嫩江流域湿地水文过程模拟及其功能评估

Severe shrinking and degradation of wetlands caused by climate change and intensive human activities have dramatically weakened hydrological function and services of wetlands, which has greatly affected and changed hydrological processes and eventually detrimental for ecological and water security within a watershed. The objective of this study is to understand hydrological function of wetlands and hydrological effect of wetlands change by estimating the influence of wetlands change on hydrological processes within a watershed. Field observation of eco-hydrological conditions, interpretation of remote sensing and data analysis will be integrated to identify and characterize hydrologic connectivity of wetlands to surface water systems as well as distinguish isolated wetlands from riparian wetlands. PHYSITEL/HYDROTEL, an international advanced eco-hydrological model coupling with wetlands modules, will be used for simulating variation of hydrological processes with respect to wetlands change (surface area, geographical location and water storage capacity of wetlands as well as wetland types). The eco-hydrological processes simulation can not only reveal the hydrological effect of wetland within a watershed, but also can quantify hydrological function of wetlands including water storage, peak flow attenuation, baseflow support and so on. The results of this study will provide key information for conversation and reconstruction planning of wetlands, integrated water resources management as well as tackling climate change in Neijiang River Basin. Simultaneously, this study will advance current scientific understanding of methodology and discipline system and promote research level of wetlands eco-hydrology in China.

针对全球气候变化与高强度人类活动的双重影响下嫩江流域湿地严重萎缩退化，水文功能急剧下降，极大影响和改变了流域水文过程，增加了水旱灾害的强度和风险，危及流域生态安全和水安全的严峻现实问题，以认识和理解湿地变化的流域水文效应和流域湿地水文功能为目标，开展流域湿地变化对水文过程的影响及其水文功能评估研究，通过野外生态水文调查监测和室内遥感解译与基础数据库建立，基于国际先进的PHYSITEL/HYDROTEL模拟平台，精准识别湿地与地表水系统水文连通性，划分湿地类型并刻画其水文特性，创建耦合湿地模块的流域生态水文模型，精细化模拟多种情景下流域湿地水文过程，提高流域水文过程的模拟精度，揭示湿地变化的流域水文效应机理，定量评估湿地的生态蓄水、削减洪峰和维持基流等水文功能。研究成果为流域水资源综合管理、湿地恢复与保护和应对气候变化提供科学依据和决策支持。同时，丰富和发展我国湿地生态水文学研究理论与方法。

针对全球气候变化与高强度人类活动引起嫩江流域湿地严重萎缩及其水文功能退化，流域水旱灾害的强度和风险增加，危及流域生态安全和水安全的严峻现实问题，以认识和理解流域湿地水文功能和湿地变化的流域水文效应为目标，在识别和刻画嫩江流域湿地水文连通性及其水文特性的基础上，构建了适合于嫩江流域的耦合湿地模块的流域生态水文模型并开展了模型模拟效率评价研究，发现耦合湿地模块的流域水文模型能较好提高流域水文过程的模拟精度，可更好地用于流域湿地水文调蓄功能定量评估。基于构建的耦合湿地模块的流域水文模型，定量揭示和评估嫩江流域湿地变化的流域水文效应及其水文功能，发现流域湿地具有显著的径流调节能力，体现在对总径流的削弱作用和对径流机制（流量、频率、历时和发生时间等）的改变作用；湿地对总径流、快径流和基流的影响效应和强度具有明显的月、季节和年尺度变化特征，总体上发挥着削减洪峰和维持基流的作用。嫩江流域湿地发挥着显著的洪水调蓄作用，对洪峰流量、洪水期间平均流量和洪量的削减量分别为23.63%、10.94%和9.50%，但湿地洪水调蓄功能的强度和效应具有明显的时空差异性。湿地可以削弱气象干旱-水文干旱的关系，延长气象干旱向水文干旱的传播时间和响应周期，降低气象干旱向水文干旱的转变概率。随着湿地面积的减少，嫩江流域湿地的径流调节、洪水调蓄和维持基流的功能逐渐减弱。尼尔基水库显著改变了下游的水文情势，进而削弱了湿地水文调蓄功能。未来气候变化情景下流域湿地保护（维持现状）与恢复，将有助于提升流域湿地水文调蓄功能。最后，基于嫩江流域湿地水文调蓄功能的时空差异性及其影响因素分析，结合生态水文学理论和基于自然的水资源解决方案的理念，综合提出了基于湿地水文服务的流域水资源综合管理的对策措施，为嫩江流域湿地恢复保护与水资源综合管控提供科学依据和决策支持。