三峡蓄放条件下御临河口水动力特性研究

Hydrodynamic Characteristics of Tributary River Estuary under TGR Water Inpouring and Drainage Conditions

摘要: 随着三峡水库的周期性运行，库区支流河口水动力特性发生相应变化，水体稀释自净能力减弱，水环境容量降低，进而影响支流水质和库区饮用水安全。研究三峡工程蓄、放条件下支流河口的水动力特性，提出改善水动力条件的有效措施，对于改善库区支流水质状况、保证供水安全具有重要作用。本文选择三峡库区一条支流-御临河为研究对象，模拟其河口在蓄、放周期内的水动力特性变化，分析了水动力学演变规律。研究结果表明，在蓄水期，河口表层的平均速率为0.026 m/s，底层的平均速率为0.027 m/s，整体流速较慢，影响污染物扩散，需加强面源的控制，防止营养物质蓄积导致次年气温升高产生水华现象；在放水期，河口表层的平均速率为0.21 m/s，底层的平均速率为0.034 m/s，虽然表层流速较大，但底层流速与蓄水期相差不大，有可能导致营养盐、重金属在底层蓄积。

Abstract: As Three Gorges Reservoir changes seasonally, hydrodynamic characteristics of tributary estuaries around vary correspondingly. Water dilution and self-purification ability faded, water environmental capacity declined, and then it influences the water quality of tributary and the safety of drinking water around reservoir area. Studying hydrodynamic characteristics under the condition of impoundment and drainage in tributary estuaries, and proposing effective measures for improving hydrodynamic condition have a significant effect on improving the tributaries’ water quality in reservoir area and guaranteeing the safety of water supplies. Yulin River, a tributary of Three Gorges Reservoir, was chosen as a studying object, simulating estuaries’ variation of hydrodynamic characteristics during its impoundment and drainage period, furthermore analyzing evolution law of hydrodynamics. The results indicated that during the period of impoundment, the average velocity of the estuary surface was 0.026 m/s; the average velocity of the estuary bottom was 0.027 m/s. The bulk velocity was slow, influencing the diffusion of waste, which strongly needs intensive control on surface source and preventing harmful algae blooming due to risen temperature by storage of nutriment. During the period of drainage, the average velocity of the estuary surface was 0.21 m/s, however, the average velocity of the estuary bottom was 0.034 m/s. Although it possessed high surface velocity, there were no much differences in bottom velocity between impoundment period and drainage period, resulting in accumulation of nutritive salt and heavy mental in the bottom.