SEAWATER INTRUSION TYPES AND REGIONAL DIVISIONS IN THE SOUTHERN COAST OF LAIZHOU BAY

The southern coast of Laizhou Bay, Bohai Sea, is one of the areas in China most seriously impacted by seawater intrusion. Based on the sources of intruding waterbodies, seawater intrusion can be divided into two types: intrusion of saline water derived from modern seawater, and intrusion of subsurface brine and saline water derived from paleo seawater in shallow Quaternary sediments. There are some distinct differences in their formation, mechanism and damage. The subsurface brine intrusion is a special type, which can cause very serious disaster. The coastal landform and the Quaternary hydrogeological environment are predominant factors in the classification of seawater intrusion types. Various coastal environments in different coastal sections result in three types of intrusion: seawater intrusion, saline groundwater intrusion, and mixed seawater and saline water intrusion, in the southern coast of Laizhou Bay, which can be divided into four areas: the seawater intrusion area in the northern Laizhou City coast, the mixed seawater and saline groundwater intrusion area in the Baisha River Jiaolai River mouth plain area, the mixed seawater and saline groundwater intrusion area in the Weihe River mouth plain area northern Changyi county coast, and the saline groundwater intrusion area in the northern Shouguang plains.

A STUDY OF THE SURFACE EMERGING PALAEOCHANNELS ON THE SOUTH COAST PLAIN OF LAIZHOU BAY

By employing many methods including distinguishing the land maps, interpreting the aerophotoes and Satellite photographes, consulting historical documents, investigating ancient cultural relics, making investigations in the field, analysing the names and features of the place, and analysing the characteristics of the deposit, etc., a systematic study of the surface emerging palaeochannels on the South Coast Plain of Laizhou Bay has been made. Twenty five surface emerging palaeochannels were discovered and verified. According to the formation age, these palaeochannels were divided into two stages: six palaeochannels were formed in the Early and Middle Holocene, and nineteen palaeochannels were formed in the Late Holocene(the historical period). According to the landform features, the palaeochannels are divided into four categories: upland palaeochannel belts, strip shaped upland palaeochannels, trough shaped depression palaeochannels and ancient riverbeds. Among the four categories, the strip shaped upland palaeochannels are the main types. The swinging and movement of the channels helped the alluvial plains expand and cause the coastal ancient lakes to vanish in succession.

Study on sea water intrusion into palaeochannels on south coastal plain of the Laizhou Bay by the Bohai Sea

The palaeochannel evolution in the study region is divided into four stages by such methods as 14C dating. Sea water intrusion through palaeochannels has been studied as a focal point. Palaeochannels are the main passageways through which the sea water intrudes at a higher speed, through many means and in a changeable dynamic state.

Environmental evolution in the salt-water intrusion area south of Laizhou Bay since late Pleistocene

The south coastal plain of Laizhou Bay is one of the typical salt-water intrusion areas in China, the occurrence and development of which was closely related with the palaeoenvironment evolution. Systematic analyses of pollen, foraminifera and grain size composition based on ^14C and luminescence dating from two sediment cores were performed for the purpose of understanding the salt-water intrusion in the coastal plain of Laizhou Bay from the perspective of environmental evolution since late Pleistocene. It could be classified into seven evolution stages since 120 kaBP： 120-85 kaBP was a transition period from cold to warm; 85-76 kaBP was a period with warm and wet climate having swamp lakes developed in the lower reaches of the Weihe River, south coastal plain of Laizhou Bay; 76-50 kaBP was characterized by grassland vegetation and coarse sediments in terrestrial environment, which was the early stage of Dali Ice-Age; 50-24 kaBP was a period with alternate sea deposition in the south coastal plain of Laizhou Bay; 24-10 kaBP was the late stage of Dali Ice-Age with coldest period of Quaternary, the south coastal plain of Laizhou Bay was dry grassland and loess deposition environment; 10-4 kaBP was another warm and wet climate period, sea level was high and regressed at 4 kaBP; and has been the modern sedimentary environment since 4 kaBP. Among the three warm stages, including 85-76 kaBP, 50-24 kaBP and 10-4 kaBP, corresponded to late Yangkou, Guangrao and Kenli seawater transgression respectively. The duration of the latter one in south coastal plain of Laizhou Bay was longer than that in west coast of Bohai Sea and east coast of Laizhou Bay. The three periods of seawater transgression formed the foundation of salt-water intrusion in this area.

