Hi

I am trying to calculate the length of the path water would take from a catchment boundary to a river within the catchment (basically the shortest path to the river taking the steepest slope each time from each position). I want to calculate this incrementally as I move around the border of the catchment until I have completed a sweep of the catchment boundary. I also want to calculate the difference in height from the start of each path at the catchment boundary to the height of where it joins the river. I have a DEM raster and polygon for the catchment and polyline file for the river already. The DEM was used to calculate the catchment size.

So my output I'd like is all the pathway lengths with their height change all the way around the catchment boundary.

If anyone can help that would be brilliant.

Thanks

Ronan

I am trying to calculate the length of the path water would take from a catchment boundary to a river within the catchment (basically the shortest path to the river taking the steepest slope each time from each position). I want to calculate this incrementally as I move around the border of the catchment until I have completed a sweep of the catchment boundary. I also want to calculate the difference in height from the start of each path at the catchment boundary to the height of where it joins the river. I have a DEM raster and polygon for the catchment and polyline file for the river already. The DEM was used to calculate the catchment size.

So my output I'd like is all the pathway lengths with their height change all the way around the catchment boundary.

If anyone can help that would be brilliant.

Thanks

Ronan

There are a few steps ;) involved before you can run the Flow Length tool, and if you are new to the ESRI hydrology toolset, take a look here 1st: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#/An_overview_of_the_Hydrology_tools/009z0000004w000000/

I, in fact, encountered the same problem like yours .

I am working on sediment delivery distributed model (SEDD) which i believe , i should calculate the travel time of the eroded particles along the hydraulic path, from the considered area /cell to the nearest STREAM REACH as per the definition,.(as shown in the fig )

I used flow-length tool, however it gives a hydraulic path length down till to the outlet of the basin , Not to the Nearest stream reach .

I was having the same problem and after a lot of tries involving the optional weight raster as input for the Flow Length tool, I found that the only solution is to manipulate the Flow Direction raster such that is has NoData values where the streams are. Using that as the input for the Flow Length tool (and using no weight raster), I now get the desired flow lengths to the nearest stream.

Additionally, as I wanted to determine the longest flow path per subcatchment, I had to extract the flow direction raster for each subcatchment and then use the Flow Length tool on each of those individually. I used a python script to automate the process.