黄河三角洲滨海湿地损失和退化的自然因素

NATURAL FACTORS FOR DETERIORATION OF COASTAL WETLAND IN THE YELLOW RIVER DELTA

黄河三角洲滨海湿地的损失和功能退化是对环境变化的响应,主要受自然因素控制。黄河入海水沙是形成滨海湿地的物质基础。自20世纪70年代以来黄河水沙减少,新生湿地的形成速率变小;波浪、潮汐、风暴潮、地面下沉和海平面上升等因素导致了滨海湿地的损失,湿地的面积呈减小趋势。由于淡水资源的短缺导致滨海湿地土壤严重的盐碱化和干旱灾害,限制了湿地植被的发育,湿地功能退化。黄河冲淡水的减弱甚至消失,导致滨海湿地海水的盐度升高,温度降低,物理环境平衡遭到破坏,生物多样性明显降低。

The area reduction and function deterioration of the coastal wetland in the Yellow River Delta,as a response to climate change,is basically controlled by natural factors.Water and sediment from the Yellow River are the fundamental materials for the survival of the coastal wetland.The rate of increment of coastal wetland has slowed down as the water and sediment discharges of the Yellow River decreased since last seventies.The joint action of the factors,such as wave,tide,storm surges,land subsidence and sea level rise has led to area loss and the negative growth of the wetland in the last decade.Owing to water shortage,soil salinization and the drought frequently happened in the coastal wetland,the diluted water from the Yellow River is nearly disappeared.It results in the increase in salinity and decrease in surface water temperature in the offshore water,the damage of environment and the reduction in biodiversity.