Formation and Evolution of Ancient Lakes on South Coast Plain of Laizhou Bay

Based on the data of historical geography, the analysis of the stratigraphic section, and the textual research of place names and satellite photographic interpretations, the authors study the formation and evolution of ancient lakes on the south coast plain of Laizhou Bay where there were once three lakes: Judian Lake, Qingshuibo Lake and Biehua Lake. All the lakes formed 6000 years ago evolved from the lagoons near the estuary and went through two periods, the golden age in the Middle Holocene and the shrinking age in the Late Holocene. The disappearance of the lakes resulted from the drying climate, the migration of the river courses and the activities of human beings. Among the three reasons, the migration of the river courses is the main one.

The paleogeographic implications of loess mounds: Laizhou Bay plain

The loess mounds are a newly discovered type of landforms on the Laizhou Bay plain south of the Bohai Sea. Research shows that they were formed in the late period of the late Pleistocene when the Bohai Sea was exposed in the period of late W黰u glacial age and changed into plain. As the exposed area is not protected by vegetation, the sediments at the sea bottom are blown and transported southward by strong north winds, and deposit on the coastal plains. As thick loess is accumulated, the loess mound landforms are formed in the direction of down wind.

Application of the Static Headland-Bay Beach Concept to a Sandy Beach: A New Elliptical Model

The headland-bay beach is one of the most common coastal types in the world.Its morphology reflects the changes that occurred during long-term evolution of the sandy coast.Several headland-bay beach models have been proposed to simulate the coastline’s configuration in equilibrium.In this paper,a new elliptical model is proposed,described,and applied.On the east coast of Laizhou Bay in Shandong Province from Longkou Port to Diaolongzui,four typical headland-bay beaches have developed,and four headland-bay beach models are used in this paper to simulate the morphology of these beaches to assess the applicability of each model.The simulation results of the elliptical model verify that it is applicable to the study area.In addition,the elliptical model is easy to use.Through simulation and field investigations,we concluded that most of the coastal segments in this area will remain in an erosion state,and the human activity has a significant impact on the shoreline’s evolution.

Study of the marine (saltwater) transgression in the palaeo-channels on the south coast plain of Laizhou Bay

The palaeochannels in the studied region are divided into four stages by such methods as 14C dating. Marine (saltwater) transgression in the palaeochannels has been studied as a focal point. Palaeochannels are the main passageway through which the seawater (saltwater) transgresses. The seawater (saltwater) transgresses at a high speed, by many means and in a changeable dynamic state.

莱州湾南岸土壤盐碱程度与养分含量空间变异

【目的】探究莱州湾南岸土壤可溶性盐含量、pH值和养分的空间分布特征,为我国北方滨海盐渍土区脆弱生境生态保护与修复提供科学依据。【方法】以莱州湾南部海岸线以南30 km的区域为研究对象,基于3 km距离的网格化布点法采集313个样点0~20、20~40、40~60 cm深度的土壤样品,经室内测定结合地统计学原理与地理信息系统等方法,揭示不同土层可溶性盐含量、pH值及表层土壤各养分指标的空间变异性特征。【结果】1)研究区域0~20、20~40、40~60 cm土层可溶性盐含量分别介于0.19~8.44、0.14~9.86、0.18~10.61 g∙kg^(−1)之间,各土层平均土壤可溶性盐含量分别为1.23±1.65、1.42±1.73、1.48±1.72 g∙kg^(−1),盐渍化等级以非盐渍化土为主,盐渍化类型以硫酸盐−氯化物型及氯化物−硫酸盐型为主,土壤含盐量随土层深度增加而增加。各土层可溶性盐含量空间分布不均,0~20 cm土层土壤盐分呈中等程度的空间自相关性,20~40 cm和40~60 cm土层盐分空间自相关性较强。2)研究区域0~20、20~40、40~60 cm土层土壤pH值分别介于7.04~9.38、7.04~9.66、7.08~9.79之间,各土层平均土壤pH值分别为8.17±0.46、8.39±0.47和8.46±0.46,整体以非碱性等级为主;0~20 cm土层pH值呈中等程度的空间自相关特征,20~40 cm和40~60 cm土层pH值空间自相关性较强。3)研究区域表层土壤有机质、全磷和全钾含量介于0.28~30.29、0.20~1.29、15.44~23.01 g∙kg^(−1)之间,平均含量分别为9.70±6.50、0.59±0.21和19.21±1.31 g∙kg^(−1);有效氮和速效钾的含量介于1.33~66.72mg∙kg^(−1)和24.90~248.20 mg∙kg^(−1)之间,平均含量分别为12.67±9.62mg∙kg^(−1)和94.64±45.60 mg∙kg^(−1)。土壤有机质和速效钾含量呈由海到陆沿平行于海岸线的方向带状增加的分布趋势,空间自相关性较强。有效氮、全磷、全钾空间分布不均,呈中等程度的空间自相关特征。【结论】莱州湾南岸土壤盐碱程度和养分含量总体呈较低水平且空间分布不均,各指标空间变异在不同程度上受到结构性因素与随机性因素的共同影响,人为活动、土壤质地与植被生长状况是莱州湾南岸土壤盐碱与养分空间变异的主控因素。本研究可为我国陆地生态系统脆弱生境生态保护与精准修复、北方滨海盐渍土科学管理与利用、边际土地产能提升与固碳增汇等工作提供理论依据。

