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1.
潮滩土壤含水量具有变化频率快、空间变化大的特征,是影响潮滩地表反射率的重要因素。潮滩土壤含水量的精确提取,可为潮滩特征地物信息遥感反演提供基础。本文利用江苏大丰王港潮滩4种典型沉积物、449组不同含水量对应的实测光谱曲线数据进行特征分析,构建高光谱预测模型,实现了潮滩沉积物含水量的遥感反演。研究结果表明:(1)在短波红外波段,沉积物含水量与反射率之间存在良好的分段线性相关关系,分段点对应的含水量分别为42%和62%;(2)1165nm、1336nm、1568nm和1780nm特征波段反射率,对含水量变化具有良好响应,由特征波段组合计算得到的差值水指数DWI、比值水指数RWI和归一化水指数NDWI与含水量呈显著线性相关,可有效改善单波段反射率与含水量之间的分段线性关系;(3)3个水指数中,DWI反演的含水量精度优于RWI和NDWI,且对不同含水量大小均有良好适应性,而RWI和NDWI更适合含水量变化范围中等的情况;(4)对于粉砂、砂质粉砂、粉砂质砂和砂4种沉积物类型,DWI1336,1780验证组模拟含水量与实测含水量的相关系数,分别为0.891、0.915、0.920和0.905,均方根误差分别为9.87%、3.56%、4.24%和2.98%,表明由DWI构建的高光谱遥感反演模型,可有效实现潮滩表层含水量的时空变化预测。 相似文献
2.
港口是物流供应链中的核心环节,港口服务效率会决定整个物流供应链的效率。本文提出了一种基于海量船舶AIS（Automatic Identification System）轨迹数据的港口服务效率计算框架,利用集装箱船舶AIS轨迹、港口地理信息等海事大数据,采用滑动窗口算法等数据挖掘方法判断船舶在港内的状态,估算出反映港口服务效率的AWT/AST指标,从时间维度对港口服务效率评价,为港口管理运营部门和航运公司决策提供参考。并以上海港、宁波港、深圳港、釜山港为例,采用2018年全年全球5600余艘集装箱船舶的AIS轨迹数据,量化评价4个亚洲集装箱港口的服务效率。结果显示:① 船舶抵港泊位作业时间近似正太分布,正太分布均值在14~18 h之间,船舶泊位作业时间集中在10~30 h;② 船舶泊位作业时间与船舶船型大小成正相关,船型越大则泊位作业时间越长;③ 32%的船舶抵达上海港会发生等待时间,体现上海港集装箱码头整体处于供不应求的状态。宁波港整体服务效率较高,船舶发生等待事件较少。作为区域性枢纽港,釜山港近洋区域性运输频繁使得釜山港抵港船舶频率较高。④ 洋山四期码头为自动化码头,其港口装卸工艺与其他码头不同,但其码头作业效率并未高很多。 相似文献
3.
顾及降雨及库水位因素的滑坡时滞分析与预测——以三峡库区新铺滑坡为例 总被引：1，自引：0，他引：1
降雨及库水位涨落是引起库岸滑坡形变失稳的主要诱发因素,但滑坡位移速率对此类诱发因素的响应具有一定的滞后性,影响人类对滑坡所处运动状态的判断与预测.针对常规预测模型中未考虑时滞效应的问题,利用三峡库区新铺滑坡的GNSS位移监测数据、奉节气象站降雨数据以及三峡库区库水位涨落数据,通过对监测区内9个GNSS监测点的位移速率序... 相似文献
4.
《中国海洋大学学报(英文版)》2015,(5)
This paper mainly analyzes the tidal characteristics and small-scale mixing process near Zhoushan Islands. First, the spectral analysis and wavelet analysis are adopted for the measured tide level data and tidal current data from the Zhoushan sea area, which indicate that the main tidal cycle near Hulu Island and Taohua Island is semi-diurnal cycle, the diurnal cycle is subordinate. Both their intensities are changed periodically, meanwhile, the diurnal tide becomes stronger when semi-diurnal tide becomes weak. The intensity of baroclinic tidal current weakens at first and then strengthens from top to bottom. Then, in this paper, the Gregg-Henyey(G-H) parameterization method is adopted to calculate the turbulent kinetic energy dissipation rate based on the measured temperature and tidal current data. The results of which shown that the turbulent kinetic energy dissipation rate around Hulu Island is higher than that around Taohua Island. In most cases, the turbulent kinetic energy dissipation rate during spring tide is larger than that during the neap tide; the turbulent kinetic energy dissipation rate in the surface layer and the bottom layer are higher than that in the intermediate water; the changes of turbulent kinetic energy dissipation rate and tidal current are basically synchronous. The modeled turbulent kinetic energy dissipation rate gets smaller with the increase of the stratification, however, gets larger with the increase of shearing. 相似文献
5.
