Three‐dimensional simulation of tsunami run‐up around conical island     

Byung Ho Choi  Dong Chule Kim  Efim Pelinovsky  Seung Buhm Woo 《Coastal Engineering》2007

At the circular Babi Island in the Flores tsunami (1992) and pear shaped island in the Okushiri event (1993), unexpectedly large tsunami run‐up heights in the lee of conic islands were observed. The flume and basin physical model studies were conducted in the Coastal Hydraulic Laboratory, Engineering Research and Development Center, U.S. Army Corps of Engineers to provide a better understanding of the physical phenomena and verify numerical models used in predicting tsunami wave run‐up on beaches, islands, and vertical walls. Reasonably accurate comparison of run‐up height of solitary waves on a circular island has been obtained between laboratory experimental results and two‐dimensional computation model results. In this study we apply three‐dimensional RANS model to simulate wave run‐up on conical island. In the run‐up computation we obtain that 3D calculations are in very good comparison with laboratory and 2D numerical results. A close examination of the three‐dimensional velocity distribution around conical island to compare with depth‐integrated model is performed. It is shown that the velocity distribution along the vertical coordinate is not uniform: and velocity field is weaker in the bottom layer and higher on the sea surface. The maximum difference (about 40%) appears at the time when solitary wave reached the circular island.  相似文献   

Possible impact of dam reservoirs and river diversions on material fluxes to the Gulf of Thailand   总被引：1，自引：0，他引：1  

Manuwadi Hungspreugs  Wilaiwan Utoomprurkporn  Penjai Sompongchaiyakul  Watanee Heungraksa 《Marine Chemistry》2002,79(3-4)

Thai people have always been agricultural-based, although rainwater is not enough to sustain year-round agricultural practice. The first earth-filled dam was built across a valley near Sukhothai over 700 years ago. Now, there are six major multipurposed dam reservoirs, among which the largest is the Sri Nakarind (SN) built across the Kwae Yai River, the main branch of the Mae Klong River in the western part of Thailand. The first multipurposed dam reservoir built on the Chao Phraya (largest) River System is the Bhumibhol Dam on the Ping River. In this paper, the two Mae Klong River Dam Reservoirs and their biology and chemistry are discussed. Also investigated are the historical records of material fluxes to the Gulf of Thailand in down-core sediment profiles and in 40-year bands of coral, Porites lutea, taken from the Upper Gulf of Thailand near Si Chang Island. Sediment cores studied did not show clear decreases in the biogenic silica concentration in the Upper Gulf area after the building of dams. Part of the reasons might be the higher rate of dissolution of silica in tropical waters bioturbation of surface layers or the constant disturbance of the bottom sediment by fishermen using bottom trawls. The record in the coral bands seems to be more promising in reflecting the material flux change due to dam construction. An attempt to detect changes in diatom population with time due to the expected decrease in siliceous material discharge was not possible because there was a change from the use of 70 μm mesh size to 20 μm mesh size resulting in the increase of species and biomass, although the diatom percentage remained above 80% in all estuarine samples.  相似文献   

Characteristics of karst groundwater system in the northern basin of Laiyuan Spring area          下载免费PDF全文

LI Bo  LI Xue-mei 《地下水科学与工程》2018,6(4):261-269

Guided by the theory of groundwater system, based on the groundwater level data from the northern basin of Laiyuan Spring area, the authors took into account factors such as the lithology, geological structure and topography to study the relationship between groundwater recharge, runoff and drainage in this area. It was concluded that the infiltration of atmospheric precipitation is the main source of groundwater supply in this area; the upper layer of the Spring area is distributed with the Cambrian-Lower Ordovician karst water, and the lower layer is filled with the Jixian system karst water. The upper layer of karst water supplies to the lower layer of karst water or the pore water in loose strata through the fault while the lower layer of karst water runs to the three strong runoff belts from the east and west sides of the watershed, southwards into the basin, partially replenishing the pore water in loose strata, or forming fault Springs (e.g. Nanguan Spring, Beihai Spring) when dolomite movement encounters faults. Replenished by atmospheric precipitation and the upper and lower layers of karst waters, the pore water in loose strata joins the groundwater in the southern basin and then flows eastwards, in the end it flows out of the system in Shangfanpu. Through the analyses of groundwater level data and hydrogeological drilling data, based on groundwater D and 18O isotope test results, the karst groundwater circulation system in the northern basin of Laiyuan Spring area is further verified, which provides hydrogeological basis for water resources development and utilization as well as protection in this area.  相似文献   

