极端降雨事件对非点源氮素淋失过程的影响机制研究

项目名称： 极端降雨事件对非点源氮素淋失过程的影响机制研究

项目编号： No.41501531

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 地质学

项目作者： 姜三元

作者单位： 中国科学院南京地理与湖泊研究所

项目金额： 23万元

中文摘要： 非点源氮素淋失与水文过程密切相关，中国近50年来极端降雨事件的强度和频次增加，极端降雨下径流过程和氮素随水文过程的迁移与非极端降雨不同，目前这些方面的研究尚显不足。本研究选择乐安河集水域下游典型源区小流域作为研究区，综合运用野外坡面小区径流实验、水文水质高频监测、流域同位素水化学流量过程线分割、流域分布式氮素迁移模拟等方法，研究极端降雨事件下径流分割和氮素随不同径流路径的迁移机制；改进现有模型水文和氮素迁移过程关键参数的计算模式，优化模型的计算步长；模拟比较极端、非极端降雨条件下河流氮素浓度变化和流域氮素输出通量。该研究基于多源数据融合技术，将野外实验、水文水质高频监测等数据信息用于模型参数率定，以达到改善参数辨识，减小参数率定和模型预测不确定性的目标。研究成果有助于加深对极端降雨事件下氮素径流淋失机制的认识，提高氮素浓度和输出通量的模拟精度，为制定流域水资源综合管理措施提供科学依据。

中文关键词： 非点源氮素淋失；径流组分；极端降雨事件；基于过程的流域分布式水文模拟；多源数据融合

英文摘要： Diffuse nitrogen leaching is closely related to hydrological processes, the intensity and frequency of extreme rainfall events have been increasing in China since 50 years ago, runoff generation and nitrogen leaching processes along with hydrological processes under extreme rainfall events are different from that under normal rainfall conditions. In this study, a small typical headwater sub-catchment located at downstream of LeAn River will be selected as study area. By combining in-situ hill slope rainfall-runoff experiments, high frequency hydrological water quality monitoring, and catchment distributed nitrogen leaching modelling, three objectives are covered, including (i) investigating the runoff separation and nitrogen leaching regimes along with different flow pathways under extreme rainfall events; (ii) modifying the calculation modes of key parametrers of hydrological and nitrogen leaching processes, optimising modelling time step; (iii) revealing the impacts of extreme rainfall events on streamwater nitrogen concentration dynamics and nitrogen fluxes by comparing modelling results with that derived from simulations under normal rainfall events. Using multi-source data fusion technique, the information contents of field experiments and high frequency hydrological water quality monitoring data are exploited in model parameter calibration, it enables to improve parameter identification and decrease the uncertainties of parameter calibration and model predictions. The outcomes of this study will enrich the understanding of nitrogen leaching along with runoff pathways under extreme rainfall events, improve modelling accuracy of streamwater nitrogen concentration and nitrogen loads, as well as provide guidelines for development of optical water resource management program.

英文关键词： Diffuse nitrogen leaching;Runoff components;Extreme rainfall events;Process-oriented catchment distributed hydrological modelling;Multi-source data fusion