大坝下游河岸带冬夏季水热交换特征对比

Comparative analysis of water-heat exchange characteristics of the riparian zone downstream of dam in different seasons

为对比水库下游河岸带冬夏季潜流交换特征及温度场分布规律,在新安江大坝下游开展了河道水、河岸带地下水的水位与温度监测,并结合达西定律推广式等理论进行了分析。结果表明:不论冬夏季,侧向潜流交换量与河道水位呈逆时针"绳套"关系,且离河道越近潜流交换强度越大;冬、夏季潜流交换强度与补给方式存在明显不同,在近河岸处单宽交换总体积分别为55.23 m3(周)、75.08 m3(周),夏季主要为河道补给河岸带,冬季相反,此外,夏季交换范围更大且交换更快;河岸带温度场受低温波动水影响显著,在垂直方向上夏季表现为"上暖下凉",冬季相反,在水平方向上夏季低温传播距离较大,且具有明显的分区。因此,在水库下游河流生态治理过程中,应适当考虑不同季节的影响。

To compare hyporheic exchange characteristics and temperature field distributions of the riparian zone following dam release in different seasons, we monitored and analysed the water level and temperature of surface water and groundwater downstream of Xin＇anjiang Dam using Darcy＇s law. Results revealed that lateral exchange flux and river water level were in a counterclockwise ＂rosette＂ relationship regardless winter or summer, and the exchange intensity was smaller away from the river. Hyporheic exchange intensity and supply way were distinctly different between winter and summer, where the total exchange volume per unit width near the bank was 55.23 m3（week） and 75.08 m3 （week） , respectively. In addition, longer lateral exchange length and shorter exchange time were observed in the summer. The temperature field of the riparian zone was significantly affected by low temperature fluctuations, and the vertical direction was characterised as ＂warmer on the surface and cooler at the bottom＂ in the summer, while in the winter it was opposite. On the other hand, low temperature propagation distance was relatively larger in the horizontal direction and had obvious zonation in the summer. Therefore, in the process of river ecological management of reservoir downstream, the influence of different seasons should be appropriately considered.