In this model, bathymetry and water level is shown (Fig1). However, what is the Vertical Datum? Is it NGVD 29 or NGVD 88? This is important for vertical height. Please verify it. By the way, in Ji’s book (HYDRODYNAMICS AND WATER QUALITY MODELING RIVERS, LAKES, AND ESTUARIES) where this model originated from, I can not find the Vertical Datum either (Fig2, which is Fig2.4.3 in book). So, could you tell me the Vertical Datum in your model? Thank you!
Fig1-2.png
Fig2-2.png
Hi In Art,I don’t know the answer, but I did do some digging.I found this dataset online that appears to be the source: https://sofia.usgs.gov/publications/maps/lakeokeebathy/It looks like the data file they provide there have elevations given in NGVD27 and NGVD88.You could test which one it is by saving out the model into a new file, overwrite the bathymetry with one datum or the other, and then do a model comparison to confirm what the original model was.Do you have comparison data you are trying to calibrate to? If so, computing the datum offsets for such a dataset could be more straightforward using a program like Corpscon or VDatum. I’ve had to do this before for observation data and it’s pretty quick. Simply, if you bring in your calibration data to compare with the model and you see a consistent offset, try using the computed datum offset between NGVD27 and NGVD88 to adjust the height of your data and see if it works.Hope that helps,Tom
Hi In Art,I don’t know the answer, but I did do some digging.I found this dataset online that appears to be the source: https://sofia.usgs.gov/publications/maps/lakeokeebathy/It looks like the data file they provide there have elevations given in NGVD27 and NGVD88.You could test which one it is by saving out the model into a new file, overwrite the bathymetry with one datum or the other, and then do a model comparison to confirm what the original model was.Do you have comparison data you are trying to calibrate to? If so, computing the datum offsets for such a dataset could be more straightforward using a program like Corpscon or VDatum. I’ve had to do this before for observation data and it’s pretty quick. Simply, if you bring in your calibration data to compare with the model and you see a consistent offset, try using the computed datum offset between NGVD27 and NGVD88 to adjust the height of your data and see if it works.Hope that helps,Tom