Flat area with culverts

[NaseefChowdhury]

I have not used ArcHydro before and am wondering if it will be appropriate to analyze a flat area with culverts as the primary tool for the water movement. From all the research I have done so far, ArcHydro seems to be made mostly for natural water movement using streams and lakes, so I am not sure if this is the right path for me to go. Thanks for the help.

[MarkBoucher]

Arc Hydro does not do pipes. It works off flow direction determined by the DEM and has tools to let you modify the DEM to make it hydrologically correct.  You can use Arc Hydro in flat areas by using its tools to "burn" in the pipes like trenches and "building walls" to control the main drainage paths and watershed boundaries in the DEM so the flow direction is hydrologically correct.

It does not calculate depth of flow for pipes or channels. There are tools to export the data from GIS to other modeling programs. HEC-GeoRAS and HEC-GeoHMS are two free programs developed by ESRI for the US Army Corps of Engineers to export data from GIS to open channel flow models and hydrology models respectively. Other software companies may have their own proprietary tools for doing the same for their models.

[ChristineDartiguenave]

Arc Hydro started with dendritic terrain processing only but has been extended over the years through work with the Southwest Florida Water Management District to handle both flat areas with sinks (what we call Deranged terrain) and structures such as culverts or pipes.

Deranged Terrain
In flat areas water may flow toward the sinks. There are catchments associated to sinks in Arc Hydro as well. The connectivity between deranged catchments is established  through the lowest point on the  shared boundary (Drainage Morphology tools). You can also set a preferential path between the catchments that will allow you to trace "downstream" like in a dendritic terrain network.


Structures
Basically you can extent your standard Arc Hydro Geometric Network with junction/edges representing the structures that you would need in your model. Arc Hydro does not do modeling but will help you with preparing the input data required for your model and with visualizing your results.

Christine Dartiguenave
Esri Water Resources Team

[NaseefChowdhury]

Sounds like I basically would need to treat culverts as streams and "burn" them. I am working through the documentation and hopefully can figure out the workflow. Thank you both, that is some very useful information.