Abstract: As a deltaic wetland system, there is freshwater (river) at one end and seawater at the other end (ocean). Between the two ends, it is the wetland with low elevation. A dynamic salinity gradient exists between the two end points. And water level gradients depend upon the interactions of river level and sea level. The water monitoring in a wetland should satisfy the requirement for understanding the dynamic changes in salinity and water level gradients between the two points.