澜沧江干流水沙、营养盐通量时空差异性及其对水电开发的响应

The People of China and five countries in Southeast Asia drink from the same Lancang-Mekong river. It is a focus of debate within riparian countries and international community on the issue of downstream discharge regulation and sediment load declining caused by present hydropower development on the Lancang River, as well as nutrient fluxes changes. This proposal is planning to employ the monthly discharge and suspended sediment concentration during 1950-2015 at three hydrological stations along mainstream of the Lancang River in Yunnan Province, to discover spatio-temporal differences of runoff and sediment loads in the Lancang River. Meanwhile, based on daily precipitation data from 23 meteorological stations in the watershed, impacts of regional climate changes on water-sediment variations could be removed, so the contribution of the reservoirs to water-sediment changes will be quantitatively assessed.Simultaneously, three reaches along the mainstream will be proposed for nutrient concentration monitoring for 2 year(2016 and 2017). Data collected from monitoring will be compared to those in past decades, thus spatio-temporal differences of nutrient fluxes in the river can be obtained, associated with their responses to dams’ blocking. The expected results of this proposal can provide more new perspectives for further understanding of environmental and ecological effects induced by resource development in the Lancang Basin, also act as a scientific reference for Chinese foreign affairs to downstream countries in southeastern Asia.

澜沧江－湄公河是中国与东南亚五国人民共饮的一江水。澜沧江水电开发引起下游河道流量调节和泥沙减少是湄公河沿岸国家和国际社会热议的焦点，水沙变化也致使营养盐输送通量的调整。本项目拟采用澜沧江云南段三个干流水文站1950-2015年月平均流量、悬移质含沙量数据，结合同期流域内23个气象站日降水监测数据，剔除区域气候变化的影响，揭示水沙时空分异对水电开发的响应；同时，对三个断面的营养盐浓度开展两年（2016、2017年）的监测，通过监测数据与历史资料的对比分析，判识水电站蓄水拦沙对澜沧江干流营养盐通量的时空分布的影响。研究结果将揭示澜沧江干流云南段主要控制断面水沙及营养盐的时空差异及其对电站建设的响应，为澜沧江水电开发与我国对东南亚的环境外交提供科学依据。

项目梳理并分析了澜沧江－湄公河主要干支流水文站水沙时空分异及其对水电开发的响应；同时，对三个断面（旧州、小湾及景洪）的营养盐浓度开展两年的监测，通过监测数据与历史资料的对比分析，判识水电站蓄水拦沙对澜沧江干流营养盐通量的时空分布的影响。. .项目完成了既定的两个目标：揭示澜沧江云南段三个重要断面的径流量、输沙量和营养盐通量时空差异性规律；量化判识梯级水电开发对河道水沙及营养盐输送的影响程度。.具体开展了如下三方面的研究工作：.水文站流量、输沙量时空差异分析：基于干流旧州、戛旧和允景洪水文站1950-2015年长序列的流量和悬移质含沙量观测数据，对比分析各水文站断面水文情势的多时空尺度变异性：.营养盐通量时空差异性评估：对澜沧江云南段干流的旧州、小湾和景洪三个断面开展两年（2016和2017年）的营养盐浓度监测，所得数据与云南省环境科学院1985-2015年在这些断面监测的营养盐数据对比，揭示不同年份澜沧江干流不同河段的营养盐输送通量的时空差异性：.水沙及营养盐时空差异对水电开发的响应判识：应用降水产流挟沙关系，以汇流区降水频率，借助水文频率曲线，恢复未受电站影响情景下的月平均流量和输沙量，求得恢复值与实测值的差值，耦合水沙、营养盐时空变化规律和干流水电的开发进程，分析水库蓄水拦沙对不同河段流量、泥沙和营养盐输送的影响：..基于项目研究内容和成果，撰写并发表学术期刊论文9篇（其中3篇SCI论文），参编专著一部，超额完成计划任务。