天山北坡融雪期非点源污染迁移机理与模式优化预报研究

The research on migration mechanism of non-point source pollutants, prediction model optimization, and the release trend of non-point source pollution during snow melting season in high elevation mountain areas is very important for the sustainable development of biological function areas in the cold water resource region. Due to limitation of monitoring conditions for data collection during snowmelt period, the knowledge on migration mechanism of non-point source pollutants on micro scale, physical processes, watershed scale effluent is still limited. This project is to apply the integration of field work and prediction modeling for the northern slope of the Tienshan Mountains in Hutubi Basin as the typical study area to: 1)Simulate the transport and fate of nonpoint source pollutants for the early stage of snowmelt on the micro scale; 2)Based on the field observed data, parameterization for the module of transport and fate of nutrient in the SWAT model can be improved; 3)Based on the innovatively developed WRF-SWAT, the continuous temporal and spatial data for non-point source pollutants can be provided, in order to understand the effluent distribution of non-point source pollution for the hutibi watershed. The purpose of this project is to apply the theoretical knowledge into practical cases to investigate the features of non-point source pollution during snowmelt season for supporting decision support system by using the newly developed prediction approach.

深入开展高山融雪期非点源污染迁移机理、模型优化预报及非点源污染输出规律研究对山区水资源涵养及生态功能区可持续发展均具重要意义。由于融雪期观测数据及各类现实因素限制,山区融雪期微观尺度非点源污染迁移机理、模式物理过程、非点源污染在流域尺度输出规律尚未理清。基于此,本项目拟采用野外实验与耦合预报模式匹配结合手段,以天山北坡呼图壁流域为典型研究区,利用野外观测实验探究天山北坡呼图壁流域融雪期非点源污染微观尺度迁移机理；基于野外观测实验完善SWAT模型营养物迁移模块参数化方案；依据WRF-SWAT创新耦合预报方法获得时空连续的非点源污染历史数据集,以理清天山北坡呼图壁流域非点源污染在流域尺度的输出分布特点。项目旨在以理论与实践相结合,有效利用野外观测实验与创新耦合预报方法,实时预报并深入挖掘天山北坡融雪期非点源污染输出规律,为融雪期非点源污染实时预报与决策探索研发一套新的技术方案。

在对天山北坡呼图壁流域融雪期氮、磷迁移机理，模型营养物迁移模块优化及融雪期面源污染实时预报等研究尚未很好开展背景下，本课题通过“野外观测实验-室内模型改进-模式耦合预报”想结合手段，重点开展了天山北坡呼图壁流域融雪期非点源污染营养物质 (氮、磷) 迁移实验，分析了融雪期非点源污染营养物质伴随不同土壤层产水过程 (地表径流、壤中流) 的迁移特点及氮、磷营养物质在多种土地利用下的动态迁移机理。基于实验数据和机理数据，本研究对SWAT模型营养物迁移模块中地表、壤中流迁移的硝酸盐迁移过程及可溶性磷在不同土壤层的迁移模型进行了重点优化，最终基于前期汇总流域内历史数据及试验周期内观测、预测数据实现WRF-SWAT实时预报耦合模式，基于耦合预报平台理清了呼图壁流域融雪期非点源污染在流域尺度的输出分布规律及非点源污染敏感热点区。基于本项目已为呼图壁水利局建立了“天山北坡融雪洪水及非点源污染预测平台”，实现了对新疆维吾尔自治区呼图壁县春季融雪洪水及水土流失等面源污染的早期预警及应急部署工作，并得到当地水利局发函致谢。本研究将为天山北坡水源生态涵养区可持续发展及丝绸之路经济带顺畅建设提供重要技术保障，更为天山北坡构建“野外-室内一体化”灾害监测体系提供重要科技支撑。