sheraz 0 Report post Posted January 20, 2009 Dear All, I m working on Upper indus Basin watershed modeling,with total area of 397984 Sq Km. I am using SRTM 90m data for delination of Watershed. Is hec hms will support the delination of total area as single watershed in a single process. Also it takes a lot of time to process. Quote Share this post Link to post Share on other sites
Clark Barlow 1 Report post Posted January 20, 2009 As HEC-HMS does not provide delineation tools, I assume you are delineating the watershed in WMS for HEC-HMS, correct? 397986 sq. km is a very large area. Even 90 m data might be difficult to process. If the delineation is taking too long, you could try filtering the data as you read it in. On the read DEMs dialog, there should be a place to enter a thinning factor. If you enter a value of 2, that mean WMS will read in every other DEM point. If you enter a value of 3, every third DEM point, and so on and so forth. Of course the more you thin the DEM, the less accurate your delineation will be so you'll have to find a good balance. I hope this helps. Quote Share this post Link to post Share on other sites
sheraz 0 Report post Posted January 22, 2009 As HEC-HMS does not provide delineation tools, I assume you are delineating the watershed in WMS for HEC-HMS, correct? 397986 sq. km is a very large area. Even 90 m data might be difficult to process. If the delineation is taking too long, you could try filtering the data as you read it in. On the read DEMs dialog, there should be a place to enter a thinning factor. If you enter a value of 2, that mean WMS will read in every other DEM point. If you enter a value of 3, every third DEM point, and so on and so forth. Of course the more you thin the DEM, the less accurate your delineation will be so you'll have to find a good balance. I hope this helps. Yes i am using HEC-HMS in WMS. Then what else can i do? Through wht technique/Model i must delinat my watershed? Quote Share this post Link to post Share on other sites
Clark Barlow 1 Report post Posted January 22, 2009 You can do it, you just have to figure out what thinning factor to use. I'm not sure how large your DEM is so I can't tell you what factor is best. Start with a factor of 3, if that doesn't work, try 4, and so on. The time it takes to run TOPAZ will give you an indication of how long the delineation might take. If it takes more than 10 minutes to run TOPAZ, you probably need to thin the DEM some more. Hope that helps. Clark Quote Share this post Link to post Share on other sites
