Hi, I try and add a topic each month to showcase the capabilities and/or datasets that are available for spatial systems/GIS. Let me know if they are helpful or if there is specific topics you would like covered.
Below I have included two links on how to delineate a watershed using GIS. The basis of most hydrology studies is to determine the size of your catchment. I have used the methods below to assist in calculating the amount of rainfall runoff that can be captured and determining the size of sedimentary dams to trap sediment runoff from construction sites.
Using ArcGIS with spatial analyst extension, there is demo data included if you want to do the tutorial.
Delineating watersheds using open source GRASS GIS.