Generally, tsunami waves become hazardous only when approaching the coast. Studying the runup and inundation of tsunami waves
is important for understanding the tsunami evolution and for tsunami hazard assessment. Here, we simulated the 1993 Hokkaido-Nansei-Oki
(HNO) tsunami using a finite-difference model based on nonlinear shallow-water equations. We focused on the runup and inundation
of tsunami wave propagation onto coastal area of Okushiri Island near Hokkaido, Japan, and investigate the relationship of
different runup heights with the morphology and bathymetry of the seashore. In the simulation, a nested 4-layer grid system
and moving boundary technique are adopted to study runup and inundation. The calculated tsunami heights and inundations in
the region agreed well with field measurements. The local bathymetric and topographic characteristics had a first-order effect
on the runup. Numerical experiments show that the focusing of certain local bathymetric features would amplify both wave height
and current velocity remarkably. The results show that computation on dense grids is necessary to reproduce the observed runup
heights, and inundation velocity is an important factor preventing tsunami devastation. In addition, we discussed the potential
capability of sediment transport to illustrate the impact of tsunami waves on coastal geomorphology. 相似文献
6.
地下水位预测对滑坡稳定性分析具有重要意义,三峡库区库岸滑坡地下水位时间序列在季节性强降雨和周期性库水位涨落等诸多因素影响下呈现混沌特征。在对地下水位序列进行相空间重构的基础上,采用饱和关联维数法和最大Lyapunov指数法对其混沌特征进行验证。再用预测性能优秀的最小二乘支持向量机(LSSVM)模型对其进行预测,并用粒子群算法优化选取LSSVM模型的参数,以克服LSSVM模型参数选取困难的缺点。以三峡库区三舟溪滑坡前缘STK-1水文孔日平均地下水位序列为例进行了混沌分析,分别运用粒子群优化的LSSVM模型(PSO-LSSVM)和BP神经网络模型对STK-1水文孔地下水位进行了预测。结果表明库岸滑坡地下水位序列存在混沌特征,PSO-LSSVM模型预测结果的均方根误差为0.193m,拟合优度为0.815,说明预测效果较理想,且PSO-LSSVM模型预测精度高于BP网络模型,具有较强的实用性。 相似文献
7.
THE RELATIONSHIP BETWEEN INLAND LAKES EVOLUTION AND CLIMATIC FLUCTUATION IN ARID ZONE 总被引：2，自引：0，他引：2
The evolution of the inland lakes in arid and semi-arid zones is accorded with the climatic fluctuation. The humid climate is in harmony with the higher water level and greater lake water quantity budget while arid climate is in correspondence with the lower water level and little water budget. Based on the analysis of the lake fluctuation and lake budget change, with the aid of the data of geom'orphology, palynology, sedimentology and chronology, It is found that the climate experienced a warm and humid period during 7000-3500 yr. B. P. and showed a drying and warming trend in the last century in the Central Asia. 相似文献
8.
Seismic surges and landslides are both major secondary mountain hazards during an earthquake. This paper investigates earthquake- and landslide-induced composite surges through large-scale shaking table water tank model experiments. A series of tests were conducted for various initial water depths, peak ground accelerations, slide impact velocities, and slide volumes. Based on the results of the tests, the effects of these parameters on the maximum wave heights of the earthquake- and landslide-induced composite surges were analyzed. An amplification coefficient of seismic surges was defined, and the prediction equation for the amplification coefficient was developed through non-dimensional multiple linear regression analysis. Then, an empirical equation for the maximum wave heights of the composite surges was developed based on the amplification coefficient and Demirel’s method. This equation provides a calculation method for earthquake- and landslide-induced composite surge waves. 相似文献
9.
延庆台五里营井泄流管憋气的影响及解决 总被引：2，自引：2，他引：0
延庆台五里营井动水位自2010年7月3日起,出现每日上下近50 cm的波动,气汞、气氡同时出现异常.经分析,此异常变化是由于该井泄流管最高端憋气造成.在泄流管最高点处开口排气,成功地解决了因泄流管憋气造成的干扰问题. 相似文献
10.
