The current version (v1.3.1) should be available through the QGIS Python Plugins Repository: launch QGIS3, go to 'Plugins → Manage and Install Plugins...', then (under the 'All' tab) enter 'survex' in ...

QSWATMOD is a QGIS-based graphical user interface that facilitates linking SWAT and MODFLOW, running SWAT-MODFLOW simulations, and viewing results. This repository contains source codes and an ...