莱州湾南岸海岸侵蚀过程与原因研究

采用历史资料对比分析的方法，对莱州湾南岸1958-2004年的海岸侵蚀进行了研究。结果表明，1958-1984年，莱州湾南岸岸线平均侵蚀后退速率为27m／a，0m等深线后退速率为27～65m／a，岸滩平均蚀低速率为2．1cm／a。1984-2004年，莱州湾南岸岸线位置基本无变化，岸滩平均蚀低速率为1.04cm／a，水深5m以浅的区域表层沉积物变粗。海面相对上升、入海泥沙量减少和风暴潮是研究区海岸侵蚀主要原因，三者对海岸侵蚀影响权重比为3：5：2。

渤海莱州湾南岸第四纪地下卤水演化的地球化学模拟

渤海莱州湾南岸地区赋存有大量的地下卤水,许多研究者认为这些卤水是第四纪地质历史时期古海水经强烈蒸发浓缩后埋藏而成的。运用反向地球化学模拟理论,选用美国地质调查局(USGS)提供的PHREEQC(1997)地球化学模拟软件,对莱州湾南岸昌邑廒里501孔各层卤水的水化学演化过程进行模拟。研究结果表明,该地区的地下卤水是由古海水经强烈蒸发浓缩后被沉积物埋藏,并在赋存过程中发生水 岩相互作用,使地下水出现方解石、石膏及CO2气体的过饱和析出,并伴随与沉积物发生K+、Na+、Mg2+、Ca2+之间的阳离子交换反应。其中的浅层地下卤水还受到地表盐场析盐后排放卤水的侵染。

莱州湾南岸平原古湖泊的形成与演变

运用查阅历史文献、地层剖面分析、地名考证、卫片解译等多种方法确证了莱州湾南岸古湖泊的存在 ,同时研究了它的形成与演变过程。莱州湾南岸有巨淀湖、黑冢泊、别画湖等古湖泊 ,它们形成于距今约 6 0 0 0年以前 ,系由河口湾泻湖演变而成。该区古湖泊经历了中全新世全盛期和晚全新世收缩期两个阶段。湖泊消亡的原因是气候变干、河道迁移、人类活动影响等 ,其中河道迁移是最主要原因。

莱州湾南岸平原地面古河道研究

利用综合方法对莱州湾南岸平原地面古河道做了系统研究，发现并验证地面古河道２５ 条，按形成时代将其分为两期，其中，早—中全新世古河道６ 条，历史时期古河道１９ 条；按地貌形态将其分为４ 种类型，包括高地古河道带、条状高地古河道、槽状洼地古河道和古河槽，其中条状高地古河道为该区主要的古河道类型。

莱州湾南岸平原浅埋古河道带研究

莱州湾南岸平原在埋深 6 0 m内的浅埋古河道带 ,可分成弥河、潍河和白浪河 3个系统 ,它们大都呈掌状、放射状分布 ,并与其所属河流的冲洪积扇范围相吻合 ,该区古河道的形成和发育是新构造运动和古气候环境演变的结果。自晚更新世晚期以来 ,该区有 4期古河道发育 ,其中玉木早冰期古河道和玉木主冰期古河道的砂体沉积粒度粗、连通性好、分布广 ,既是富水性强、水质好的淡水含水层 ,又是该区海 (咸 )水入侵的主要通道 ,控制在浅埋古河道带超采地下淡水 ,并在丰水季节利用其进行地下水回灌 ,是治理该区海 (咸 )水入侵灾害的重要措施之一。

山东莱州湾南岸平原古湖泊消亡原因初探

莱州湾南岸平原是指西起小清河口 ,东至胶莱河口的广大沿岸地区 ,这一地区近年来是我国工农业发展较快的地区 ,也是我国地下咸水入侵较为严重的地区。历史上 ,莱州湾南岸平原地区曾有一些湖泊存在 ,如巨淀湖、黑冢泊、别画湖 ,但现在早已荡然无存了。研究这些古湖泊的消亡原因对于恢复该区古地理环境以及确立湖迹区今后的发展方向具有十分重要的意义。通过查阅历史文献、地层剖面分析、地名考证、遥感解译等多种途径和方法 ,对莱州湾南岸古湖泊的消亡原因进行了研究与分析 ,并指出该区古湖泊消亡的原因是气候变干、河流变迁、人类活动影响等 ,其中气候变化是古湖泊消亡的根本原因 ,河流变迁是古湖泊消亡的直接原因 ,而人类活动则加速了古湖泊消亡的进程。

