西南弯曲河道栖息地地貌特征及适宜性研究

Curved river has the unique geomorphological characteristics, and provides diverse habitats for instream and riparian living organisms as well. Human activities caused stress on river habitat which makes river restoration be necessary by taking effective methods. In order to solve the problem of how to restore the river morphology, Chishui River is selected as the research area and fish is selected as the biological indicator in this study. There is no hydropower development activity in the main stream of Chishui River yet and the ecosystem structure and function is complete relatively. Multi-scale geomorphological index of curved river are defined based on the river ecosystem integrity, considering the situation of hydraulic and hydroelectric engineering development, river classification and ecological protection status. Through field investigation and numerical simulation, combining three-dimensional laser scanning technology, remote sensing image and fractal theory, quantitative method of the geomorphological index is researched. Then the geomorphological characteristics of certain rare and endemic fishes in Chishui River are confirmed according to their life habits. The response of fish habitat suitability to geomorphological characteristics alteration is researched by hydrodynamic model. The research of curved river habitat characteristics analysis and its ecological responses will provide direct theoretical supports for mitigation the ecological effects of hydraulic and hydroelectric engineering development in southwest area, and is significant for river restoration in southwest and other regions for reference.

弯曲河流具有独特的地貌学特征，也为河道内和河岸带生物提供了多样化生境。裁弯取直、大坝拦截等人类活动对河流栖息地质量造成了胁迫，需要采取有效手段进行修复和保护。为解决河流生态修复与保护中河流地貌形态如何进行修复保护的问题，本研究选择长江一级支流赤水河典型弯曲河段为研究区，以鱼类为指示生物，通过野外调查和数值模拟，采用遥感影像分析、分形理论和水动力学模型相结合的手段，识别宏观、中观、微观多尺度弯曲河流地貌特征指标，研究弯曲河流地貌特征指标量化方法和取值范围，明晰赤水河典型的特有珍稀鱼类在生活史的不同阶段中所需栖息地的地貌特征，获得关键地貌因子的适宜曲线，揭示鱼类栖息地适宜程度对地貌特征的响应机制。本研究可为我国西南地区水电开发的生态影响及减缓措施提供直接技术支撑，为西南及其他地区河流生态修复和保护提供依据。

本研究选择赤水河典型弯曲河段为研究区，以岩原鲤为指示生物，通过野外地貌调查和水动力、栖息地数值模拟，建立了整体河段尺度、局部河段尺度和地貌单元尺度弯曲河流地貌特征指标体系，提出了弯曲河流地貌特征指标量化方法，计算获得了局部河段尺度下典型河段部分地貌指标的取值范围，模拟了地貌单元尺度下无深潭-浅滩结构弯曲河段、有深潭-浅滩结构弯曲河段和顺直微弯河段的水深与流速分布情况，明晰岩原鲤生长所需栖息地的地貌特征，获得其水深、流速适宜曲线，对比顺直微弯河段和弯曲河段鱼类栖息地适宜程度和加权可利用栖息地面积，对比无深潭-浅滩结构弯曲河段和有深潭-浅滩结构弯曲河段鱼类栖息地适宜程度和加权可利用栖息地面积，初步明确了鱼类栖息地适宜程度对地貌特征的响应机制。结果表明：弯曲河段加权可利用栖息地面积在丰水季内Q=540.4m3/s达到最大值10.40%后降低，并在两年一遇洪水流量Q=3260m3/s有所提高至8.17% ，随后降低。顺直微弯河段加权可利用栖息地面积先增加后减小，在平水季内流量Q=306.9m3/s时最大，所占总面积比例为11.67%。弯曲河段可稳定提供适宜的栖息地并为鱼类在丰水期提供遮蔽所。本研究可为我国西南地区水电开发的生态影响及减缓措施提供直接技术支撑，为西南及其他地区河流生态修复和保护提供依据。