錢塘江鹽水入侵及對地形下切的響應
發(fā)布時間：2019-02-27 10:21
【摘要】：錢塘江河口是典型的_7潮河口,以涌潮奇觀聞名中外,在其強勁的潮汐動力影響下,下游含鹽水體漲潮上溯距離長,入侵較遠時可至上游飲用水源地。由于枯季徑流作用弱,致使取水口附近鹽度居高不下,影響水廠正常取水,對杭州市的飲用水安全造成了極大的威脅。因此,研究錢塘江鹽水入侵問題,為飲用水源地避咸蓄淡提供對策,對于保障杭州市飲用水安全、提高居民生活質(zhì)量與促進城市經(jīng)濟發(fā)展具有重要意義。 本文利用錢塘江河口沿程7個測站2012年實時連續(xù)監(jiān)測的潮位和鹽度資料,研究了錢塘江河口鹽度的時間變化規(guī)律和縱向分布,彌補了以往鹽度資料測量頻次低、時間間隔長的不足�；谖宸昼婇g隔的鹽度監(jiān)測資料分析,比較準確地計算出鹽度的“升降歷時”。七堡、鹽官、澉浦、乍浦鹽度“下降歷時”與“上升歷時”之比依次為5.71,1.67,1.12,1.08,據(jù)此發(fā)現(xiàn)其具有向下游呈冪函數(shù)減小的變化規(guī)律。進一步研究發(fā)現(xiàn)鹽度上升過程存在突變點,這一突變過程通常發(fā)生在5-10分鐘之內(nèi),尤以鹽官站最為顯著,此與涌潮過程密切相關；而其余時間鹽度變化率較小。鹽官站突變點鹽度增量為2.63,占鹽度峰谷差值的27.2%,而突變歷時僅占鹽度“上升歷時”的2.1%�；谘爻�7個測站的鹽度資料研究了鹽度的縱向分布,揭示了鹽度峰谷差值具有先沿程增大繼而逐漸減小的縱向變化規(guī)律,鹽官站鹽度變化最為劇烈,峰谷差值可達倉前站的12.6倍。 建立了平面二維水動力鹽度數(shù)學模型,對聞家堰至倉前河段的水動力及鹽度輸移進行了數(shù)值模擬,據(jù)以研究了典型斷面垂線平均流速和水位的橫向分布,發(fā)現(xiàn)七堡彎道斷面最大垂線平均流速1.85m/s,出現(xiàn)在離凹岸600m處,水面線自凹岸向凸岸呈下凹狀傾斜,凹岸水位比凸岸水位高9.71cm�；邴}度平面分布分析,揭示了鹽水主要沿深槽上溯、凹岸鹽度及其變幅大于凸岸的客觀規(guī)律。分別在七堡彎道凹、凸岸離岸300m處設立測點,平水大潮情況下凹岸測點的峰值比凸岸大0.52。鹽度縱向分布顯示,富春江水電站徑流量823m3/s,倉前潮差3.52m條件下上溯鹽水在七堡斷面附近形成鋒面,計算結(jié)果細致地刻畫了鹽水上溯和下移過程中的鋒面變化,揭示了鹽水上溯時鋒面梯度先增大后減小、下移過程中梯度不斷減小的變化特征。 在保持上邊界流量和下邊界潮位過程不變的條件下,數(shù)值試驗了洪水沖刷后地形下切引起的鹽度變化,著重對地形變化前后的鹽度分布進行對比分析,結(jié)果顯示：地形下切會導致下邊界流量過程發(fā)生改變,大潮進潮量增加370萬m3,同時地形下切使得低潮位降低幅度大于高潮位,從而潮差有所增大。研究發(fā)現(xiàn)地形下切后鹽水入侵最強時刻鋒面鹽度梯度增大。論文提出了“抵消流量”概念,在下邊界潮差3.52m、上邊界流量993m3/s的條件下,經(jīng)數(shù)值計算得出地形下切1.31m(平均)時所需“抵消流量”為330m3/s。對比地形下切增加“抵消流量”和原地形原徑流條件下鹽水入侵最強時刻的鹽度縱向分布,發(fā)現(xiàn)使用“抵消流量”之后鋒面中部回到地形下切前位置,但鋒面鹽度梯度有所增大,使鋒面上游段的鹽度減小,與地形下切前相比0.5鹽度線向下游移動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.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：P731.23;P737.1
本文編號：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.
【學位授予單位】：浙江大學
【學位級別】：碩士
【學位授予年份】：2014
【分類號】：P731.23;P737.1
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