莱州湾南岸滨海平原地下卤水水化学特征

综合运用数理统计分析方法对莱州湾南岸滨海平原地下卤水样品的水化学特征进行分析,结果表明:莱州湾南岸地下卤水水化学总体特征与海水一致,rNa/rCl,rK/rBr和rMg/rCa系数反映出当地地下卤水来源于沉积古海水,并且海水浓缩程度很高,而变质作用较弱;主成分分析中,第一主分量可以用来解释地下卤水形成时的海水浓缩程度,第二主分量反映的是在第一主分量海水浓缩强度大体一致的情况下,可逆反应CaCO3+CO2+H2OCa2++2 HCO3-的进行情况。

莱州湾南岸滨海湿地变化及其原因分析

以1992年和2004年的TM遥感影像为数据源,从景观生态学角度,对1992年和2004年的莱州湾南岸湿地及其变化进行了研究。结果表明,与1992年相比,2004年研究区湿地面积减少了32.339km2,其中,自然湿地面积减少了246.189km2,而人工湿地面积却增加了213.851km2,至2004年,人工湿地面积已占研究区湿地总面积的78.22%;湿地景观多样性指数下降了0.1077,景观优势度指数和景观破碎化指数分别上升至0.109和0.0089。自然湿地被大面积垦殖,湿地淡水资源不足,大规模开采沿海卤水资源,环境污染加剧,风暴潮等自然灾害频发,是导致研究区自然湿地萎缩的主要因素。

莱州湾南岸滨海平原晚更新世以来古环境演变的孢粉记录

依据莱州湾南岸A1钻孔孢粉分析 ,结合14 C、热释光测年、沉积物粒度、岩性等资料 ,对A1钻孔自下而上划分为 7个孢粉组合带 ,并概括它们的主要特征。利用孢粉组合 ,探讨了 12 0kaB P 以来莱州湾南岸咸水入侵区的植被发展以及气候的冷暖、干湿交替变化。在 85～ 76kaB P 、 5 0～ 2 4kaB P 和 10～ 4kaB P 出现三次暖湿期 ,分别对应于“羊口海侵”、“广饶海侵”和“垦利海侵”。在三次暖湿期中发生海陆交互相滨岸沼泽或湖泊相沉积 ,植被类型为落叶阔叶林或针阔叶混交林滨岸草原。在 76～ 5 0kaB P 和 2 4～ 10kaB P 两次冷干期为陆相沉积环境 ,前者出现以针叶林为主的草原植被类型 ,后者出现干冷的针叶林干旱草原或荒漠草原植被类型 ,它们分别对应于早大理亚冰期和晚大理亚冰期。

渤海莱州湾南岸平原浅埋古河道带及其与海(咸)水入侵关系研究

根据２１００余个钻孔资料，并结合大比例尺地形图、航片、卫片判读分析，以及野外实地考察和沉积物样品的粒度分析、岩相分析、１４Ｃ测年，研究了莱州湾南岸平原浅埋古河道带的分布规律、埋藏和沉积特征、古河道的分期断代以及与海（咸）水入侵关系．该区在埋深６０ｍ内的浅埋古河道带，可分成弥河、潍河和白浪河３个系统，它们大都呈掌状、放射状分布，并与其所属河流的冲洪积扇范围相吻合．该区古河道的形成和发育与古气候和海平面变化密切相关．自晚更新世晚期以来，该区有４期古河道发育，其中玉木旱冰期古河道和玉术主冰期古河道的砂层沉积粒度粗、连通性好、分布广，既是富水性强、水质好的淡水含水层，又是该区海（咸）水入侵的主要通道．控制在浅埋古河道带超采地下淡水，并在丰水季节利用其进行地下水回灌，是治理该区海（咸）水入侵灾害的重要措施之一．

莱州湾南岸海水入侵发展动态和原因

以莱州市监测资料为基础,结合已有的研究结果,对莱州湾南岸海水入侵发展动态进行了研究。研究结果表明,1980—1989年是莱州湾南岸海水入侵发展最快的时期,其后海水入侵发展速度有所减缓,入侵南界基本在1995年线附近摆动。BP网络计算结果表明,莱州湾南岸海水入侵主要原因是降水量减少,直接原因则是地下水超采。降水量增加比地下水超采量减少所引起的海水入侵速度降低量要大;即使恢复了海水入侵前的水量供需状况,海水入侵也不会完全停止。