鄱阳湖与长江干流水沙交换过程及其对闸坝调控的响应

Today, researching the relationship of lake-river is one of the hot topics in academic world. In recent years，as the rapid social economic development, human activities and global climate change, which increased river hydrological process change and caused the river-lake water and sediment exchange process change, and then promoted the relationship between river and lake accelerated evolution. The exchange and variation of water and sediment between river and lake are the direct driving force and connecting of the evolution of relationship between river and lake. It is the premise and foundation that the exchange and variation of river-lake's water and sediment research is to figure out the evolution of the relationship between river and lake. This project based on accumulated hydrologic, sediment and satellite remote sensing data already have, paying attention to obtain the first-hand data by field investigation and observation, using of the interdisciplinary means, carrying through the water and sediment exchange research between the Changjing River and the Poyang Lake. In this project, the process of water and sediment exchange between the Poyang Lake and the Changjiang River, and the driving factors for its changes will be analyzed, these changes' driving mechanisms will be expound, based on clarify the water levels linkage fluctuate of the Poyang Lake and the Changjiang River. The multiple regression analysis models will be built to predict the water levels of Hukou gauging station. It will be explore that the influence of water and sediment exchange under the control of dams, big water conservancy projects, which lies Hukou and main stream, and the influence mechanism will be expound. It will be built the quantification model to predict the degree of the influence. After the implementation of the project, it has an important theoretical and practical significance that the results can provide the scientific basis for large and medium-sized water conservancy project construction, water resources development and utilization and management, the regional economic development, in the middle and lower Changjiang River.

河湖关系是当今学术界普遍关注的研究热点。近年来人类活动和全球气候变化加剧了河流水文情势变化，引起河湖水沙交换过程嬗变，促使河湖关系加速演变。河湖水沙变化和交换是河湖关系演变的纽带和直接驱动力，河湖水沙变化和交换的研究是弄清河湖关系演变的前提和基础。利用前期积累的卫星遥感、水文泥沙等资料，注重实地调查和现场观测获得资料，采用多学科交叉手段展开研究。在分析鄱阳湖与长江干流水位联动关系的基础上，建立多元回归模型预测湖口水位，重点分析河湖水沙交换过程及水沙交换变化的驱动因素，阐明其驱动机制；探讨鄱阳湖与长江干流水沙交换对干流和湖口等大型水利工程调控的响应，阐明其机制；借助GIS技术在DEM高程基础上建立五河径流与鄱阳湖水位模型，初步预测闸坝调控对河湖水沙交换影响的程度。本项目实施后，其成果可为长江中下游水资源开发利用与管理、大中型水利工程建设及区域经济发展提供科学依据，具有重要的理论和现实意义。

全球气候变暖，极端气候频繁发生，以及强烈的人类活动等事件都深刻地影响着流域水文循环、水资源的形成与转化过程以及水环境变化。进入21世纪以来，长江上游水库群的运行使鄱阳湖与长江之间物质和能量的交换过程发生了变化，鄱阳湖流域的秋旱现象逐渐严重，江湖关系加速演变。. 通过对河湖连通关系的讨论，认为在健康的河湖连通系统中，存在着“物质流”、“能量流”、“信息流”和“价值流”，正是诸“流”完成了河湖之间的“量质交换”，实现了河湖相互作用。河湖之间的“量质交换”是河湖连通关系演变的途径和动力之一。在河湖系统中，任何一个要素发生变化，其余各要素就会发生连锁反应，形成反馈，从而影响整个系统功能的发挥，最终会影响流域内防洪、生态、资源利用和环境变化。. 近60年来鄱阳湖水位分阶段降低，2006～2015年水位降低最明显，平均值比2000年之前低了1m多，枯水水情突出；枯季主湖区比入江水道枯水程度更严重。定量检验结果表明：鄱阳湖10月份平均水位有非常显著的减少趋势；湖口站水位在秋季有显著的减少趋势；鄱阳湖冬季水位减小有较强的持续性。流域气候因素和五河径流量奠定了鄱阳湖水位年际变化的基本过程，长江干流及其上游以三峡水库为主的水库群调节对鄱阳湖水位时空变化有着深刻的影响；近15年来鄱阳湖水位趋势性减小主要与长江上游水库群调节和湖区人工挖砂等人类活动有关。. 长江与鄱阳湖汇流区域河道冲淤研究表明：张家洲河段目前处于适应流域来沙量减少以及河流控制工程的过程中，整体表现为冲刷，净冲刷量为172万立方米，其中，张家洲南水道为强冲刷区。张家洲河槽表层沉积物中值粒径为149.1~226.3 μm，与历史资料相比呈粗化趋势。1998-2013年，汇流河段整体冲刷635万立方米。长江与鄱阳湖汇流上段主要发育了沙波、平床及冲刷痕等微地貌。长江流域来沙量减少导致床面泥沙粗化，为研究河段沙波的广泛发育提供了物质基础。江湖汇流区水沙变化和河道冲淤的研究结论对流域水利工程建设和治理江湖关系有着重要而深远的意义。