基于IBIS改进模型的鄱阳湖信江子流域非点源磷输移过程模拟

Coupling ecological model, hydrological model and non-point source pollution model and integrating 3S technology to predict non-point source phosphorus transport has become an international research focus in the current watershed scale ecological, hydrological and environmental sciences. In recent years, Poyang Lake and Xinjiang River's water was moderately polluted and one of the major pollution indicators is total phosphorus, so it has become very important to identify critical phosphorus source areas and predict non-point source phosphorus transport from Poyang Lake watershed using non-point source pollution model. To better understand hydrological processes and non-point source phosphorus transport processes, the Integrated Biosphere Simulator (IBIS), a new generation dynamic vegetation model, will be modified in seven aspects as follows: adding an impervious surface hydrology sub-model, adding a soil erosion on slopes sub-model, adding an artificial production of phosphorus sub-model, adding a phosphorus migration and transformation on slopes sub-model, adding a sediment and phosphorus transport in river sub-model, adding an input and output for phosphorus transport simulation sub-model, and modifying the irrigation sub-model. The Xinjiang River sub-watershed will be selected as the case study area and the modified IBIS model will be used to simulate the temporal and spatial distribution of land surface eco-hydrological parameters and the non-point source phosphorus transport processes under the support of input data such as LULC, DEM and meteorological data. The performance of model will be evaluated using field survey data and four indicators, including the Nash coefficient (NSC), the correlation coefficient (r), the relative error (RE) and the root-mean-square error (RMSE). And on this basis, the temporal and spatial variations of non-point source phosphorus loss in Xinjiang River sub-watershed will be analyzed and then the critical phosphorus source areas will be identified.

耦合生态模型、水文模型和非点源污染模型并集成3S技术进行非点源磷污染输移模拟是当前流域生态、水文和环境科学的国际前沿和热点研究领域，利用模型识别鄱阳湖及其入湖河流主要超标项目如总磷的流域来源及其关键源区对于保障鄱阳湖"一湖清水"具有重要意义。针对国际先进的新一代动态植被模型IBIS在水文和非点源磷输移模拟方面的不足，对IBIS进行7方面的扩展改进，即增加不透水面水文、坡面土壤侵蚀、人工产磷、坡面磷迁移与转化、河道泥沙与磷输移、磷模拟输入输出等模块，并改进灌溉模块；选择鄱阳湖信江子流域为研究区，利用扩展改进后的IBIS模型对鄱阳湖信江子流域生态水文和非点源磷输移过程进行分布式模拟实验和精度评价，进而分析鄱阳湖信江子流域非点源磷流失空间分布特征和时间演化规律，并识别非点源磷流失关键源区。

据《中国五大淡水湖保护与发展》与近几年《江西省环境质量状况公报》，总磷（TP）是鄱阳湖湖区及入湖河流信江的主要超标项目之一；磷污染已成为鄱阳湖及信江子流域的主要水污染指标，定量核算鄱阳湖入湖河流信江子流域非点源磷流失、进行非点源磷输移过程模拟并识别关键源区显得迫在眉睫。本项目主要研究内容为对生态模型IBIS进行水文过程、非点源磷输移过程模拟功能进行扩展改进，进而开展鄱阳湖信江子流域生态水文和非点源磷输移过程分布式模拟，识别非点源磷流失的关键源区。通过项目实施，形成了一套适合于鄱阳湖信江子流域非点源磷对河道水生态环境影响分析的数据集，研发了一套适合于鄱阳湖信江子流域生态水文过程和非点源磷输移过程模拟的IBIS 扩展改进模型，主要对IBIS 进行8方面的扩展改进，即增加不透水面水文、湖泊水文、坡面土壤侵蚀、人工产磷、坡面磷迁移与转化、河道泥沙与磷输移、磷模拟输入输出等模块，并改进灌溉模块，开展了鄱阳湖信江子流域非点源磷输移过程分布式模拟、气候变化和土地利用变化对河道径流的影响分析，制作了一幅鄱阳湖信江子流域非点源磷流失关键源区分布图。形成的数据集除可用于支撑本项目的研究外，还可用于支撑信江流域水环境水生态评价、流域土地利用变化对河道水环境水生态影响评价与模拟分析、流域污染负荷及其水生态环境效应等方面的研究；扩展改进后的IBIS模型不仅可以用于信江流域生态水文过程和非点源磷的模拟，以后可进一步推广应用于其它类似流域；鄱阳湖信江子流域非点源磷流失模拟结果及其关键源区识别结果有利于鄱阳湖及其入湖河流流域非点源磷流失的污染控制，进而为鄱阳湖生态建设和环境保护提供决策支持。