I am trying to determine the sites for small hydropower. I have a elevation dem, rainfall data, Curve number data (from soil and landuse shapefiles). I have already used the DEM to fill sinks, find flow direction and accumulation...up to the creation of catchment polygons and slope. I am stuck here. Is there a way to use this to generate points for potential sites?
This sounds like a fairly routine site suitability analysis. You can generate best suited locations anywhere, provided you establish criteria. Things like "must be in an area of less than 10% slope," "must achieve x level of flow accumulation," "must be within x distance of a highway," etc., can enrich the analysis and help you arrive at a final answer that you can defend. If this is a project for a client, I recommend talking to them and/or the engineer to figure out what works best for them.
Using other tools such as reclassify, zonal statistics, euclidean distance/cost distance, etc., you can establish what is a "good" location and what is a "bad" location. You can use raster calculator to weight variables, giving higher priority to what is considered more important. Ultimately, you'll want to establish a way of combining these variables together in a single scale (usually from 1-10, with 10 being the best). From there, you could select locations from the areas of highest suitability.
Take a look at some of these site suitability discussions and overviews:
http://web.mit.edu/11.520/www/recitation/rec3_site_suitability.pdf http://blogs.esri.com/esri/arcgis/2011/07/01/locating-a-park-through-suitability-analysis/ http://resources.arcgis.com/en/help/main/10.1/index.html#//00nt00000008000000 http://www4.ncsu.edu/~wray2/Siteselection.html