《山地科学学报》2019,(12)
Land creation projects have been implemented in China to expand urban space in mountainous areas. In addition to the predictable settlement brought about by filling construction,varying degrees of land subsidence and engineering failures have a demonstrated relationship to groundwater level fluctuation induced by land creation engineering. In this work, we adopted a typical large-scale land creation project, Yan'an New City in Shaanxi province, West China, as our study area. Prior to conducting the main experiment,preliminary field investigation and groundwater level monitoring were conducted to determine the groundwater fluctuation trend induced by land creation engineering. Although a blind drainage system was implemented, the depth aspect of groundwater level changes after large-scale land creation still needed to be addressed. To study the degree of impact and the settlement mechanism induced by the rising groundwater level, we conducted a Water Immersion Test(WIT) in a typical land creation site for 107 days. The rising groundwater level was simulated by injecting water from the bottom of the filling foundation. During the WIT, the soil water content, surface subsidence, and internal settlement of soil at different depths were obtained. Surface subsidence development could be categorized into four stages during the water level increase. The second stage, which is defined as the point when the groundwater level rises to 10 m,marked the critical point in the process. Furthermore,it was ascertained that the local settlement in regions that were originally composed of steep slopes is larger than that in originally flat areas. In addition, ground cracks and sinkholes in the study area were inspected;and it was determined that they would become new channels that would accelerate water infiltration and exacerbate the settlement. Based on the results from our field investigation and testing, several suggestions are proposed for land creation projects to mitigate issues associated with construction-induced groundwater level rising. 相似文献
11.
Significant wave height is an important criterion in designing coastal and offshore structures. Based on the orthogonality
principle, the linear mean square estimation method is applied to calculate significant wave height in this paper. Twenty-eight-year
time series of wave data collected from three ocean buoys near San Francisco along the California coast are analyzed. It is
proved theoretically that the computation error will be reduced by using as many measured data as possible for the calculation
of significant wave height. Measured significant wave height at one buoy location is compared with the calculated value based
on the data from two other adjacent buoys. The results indicate that the linear mean square estimation method can be well
applied to the calculation and prediction of significant wave height in coastal regions. 相似文献
12.
《中国海洋湖沼学报》2017,(6)
Using an improved FVCOM numerical model, combined with the momentum-sinking scheme based on the structural characteristics of specific turbines, this study analyzed the temporal and spatial distributions of tidal energy resources before and after the deployment of tidal turbines near Pingtan Island, China. Considering factors such as the distribution of tidal stream energy, bathymetry, topography, and the design parameters of the turbines, an appropriate location for a demonstration tidal turbine was selected and the corresponding energy resource was evaluated. Several sites with strong tidal streams were considered: south of the northern cape, east of the southern cape, and the southern end of Haitan Bay. The former was thought most suitable for the deployment of a tidal energy turbine, with projected power generation for approximately 470 h per month. The average power of this demonstration was about 2.4 k W, and the annual electricity output was approximately 17.47 MWh. The intervention of the turbine device had little influence on the near-field tidal stream or water level. The tidal stream was reduced slightly in the area south of the northern cape, although the ef fect weakened further from the turbine. Conversely, the velocity increased slightly on both sides of the demonstration site. The dif ference in current speed with and without the turbine was greater at slack tide than still tide. The influence of turbine operation on water level was minor. The method adopted in this study can be considered a reference for the selection of sites for the demonstration of tidal stream energy. However, the method is unable describe the dynamic characteristics of the turbulent flow surrounding the deployed turbines, which has an important role regarding the optimal designs of the turbine blade and pile foundations. Therefore, we will continue to work to improve this model in future research. 相似文献
13.
The sea area east of Chenshan Cape has peak tidal current flows that exceed 2.3 m s-1, which make it a promising site for the development of tidal current energy. Before these resources can be exploited, a comprehensive assessment is needed of the potential environmental impacts of the extraction of this energy. In this paper, we describe our construction of a three-dimensional hydrodynamic model of the waters near Chengshan Cape, and verify the performance of the model using continuous data measured in situ. We modeled the potential impacts of the exploitation of these resources on the flow field by adding a momentum loss term in the governing equation of the model. Simulation results show that an assumed tidal farm with an estimated power output of 20.34 MW would have a significant impact on the surrounding water level, especially next to the farm, where fluctuation could reach 6 cm. The maximum drop in the flow velocity in the wake of the farm was predicted to be more than 0.8 m s-1, and this influence would extend 10 km downstream. 相似文献
14.
In order to reach the designated final water level of 175 m, there were three impoundment stages in the Three Gorges Reservoir, with water levels of 135 m, 156 m and 175 m. Baishuihe landslide in the Reservoir was chosen to analyze its displacement characteristics and displacement variability at the different stages. Based on monitoring data, the landslide displacement was mainly influenced by rainfall and drawdown of the reservoir water level. However, the magnitude of the rise and drawdown of the water level after the reservoir water level reached 175 m did not accelerate landslide displacement. The prediction of landslide displacement for active landslides is very important for landslide risk management. The time series of cumulative displacement was divided into a trend term and a periodic term using the Hodrick-Prescott(HP) filter method. The polynomial model was used to predict the trend term. The extreme learning machine(ELM) and least squares support vector machine(LS-SVM) were chosen to predict theperiodic term. In the prediction model for the periodic term, input variables based on the effects of rainfall and reservoir water level in landslide displacement were selected using grey relational analysis. Based on the results, the prediction precision of ELM is better than that of LS-SVM for predicting landslide displacement. The method for predicting landslide displacement could be applied by relevant authorities in making landslide emergency plans in the future. 相似文献
15.
