Is anyone aware of the level of preciseness using the GIS Hydro Services as compare with Arc Hydro processing tools on the same DEM?
Not familiar with "GIS Hydro Services" would you elaborate? Not the old Univ of Maryland CE project (G. Moglen) that was picked up by NRCS?
Anyone in the The specified item was not found. or The specified item was not found. s.Groups have any feedback for Cynthia Castro?
The experience would be shared with you, not to directly answer your question (because of ‘very wide’ topic that you raised):
With ArcGIS Online, there are some GIS Hydro services from national-wide US available to the public, such as ‘wetlands’, ‘surface water’ and ‘NHDPlusV2’…
It look to me that those are produced by different authorities from different data sources. Generally speaking, it is very hard to evaluate from those services powered by ESRI. If really want to get deep insight into individual accuracy onto…, better to contact the responsible authority to retrieve the metadata, including accuracy evaluation report / white paper…
Generally, national-wide hydro mapping services are derived from relatedly lower accurate hydro data.
In fact, most local hydro analysis tools /applications are used to assist engineers to ‘more accurately’ model, analyze and simulate in 3D GIS or 3D CAD environments for water management and flooding risk management, including rivers / lakes/ reservoirs and urban areas. Certainly, hydro data with high accuracy are required for this type of hydro mapping and analysis.
Worth to mention, with same hydro data, the results' or services' accuracy is highly related to the methods that enineers/ hydrologists are using, in particular, doing flooding risk analysis, because many overlaying analysis is highly required to use human logic (Fuzzy Logic)...
Cyndi - if the hydro services you are referring to are the ArcGIS Online hydrology analysis services that were released last week, these services are built on the same Arc Hydro and Spatial Analyst functionality you are already using in ArcGIS, just with some additional preprocessing of the data to make them fast.
The accuracy of the services is determined by the source data. The services are built on best-available authoritative content, within the US that is the NHDPlus version 2, and internationally is HydroSHEDS. We will increase the coverage at finer resolutions through contributions to the Community Maps program, which is now set up for people to contribute hydrologic content.
If NHDPlus or HydroSHEDS was going to be your source data, I suggest you just use the service, it will save you a lot of data processing time.
Note that if you want to use these in Desktop 10.2.1 or 10.2.2 there is a patch available to make these analysis services show up as tools in your ArcCatalog window at the bottom under Ready to Use services. All you have to do is login to your ArcGIS Online account and run it like any other tool, you do not need to do the "Add ArcGIS Server" step to create a server connection.
On GIS hydro services derived from national/ state-wide hydro data as metadata, it is good idea also to put the interpolation algorithm (Krigging, IDW, etc.) with accuracy evaluation as a part of metadata in ArcGIS Online … In fact, when providing related services to customers, they demand those as a part of operational requirements…
Besides, for ‘regional & local’ hydro survey/ analysis/ services with higher accuracy, 3D geological model is highly required (‘must-do’ for local hydro services) to understand soils/ rocks, rock aquifer, drainage system, etc. In other word, the right operational/ research approach decides the service accuracy as well. Pls refer to http://rd.springer.com/article/10.1007/s10040-004-0365-x#
Retrieving data ...