钱塘江盐水入侵及对地形下切的响应
发布时间：2019-02-27 10:21
【摘要】：钱塘江河口是典型的_7潮河口,以涌潮奇观闻名中外,在其强劲的潮汐动力影响下,下游含盐水体涨潮上溯距离长,入侵较远时可至上游饮用水源地。由于枯季径流作用弱,致使取水口附近盐度居高不下,影响水厂正常取水,对杭州市的饮用水安全造成了极大的威胁。因此,研究钱塘江盐水入侵问题,为饮用水源地避咸蓄淡提供对策,对于保障杭州市饮用水安全、提高居民生活质量与促进城市经济发展具有重要意义。 本文利用钱塘江河口沿程7个测站2012年实时连续监测的潮位和盐度资料,研究了钱塘江河口盐度的时间变化规律和纵向分布,弥补了以往盐度资料测量频次低、时间间隔长的不足。基于五分钟间隔的盐度监测资料分析,比较准确地计算出盐度的“升降历时”。七堡、盐官、澉浦、乍浦盐度“下降历时”与“上升历时”之比依次为5.71,1.67,1.12,1.08,据此发现其具有向下游呈幂函数减小的变化规律。进一步研究发现盐度上升过程存在突变点,这一突变过程通常发生在5-10分钟之内,尤以盐官站最为显著,此与涌潮过程密切相关；而其余时间盐度变化率较小。盐官站突变点盐度增量为2.63,占盐度峰谷差值的27.2%,而突变历时仅占盐度“上升历时”的2.1%。基于沿程7个测站的盐度资料研究了盐度的纵向分布,揭示了盐度峰谷差值具有先沿程增大继而逐渐减小的纵向变化规律,盐官站盐度变化最为剧烈,峰谷差值可达仓前站的12.6倍。 建立了平面二维水动力盐度数学模型,对闻家堰至仓前河段的水动力及盐度输移进行了数值模拟,据以研究了典型断面垂线平均流速和水位的横向分布,发现七堡弯道断面最大垂线平均流速1.85m/s,出现在离凹岸600m处,水面线自凹岸向凸岸呈下凹状倾斜,凹岸水位比凸岸水位高9.71cm。基于盐度平面分布分析,揭示了盐水主要沿深槽上溯、凹岸盐度及其变幅大于凸岸的客观规律。分别在七堡弯道凹、凸岸离岸300m处设立测点,平水大潮情况下凹岸测点的峰值比凸岸大0.52。盐度纵向分布显示,富春江水电站径流量823m3/s,仓前潮差3.52m条件下上溯盐水在七堡断面附近形成锋面,计算结果细致地刻画了盐水上溯和下移过程中的锋面变化,揭示了盐水上溯时锋面梯度先增大后减小、下移过程中梯度不断减小的变化特征。 在保持上边界流量和下边界潮位过程不变的条件下,数值试验了洪水冲刷后地形下切引起的盐度变化,着重对地形变化前后的盐度分布进行对比分析,结果显示：地形下切会导致下边界流量过程发生改变,大潮进潮量增加370万m3,同时地形下切使得低潮位降低幅度大于高潮位,从而潮差有所增大。研究发现地形下切后盐水入侵最强时刻锋面盐度梯度增大。论文提出了“抵消流量”概念,在下边界潮差3.52m、上边界流量993m3/s的条件下,经数值计算得出地形下切1.31m(平均)时所需“抵消流量”为330m3/s。对比地形下切增加“抵消流量”和原地形原径流条件下盐水入侵最强时刻的盐度纵向分布,发现使用“抵消流量”之后锋面中部回到地形下切前位置,但锋面盐度梯度有所增大,使锋面上游段的盐度减小,与地形下切前相比0.5盐度线向下游移动4km。
[Abstract]:The Qiantang River estuary is a typical _ 7-tidal estuary, and is well-known for the tide of the tide. Under the influence of its strong tide and power, the rising tide of the downstream salt-containing water body is long, and the invasion is far away from the upstream drinking water source. The low-season runoff is weak, so that the salinity in the vicinity of the water intake is high, the normal water intake of the water plant is affected, and the safety of the drinking water in the Hangzhou is greatly threatened. Therefore, it is of great significance to study the problem of salt water intrusion in Qiantang River, and to provide the countermeasure to avoid the salt storage of the drinking water source, and to guarantee the safe drinking water in Hangzhou, improve the quality of the residents' life and promote the development of the city economy. In this paper, the time variation and the longitudinal distribution of the salinity in the estuary of Qiantang River are studied by using the tidal level and the salinity data of 7 stations in the Qiantang River estuary in real time in 2012. Based on the analysis of the salinity monitoring data of five-minute intervals, it is more and more accurate to calculate the . The ratio of the "drop-duration" ratio of the salt, salt, pumping, and first salinity is 5.71, 1.67, 1.12, 1.08, and it has been found that it has a variation rule with the power function reduced to the downstream. The further study found that there is a point of mutation in the rising of salinity, which usually occurs within 5-10 minutes, especially in the salt office, which is closely related to the tide process, while the rate of change of salinity in the rest of the time is higher. The salinity of the mutation point in the salt station is 2.63, accounting for 27.2% of the peak-to-valley difference of the salinity, and the mutation duration only accounts for 2.1% of the salinity "rising duration". In this paper, the longitudinal distribution of salinity is studied on the basis of the salinity data of seven stations, and the variation of the salinity and the peak-to-valley difference is revealed. The salinity change of the salinity is the most severe. The difference of the peak-to-valley difference can reach to 12.6 in the front of the silo. In this paper, a mathematical model of the two-dimensional water dynamic salinity is established, and the hydrodynamic and salinity transport of the Wenjiyan to the front section of the warehouse are simulated. The mean velocity and the lateral distribution of the water level are studied. The mean velocity of the maximum vertical line of the cross section of the seven-point curve is found to be 1.85. M/ s, at 600m from the concave bank, the water surface line is inclined downward from the concave bank to the convex bank, and the water level of the concave bank is higher than the water level of the convex bank. 1 cm. Based on the analysis of the salinity plane