【摘要】：本文采用非結(jié)構(gòu)化三角網(wǎng)格在綜合考慮了大氣溫度、相對濕度、云量、降雨量、蒸發(fā)量和入海徑流等因素的基礎(chǔ)上首先構(gòu)建了大尺度渤海三維斜壓水動力模型。通過12個潮汐站點、5個潮流站點的實測數(shù)據(jù),M2、S2、K1、O1四大分潮的同潮曲線及溫鹽的時空分布特征對模型進行了驗證,結(jié)果表明模型能較好地再現(xiàn)渤海水動力及溫鹽變化過程,可以為后續(xù)萊州灣小尺度模型的構(gòu)建提供水動力及溫鹽背景場。依托渤海大尺度模型,構(gòu)建了萊州灣小尺度水動力水質(zhì)耦合模型并著重對鹽度和水質(zhì)模擬結(jié)果進行了分析論證。結(jié)果表明夏季萊州灣鹽度平面分布的基本規(guī)律是自西向東、從灣內(nèi)向灣外遞增,黃河口及小清河口為低值區(qū),北部和東部為高值區(qū)。垂向上海區(qū)大部呈均勻分布,只是在河口地區(qū),淡水大量輸入導(dǎo)致垂向上有一定的鹽度梯度。冬季,鹽度平面分布格局和夏季保持一致,垂向分布更加趨于均勻,但整體鹽度由于降水及河流入海徑流的減少較夏季明顯偏高。另外,分析得出夏季萊州灣鹽度分布的主導(dǎo)因素是黃河徑流量,潮流對其影響較弱。05年萊州灣的水質(zhì)模擬再現(xiàn)了浮游植物典型的雙峰分布現(xiàn)象,結(jié)合氮磷營養(yǎng)鹽的變化過程對該現(xiàn)象的發(fā)生機理進行了闡述。依據(jù)Redfield數(shù)分析了菜州灣營養(yǎng)鹽的組成結(jié)構(gòu),海域整體營養(yǎng)鹽水平處于磷限制,但局部海區(qū)仍存在氮限制。通過兩組數(shù)值試驗,研究了灣內(nèi)最重要的兩個污染源黃河和小清河對水質(zhì)的影響,探討了營養(yǎng)鹽的構(gòu)成比例對浮游植物生長所起的作用：無機磷對浮游植物生長的影響程度要高于無機氮,無機氮的增加也能促進浮游植物含量的升高說明海域整體磷限制作用突出,但是部分海域存在氮限制；小清河點源對萊州灣氮磷無機鹽及浮游植物含量水平的影響程度均要弱于黃河。應(yīng)用模型從潮流場、鹽度場、納潮量和潮通量、水交換能力和營養(yǎng)鹽組成五個角度預(yù)測了四大集約用海工程的實施給萊州灣水動力及水環(huán)境造成的影響。工程對萊州灣全場流場造成的影響有限,影響主要集中在工程附近。由于工程后大潮漲憩時刻高潮位降低,鹽水向灣頂?shù)纳纤菽芰p弱,工程后鹽度等值線有一定的回退,這在灣內(nèi)表現(xiàn)尤其明顯。落憩時,工程后灣頂潮位回落幅度降低,鹽度交換減慢使得灣內(nèi)鹽度等值線后退,低鹽區(qū)面積增大。填海造陸直接造成的海灣面積減小導(dǎo)致納潮量和灣口斷面潮通量均有不同程度減小。保守物質(zhì)對流擴散模型表明海灣水體半交換時間較工程前增大45天,增幅達26.9%,海灣水交換能力明顯減弱。水體交換不暢使得PO4整體水平升高,DIN含量下降,N/P比普遍降低,海域磷限制作用被削弱。
[Abstract]:In this paper, a large scale baroclinic hydrodynamic model of Bohai Sea is constructed based on unstructured triangular meshes, which take into account the factors of atmospheric temperature, relative humidity, cloud amount, rainfall, evaporation and runoff into the sea. The model is verified by the measured data from 12 tidal stations and 5 tidal stations, the same tide curve of M2S2S2K1O1 and the temporal and spatial distribution characteristics of temperature and salt. The results show that the model can well reproduce the hydrodynamic and thermo-salt variation process in Bohai Sea. It can provide hydrodynamic and temperature-salt background field for the construction of small-scale model in Laizhou Bay. Based on the large scale model of Bohai Sea, the coupling model of small scale hydrodynamic water quality in Laizhou Bay was constructed, and the simulation results of salinity and water quality were analyzed and demonstrated. The results show that the basic law of salinity plane distribution in the Laizhou Bay in summer is from west to east, increasing from the inside of the bay, the estuary of the Yellow River and the mouth of Xiaoqing River is the low value area, and the north and east are the high value areas. Most of the vertical Shanghai area is uniformly distributed, but in the estuarine area, a large amount of fresh water input leads to a certain vertical salinity gradient. In winter, the distribution pattern of salinity plane is consistent with that in summer, and the vertical distribution tends to be more uniform, but the overall salinity is obviously higher than that in summer because of the decrease of precipitation and river runoff into the sea. In addition, the main factor of salinity distribution in Laizhou Bay in summer is the runoff of the Yellow River, and the tidal current has a weak influence on it. The simulation of water quality in Laizhou Bay in 2005 reproduced the typical bimodal distribution of phytoplankton. The mechanism of this phenomenon was explained by the changing process of nitrogen and phosphorus nutrients. According to the Redfield number, the composition of nutrient salt in Caizhou Bay was analyzed. The total nutrient level in the sea area was limited by phosphorus, but there was still nitrogen limitation in the local sea area. The effects of the Yellow River and Xiaoqing River, two of the most important pollution sources in the Bay, on the water quality were studied through two groups of numerical tests. The effect of the proportion of nutrients on phytoplankton growth was discussed: inorganic phosphorus had higher effect on phytoplankton growth than inorganic nitrogen. The increase of inorganic nitrogen also promoted the increase of phytoplankton content. The effect of point source of Xiaoqing River on nitrogen and phosphorus inorganic salt and phytoplankton content in Laizhou Bay was weaker than that in Yellow River. The effects of the four intensive sea projects on the hydrodynamics and water environment of Laizhou Bay were predicted from five aspects: tidal current field, salinity field, tidal capacity and tidal flux, water exchange capacity and nutrient composition. The effect of the project on the whole field of Laizhou Bay is limited, and the effect is mainly near the project. Due to the decrease of high tide level and the abatement of saltwater to the top of the bay after the project, the salinization isoline has a certain retrogression, which is especially obvious in the bay. During the period of falling and resting, the tidal level of the top of the bay decreases after the project, and the salinity exchange slows down, which results in the retrogression of the salinities isoline and the increase of the area of the low salt area in the bay. The decrease of bay area caused by reclamation directly results in the decrease of tidal absorption and tidal flux at the mouth of the bay. The model of conserved material convection and diffusion shows that the half-exchange time of the water body in the bay is increased by 45 days, the increase is 26.9days, and the water exchange capacity of the bay is obviously weakened. The level of PO4 was increased, the content of DIN was decreased, the N / P ratio was generally decreased, and the limiting effect of phosphorus was weakened.
【學(xué)位授予單位】：大連理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：P731.2;P75

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