基于数值模拟的厦门湾波浪特征研究          下载免费PDF全文

朱君  蔡锋  戚洪帅  郑吉祥 《应用海洋学学报》2017,36(3):341-348

本研究使用成熟的SWAN模型对厦门湾的波浪场进行了1a的数值模拟,通过与同期的珍珠湾波浪观测数据进行对比验证了模型的可靠性.根据模型的计算结果,分析了厦门湾年平均和夏、冬两季平均波高和波向的分布特征,厦门湾的风浪和涌浪组成,珍珠湾波浪观测海域主要的波浪能量生成和能量耗散过程.结果表明,厦门湾年平均有效波高较小,且有较明显的季节变化特征,夏季厦门湾平均有效波高较小,且湾内波向多为偏南向;冬季厦门湾平均有效波高相对较大,厦门岛北侧和东侧海域波向均为NE向.厦门湾湾内以风浪为主,涌浪较小,风浪、涌浪比较大,均在3以上;从湾外向湾内,风浪、涌浪比逐渐增加,至厦门湾南岸和泉州石井镇附近海域,风浪、涌浪比增加到5~6;在厦门湾东部和北部海域,风浪、涌浪比均在10以上.珍珠湾海域波浪最主要的能量耗散过程是由底摩擦引起的能量耗散,虽然冬季风速较大,但夏季风能输入的能量和白帽破碎耗散的能量均大于冬季;因冬季波浪相对较大,夏季底摩擦耗散的能量要小于冬季.  相似文献   

Shallow sea topography detection using fully polarimetric Gaofen-3 SAR data based on swell patterns     

Longyu Huang  Chenqing Fan  Junmin Meng  Jungang Yang  Jie Zhang 《海洋学报(英文版)》2023,42(2):150-162

Compared to single-polarization synthetic aperture radar(SAR) data, fully polarimetric SAR data can provide more detailed information of the sea surface, which is important for applications such as shallow sea topography detection. The Gaofen-3 satellite provides abundant polarimetric SAR data for ocean research. In this paper, a shallow sea topography detection method was proposed based on fully polarimetric Gaofen-3 SAR data. This method considers swell patterns and only requires SAR data and ...  相似文献   

浙江中部三门湾波浪特征统计分析   总被引：2，自引：0，他引：2  

周阳  叶钦  施伟勇  杨斌  宋泽坤  闫东号 《海洋学报》2021,43(3):13-23

为了研究浙江中部三门湾海域的波浪特征,本文基于AWAC波浪观测仪在该海域进行了连续1年的观测,对观测得到的波浪参数进行了统计分析、线性回归分析,同时研究分析了三门湾海域受台风影响时,波浪参数和波浪谱的变化情况,探讨了波浪变化的原因。研究表明,三门湾海域常浪向和强浪向均为E向,地形是主导因素;显著波高绝大部分在0.8 m以下,期间的最大波高为2.71 m;该海域的波浪特征分布是一个比较典型的瑞利分布;台风“泰利”期间波能谱以双峰为主,外海涌浪和研究海域风区内的风浪形成混合浪,其中0.08 Hz左右的低频涌浪成分占比很大,而0.25 Hz左右的高频风浪成分占比较小。本文的研究工作为沿海海洋工程结构物的设计建造以及防灾减灾提供重要参考依据。  相似文献   

台风涌浪进入东海形成浪区的空间分布特征     

陆恒星  高志一  魏永亮  孟凡昌  唐泽艳 《海洋通报》2021,40(3)

西北太平洋台风外围的涌浪可穿过琉球群岛的海峡传入东海。本文采用1978—2018年的历史资料研究了有效波高2 m及以上的涌浪穿过琉球群岛在东海所形成浪区的空间分布特征。结果表明,沿适当角度的台风外围涌浪主要通过与那国海峡、宫古海峡、边户岬-与路岛水道、奄美-吐噶喇海峡传入东海,其余受到岛屿阻挡。筛选得到的40个台风案例中,宫古海峡入射次数最多,为33次,其次是边户岬-与路岛水道和奄美-吐噶喇海峡,均为17次,与那国海峡为11次。奄美-吐噶喇海峡,宫古海峡、边户岬-与路岛水道和与那国海峡的涌浪入射深度达到最大时分别约为570 km、480 km、380 km和234 km。多元线性回归分析结果表明,登陆型台风和西进型台风10级风半径、台风平均移动速度、入射角度对涌浪入射深度的影响较大,单独台风要素与涌浪入射深度无统计学上的相关性。  相似文献   

Comparison of nutrient loss pathways: Run‐off and seepage flow in Vertisols     

Robert Daren Harmel  Douglas R. Smith  Rick L. Haney  Peter M. Allen 《水文研究》2019,33(18):2384-2393

Recent studies have highlighted the agronomic and environmental importance of phosphorus (P) movement through the soil profile. Thus, faced with challenges such as high‐profile cases of P enrichment of surface water, better understanding of nutrient movement through soil is needed to better manage agricultural fertilizers and manures and their contribution to water quality degradation. In particular, field‐scale research is especially needed in soils with preferential flow transport pathways. Thus, we collected nitrogen (N) and P transport data in run‐off and seepage (lateral subsurface return flow) from 13 field‐ and farm‐scale watersheds on Vertisols in Central Texas for a 14‐year period. For 2004–2017, seepage accounted for ~20% of the total surface flow, and nutrient concentrations were generally similar in run‐off and seepage. As surface run‐off contributed ~80% of the flow, it follows that median annual N and P loads in run‐off were significantly greater than in seepage for every watershed. N loads in both run‐off and seepage flow from cultivated land were an order of magnitude greater than in native prairie and improved pasture, and the highest run‐off and seepage P loads both occurred on cultivated land with organic fertilizer sources. Increasing watershed scale (size) did not to produce consistent patterns in N or P loss in run‐off or seepage. Land use and watershed scale produced significant differences in seepage volume but did not affect run‐off volumes or total surface flow/rainfall. Although less significant in terms of total offsite flux, nutrient movement in vadose zones has important agronomic and environmental implications as considerable N and P are transported through and within the root zone and eventually offsite. And in terms of P, this contradicts the traditionally held scientific viewpoint that P movement through the vadose zone is unimportant agronomically and environmentally.  相似文献   

