洪水生态风险管理研究进展及发展趋势

洪水生态风险是一类由洪水诱发灾害引起的风险,主要是由于人类活动的盲目性和不科学性引起的。从防洪工程建设对生态环境的影响评估、洪水生态风险评价研究及改善环境和生态保护管理对策三个方面对洪水生态风险管理的研究进展情况进行了归纳和评述。并据此阐述了需要深入研究的方向及其发展趋势。

洪水生态环境风险管理浅议

论述了洪水生态环境风险管理的主要内容,包括各类防洪工程建设对流域内生态系统、环境质量的影响评价;对洪水灾害发生后产生的环境和生态影响进行调查评价,制定改善环境、保护生态的补偿计划及管理对策。并通过对各种风险进行评价,提出了一系列改善环境、保护生态的补偿计划及管理对策。

水库生态调度模型及其应用

为了减轻水利工程对河流生态系统造成的不利影响,针对汉江中下游的主要生态问题,结合不同时期生态因子和水文观测资料,分析计算了汉江的最小生态流量、适宜生态流量以及四大家鱼产卵所需要的洪水脉冲过程。通过建立丹江口水库生态调度模型,选取典型代表年,对丹江口水库进行河流生态需水量和人造洪水调度。计算结果表明,丰水年和平水年能满足最小和适宜生态流量的需求,典型枯水年能满足最小生态流量,特枯年份无法满足适宜生态流量过程。分析了生态调度对水库发电效益产生的影响,丰水年影响甚微,平水年和枯水年的影响逐渐加大。通过水库的人造洪水调度可以满足四大家鱼产卵所需要的洪水脉冲环境。实施水库的生态调度有益于人水和谐的可持续发展。

保护四大家鱼产卵的三峡水库生态调度研究

为了减轻三峡水库运行对流域生态系统的不利影响,针对四大家鱼产卵问题,结合历史水文数据,通过生态流组法分析其产卵期的生态水文事件组成,推求满足其产卵需求的流量过程,并通过生态调度对流量过程进行改进。结果表明,四大家鱼产卵过程是由低流量事件及高流量脉冲事件组成,构建的流量过程能够较好地满足四大家鱼产卵对洪水脉冲的需求,实施生态调度能够减轻三峡运行对其产卵造成的不利影响,有利于流域生态环境的改善和修复。

大通河流域水能水资源开发对河流水文过程和环境的影响

根据水文观测和引水与水电开发资料,分析了大通河流域水能水资源开发利用现状及其对河流水文过程与生态环境的影响.结果表明：由于区域用水和跨流域引水,使大通河中下游河道的水量减少,水环境容量减小,其中,青石嘴、天堂、连城（二）站3-11月平均流量分别减少0.6%~9.6%、0.5%~3.8%、1.7%~52.9%.自1994年引大入秦工程建成跨流域引水后,连城（二）站年径流量开始减少,1994-2010年平均径流量比1977-1993年减少了5.7%;引大济湟工程建成通水后,加上引大入秦和引硫济金工程,引水总量将达到12.33×108 m3,占大通河多年平均径流量28.16×108 m3的43.8%,对河川径流的影响十分显著.至2011年,大通河上已建成梯级电站34座,洪水期电站同时泄水会瞬间加大河道流量,枯水期蓄引水又使减水河段水量减少.梯级水电站群无序蓄放水使洪水过程由天然的平稳状态转变为人工干预的剧烈变化状态,上下游洪峰不对应,对下游地区的防洪安全产生极大威胁.过度的水能水资源开发,使大通河中下游部分自然河段出现淹没、断流,水生物和两岸的植物萎缩,水环境污染加重,对生态环境产生负面影响.建议实行流域水资源统一管理,对梯级电站下泄水量统一调度,在减水河段预留必须的生态基流,确保河道内外生态用水;加强河道水位、流量、泥沙、水环境、水生物监测,为流域防汛、水资源管理、生态环境保护等提供决策依据.

