Abstract: Wetland is an unique ecosystem which perform a number of hydrologic and biological functions that make it valuable. This system provides functions such as habitats for plants and animals,place of recreation and education water quality filtration including removal of nutrients and silt, ground water recharge, soil formation, interception of aieborne pollutants and protection against erosion. Wetland also is functioned to retard floodwater and provide surface water storage. Improving the function quality of overdrained watershed wetland has been identified as potential water management option that could also contribute towards attenuation of excessive stormwater runoff. Based on these studies, we draw some conclusion about the 98' flood in Changjiang and Nenjiang catchment and put forward some countermeasures for flood control.

Key words: atmospheric nitrogen deposition, dry and wet deposition, ecological effect, critical loads, monitoring method.