Long-term trend analysis of wave characteristics in the Bohai Sea based on interpolated ERA5 wave reanalysis from 1950 to 2020     

Jichao Wang  Peidong Sun  Zhihong Liao  Fan Bi  Guiyan Liu 《海洋学报(英文版)》2022,41(7):97-112

Reasonably understanding of the long-term wave characteristics is very crucial for the ocean engineering. A feedforward neural network is operated for interpolating ERA5 wave reanalysis in this study, which embodies a detailed record from 1950 onwards. The spatiotemporal variability of wave parameters in the Bohai Sea, especially the significant wave height (SWH), is presented in terms of combined wave, wind wave and swell by employing the 71 years (1950–2020) of interpolated ERA5 reanalysis. Annual mean SWH decreases at ?0.12 cm/a estimated by Theil-Sen estimator and 95th percentile SWH reflecting serve sea states decreases at ?0.20 cm/a. Inter-seasonal analysis shows SWH of wind wave has steeper decreasing trend with higher slopes than that of swell, especially in summer and winter, showing the major decrease may attribute to the weakening of monsoon. The inner Bohai Sea reveals a general decreasing trend while the intersection connecting with the Yellow Sea has the lower significance derived by Mann-Kendall test. Meanwhile, 95th percentile SWH decreases at a higher rate while with a lower significance in comparison with the mean state. The frequencies of mean wave directions in sub-sector are statistically calculated to find the seasonal prevailing directions. Generally, the dominant directions in summer and winter are south and north. A similar variation concerning to SWH, the trend of the mean wave period is provided, which also shows a decrease for decades.  相似文献   

Hillslope run‐off thresholds with shrink–swell clay soils          下载免费PDF全文

Ryan D. Stewart  Majdi R. Abou Najm  David E. Rupp  John W. Lane  Hamil C. Uribe  José Luis Arumí  John S. Selker 《水文研究》2015,29(4):557-571

Irrigation experiments on 12 instrumented field plots were used to assess the impact of dynamic soil crack networks on infiltration and run‐off. During applications of intensity similar to a heavy rainstorm, water was seen being preferentially delivered within the soil profile. However, run‐off was not observed until soil water content of the profile reached field capacity, and the apertures of surface‐connected cracks had closed >60%. Electrical resistivity measurements suggested that subsurface cracks persisted and enhanced lateral transport, even in wet conditions. Likewise, single‐ring infiltration measurements taken before and after irrigation indicated that infiltration remained an important component of the water budget at high soil water content values, despite apparent surface sealing. Overall, although the wetting and sealing of the soil profile showed considerable complexity, an emergent property at the hillslope scale was observed: all of the plots demonstrated a strikingly similar threshold run‐off response to the cumulative precipitation amount. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

南水北调中线河北段膨胀土特性及改性试验研究     

邢忠信  刘增寿  周海军 《华北地质矿产杂志》1999,(2)

本文通过对南水北调中线总干渠河北段穿越地带膨胀岩土的勘查研究,总结了该区膨胀岩土成因、成分及结构特征,对其胀缩特性以及相关因素进行了分析探讨,并提出了其对南水北调中线工程不良地质现象的防治措施。阐述了用生石灰改良本区膨胀岩土的试验方法和效果。  相似文献   

Hazardous earth processes in parts of Bauchi State,Nigeria: Their causes and environmental implications     

D. M. Orazulike 《Natural Hazards》1988,1(2):155-160

The August 1985 crack has focussed attention on passive earth processes in parts of Bauchi State, Nigeria. These processes, encompassing groundwater solution and roof collapse, soil shrink-swell, and gullying, are widespread in the Akko, Gombe, and Bauchi Local Government Areas (LGAs) of the State. Soils in these areas are rich in montmorillonite clay minerals and possess appreciable shrink-swell capabilities. Surface heave ranges from 8.1 to 11 cm. Preliminary data on plasticity measurement show a plasticity index (PI) of 13.4 to 15%. Consequently, in response to seasonal changes, the soil usually splits, leaving gaping cracks. These cracks, once formed, constitute channels throug which meteoric water easily penetrates the bedrock. The water is chemically acid and the underlying bedrock contains layers of limestone and shale. Systematic solution of these chemically reactive rocks results in the formation of caverns, the roof of which may ultimately collapse leaving randomly distributed sink holes. These cracks and sink holes run through villages, destroying mud buildings, which often collapse overnight, and transforming most modern block buildings into death traps. They affect roads, bridges, and other foundations, and render farmlands waste, swallowing up livestock.The expansive soil processes, solution and roof collapse phenomena currently identified in these places, are passive phenomena and have been overlooked as geologic hazards. Preliminary results of investigations on the physical and chemical properties of the soils and underlying rocks indicate that these areas of Bauchi State of Nigeria need to be monitored closely to avert disaster.  相似文献   

冻结凿井中冻结壁位移规律及影响因素的研究   总被引：6，自引：0，他引：6  

马英明  郭瑞平 《冰川冻土》1989,11(1):20-33

  相似文献