蜿蜒型河岸带潜流层水动力学机制及溶质运移规律研究

Hyporheic layer is the transition area between surface water and subsurface water in riparian zone, which can adjust the flood, buffer the pollution and provide the suitable habitats for many species. It plays an important role in river ecosystem. After Youcheqiao River and Wuhexi Stream are estabilished as observation stations, a series of field observations and survey will be conducted via tracers amd particls in numbers of wells and new riparian zone experimental model so that the mechanics of hyporheic flux, solute transportation will be investigated.Once the numerical models of surface-subsurface-solute and the prediction model of hyporheic layer size are established by use of Small Disturbace Principle and Groundwater Simulation Software, surface flow head distribution, hyporheic path and solute degradation are simulated. As a result of that, the hyporheic path, exchange rate, resident time under the effect of multi-factos at muti-scales. When Partial Least Square regression method and Fractal theory are appled, the size of hypoheic layer can be calculated. This study maks it possible to understand the hydrodynamics edge-effect and solute transport in hyporheic layer of meandering riparian zone and estabilish the pridiction model of hyporhec layer. These results are very richful to develope the edge-effect theory of riparian zone and useful to determine the suitable width of riparian and very helpful to make good decision for ecological construction and conservation for riparian zone.

河岸带潜流层具有重要的水文调蓄、环境缓冲功能，对维护地表水、地下水健康具有重要意义。本项目以油车桥港和五鹤溪为野外监测区，通过布置测井，采用示踪法、图像法，监测分析蜿蜒型河岸带潜流形成、发展机制。利用新型双循环可控式河岸带模型，通过物理模型试验，研究掌握不同工况下，蜿蜒型河岸带潜流交换通量、溶质衰减规律。通过耦合地表水-地下水-溶质迁移模型，应用小扰动理论和地下水模型软件，精细模拟蜿蜒性河岸带坡面地表水水头分布、潜流流径三维特征、溶质衰减过程，掌握多尺度、多因子条件下，蜿蜒型河岸带潜流流径、交流率、驻留时间等水动力学机制，明确溶质运移规律。应用偏最小二乘法和分形算法，建立潜流层三维特征长度计算模型。通过研究，可揭示河岸带潜流层水动力学边缘效应机理和溶质运移规律，建立潜流驻留时间和潜流层范围计算模型，从而丰富和发展河岸带边缘效应理论，为确定河岸带适宜宽度以及河岸带生态建设和保护提供科学依据。

河岸带潜流层具有重要的水文调蓄、环境缓冲功能，对维护地表水、地下水健康具有重要意义。项目从分析平原、山丘区河岸带边缘特征出发，通过野外监测、室内物理模型试验以及数值模拟等，深入探究了不同地貌区域、不同基质组成、不同植被布置条件下，蜿蜒性河岸带中潜流层水动力学机理和溶质迁移变化规律。明确了蜿蜒性河岸带潜流发生的主要因素，推导出了蜿蜒型河岸带坡面水压力分布方程及其解析解，阐明了蜿蜒性河岸带潜流的发生机制，探明了蜿蜒型河岸带潜流交换量、交换率、驻留时间的变化规律，建立了潜流驻留时间计算经验方程，揭示了河岸带潜流水动力边缘效应机理，掌握了蜿蜒性河岸带潜流驱动下溶质浓度变化规律，揭示了河岸带潜流层溶质迁移机理，掌握了蜿蜒性河岸带潜流在三维方向的流动路径，建立了蜿蜒性河岸带潜流层区域大小计算模型，开发出了河岸带滩地三维动态仿真系统。形成了多尺度、多因子条件下蜿蜒型河岸带潜流层水动力学边缘效应理论，进一步丰富和发展了河岸带边缘效应理论。研究成果已在浙江省、江苏省等地河道生态建设与管理中得到很好应用，有效指导了当地河道岸线的科学规划、设计与管理，为我国河道生态修复与管理提供了理论基础。