钱塘江河口盐水入侵数值模拟

发布时间：2018-04-29 16:55

本文选题：盐水入侵 + 数值模拟　；参考：《浙江大学》2017年博士论文

【摘要】：钱塘江河口潮强流急,淤变化剧烈,是典型的强潮河口。该河口供应了杭州市80%的饮用水,是城市重要的水源地。多年来盐水入侵严重影响取水口水质。研究钱塘江河口盐水入侵对于保障城市饮用水安全具有十分重要的意义。论文依托国家科技重大专项课题-潮汐影响城市饮用水安全保障共性技术研究与示范(2009ZX07424-001)对钱塘江河口盐水入侵及其影响因子展开系统研究。在钱塘江河口开展了多站同步潮位和盐度实时观测,据此分析了潮周期、半月潮、季节性及年际的盐度时间变化。在潮周期和半月潮短历时尺度上,盐度变化取决于潮汐作用;在季节和年际的长历时尺度上,盐度变化则取决于径流量。钱塘江河口盐度的空间分布上,纵向上沿程递减,最大梯度发生在仓前附近;垂线平均盐度一般主槽低于边滩,但变幅不大;盐度垂向分层现象不明显,分层系数多数小于0.3,表明钱塘江河口为强混合型。基于Savenije一维盐度平衡方程,建立了钱塘江河口涨憩和落憩时刻盐度的经验解析模型,并对盐度沿程空间分布及盐水入侵距离进行了计算,结果与实测较为一致。提出一种改进粒子群算法优化的小波神经网络模型(IPSO-WNN),据此对钱塘江河口七堡盐度时间序列进行了较好地模拟。基于FVCOM模式建立了钱塘江河口三维潮流盐度数值模型,模拟的潮位、流速、流向和盐度整体上与实测资料吻合良好,说明模型能有效反映钱塘江河口水动力及盐水入侵过程。基于模拟结果分析了枯季强潮期钱塘江河口富春江电站-澉浦水域盐度的时空变化。平面分布上,盐水随潮流周期性往复运动,大潮期盐水入侵严重,0.45等盐度线可上溯至闸口与闻堰之间;小潮期盐水入侵程度减弱,0.45等盐度线回落到仓前与七堡之间。盐度垂向分布均匀,紊动混合较充分,无论大潮还是小潮,涨憩时刻盐度分层现象较涨急及落潮期明显。基于三维盐度的一系列数值试验,研究了径流量、潮汐、风速、风向及海平面上升等动力因子单独变化时对钱塘江河口盐度分布和入侵距离的不同影响。径流和潮差是盐水入侵的两个主要影响因素。河口盐度及盐水入侵距离随着上游径流量的增加而减小,随着下游潮差的增加而增加。风对盐水入侵的影响表现在,与涨潮流向一致或相近的风应力作用下,河口整体盐度大潮期降低而小潮期则有所增加,与落潮流向一致或相近的风应力作用下恰好反之。海平面上升后,盐水入侵加剧,上升幅度越大,作用越显著。相对海平面分别上升0.3、0.6和1.0m,盐水入侵距离大潮期分别增加了 1.1、2.2和6.0 km,小潮期则增加了 2.8、5.9和9.8 km。基于数模结果,发现盐水入侵距离与径流量大小成负指数关系,与潮差大小呈指数关系。通过非线性多元回归分析,建立了盐水入侵相对距离的指数函数(exp×(L/L_0)与相对潮差(H/h)和径流弗劳德数(qr/(?))的幂函数之间的正比关系。在澉浦枯季8.21 m最大实际潮差下,南星桥和珊瑚沙取水口在径流量为50和300 m3/s时半月内连续最长超标时间分别为10.4-11.5和0.2～1.4d,当流量达到500m3/s以后,两个取水口均不超标。在澉浦15d最大潮差8.52和6.79 m情况下,满足南星桥和珊瑚沙取水要求的最小抗咸流量分别为410和250 m3/s。两个取水口在最不利风向(东向)作用下,两个取水口平均盐度增值分别为0.18和0.15,连续最长超标时间增值分别为2.1d和1.9h。
[Abstract]:The Qian Tang River estuary is a typical strong tidal estuary. The tidal current is a typical strong tidal estuary. The estuary is 80% of the drinking water in the city of Hangzhou. It is an important source of water in the city. For years, salt water intrusion seriously affects the water quality of the water intake. It is of great significance to study the intrusion of salt water in the estuary of the Qian Tang river. A major project of family science and technology - the research and demonstration of the common technology of tidal impact on the safety and support of urban drinking water (2009ZX07424-001), a systematic study on the intrusion of brine and its influence factors in the Qian Tang River Estuary was systematically studied. The real-time observation of multi station synchronized tidal level and salinity was carried out in the Qian Tang River Estuary. The salinity change depends on the tidal effect on the tidal cycle and the short diachronic scale on the tidal cycle and the half moon tide, and the salinity change depends on the runoff on the long calendar scale of the season and the interannual. The spatial distribution of the salinity of the Qian Tang River Estuary decreases in longitudinal direction and the maximum degree occurs near the warehouse; the vertical average salinity is the main main trough. It is lower than edge beach, but the variation is not obvious; the vertical stratification phenomenon of salinity is not obvious, and the stratification coefficient is less than 0.3, which indicates that the Qian Tang River estuary is a strong mixture. Based on the one dimensional salt balance equation of Savenije, the empirical analytical model of the salinity of the rise and rest at the Qian Tang River estuary is established, and the spatial distribution of salinity along the salinity and the intrusion distance of salt water are carried out. The results are in agreement with the measured results. A wavelet neural network model (IPSO-WNN) is proposed to improve the seven Fort salt