Abstract: Charhan Salt lake, locating in the middle of Qaidamu basin, consists of the shallow depression which is fed by phreatic water and outside water system, and salt marsh. Its areas is 5856 km , and the highest ratio of solid/liquid of salt mineral resorces is 1/3.46 . the lowestl/1. 28. The salt－out action is a typical process of charhan lake, and so it is a ＂live＂mineral.
In this paper , the property and effect of catastrophic flood that have occured in 1989 is studied by satelliate remote image and field exploration. The flood is the largest one since there are a hydrologic record and have made the lake expension, desalination and karst. Germu river Whose 70% water flows into the lake is the cause of the flood. The data of hydrology and meteorology in Germu river during past 28 year shows that bigger flood (about 300±m/S) in the area will occur with the interval of 7or8year, and the Catastrophic fiood is about 300 year. The author Considers that the flood over 200 m/S will occur for 2to 3times and that of 500 m/S occur 1 times in the next decade.
The Suggestion of studing the dynamic balances of the flood-salt lake by using remote Sensing methods are proposed.