空间显式模型模拟河流岸边带植被在水库运行作用下的演替

岸边带是水-陆之间的过渡和缓冲地带,是河流生态系统的重要组成部分.岸边带对拦截径流中的固体颗粒、吸收营养盐、减少入河污染负荷有重要作用.受河流水位季节性波动的影响,岸边带生态系统的变化非常剧烈,而当水库等水工建筑的运行剧烈改变河流的水文情势时,水库下游的岸边带生态系统将受到长期的累积性影响.因此,研究复式河道岸边带植被动态对于受损河流生态修复以及河流开发运行的生态环境影响规避具有重要意义.通过原位样方观测和室内水槽模拟试验,开发了岸边带植被演替模型,该模型耦合了全局基于连续性模式的水动力模块和局部基于元胞自动机模式的植被演替模块,并以漓江中游的一段复式河道为例,通过模拟水库运行前后长序列的水文情势变化和3种岸边带植物(刺果酸模、水蓼和益母草)的生长演替,分析了为满足旅游航道需求上游水库补水运行对下游岸边带植被的影响.

Spatially-explicit modelling of riparian vegetation dynamics under reservoir operations

Riparian zones are important to the interception of diffusive pollutants and the rehabilitation of aquatic ecosystems. Due to the fluctuations of the water levels, riparian ecosystems usually have strong dynamic behaviors. This study focuses on the understanding of the vegetation dynamics and successions of riparian zones of compound channels when the flow regimes are fundamentally modified by river regulations such as reservoir operations. The research developed an integrated riparian vegetation model which couples the global continuum formulations of hydrodynamics with the local cellular automata of vegetation evolution. The model was then applied to a compound channel of Lijiang River in the Southwest China, which has been affected by the flow regulations for navigation purpose. Through the simulations, the previous changes of the riparian vegetations were analyzed and their future developments under the new flow regulation scheme were predicted. In particular, the potentials of integrating global formulation and cellular automata were well studied.