time sequence of the Qian Tang River Estuary. Based on the FVCOM model, the three-dimensional tidal salinity numerical model of the Qian Tang River estuary is set up, and the simulated tidal level, flow velocity, flow direction and salinity are simulated. On the whole, the model is in good agreement with the measured data, indicating that the model can effectively reflect the hydrodynamic force of Qian Tang River and the process of brine invasion. Based on the simulation results, the spatio-temporal variation of the salinity of the Qian Tang River Kawaguchi Fuharuko power station, Kawaguchi Fuharuko power station in the season of dry season and strong tide is analyzed. In the plane distribution, the brine has a weekly reciprocating movement with the tidal current, and the brine invasion is serious in the tide period, 0 The salinity lines, such as.45, can be traced back to the gate and the weirs; the salinity of the salinity line falls down to the front of the storehouse and between the seven fort. The salinity vertical distribution is uniform and the turbulent mixing is more fully, no matter the tide or the small tide, the salinity stratification phenomenon is more urgent and the ebb period is obvious. A series of numerical tests based on the three-dimensional salinity. The effects of the dynamic factors such as runoff, tide, wind speed, wind direction and sea level rise on the salinity distribution and invasion distance of the Qian Tang River estuary are studied. The runoff and tidal difference are the two main factors affecting the intrusion of salt water. The salinity and the intrusion distance of the estuaries decrease with the increase of the upstream flow, with the downward tide. The effect of wind on the intrusion of salt water shows that under the action of wind stress that is consistent or close to the tide flow direction, the whole salty tide period of the estuary decreases and the tidal period increases, and the wind stress is the same as the wind stress which is consistent with the tide flow direction. The more significant the relative sea level rises 0.3,0.6 and 1.0m respectively, the intrusion distance of salt water increases 1.1,2.2 and 6 km respectively, while the tide period increases 2.8,5.9 and 9.8 km. based on the numerical model results, and finds the negative exponential relationship between the saline intrusion distance and the size flow size, and the exponential relationship with the tidal range. The proportional relationship between the exponential function (Exp * (L/L_0) and relative tidal range (H/h) and the Froude number of runoff (qr/)) is established. Under the maximum actual tidal range of 8.21 m in the dry season, the longest continuous exceeding standard time of the South Star Bridge and the coral sand intake in the half month of the runoff of 50 and 300 m3/s, respectively, is 10.4-11.5 and 0.2 ~ 1.4d, when the flow rate reaches 500m3/s, the two water intake is not exceeding the standard. Under the condition of the maximum tidal difference 8.52 and 6.79 m, the minimum salt resistance of the South Star Bridge and the coral sand water intake is 410 and 250 m3/s., respectively, and two water intake at the most unfavorable wind direction (East), and the average salinity of two intake ports is 0.18 and 0.18, respectively. 0.15, the longest time of exceeding the standard is 2.1d and 1.9h. respectively.

【学位授予单位】：浙江大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU991

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