Text this: Source term treatment of SWEs using surface gradient upwind method

  ______     ___     __   __    _____     _____   
 /_   _//   / _ \\   \ \\/ //  |  ___||  / ____|| 
 `-| |,-   / //\ \\   \   //   | ||__   / //---`' 
   | ||   |  ___  ||  / . \\   | ||__   \ \\___   
   |_||   |_||  |_|| /_//\_\\  |_____||  \_____|| 
   `-`'   `-`   `-`  `-`  --`  `-----`    `----`