Exploration on ecological regulation of the reservoirs

Reservoir regulation process in the Yangtze River basin is mainly divided into two types of flood regulation and initiating benefit regulation. The present reservoir management system and operation mode are mainly for dealing with or coordinating of flood control and benefit initiation as well as benefit distribution among various beneficial functions. From the view point of river ecosystem protection, the current regulation mode has two kinds of problems: firstly, most of the reservoir regulation plans do not consider ecosystem protection at downstream of dams and needs of environment protection in reservoir areas; secondly, integrated regulation or management of water resources is ignored. It is very necessary to improve reservoir regulation mode, bearing problems faced by regulation of the Three Gorges reservoir and issues related to cascade development and regulation in Tuojiang and Minjiang River basins in mind. In accordance with the concept of scientific development, and the philosophy of "ensuring a healthy Yangtze River and promoting the harmony between human and water", taking flood control, benefit initiation and eco-system as a whole, this paper put forward the basic consideration to improve reservoir regulation as follows: on the basis of requirements of ecosystem protection at downstream of dams and needs of environment protection in reservoir areas, we should bring the functions of reservoir such as flood control and benefit initiation into full play, control the negative influence to the ecosystem at downstream of dams and the environment in reservoir areas in an endurable scope, and restore the ecosystem and the environment step by step. This paper put forward the relevant regulation process aiming at the idiographic problems such as protection of ecosystem at downstream of dams and environment in reservoir areas, protection of aquatic wildlife species and fish species, regulation of sediment and protection of wetland.

额尔齐斯河水库群多尺度耦合的生态调度研究

针对我国额尔齐斯河流域生态问题,给出了水库群生态调度的定义。以保障河流健康、河谷生态系统安全为目标,构建了宏观、中观、微观相互嵌套多尺度耦合的水库群生态调度体系;结合生态调度的原则和依据,建立了水库群多尺度耦合的生态调度多目标模型,以及水库群中长期、短期和实时生态调度模型;提出了多时间尺度耦合的水库生态调度技术、多目标非线性水库调度模型求解技术和生态系统漓漫灌溉技术;定义了漓漫灌溉,构建了生态漓漫灌溉系统。应用上述体系、模型和方法,计算结果表明,中长期调度方案能满足额尔齐斯河流域水资源综合利用各部门的供水量及保证率要求,尤其是满足河谷林草生态供水的破坏深度要求和最大连续缺水年数的限制;水库群实时生态调度模型的计算结果表明:模型计算的河谷林草、湿地的水库人工生态洪水过程与实测值比较接近,相对误差为0.04%,说明模型结果合理。实时监测了河谷林草的漓漫灌溉效果,包括范围、面积、水深等,监测结果表明:水库人工生态洪水过程基本满足河谷林草漓漫灌溉面积、水深等生态需水要求。研究成果对额尔齐斯河维持河流健康、保障生态安全、解决国际河流的水资源综合利用问题、发展水库群生态调度的理论和方法,具有重要的理论意义与应用价值,可供我国北方河流生态调度借鉴。

基于景观生态学的城市化背景下洪灾风险评估

以秦淮河流域为例,构建HEC-HMS模型,采用统计学分析方法,在两期历史景观分布情况下,研究洪水特征值(洪量、洪峰)与不同景观的景观格局指数间的响应关系,提出并构建基于景观格局的洪水生态风险(洪水—景观生态风险)指数,结合空间分析方法,进行全流域风险的时空变化分析和特征子流域间的对比分析。结果表明:不同类型景观的景观格局与洪水特征值间均具有一定程度的响应关系,景观类型不同,其响应指标与程度不同;2003—2017年,研究区风险程度有所增加,空间差异明显;景观格局对区域洪水影响显著,避免景观的大面积聚集发展,增加各类景观周边的景观丰富度,提高景观间的接触面积,有助于减弱城市化进程中建设用地景观面积增加带来的洪水危害,发挥景观的生态正效应。

Spatio-temporal variations of the flood mitigation service of ecosystem under different climate scenarios in the Upper Reaches of Hanjiang River Basin, China

Extreme rainstorm and the subsequent flood increasingly threaten the security of human society and ecological environment with aggravation of global climate change and anthropogenic activity in recent years. Therefore, the research on flood mitigation service(FMS) of ecosystem should be paid more attention to mitigate the risk. In this paper, we assessed FMS in the Upper Reaches of Hanjiang River(URHR), China from 2000 to 2014 using the Soil Conservation Service Curve Number(SCS-CN) model, and further simulated the future FMS under two climate scenarios(in 2020 and 2030). The results reveal that the FMS presented a fluctuating rising trend in the URHR from 2000 to 2014. The FMS in southern URHR was higher than that of northern URHR, and the change rate of FMS in the upstream of URHR(western URHR) was higher than the downstream of URHR(eastern URHR). The future FMS under scenarios of Medium-High Emissions(A2) and Medium-Low Emissions(B2) will decrease consistently. As land use/land cover changes in the URHR are negligible, we concluded that the change in FMS was mainly driven by climate change, such as storm and runoff. Our study highlights that climate scenarios analysis should be incorporated into the assessment of hydrologic-related services to facilitate regional water resources management.