三峡库岸滑坡变形特征及影响因素分析          下载免费PDF全文

李远宁  潘勇  冯晓亮  陈龙  程奎 《探矿工程》2018,45(8):127-131

三峡库区涉水滑坡主要影响因素是水位和降雨量,也是库区滑坡体失稳的主要影响因素和诱发因素。库区每年重复着水位升降不利于滑坡的稳定,而降雨特别是大强度的降雨也诱发产生滑坡。当水位波动遇到降雨,出现工况叠加,滑坡将加剧。因此,有必要对影响滑坡变形的主导因素进行了解分析。2016年6月三峡库区全面展开了自动化监测,使得数据统计方便可靠。本文采用滑坡变形速率、降雨量、库水位变化、最大水位变化速率、淹没程度,运用灰色关联度分析法对涉水滑坡进行了计算分析。水位下降阶段,文中土质滑坡变形受库水位影响最大。水位上升阶段,该土质滑坡上部变形受降雨影响最大,下部受水位影响最大。文中岩质滑坡总是受库水位影响最大。  相似文献   

Provenance Study of Fe–Ti Oxide Minerals in the Quaternary Sediments in Yichang Area and Its Implication of Formation Time of the Yangtze Three Gorges, China     

XIANG Fang  DU Wen  HUANG Henxu  KANG Dongy  ZHU Hongbo  FENG Qin 《《地质学报》英文版》2018,92(4):1598-1608

The Three Gorges are considered to be critical to understand the formation of Yangtze River. Recent research results suggest that the Yangtze Three Gorges was created during the Quaternary but the exact time is debatable. Fe–Ti oxide minerals are seldom used to study sediment provenance, expecially using scanning electron microscopy(SEM), and energy dispersive spectrometer(EDS). In this study, the provenance of Quaternary sediments in Yichang area, which is located to the east of the Yangtze Three Gorges, was investigated by using SEM and EDS to research Fe–Ti oxides. The Panzhihua vanadium titanomagnetite and Emeishan basalt outcrop are located to the west of the Three Gorges. Further, the materials from them are observed in the Quaternary sediments of Yichang area. Fe–Ti oxide minerals from the Huangling granite are observed in the Yunchi and Shanxiyao Formations, which were formed before 0.75 Ma B.P., whereas Fe–Ti oxide minerals from the Huangling granite, Panzhihua vanadium titanomagnetite, and Emeishan basalt are observed in the riverbed and fifth-terrace sediments of the Yangtze River, which were formed after 0.73 Ma B.P.. Thus, we can infer that the Three Gorges formed after the deposition of the Shanxi Formation and before the fifth-terrace; i.e., 0.75–0.73 Ma B.P..  相似文献   

柴西地区扎哈泉致密油储层特征及评价     

吴颜雄  薛建勤  杨智  施奇  李海鹏  刘刚  夏晓敏 《世界地质》2018,37(4):1167-1176

柴西地区致密油储层内部结构复杂、非均质性强,为了更高效地进行致密油勘探开发,利用岩芯薄片、X衍射、场发射扫描电镜、CT扫描和物性分析等方法,对扎哈泉地区上干柴沟组开展致密储层特征及储层物性控制因素研究。研究表明,上干柴沟组为典型的致密储层,以细砂岩和粉砂岩为主,填隙物含量较高,以原生孔隙为主,微米级孔隙是主要的储集空间,有效储层平均孔隙度为5. 9%,平均渗透率为0. 43 m D。储层内部孔隙分布较均匀,总体呈现微米级孔隙加纳米级喉道的特征,其中微米级孔隙基本呈片状分布,连通性好,纳米级孔隙则呈点孤立状分布。储层物性受原始沉积条件和后期成岩作用控制,坝砂泥质含量低,纯度高,物性较好。压实作用和碳酸盐胶结使储层变差,硬石膏胶结对孔隙的影响具有两面性,晚成岩期的溶蚀作用对储层改善作用明显。研究区致密油有效储层可分为三类,其中Ⅰ类有效储层为本区的"甜点"区,是下一步优先勘探开发的重点区块,Ⅱ-Ⅲ类有效储层则是重要的挖潜区,通过工程技术攻关可切实实现柴西地区的增产扩能。  相似文献   

