水电开发下河流生态流量的水库调度方法研究

Sustaining environmental flows (e-flows) is a critical measure to address the conflict between hydropower generation and river protection. The present e-flow management rules are "static", which do not update with the change of the conditions of reservoirs, and thus are not beneficial for the balance of human and riverine ecosystem needs; in addition, the e-flow management rules towards the river protection at the ecosystem scale are based on the hypothesis of minimizing flow regime alteration but do not consider the complex relationship between flow factors and ecosystem factors, which can not predict the ecological results after applications and is a "black box" model. In this research, a new e-flow management method is proposed. In this method, the reservoir space is divided into several zones, and different e-flow rules are triggered when the reservoir water level is in different zones. This "dynamic" method could help to address the conflict between river protection at organism and ecosystem scale, and the conflict between human and ecosystem needs. The stable isotope technique is used to investigate the structure of food web and the nutrient circulation, and the multi-agent method is adopted to develop the model of nutrient circulation in food web, which could reduce the complexity of food web simulation. Based on the theory of food web for quantitative analysis of the relationship between flows and riverine ecosystem, the e-flow management rules towards the river protection at the ecosystem scale could changed from "black box" to near "white box" model. This research will be helpful to river protection at the ecosystem scale and the balance of human and ecosystem needs.

保证河流生态流量是解决水电开发和河流保护矛盾的一项关键措施。现有生态流量调度方法不随着水库实际情况调整，是一种"静态"模型，不利于人类和生态需求的协调；另外，面向生态系统层面保护的生态流量调度方法是通过最小化水文情势扰动来间接实现，未考虑生态流量影响下的生态系统各物种间相互联系的复杂变化，难以预测调度的生态结果，是一种近"黑箱"模型。本项目提出对水库库容进行分区，根据水库水量变化，"动态"调整生态流量调度规则，解决面向目标物种和面向生态系统保护的生态流量调度方法间协调以及发电和生态保护间协调的问题；利用稳定同位素技术研究食物网结构和营养循环，并采用多Agent系统开发食物网营养循环模型，以降低食物网模拟的复杂性。采用食物网理论定量研究生态流量影响下生态系统的变化，使面向生态系统层面的生态流量调度从"黑箱"变到接近"白箱"。本研究有利于实现生态系统层面河流保护，以及有效协调人类和生态需求。

水电开发是实现2020年国家能源目标的必然方式，但水电开发会造成河流生态系统的退化。河流生态系统保护已成为影响我国能源目标实现的一个重要瓶颈因素。在开发水电的同时，对河流生态流量进行有效的调度，是解决水电开发和河流保护矛盾的关键措施。为建立有效的生态流量调度措施，本研究重点开展了水电开发对水文情势改变程度度量方法建立及改变特征分析研究，以及水电开发下生态流量调度方法建立研究。1）多数生态水文学研究忽视了水文指标次序变化对水文情势扰动评价的影响，本研究利用水文序列周期变化代替其次序变化，研究了水文指标次序变化对水文情势扰动评价的影响。结果表明以RVA为代表的传统水文情势扰动评价方法低估了水文情势改变。2）发电量确定是生态流量调度方法建立的关键内容，针对径流和电价的不确定性的问题，采用场景树模型模拟未来径流和电价的可能场景，对未来径流和电价进行预测；根据库容大小以及生态流量管理目标设计了四种水库发电量的优化情景；针对四种发电量优化情景构建了面向河流生态需求的水库发电量优化模型，进而对生态流量调度参数进行优化和调整。本项目成果初步建立了河流生态流量调控方法，可用于缓解水电开发和河流保护之间的矛盾。