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Is there a method in Arc Gis for mapping storm water runoff in an urban environment assuming that the sewers are at full capacity. I just want to map roughly where the water will flow over the land over paved surfaces

I have a DEM, a land use map and have already calculated the flow direction and streams network. I wish to find out what areas will flood in the study area during an extreme rainfall event.

closed as too broad by PolyGeo Jun 13 '16 at 3:54

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    What is it exactly that you want to model? Water volumes in the area, water volumes in pipes, flooded areas, water depth in flooded areas, theoretical flow paths with/without sewers..? Also, what data have you got? LAS files (precision, density?), pipe network, land use (eg. hardened/not hardened surfaces and degrees thereof) etc. Please use the edit button to update your question. – Martin Mar 11 '14 at 13:16
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    In that case you probably won't get very far with ArcMap. You need specialized software like MikeFlood. If you also want to include pipe flow you need to set up a model in MikeUrban first to connect to the Flood model. There are other programs as well, like HEC-RAS, but I don't think it can handle pipes. – Martin Mar 12 '14 at 15:28
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When you start getting into hydrograph routing (flow rate vs time), you are leaving the GIS realm and get into specialized hydraulic modeling software. HEC-RAS is great for open channels, and can handle pipe flow, but needs hydrology (how much runoff are you getting) input (often from HEC-HMS). The mix of hydrologic and hydraulic modeling required to (relatively accurately) do urban stormwater flood modeling is a really narrow niche field. The models all have a bunch of calculation options and methodologies, various input parameters to select from and assumptions to make. Plus, most of the commercial software is pretty expensive.

Don't be offended by this, but rather than look for another piece of software, I suggest you look for another person to take this off your desk. For perspective, if a civil engineer with a CAD background said he was going to create some massive multi-user spatial database from scratch and wanted to know which software to use, what would you tell them?

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I would suggest you take a look at Aquaveo's WMS. It is a GIS platform in which you can actually run most of HEC's applications. It is actually a swiss army knife for leveraging water resources issues. It seamlessly integrates CAD, GIS and raster data features with the intent to handle better and visualize multiple water resources scenarios. It handles almost any file format that you throw into the mix. I believe this to be one of the toughest challenges a water resources engineer faces on a daily basis. Data interoperability is key, as most Hydrology & Hydraulics studies demand quite a bit of research. In the process, you will most likely end up with an array of files of different sources and therefore different file formats. The ability of your main GIS platform to read and process all the raw data, i.e.(.dwg,.shp,.txt,.csv,.tin,.jpg,.gpx,.ras,.hms, etc) along with its capability of using all of your graphics card juice and core processors hardware efficiently, for visualization and rendering; are the true value of the same.

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