柴达木盆地东部上石炭统克鲁克组碎屑岩储层特征及控制因素     

祁柯宁  彭博  李宗星  刘成林  谢庆宾 《地质论评》2018,64(5):1263-1276

柴达木盆地上石炭统克鲁克组是该区重要的古生界勘探层位,组内发育多套良好的碎屑岩层。为探究其岩石物性特征及控制因素,本次以野外露头调查为基础,利用普通薄片、铸体薄片鉴定及扫描电镜等手段,结合物性测试和压汞资料,对克鲁克组碎屑岩纵向分布规律,储层岩性、物性、孔喉特征及孔隙类型进行分析。认为克鲁克地层中克2段发育的三角洲前缘亚相和克3段的具障壁海岸潮坪相的大套含砾粗砂岩、粗砂岩砂体原生、次生孔洞发育,孔喉大、分布集中、分选好,为有利的碎屑岩储层。早成岩期压实作用、重结晶及胶结作用对克鲁克组砂岩的原生孔隙破坏严重,晚成岩期储层改造形成的溶孔、裂缝—溶孔是油气成藏的主要储存空间。该研究为预测柴东石炭系克鲁克组油气有利区域提供依据,为今后该地区的油气勘探提供理论支撑。  相似文献   

Abiotic Methane Reservoirs in the Western Tianshan HP–UHP Metamorphic Belt,China          下载免费PDF全文

ZHANG Lijuan  ZHANG Lifei  LI Xiaowei  WANG Xiao 《《地质学报》英文版》2023,97(1):337-349

Natural gas, consisting primarily of methane(CH₄), has become a major source of clean energy in modern society in many parts of the globe. Recent experimental observations and discoveries of deep-sourced abiotic CH₄ in cold subduction zones indicate the important ability of cold subducted slabs to generate natural gas reservoirs. However, most CH₄ flux and reservoirs remain unknown and their potential is overlooked in global carbon flux estimations. Massive abiot...  相似文献   

Petroleum in the Jurassic Reservoirs within the Eastern Fukang Sub-depression, Junggar Basin, NW China: Correlation and Source Rock     

CHENG Bin  LIU Hu  ZHANG Kuihu  REN Xincheng  MENG Xiangyu  LIU Dezhi 《《地质学报》英文版》2023,97(3):777-795

The origin and source of the petroleum in the Jurassic reservoirs within the eastern Fukang sub-depression were geochemically investigated. They show thermal maturities matching the peak generation stage, while the condensates are at the early stage of intense cracking. Oils and condensates may have experienced mild evaporative fractionation, while mixing of severely biodegraded with non-biodegraded oils has occurred. Using biomarkers and isotopes, petroleums were classified into Group I, II and III genetic groups, with Group III further divided into IIIa and IIIb subgroups. Group I petroleum displays heavy carbon isotopes, a strong predominance of pristine over phytane, high C19 and C20 tricyclic and C24 tetracyclic terpanes, low gammacerane, and dominant C29 steranes, while Group II shows light carbon isotopes, a predominance of phytane over pristine, high C21 and C23 tricyclic with low C24 tetracyclic terpanes, high gammacerane and dominant C27 steranes. Group IIIa petroleum shows mixing compositions of Group I and II, while Group IIIb displays similar compositions to Group I, but with significantly higher Ts, C29Ts and C30 diahopane proportions. Oil-source rock correlation suggests Group I and II petroleums originate from Jurassic and Permian source rocks, respectively, while Group IIIa are mixtures sourced from these rocks and IIIb are mixtures from Jurassic and Triassic source rocks.  相似文献   

三峡工程蓄水运用以来水库排沙效果   总被引：1，自引：0，他引：1       下载免费PDF全文

陈桂亚  袁晶  许全喜 《水科学进展》2012,23(3):355-362

针对三峡水库蓄水运用以来排沙比问题,在深入研究三峡水库不同蓄水运用阶段水库排沙效果的基础上,着重研究各年年内蓄水排沙过程,系统地分析水库排沙效果的影响因素。结果表明:库区河道特性、入库水沙条件以及坝前水位的高低是水库排沙比变化的主要影响因素。2003年6月~2010年12月,水库排沙比为26.1%。水库排沙主要集中在汛期5~10月,排沙比为29.0%。尤其是在洪峰期间,库区水流流速较大,水流挟沙能力强,进入水库的泥沙大部分能输移到坝前,水库排沙比较大,当入库流量大于30000m³/s时,水库最大排沙比可达81.0%。此外,随着汛期坝前水位的抬高,水库排沙效果有所减弱,尤其是粗颗粒泥沙的多少也很大程度上影响水库排沙效果,水流的挟沙能力随着水流流速的减小而减小,粗颗粒泥沙的排沙比随之发生较全沙更为明显的减小。  相似文献