河道水位变化对河岸带潜流层侧向水文连通及营养物运移通量的影响机制

River flow regime variability in downstream directly caused by Reservoir operation，which can cause water depth fluctuations on the longitudinal section of the river, therefor changes the SW – GW exchange, resulting in hydrological cycle and its carrying solute change in riparian, and the quality of surface – ground water, to study the effect of water level of rivers changes to hydrological-ecological processes in riparian is of great significance, not only to comprehensive evaluation of the ecological impact of the the reservoir, but also to providing scientific basis for the ecological construction of riparian zone and for river control measures. It is a typical area to study effect of water.level change to the hydrological - ecological processes in hyporheic zone in the riparian zone in the middle reaches of the Yangtze River in Jingzhou region. for the reason of the shallow groundwater level and the diversity of channel morphology in the region, a significant positive correlation of groundwater level change and the water level of the Yangtze River. Numerical simulation and field experiment, physical model test and tracer techniques were used to study:(1) the characteristics of hydrological lateral exchange and pollutants flux in migration and transformation between river and hyporheic zone of different forms in the riparian zone; (2) Impact of water lateral exchang to migration and transformation of pollutants between river and hyporheic zone in Riparian zone; (3) Explain the effect of hydrological processes on solute transport, study the mechanism of the effect of river water level changes on hydrology - solute fluxes and processes, quantitatied the effects of different water levels on solute flux, in order to provide a basis for estimating the environmental capacity in riparian zone.

水库调度直接引起下游河道流量变异，导致河流横纵断面上的水深波动，地表水地下水交换的变化，导致河岸潜流带水文交换及溶质运移发生变化，最终影响地表、地下水水质，因此，研究河道水位变化对河岸潜流带水文交换和溶质运移过程的影响规律，不仅对全面评价水库调度的生态影响具有重要意义，对科学进行河岸带生态化建设与河势控制有也重要意义。长江中游地下水埋深浅，河道形态多样，地下水水位变化与长江水位呈显著正相关，地下水位及其与河道水位重要相关性使之成为研究水位变化对岸边带潜流层水文、溶质输移过程影响的典型区域。本研究综合应用现场实验、模型试验，示踪技术和数值模拟，研究：(1)不同水位条件下河岸潜流带水文连通特征及溶质运移通量的时空变化；(2)河岸潜流带水文连通对溶质运移的影响；(3) 解释水位变化对河岸带潜流带溶质输出的影响机理，量化水位变化对水文交换和溶质运移的影响，以期为河岸带环境容量估算提供依据。

水库调度直接引起下游河道流量变异，导致河流横纵断面上的水深波动，地表水地下水交换的变化，导致河岸潜流带水文交换及溶质运移发生变化，最终影响地表、地下水水质，因此，研究河道水位变化对河岸潜流带水文交换和溶质运移过程的影响规律，不仅对全面评价水库调度的生态影响具有重要意义，对科学进行河岸带生态化建设与河势控制有也重要意义。长江中游地下水埋深浅，河道形态多样，地下水水位变化与长江水位呈显著正相关，地下水位及其与河道水位重要相关性使之成为研究水位变化对岸边带潜流层水文、溶质输移过程影响的典型区域。本研究综合应用现场实验、模型试验，示踪技术和数值模拟，研究：(1)不同水位条件下河岸潜流带水文连通特征及溶质运移通量的时空变化；(2)河岸潜流带水文连通对溶质运移的影响；(3) 解释水位变化对河岸带潜流带溶质输出的影响机理，量化水位变化对水文交换和溶质运移的影响，以期为河岸带环境容量估算提供依据。. 研究表明，蓄水后河岸带向河流交换量提高，河岸带地下水水位变化趋势大致与河道水位变化同步，5-8月为干流江水补给地下水的主要时间。地表水和地下水交换的时空变化规律和滞留时间变化规律发现，洪峰大小显著影响交换总量和滞留时间，涨洪历时会增加潜流滞留时间，但对交换量通量的影响较小。研究区域地下水和水进行交换的主要影响因素为涨洪持续时间和洪峰流量。水力梯度现象显著增加了潜流交换通量。.蓄水后营养物的运移通量比蓄水前的运移通量增加，主要与潜流交换量即地表水与河岸地下水交换量动态相关，同时，水位梯度变化促进了水流、营养物的交换通量，营养物的浓度也是重要的影响因素。