河库系统内供水-发电-环境互馈关系机理与演进规律

The water supply-hydropower generation-water environment nexus in river-reservoir system is important for water use, reservoir operation and water resources management. The water supply-hydropower generation-water environment nexus has been determined by the results from multi-objectives model in reservoir operation and cannot reflect the all interactions among the water supply, hydropower generation and water environment. Furthermore, the nexus is static which is contradicted with the impacts of the variations from climate change and human activities. We will take the cascade reservoirs or hydropower plants which are located above Rumei hydropower plant in Lancang River as the case study. In essence, the water supply-hydropower generation-water environment nexus is the water flow in the river-reservoir system because the interactions among the water supply, hydropower generation and water environment are in the forms of the discharge, and velocity, quality of the water flow in river-reservoir system. Therefore, the de Saint-Venant system of equations and the convection diffusion equation, which can be used to reflect the laws of water quality, sediment transportation and biogenic element, are adopted to simulate the temporal and spatial distribution of the discharge, and velocity, quality of the water flow in river-reservoir system. Then, the water supply-hydropower generation-water environment nexus equation will be determined through the water supply, hydropower generation and water.environment functions whose input are the discharge, and velocity, quality of the water flow in river-reservoir system. If the boundary condition of the river-reservoir system is varied with the climate change and human activities, the evolution of the nexus can be derived from the water supply-hydropower generation-water environment nexus equation which response to the varying boundary conditions. And the law and characteristics of the nexus will be obtained. Our study results help the water resources manager to mediate the conflicts from the different agents in the basin, reservoir operation and the adaptive water resources management. The conclusions will also be used for supporting improvement in the water security, energy security and environment protection in our country.

河库系统内供水-发电-环境互馈关系是水资源开发、调度和决策的理论基础。针对现有以多目标优化模型为手段所求得的互馈关系仅是优化条件下的一种数学关系且未能反映出这种关系的机理，也尚未能反映出气候变化和人类活动对该关系的影响及其动态性特点，本申请书将以西南河澜沧江如美梯级电站以上河段为典型研究对象，根据河库系统内供水、发电、环境之间相互作用是通过径流的量、能、质属性相互连接的特性，利用河库系统内径流连续方程、水动力方程、水质方程、泥沙方程和生源要素迁移转化方程及其各自数值求解技术，在求得径流属性时空分布的基础上，结合供水、发电、环境与径流属性的函数关系，确定出供水-发电-环境之间的互馈关系模型及其随边界条件动态变化的演化规律。该项目研究将为协调流域梯级开发中供水-发电-环境不同主体间的利益以及变化条件下的径流适应性利用提供理论与方法，从而为保障我国水、能源安全和生态环境提供理论与技术支撑。

河库系统内供水-发电-环境互馈关系是水资源开发、调度和决策的理论基础，也是水资源安全、能源安全和环境保护的重大国家现实需求。但现有互馈关系的研究主要还集中在评估方面，采用的模型和方法也主要属于统计方法范畴，未能反映出不同互馈关系连接体的内部结构，从而不能揭示互馈关系的机理及其演化规律。本项目以西南河流澜沧江流域为例，将其河库系统为主要研究对象，从研究供水、发电、环境各系统与径流不同属性之间的关系入手，重点研究了：河道径流与污染物输移扩散为连接体下推求的供水-发电-环境互馈函数关系；水资源与能源连接体下构建的供水-发电-环境互馈关系的网格描述与优化模型；以及应用量化的供水-发电-环境互馈关系，模拟与预测水资源系统中不同子系统面临外来扰动事故的应对过程及动态回弹性能。主要结果如下：（1）以来水量和水质保护目标为边界条件，推求了发电量、环境（污水允许排量）与供水量之间的函数关系，由于生态流量与发电流量未分离，供水和发电的关系不随水质指标及其保护目标而改变；来水量的增加会相应提高发电量及污水允许排量；而在给定供水量的情况下，发电的效率和污水允许排量的敏感性对来水量这一边界条件不敏感。（2）以供水量与能源产耗量构建二维关系图定量分析需水与来水量对供水-发电-环境互馈关系的影响，并设置分别以最大电能产量和最大供水满足为目标对供水-发电互馈关系进行优化。结果表明供水量主要取决于需水，而来水量主要影响发电量大小；优化目标的选择对供水-能源之间互馈关系影响甚微，主要是由于供水与污水处理消耗的能源在发电量中所占比例较小。（3）假定突发水污染事故为外在扰动，利用脉冲响应函数量化外在扰动影响强度及影响过程，并通过供水-发电-环境互馈关系实现各子系统中扰动的传递与再分配过程，进而实现了各子系统动态回弹性能的参数化表征以及面临外在扰动时各子系统的响应过程模拟预测。