distribution, it is revealed that the salt water is mainly in the deep groove, and the salinity and the amplitude of the concave bank are larger than that of the convex bank. The rule of view is to set the measuring point at 300 m on the off-shore of the Qibao curve respectively, and the peak of the concave-land measuring point in the case of flat-water spring tide is larger than that of the convex bank. .52. The longitudinal distribution of salinity shows that the runoff of the Fuchun River Hydropower Station is 823m3/ s, and the back-up brine is formed in the vicinity of the seven-castle section under the condition of 3.52 m of the pre-warehouse tidal difference. The result of the calculation shows the frontal change of the back-up and down-moving process of the brine, and reveals that the gradient of the frontal surface in the back-up of the brine is increased first. The change of the gradient is reduced in the process of moving down and down. Under the condition that the upper boundary flow and the lower boundary tidal level process are not changed, the salinity change caused by the topography under the flood erosion is tested by the numerical value, and the salinity distribution before and after the change of the terrain is analyzed and analyzed. The results show that under the terrain, the flow process of the lower boundary can be changed, the tidal volume of the spring tide is increased by 3.7 million m3, and at the same time, the lower tide level is reduced to be greater than the high tide level at the same time, so that the tide The difference has increased. The study found that the salt water intrusion was the strongest at the time of the post-cutting of the terrain. In this paper, the "offset flow" concept is put forward, under the condition that the lower boundary surface is 3.52 m and the upper boundary flow is 993 m3/ s, the required "offset flow" is 33 when the terrain is cut to 1.31m (average) by the numerical calculation. It is found that the salinity gradient of the front surface of the front surface is increased and the upstream section of the frontal surface is increased by the increase of the salinity gradient of the front surface after the "offset flow" is used, the salinity and the longitudinal distribution of the salt water at the strongest moment in the original runoff condition under the original runoff condition are cut and added under the comparison of the terrain. The middle part of the front surface is found to be returned to the pre-cutting position after the "offset flow" is used, but the gradient of the front surface The salinity is reduced to the downstream of the 0.5-salinity line as compared to the pre-cutting of the terrain.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.23;P737.1
本文编号：2431361
[Abstract]:The Qiantang River estuary is a typical _ 7-tidal estuary, and is well-known for the tide of the tide. Under the influence of its strong tide and power, the rising tide of the downstream salt-containing water body is long, and the invasion is far away from the upstream drinking water source. The low-season runoff is weak, so that the salinity in the vicinity of the water intake is high, the normal water intake of the water plant is affected, and the safety of the drinking water in the Hangzhou is greatly threatened. Therefore, it is of great significance to study the problem of salt water intrusion in Qiantang River, and to provide the countermeasure to avoid the salt storage of the drinking water source, and to guarantee the safe drinking water in Hangzhou, improve the quality of the residents' life and promote the development of the city economy. In this paper, the time variation and the longitudinal distribution of the salinity in the estuary of Qiantang River are studied by using the tidal level and the salinity data of 7 stations in the Qiantang River estuary in real time in 2012. Based on the analysis of the salinity monitoring data of five-minute intervals, it is more and more accurate to calculate the . The ratio of the "drop-duration" ratio of the salt, salt, pumping, and first salinity is 5.71, 1.67, 1.12, 1.08, and it has been found that it has a variation rule with the power function reduced to the downstream. The further study found that there is a point of