本文選題：海岸帶 + 咸淡水界面�。� 參考：《中國地質(zhì)大學(xué)(北京)》2015年碩士論文

【摘要】：改革開放以后,濱海地區(qū)進入高速發(fā)展階段,市場化、工業(yè)化程度不斷提高,外來人口不斷增加,工農(nóng)業(yè)和市政用水需求日益增長,科學(xué)評價和合理開發(fā)濱海含水層地下水資源成為一個重要的研究課題。20世紀60年代以來,由于濱海地區(qū)不合理的開采地下水資源,含水層中地下水位下降,致使淡水水頭低于咸水楔形體的水頭,咸淡水界面向內(nèi)陸方向移動。這種在地下水開發(fā)利用的影響下,海水向內(nèi)陸方向遷移的現(xiàn)象稱為海水入侵。我國海水入侵現(xiàn)象最早出現(xiàn)于大連市,其后青島市、萊州市、北海市等地也相繼出現(xiàn)海水入侵問題。據(jù)統(tǒng)計現(xiàn)今我國主要受災(zāi)城市海水入侵總面積已達900 km2。濱海含水層中咸淡水之間的界面形態(tài)特征和運移規(guī)律是研究海水入侵現(xiàn)象的重要內(nèi)容。本文建立濱海潛水含水層咸淡水界面實驗室模擬實驗,采用不同的咸水密度和咸水水頭,研究咸淡水突變界面的動態(tài)及平衡特征,分析平衡條件下,咸淡水界面向內(nèi)陸延伸最遠距離與咸水水頭和咸水密度之間的關(guān)系。實驗結(jié)果表明咸水密度和咸水水頭的增大都會導(dǎo)致咸淡水界面向內(nèi)陸方向延伸最遠距離變大,界面形態(tài)主要受咸水密度控制,當咸水密度由大變小時,界面由陡峭變緩傾。采用MODFLOW中的SEAWAT模塊建立了數(shù)值模型模擬實驗過程,模型運行結(jié)果顯示咸水密度是界面形態(tài)的主要控制因素,當咸水水位為45 cm時,咸水密度由1.060 g/cm3增大到1.1 g/cm3,咸水邊界處淡水排泄口長度由28 cm減小為17 cm,咸淡水界面向淡水邊界方向延伸最遠距離由21.5 cm增加為50.5 cm,界面由陡峭變緩傾,這與咸水密度是控制咸淡水界面形態(tài)的主要因素的實驗結(jié)果是相符的。抽水導(dǎo)致的海水入侵距離是研究海水入侵問題的核心。文中給出咸淡水界面之上淡水帶抽水導(dǎo)致的咸淡水界面升錐高度和界面之后淡水帶抽水引起的界面入侵距離的計算公式,經(jīng)實驗結(jié)果驗證,公式能比較準確的反應(yīng)實際情況,由于實驗中用于計算潛水含水層中淡水流量的水位測壓孔距咸淡水界面距離較近,給計算結(jié)果帶來了一些誤差。抽水狀態(tài)下的數(shù)值模型運行結(jié)果表明咸水水位是控制抽水導(dǎo)致的咸淡水界面入侵距離的主要因素,當咸水密度恒定為1.050 g/cm3,抽水量為1 m3/d,咸水水位由45 cm升高到46 cm時,界面入侵距離由13 cm增大為27 cm。
[Abstract]:After the reform and opening up, Binhai area has entered a stage of rapid development, with the marketization, the degree of industrialization continuously increasing, the foreign population increasing, and the demand for water for industry, agriculture and municipal water increasing day by day. Scientific evaluation and rational exploitation of groundwater resources in coastal aquifers have become an important research topic. Since the 1960s, groundwater levels in aquifers have declined due to unreasonable exploitation of groundwater resources in coastal areas. The head of fresh water is lower than that of wedge of salt water, and the boundary of salt water moves inland. Under the influence of groundwater exploitation and utilization, sea water migration inland is called seawater intrusion. Seawater intrusion was first found in Dalian, and then in Qingdao, Laizhou, Beihai and other places. According to statistics, the total area of seawater intrusion in the main affected cities in China has reached 900 km ~ 2. The characteristics of interface morphology and migration between brackish and fresh water in coastal aquifers are important for the study of seawater intrusion. In this paper, the laboratory simulation experiment of salt-fresh water interface of coastal diving aquifer is established. Different salt water density and salt water head are used to study the dynamic and equilibrium characteristics of salt-fresh water abrupt interface, and the equilibrium conditions are analyzed. The relationship between the furthest distance of the salt water boundary extending inland and the salt water head and the salt water density. The experimental results show that both the increase of the salt water density and the increase of the salt water head will result in the furthest extension of the salt water boundary towards the inland direction. The interface morphology is mainly controlled by the salt water density. When the salt water density changes from large to small, the interface changes from steep to slow. The numerical model is established by using the SEAWAT module in MODFLOW. The results show that the salt water density is the main controlling factor of the interface, and the salt water level is 45 cm. The density of salt water increased from 1.060 g/cm3 to 1.1 g / cm 3, the length of fresh water outlet at the salt water boundary decreased from 28 cm to 17 cm, and the furthest distance from 21.5 cm to 50.5 cm was increased from 21.5 cm to 50.5 cm. This is consistent with the experimental results that the density of salt water is the main factor controlling the interface morphology of salty and fresh water. The distance of seawater intrusion caused by pumping water is the core of the study of seawater intrusion. In this paper, the formulas for calculating the height of the rising cone of the salt-fresh water interface caused by the pumping of the fresh water zone above the salt-fresh water interface and the distance of the interface invasion caused by the pumping of the fresh water belt after the interface are given. The experimental results show that the formula can reflect the actual situation more accurately. Because the water level pressure hole used to calculate the fresh water flow in the phreatic aquifer is close to the interface of the salt and fresh water in the experiment, some errors have been brought to the calculation results. The operation results of the numerical model under pumping state show that the salt water level is the main factor to control the invasion distance of salt-fresh water interface caused by pumping water. When the salt water density is 1.050 g / cm ~ (-3), the pumping capacity is 1 m3 / d, the salt water level increases from 45 cm to 46 cm. The interfacial invasion distance increased from 13 cm to 27 cm.
【學(xué)位授予單位】：中國地質(zhì)大學(xué)(北京)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P731.2;P641.8

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