I am using Modflow 2000 code in GMS 10.2.6 64bit version for the simulation of groundwater flow and MT3DMS for the transport and fate of nitrates in a aquifer study area. The study of the aquifer’s pollution by nitrates is carried out at the level of Municipal Districts (30 Municipal Districts, each has a unique polygon). Τhe reason why I'm communicating with you is that I have a problem with MT3DMS calibration.
I follow all the steps along with the default times described in the tutorial of MT3DMS Conceptual Model Approach to set up my MT3DMS simulation which runs successfully.
The sensitivity analysis indicates that the nitrate leaching parameter is the most uncertain parameter. As a result, the calibration is based on the nitrate leaching rate using a trial and error method, but every time I change the nitrate leaching, no significant difference noted to any polygons .
Ιt may be a silly mistake that I can not figure out.
Μaybe the answer would be to do an observation point to each polygon? but it is a whole area with consists of polygons.