| Reed wetland in the Liao River estuary is one of the largest,the best preserved and the most integral vegetation types included wetlands in the world. It has an important role in water purification, climate regulation, and seawater intrusion prevention.etc. But in recent years, the reed wetland in the Liao River estuary was severely damaged because of the multiple effects of natural and man-made activities which leads to ecological functions of wetland disordered,and further affects the ecological environment of the whole region of the Liao River estuary.To ease the increasingly prominent contradiction between the ecology water requirement and water shortage of the reed wetland, which will ensure the healthy growth of reeds, this paper established MIKE 21 two-dimensional hydrodynamic and water quality model of the Yangjuanzi reed fields using the collected terrain data of the study area on the basis of analyzing hydrodynamic conditions of the reed fields. It combined the hydrodynamic processes and the processes with changes in water quality, and analysed water conservancy projects’impact on the flow of the reed fields, and finally proposed the water regulation program meeting the requirements of discharge water quality and ensuring the healthy growth of reeds, which can provide technical reference for the estuary reed fields’ecological water regulation, while can provide evidence for the recovery and purification of estuarine wetland research.The major results are as follows:On the condition of non-culvert, after irrigation completed, the study area’s average water level was much higher than required water level for growth of reeds, which would cause a huge waste of water resources.Based on the condition of non-culvert, after adding ring grooves which could accelerate the flow of water, the flooding situation had improved and water distribution was more uniform. When the water level satisfied the growth of reeds, time this process used was shortened and the non-water area was reduced. But considering the costs, this plan was infeasible.Setting a culvert at 1st water intake, the flooding situation of mos reed fields was not improved after irrigation, but the flooding situation of 1st reed field near the culvert was better which showed culvert contributed to water regulation.Setting a culvert at 2nd water intake, the reed fields near the culvert and away from the culvert had extremely uneven water distribution which showed setting a culvert at an intake alone could not achieve the purpose.When setting culverts at 2nd,4th and 5th water intakes, water could flow uniformly as well as steadily over the entire study area in the late period of irrigation. Final water distribution was very uniform and the time reached the needed water level was the least. So it is certain this inflow program is the best.When the simulation period was from July to August for the experimental field, concentration of COD could not meet the emissions target after 60 days’degradation. So it need to combine with other pollutant treatment methods in order to meet the emission requirements when reed fields are under the less degradation period. When the simulation period was from August to September, concentration of COD could meet the emission requirement after about 21 days. So when the concentration of pollutants in the water of the reed fields is low, or the reed fields are under a higher degradation rate period, it can be used to purify the water by circulating water flow based on a small experimental reed field to meet the emission target. |
PDF Full Text Request