mutation in the rising of salinity, which usually occurs within 5-10 minutes, especially in the salt office, which is closely related to the tide process, while the rate of change of salinity in the rest of the time is higher. The salinity of the mutation point in the salt station is 2.63, accounting for 27.2% of the peak-to-valley difference of the salinity, and the mutation duration only accounts for 2.1% of the salinity "rising duration". In this paper, the longitudinal distribution of salinity is studied on the basis of the salinity data of seven stations, and the variation of the salinity and the peak-to-valley difference is revealed. The salinity change of the salinity is the most severe. The difference of the peak-to-valley difference can reach to 12.6 in the front of the silo. In this paper, a mathematical model of the two-dimensional water dynamic salinity is established, and the hydrodynamic and salinity transport of the Wenjiyan to the front section of the warehouse are simulated. The mean velocity and the lateral distribution of the water level are studied. The mean velocity of the maximum vertical line of the cross section of the seven-point curve is found to be 1.85. M/ s, at 600m from the concave bank, the water surface line is inclined downward from the concave bank to the convex bank, and the water level of the concave bank is higher than the water level of the convex bank. 1 cm. Based on the analysis of the salinity plane distribution, it is revealed that the salt water is mainly in the deep groove, and the salinity and the amplitude of the concave bank are larger than that of the convex bank. The rule of view is to set the measuring point at 300 m on the off-shore of the Qibao curve respectively, and the peak of the concave-land measuring point in the case of flat-water spring tide is larger than that of the convex bank. .52. The longitudinal distribution of salinity shows that the runoff of the Fuchun River Hydropower Station is 823m3/ s, and the back-up brine is formed in the vicinity of the seven-castle section under the condition of 3.52 m of the pre-warehouse tidal difference. The result of the calculation shows the frontal change of the back-up and down-moving process of the brine, and reveals that the gradient of the frontal surface in the back-up of the brine is increased first. The change of the gradient is reduced in the process of moving down and down. Under the condition that the upper boundary flow and the lower boundary tidal level process are not changed, the salinity change caused by the topography under the flood erosion is tested by the numerical value, and the salinity distribution before and after the change of the terrain is analyzed and analyzed. The results show that under the terrain, the flow process of the lower boundary can be changed, the tidal volume of the spring tide is increased by 3.7 million m3, and at the same time, the lower tide level is reduced to be greater than the high tide level at the same time, so that the tide The difference has increased. The study found that the salt water intrusion was the strongest at the time of the post-cutting of the terrain. In this paper, the "offset flow" concept is put forward, under the condition that the lower boundary surface is 3.52 m and the upper boundary flow is 993 m3/ s, the required "offset flow" is 33 when the terrain is cut to 1.31m (average) by the numerical calculation. It is found that the salinity gradient of the front surface of the front surface is increased and the upstream section of the frontal surface is increased by the increase of the salinity gradient of the front surface after the "offset flow" is used, the salinity and the longitudinal distribution of the salt water at the strongest moment in the original runoff condition under the original runoff condition are cut and added under the comparison of the terrain. The middle part of the front surface is found to be returned to the pre-cutting position after the "offset flow" is used, but the gradient of the front surface The salinity is reduced to the downstream of the 0.5-salinity line as compared to the pre-cutting of the terrain.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P731.23;P737.1
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