me and send it to my shape file in ArcGis, how do I do it?

There is a conversion tool for this: ArcToolbox>Conversions>From KML

what are the procedures for calculating the watershed?

Once you get a DEM as bjardot explained, you will need to manipulate the DEM in a series of steps called Terrain Preprocessing. There are hydrology tools in Spatial Analyst Tools>Hydrology to do this. There are also specialized tools for this also created by ESRI for the US Army Corps of Engineers. You can get them for free from their website. I posted their link at this post http://forums.arcgis.com/threads/58594-DEM?p=202093#post202093.

The GeoHMS install exe will install both ArcHydro and HEC-GeoHMS. Both have similar toolbars with functions that will do what you want. It is not "simple". The order you do things in is important. Be careful to install the version of GeoHMS that goes with your version of ArcMap

I detailed this once in this thread: http://forums.arcgis.com/threads/53316-Why-can-t-I-define-a-stream-network?p=182644#post182644

I believe you need the Spatial Analyst to use any of these tools as Spatial Analyst is needed to manipulate rasters.