海岸带典型盐沼植被消浪功能观测研究

河口海岸带盐沼植被的消浪护岸功能一直备受国内外学者关注。以长江河口地区海岸带盐沼植被为研究对象，在长江口崇明岛东滩、北八滧和东南部区域设置6条样带，每条样带布设3个测点，测点位置依据“光滩与盐沼交界-盐沼-盐沼”的模式布设，利用波潮仪、Trimble R8卫星接收机等仪器开展野外波浪数据、地形坡度、植被生长状况等综合测量，分析不同盐沼植被的消浪功能。研究结果表明：(1)自然状态下，典型盐沼植被，距海同等距离下的消浪强弱关系为互花米草＞芦苇＞海三棱藨草。波浪经过30 m宽的互花米草时，有效波高衰减80%，波能衰减90%；同样衰减80%的有效波高，则需要经过40 m宽的芦苇，或185 m的海三棱藨草区域。（2）植被消浪护岸功能受植被生长特征、空间分布、植被密度、坡度、土壤特性等多重要素影响，但植被密度是影响植被消浪护岸功能的主要因素，波浪在海三棱藨草区的衰减规律为多项式函数关系，在互花米草区域呈现为指数函数关系，在芦苇区呈现对数函数趋势。 关键词： 盐沼植被；生态功能；消浪护岸；波浪衰减；长江口

#br# Analyzing the Role of Salt Marshes on Attenuating Waves with #br# Rb16 2050 Mesearues in Changjiang Estuary#br#

Salt marshes in estuarine and coastal zone play a key role on erosion control and coastal protection for their attenuating wave height and dissipating wave energy. In this study, we selected three typical salt marsh species: Spartina alterniflora, Phragmites australis, Spirpus×mariqueter in Changjiang estuary to measure the capability of attenuating and dissipating wave with self logging wave sensors and Trimble GPS. Six sampling lines offshore and three sites on each transect with the pattern of “mudflat salt marsh frontier salt marsh” have been set up. Wave attenuation onshore in terms of significant wave height and wave energy have been analysed through 19 tidal periods with three salt marshes distribution patterns. The results show that: 1) The capability of coastal protection in typical salt marshes ranks with an order Spartina alterniflora＞Phragmites australis＞Spirpus×mariqueter. They attenuated 80% of wave heights (average) and dissipated 90% of total wave energy (average) as the wave crossed over the Spartina alterniflora 30 m wide, or Phragmites australis 40 m wide, or Spirpus×mariqueter 185 m wide. 2) Vegetation density is the crucial factor for coastal protection which affected by plant characteristics, plant height, bed gradient, wave action and so on. There was obviously polynomial relation between Spirpus×mariqueter width and wave attenuation, exponential relation between Spartina alterniflora width and wave attenuation, logarithmic relation between Phragmites australis width and wave attenuation. Key words：salt marsh; ecological function; coastal protection; wave attenuation; the Changjiang estuary