Latest Contributions by MarkBoucher

The "Flow Accumulation" creates a raster of accumulated flow into each cell. A weight factor can optionally be applied. Please understand that the numbers in the "Flow Accumulation" raster have little to do with the amount of water that is flowing off of the watershed. It is derived from the "Flow Direction" raster and is simply a count of the number of raster cells that are upstream of that cell (and maybe including that cell) and nothing more. It is a count and not an actual "flow" such as cubic feet per second or gallons per minute. It can represent the area if you multiply that grid's value by the area of the grid cells. The term "flow" comes from the fact that it is created using the flow direction grid. Noting the possible confusion would make me tend to want to rename it to "Cell accumulation count based on flow direction grid", but that's too long. Estimating the flow rate (discharge) at a point in a pipe/creek/stream/river can be done several ways. There is the: Rational Method (easy by hand), Unit hydrograph methods (can be done by hand but is normally done using software such as HEC-HMS), Other methods that require specialized software (such as that created by Vieux, Inc.  http://www.vieuxinc.com/about.html). Each method requires a different level of data for input and provides a different level of detail in the output. the Spatial Analyst tools Arc Hydro tools can be used to measure the inputs for several different methods. The acceptable method is usually determined by the size and complexity of the watershed and sometimes the accuracy you need for your situation. The purpose (planning or design) will also determine if you need a back of the envelope number or a hydrograph with 5-min time steps. Normally, the local jurisdiction will have hydrology standards that they accept for the different purposes. ... View more

You can find posts at http://forums.arcgis.com/threads/48100-ArcHydro-Problem-Solvers that may be of help in making sure you are setting your project up in a way that reduces errors. ... View more

I make the pipes part of my agreestream layer (Arc Hydro term) and burn them into the DEM. In the bigger picture, this is accurate enough for me. It may cause the flow direction in some very small sub-watersheds to be inaccurate. Using the pipes to set the flow direction (Arc Hydro - Adjust flow direction in streams) is not a bad idea either. You may have to deal with flipping the polyline directions if they were not drawn from upstream to down stream. I've not done much of this. An important concept is to not get to tied up in the importance of elevations of the DEM. The important thing is the flow direction. The burning, building walls, and filling sinks is all done to get the flow direction as close to reality as possible. Fro example, if the stream is burned 1000' into the DEM, still the flow direction will come out right. ... View more

I got nothing else. Here's the ESRI explaination of that error: http://resources.arcgis.com/en/help/main/10.1/index.html#//00vq0000000z010429 ... View more

Two initial thoughts... Make sure your processing extent covers the limits of the DEM you are filling. (Geoprocessin>Environments>Processing Extent) If you have a large DEM, try putting it on your local machine and process it there as apposed to over a network. ... View more

I  could be wrong,  but this might not be the best forum to post this question. If you post it on one of the other communities, you might get a faster and specific response. http://forums.arcgis.com/index.php ... View more

There are several things that could be causing this error. I don't have time investigate further or explain them all. You can go to the forum at this link (http://forums.arcgis.com/threads/48100-ArcHydro-Problem-Solvers) where others and I have posted several solutions. ... View more

The Arc Hydro tools will create a network of polylines for the drainage lines (polylines) in a watershed. ... View more

HEC-GeoHMS has a tool that imports points to the batch point layer no matter what other feature class they are in. If you can get that tool into your model, all you need is to figure out how to create some points be made batch points (Feature to Point?) and have that tool act on them when they are selected. Even when I'm using ArcHydro, GeoHMS tools work on the ArcHydro layers. I don't have to create a GeoHMS project. ... View more

... the shapefiles I was using to define the basin boundaries and flow paths. ... Lisa Lisa, What kind of shape files are you using to define the basin boundaries and flow paths? I always start with rawdem (raster) and agreestream (polyline) file. I only use the innerwalls, and outerwalls if needed. Are you using another function that creates watersheds based on polygons? There appears to be one (Batch watershed delineation for polygons), but I've never used it and also I believe it is used after all the Terrain Preprocessing. ... View more

My first suspicion is that the processing extent needs to be set to cover the area you are working on. Go to Geoprocessing > Environments > Processing Extent and in the pull-down menu choose a shape file or raster that covers they extent of the area you want to work on. It will place the right numbers in the "Top/Bottom/Left/Right" boxes. ... View more

It just worked for me. ... View more

I've collected an posted several Arc Hydro problem solvers on a thread. See link below my signature. ... View more