The current storm wave hazard assessment tends to rely on a statistical method using wave models and fewer historical data which do not consider the effects of tidal and storm surge.In this paper,the wave-current coupled model ADCIRC+SWAN was used to hindcast storm events in the last 30 years.We simulated storm wave on the basis of a large set of historical storms in the North-West Pacific Basin between 1985 and 2015 in Houshui Bay using the wave-current coupled model ADCIRC+SWAN to obtain the storm wave level maps.The results were used for the statistical analysis of the maximum significant wave heights in Houshui Bay and the behavior of wave associated with storm track.Comparisons made between observations and simulated results during typhoon Rammasun(2014)indicate agreement.In addition,results demonstrate that significant wave height in Houshui Bay is dominated by the storm wind velocity and the storm track.Two groups of synthetic storm tracks were designed to further investigate the worst case of typhoon scenarios.The storm wave analysis method developed for the Houshui Bay is significant in assisting government's decision-making in rational planning of deep sea net-cage culture.The method can be applied to other bays in the Hainan Island as well. 相似文献
16.
刘天仇 《中国地理科学(英文版)》1995,5(4):344-354
ＳＴＵＤＩＥＳＯＮＷＡＴＥＲＳＴＡＧＥＦＬＵＣＴＵＡＴＩＯＮＯＦＹＡＭＺＨＯＬＡＫＥＩＮＸＩＺＡＮＧＬｉｕＴｉａｎｃｈｏｕ（刘天仇）（ＴｉｂｅｔａｎＢｕｒｅａｕｏｆＷａｔｅｒＲｅｓｏｕｒｃｅａｎｄＨｙｄｒｏｌｏｇｉｃａｌＳｕｒｖｅｙ，Ｌｈａｓａ３５０... 相似文献
17.
The wave crest is an important factor for the design of both fixed and floating marine structures. Wave crest height is a
dominant parameter in assessing the likelihood of wave-in-deck impact and resultant severe damage. Many empirical and theoretical
distribution functions for wave crest heights have been proposed, but there is a lack of agreement between them. It is of
significance to develop a better new nonlinear wave crest height distribution model. The progress in the research of wave
crest heights is reviewed in this paper. Based on Stokes’ wave theory, an approximate nonlinear wave crest-height distribution
formula with simple parameters is derived. Two sets of measured data are presented and compared with various theoretical distributions
of wave crests obtained from nonlinear wave models and analysis of the comparison is given in detail. The new crest-height
distribution model agrees well with observations. Also, the new theoretical distribution is more accurate than the other methods
cited in this paper and has a greater range of applications. 相似文献
18.
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19.
《中国海洋湖沼学报》2019,(6)
In recent years, fast economic development demands for more land use and thus many reclamation projects are initiated around the Sanmen Bay, Zhejiang, SE China in the East China Sea, for which tidal and storm surge levels are reassessed. A two-dimensional numerical model based on an advanced circulation model(ADCIRC) was applied to evaluate the impact of reclamation projects on tidal and storm surge levels in the bay. The results show that the shoreline relocation and topographic change had opposite effects on tidal heights. Shoreline relocation decreased the tidal amplitude, while siltation caused topographic change and increased the amplitude. Such variations of the amplitude were significant in the top areas of Sanmen Bay. Three types of typhoon paths were selected for a case study to investigate the impacts of shoreline relocation and topographic change on storm surge level. Results show that the maximum increase in storm surge level due to shoreline relocation was less than 0.06 m. The rise of peak surge level due to the change of topography was significant and the peak surge level rose when siltation increased. The maximum surge level rise occurred in the path of northwest landing typhoons, which exceeded 0.24 m at the top of the bay. The rise in peak surge level can potentially lead to severe damages and losses in Sanmen Bay and more attention needs to be paid to this problem of shoreline change in the future. 相似文献
20.
《山东国土资源》是国内外公开发行的,以报道最新地质调查及矿产勘查的地学类期刊.该文根据万方数据提供的历年期刊引证数据,科技期刊的评价方法及基本计量指标,对《山东国土资源》的期刊现状进行了分析与评价,认为期刊应建立健全符合实际的审稿流程,建立健全专家库制度,捕捉地学热点,并与科研人员保持深入有效的联系. 相似文献