Hi all! (I hope there is some Ghost busters reading me)
Well, after months of work, I finally have my culverts and bridges watersheds well defined by ArcGIS(MAP) with ArcHydro! I'm working in a mask with 'only' 172 of them. Now I need to perform complex hydrologic and hydraulic calculations, but strange things have happened... Believe me, there are GHOSTS in the ArcHydro outputs! I have 2 examples:
1) I used the 'Join Field' function (ArcMap/Data Management) to bring 'L' and 'S' from the layer 'Long Flow Path' to the layer 'Watershed' (where I was planning to concentrate my automatic calculations, the model I want to build). The fields are copied, but... with 172 "NULL" values!? Well, let us right-click and delete them, right? Wrong: the 'delete field' button is not iluminated, not available for use. Of course I tried to use the 'delete field' function (ArcMap/Data Management), but guess what? The fields brought by 'Join Field' with no values are not listed! I'm quite convinced they are ghost fields. But they are not the only ones...
2) I created a raster of slopes (actually two, one with ArcMap and another one with ArcHydro, both perfect!) and was finally going to obtain the average slope of each one of the 172 watersheds! How excited I was about that! The best way I've found to do it, as a newcomer self-learner of ArcGIS, was the 'zonal statistics', maybe 'zonal statistics as table'. The zone data was, of course, my brand new watershed layer, a polygon feature (a perfectly valid one, according to the ArcGIS Desktop Help). The input value raster was the slope layer (I tried both of them). Could I have the mean values, please? NO, ArcGIS answered me. WHY, did I ask? Error 010160, unable to open raster watershed. But this is not a raster and you are not supposed to assume that it's a a raster! OK, I changed the zone field, the one which is supposed to indentify each one of the waterhseads; maybe it could help. YES, now ArcGIS could read the feature zone data! YET it told me: error 010067 now, 'error in executing grid expression'. You must check your Map Algebra expression: it's probably wrong, because I can't understand it, 'he' told me. But that Map Algebra is actually a function created by ESRI!!! How could I revise it? Well, a whole lost day with dozens of unsuccessful tries... I can't perform any statistics or operation within my 172 watersheds... THEY ARE LIKE GHOSTS.
Well, if someone doubt that softwares (even a sofisticated one, like ArcGIS), have the power to produce GHOSTS, please answer this post with at least one good explanation for the useless of layers and fields constructed in months of hard work with this sofisticated software (which is driving me crazy). THANK YOU, GHOST BUSTERS ON CALL!!!
