THE PILOT WAS LANDING AT AN AIRPORT SITUATED ON A HIGH MESA. THE AIRPORT DIRECTORY NOTES THAT TURBULENCE MAY BE EXPEREINCED NEAR THE AIRPORT. DURING THE LANDING ROLL, THE PILOT LOST DIRECTIONAL CONTROL OF THE AIRPLANE WHICH DEPARTED THE RUNWAY AND STRUCK A DITCH. THE PILOT HAD ACCUMULATED 28 HOURS OF EXPEREINCE IN THE TWIN ENGINE AIRPLANE.