弯曲河流水文地貌过程复杂行为及其生态效应研究

Human activities have modified the structure of river and stream habitats across the world.Habitat diversification is a common practice used in river restoration efforts to improve the ecological status of streams and rivers,ammong which re-meandering is a favored restoration approach.Stream macroinvertebrates are generally recognized as good indicators of ecosystem health, and the species richness metric is often used to monitor the restoration success.Meanders support a diversity of geomorphic units. Ideally, the meanders echibit complex hydrodynamics that favor high biodiversity.However, comprehensive field studies that provide direct comfirmation are still lacking. In this study, based on the specific hydromorphological characteristics of meanders and the potential applications in river restoration involving channel re-meandering, we select several meandering reaches in Haihe River as the references, and carry out the study by field experiment,theoretical analysis,and numerical modelling.At first, Complex behaviors in hydromorphological process in meandering are to be conducted to exhibit the specific hydro-morphological processes occurring in meanders.Secondly,we study the dynamics of macroinvertebrate responded to habitat dynamics at various spatial and temporal scales, to elaborate the mechanistic interactions between hydromorphological processes, habitat dynamics, and benthic invertebrates distributed at various spatial and temporal scales. And then,a comparative analysis of re-meandering measures and their effects on hydromorphology and benthic macroinvertebrates is to be carried out as the case study. The research will provide the strong technological and theoretical support to river ecological restoration, and make contributions in developing the river ecological restoration theory.

河流丰富的地貌形态是河流生物多样性的基础。以河道形态弯曲化为代表的地貌多样性修复是河流生态修复中最受关注的方法，但对河流生态系统的整体恢复效果并不明显。本项目针对河流弯曲化生态修复巨大应用潜力与相关基础理论薄弱之间的矛盾，选择底栖动物为生态指示物，拟以东江、海河流域典型弯曲河流（河段）为研究对象，采用现场试验、室内分析、数值模拟计算等手段开展课题研究。通过对弯曲河流水文地貌过程复杂行为研究，探讨弯曲河流生境异质性和动力学特征，揭示弯曲河流生态作用的物理基础；通过底栖动物对弯曲河流生境变化的动态响应研究，揭示底栖动物对弯曲河流水文地貌结构调整的响应与适应机制；通过对弯曲化生态恢复河流（河段）的监测与评估，系统研究河流弯曲化整治对河流生态系统恢复的效果。本研究将为正在大规模开展的河流生态治理提供新颖的思路和理论依据，为丰富和发展河流生态修复理论做出贡献，具有较高的理论研究意义和工程应用价值。

河流是地貌演变和生态系统中最具活力的部分。河流丰富的地貌形态为流域生物多样性创造了很好的条件，是生物群落多样性的基础。自然界中，弯曲河流是冲积河流的基本河型之一。弯曲河流水文地貌形态多样，生境异质性较高，以河道形态弯曲化为代表的多样性修复也就成为河流生态修复中最受关注的方法。本项目针对河流弯曲化生态修复巨大应用潜力与相关理论基础薄弱之间的矛盾，围绕着弯曲河流生境质量关键因子的识别、局地生境和底栖动物生物群作用机制关系定量表达、底栖动物对河流水文地貌过程响应的尺度效应等科学问题，基本按照研究计划开展项目各项工作。首先通过大量文献调研和总结，开展了水文地貌评价方法比较研究，梳理了水文地貌评价方法发展方向，为项目各项内容开展准备了理论基础。在云南省普洱市补麻河开展了弯曲河流典型河段河道断面物理生境变化对底栖动物的影响研究，构建了中小尺度下生物栖息地多样性指数，通过现场调查，研究了较小尺度下弯曲河流生境异质性特征，量化研究了生物栖息地多样性指数与底栖动物生物多样性之间的关系。以黑河流域和海河流域北运河水系为研究对象，通过系统的现场实验和调查，综合考虑了底质、流速、水深、河道形态及稳定性、河岸稳定性等指标，构建了流域尺度河流水文地貌评价指标，研究了流域尺度下底栖动物对河流水文地貌变化的响应。同时，项目以云南省普洱市补麻河为研究对象，通过对比研究，定量研究人工顺直渠化河道治理对河流生物栖息地质量的影响。项目研究表明，弯曲河段河湾的凹部，水流较浅，流速较慢，底质以卵石、砾石为主，其生物栖息地多样性较高，其底栖动物单位面积生物量、底栖动物密度、生物多样性指数、BMWP等指数明显高于河湾凸部。在黑河流域和海河流域北运河水系等流域尺度上，生物栖息地多样性指数与底栖动物生物多样性指数、BMWP指数呈正相关关系，而与Berger-Parker优势度指数呈负相关关系。人工顺直渠化河段与弯曲河段对比研究表明，人工顺直渠化措施，极大地降低了河道内生物栖息地多样性，其底栖动物生物多样性指数、BMWP指数、EPTr指数明显低于弯曲河段，而Berger-Parker优势度指数呈现相反的分布规律。项目研究结果进一步证明了弯曲河流较高生物栖息地多样性支持了较高的生物多样性。