Abstract: Change of the hydrological environment in the Wuyur catchments (Helongjiang Province,northeastern China) resulted in the rapid degradation of the wetland in the lower reaches.The hydrological response of the Zhalong saline marsh system to the change of runoffs in the Wuyur catchments was analyzed with the MannKendall test and moving t test method.The results indicated that the runoff entering the wetland was significantly decreased since 1980s,i.e.,the runoffs was decreased from 0.8×10⁸ m³ in 1960s to less than 0.5×10⁸ m³ in the 21^st century,with an exception of less than 0.1×10⁸ m³ in 1979 due to lack of precipitation.Change of the runoff in Wuyur catchments caused water shortage and the water area in Zhalong wetland shrunk significantly,and the water level decreased since 2003.The consistent drought and water depletion caused a large area of marsh to be disappeared and generated large area secondary salinization.The area of saline soil was merely 192 km² in 1950,nevertheless,it was significantly increased up to more than 200 km² in 1995,and reached 260 km² in 2010,of which a large portion was located in the core area of the Zhalong wetland.The wetland degradation would bring about great impact on the rare species which habitat and breed in this area.

Key words: inland saline marsh, degradation of wetland, salinization, drought stress