Wetlands have many functions. They can be used as direct water source or supplementary groundwater, effectively control floods and prevent soil desertification, and can also retain sediments, toxic substances and nutrients, thus improving environmental pollution. It can store carbon in the form of organic matter, reduce the greenhouse effect, protect the coast from wind and waves, and provide clean and convenient transportation ... It is called "kidney of the earth" because of its rich and beneficial functions. Wetland is also a paradise for many plants, animals, especially waterfowl. At the same time, providing food (aquatic products, livestock products, grains), energy (hydropower, peat, firewood), raw materials (reeds, wood, medicinal plants) and tourist sites for human beings is an important foundation for human survival and sustainable development.