Hydrologic variation affects many functions of wetlands.Rapidly and accurately measuring hydrologic dynamics in a wetland watershed has become a fundamental need for estimating functional changes of wetlands.The satellite altimeters have become good data sources that can complement the measurements of gauge stations.As a case project applied in the Poyang Lake watershed,this study has developed a technical approach that integrates the altimeter measurements with the in situ water level data.The derived water surface heights with Envisat RA-2 data are compared with the daily observations of in situ water levels.The average absolute observation difference between the "altimeter station" and its nearest gauge station is 0.307 m,which is comparable to the average differences among the gauge stations.The results suggest that the derived water surface heights from the altimeter data have a good accuracy,which can be used along with the in situ observations as supplements to fill the ungauged area in Poyang Lake wetlands.