CRUZ

Hi Volker, Thanks again for you help. You are right, there is something wrong with preprocessing step. when I was applying "sink removal " function, there is a threshold default value is 100, my targeting area is quite flat (0-140m), that is why the channel network looks very strange, now changed threshold value to 20, everything looks fine now. Thank you very much. Cheers Yi

Hi Volker, Thank you very much for help, I think it works fine now, Just have a one more question about setting threshold values for creating channel network, I know I got to try with different values and finally decide it. I am just wondering if there is any "rule of thrum" for this value? my targeting area is relatively small (2000km2) and flat with elevation 0-140m, the catchment area range from 100 to around 5,000,000. Catchment map looks fine (attached) I set up with different values, but resulting...

Hi Volker, Thanks for reply, I am not 100% understand what did you mean about preprocessed DEM, but I always used the original DEM data without any preprocess. I also tried to preprocess DEM with terrain analysis-> preprocessing->fill sinking (Wang liu). The resulting map looks quite strange for me, so i did not continue with this preprocessed DEM for developing catchment area. Do you think I continue with the one preprocessed ? Cheers Cruz

Hi, I have a question about using SAGA gis to calculate horizontal overland flow distance, the resulting raster map showed a lot of NA value pixels. Here is my procedure: I have a area around 2000 km2, with 10m resolution DEM. So what I did is first to develop catchment area map using: terrain analysis-> hydrology-> SAGA wetness index. One outcome from here is catchment area, the map shows range between 100 to almost 20000. Then I used catchment map to develop channel network using terrain analysis->...