粤东海涂土壤及其利用     

张希然 《云南地理环境研究》1990,2(1):72-81

粤东海岸东起闽粤交界的大埕湾,西迄深圳市的大鹏湾,岸线曲折,港湾较多,河溪人海泥沙在潮间带及紧邻5m 等深线以内形成大片海涂,土壤类型多样,以泥质和沙泥质土壤为主;除河口湾的土壤含盐量低外,其余较高;土壤有机质含量中等,钾素较丰富,磷素较低。因地处亚热带南缘,光、热和水资源条件较好,且多数海湾有深入内地的小海湾和潮沟,甚适合发展海水养殖与晒盐,韩江口的义丰河和海门龟头海大闸外等滩地尚有围垦价值。多处海湾潮滩沙土适合作海滨浴场,也有小片滩地红树林适合旅游观赏。  相似文献   

Spatial measurements of stream baseflow,a relevant method for aquifer characterization and permeability evaluation. Application to a hard‐rock aquifer,the Oman ophiolite     

B. Dewandel  P. Lachassagne  A. Qatan 《水文研究》2004,18(17):3391-3400

The structure, functioning and hydrodynamic properties of aquifers can be determined from an analysis of the spatial variability of baseflow in the streams with which they are associated. Such analyses are based on simple low‐cost measurements. Through interpreting the hydrological profiles (Q = f(A)) it is possible to locate the aquifer(s) linked to the stream network and to determine the type of interrelated flow, i.e. whether the stream drains or feeds the aquifer. Using an analytical solution developed for situations with a positive linear relationship, i.e. where the baseflow increases linearly with increasing catchment size, it is also possible to estimate the permeability of the aquifer(s) concerned at catchment scale. Applied to the hard‐rock aquifers of the Oman ophiolite, this method shows that the ‘gabbro’ aquifer is more permeable than the ‘peridotite’ aquifer. As a consequence the streams drain the peridotites and ‘leak’ into the gabbro. The hydrological profiles within the peridotite are linear and positive, and indicate homogeneity in the hydrodynamic properties of these formations at the kilometre scale. The permeability of the peridotite is estimated at 5 · 10^?7 to 5 · 10^?8 m/s. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

STUDY ON THE INTERACTION BETWEEN NDVI PROFILE AND THE GROWING STATUS OF CROPS   总被引：5，自引：1，他引：4  

JIANGDong WANGNai-bin YANGXIao-huan WANGJi-hua 《中国地理科学(英文版)》2003,13(1):62-65

Daily and ten-day Normalized Difference Vegetation Index(NDVI) of crops were retrieved from meteorological statellite NOAA AVHRR images ,The temporal variations of the NDVI were analyzed during the whole growing season,and thus the principle of the interaction between NDIV profile and the growing status of crops was discussed,As a case in point,the relationship between integral NDVI and winter wheat yield of Henan Province in 1999 had been analyzed.By putting integral NDVI values of 60 sample counties into the winter wheat yield-integral NDVI coordination,scattering map was plotted. It demonstrated that integral NDVI had a close relation with winter wheat yield.These relation could be described with linear,cubic polynomial ,and exponential regression,and the cubic polynomial regression was the best way,In general ,NDVI reflects growing status of green vegetation ,so crop monitoring and crop yield estimation could be realized by using remote sensing technique on the basis of time serial NDVI data together with agriculture calendars.  相似文献   

On salinity regimes and the vertical structure of residual flows in narrow tidal estuaries     

D. Prandle 《Estuarine, Coastal and Shelf Science》1985,20(5):615-635

An examination is made of the circulation in narrow estuaries subject to a predominant tidal forcing. Velocity structures are derived separately for residual flow components associated with (a) river flow, (b) wind stress, (c) a well-mixed longitudinal density gradient and (d) a fully stratified saline wedge. Dimensionless parameters are introduced to indicate the magnitude of each component and these parameters are evaluated for 9 major estuaries, thereby revealing their sensitivity to each component.For a channel of constant breadth and depth, formulae are deduced for the length of saline intrusion, L. Comparisons with observed data show that such formulae may be used with confidence to predict changes in L arising from variations in river flow, tidal range or channel depths.The level of stratification is shown to be related to a product of two parameters, one associated with velocity structure and a second involving the square of the ‘flow ratio’ $\text{u}\text{u}\text{?}$ (i.e. residual velocity/amplitude of the tidal velocity). This relationship provides a simple classification system for estuarine stratification which can be used to indicate the sensitivity of any particular estuary to changing conditions.  相似文献   

VERTICAL PROFII,ES OF CHL-A AND PRIMARY PRODUCTIVITY IN THE MIDDLE CONTINENTAL SHELF AREA AND EDDY AREA OF THE EAST CHINA SEA     

Wu Yu-lin  Zhou Cheng-xu  Zhang Yong-shan 《中国海洋湖沼学报》2002,20(1):74-80

Vertical profiles of chl-a and primary productivity in the middle continental shelf area and eddy area of the East China Sea were studied using data from a cruise in the East China Sea in February to March, 1997 and a cruise in July, 1998. The results showed that chl-a vertical distribution closely related to in situ hydrological and nutrient conditions. Chla-a concentration ranged from 0.22 to 0.35 mg/m³ and 0.93–1.09 mg/m³ in the eddy area and in the middle continental shelf area, respectively. In both areas, chl-a concentrations in deep layers were slightly higher than those in shallow layers, but was of the same order of magnitude. In summer, when a thermocline existed in the water column, highest chl-a concentrations appeared at the base of the thermocline layers in both areas. In the eddy area, chl-a concentration maximized at 31.743 mg/m³, and averaged 1.143 mg/m³ below 30 m depth. In the middle continental shelf area, the highest chl-a concentration was 2.120 mg/m³, the average was 1.168 mg/m³. The primary productivity reached 1418.76 mgC/(m²·d) in summer and 1360.69 mgC/(m²·d) in winter. In the eddy area, the primary productivity was 787.50 mgC/(m²·d) in summer and 159.04 mgC/(m²·d) in winter. Vertical carbon sinking rate from the deep layer to the bottom in both areas is also discussed in this paper. Contribution NO. 4183 from the Institute of Oceanology, Chinese Academy of Sciences. Project No. 49636210 supported by NSFC.  相似文献   

RETRACTION: Numerical simulation of a wind-sand flow under different conditions of atmospheric stability     

LÜ PING  ZHIBAO DONG 《Sedimentology》2008,55(3):721-721

A theoretical model for wind‐sand flow is developed by considering the coupling between wind flow and sand particle motion, the latter subject to the Magnus effect, under different atmospheric stability conditions. Using this model, the characteristics of the wind‐sand flow are discussed in detail. The results show that the atmospheric stability and the Magnus effect both have a strong influence on wind profiles and on the trajectories of sand particles. This approach produces results with characteristics that differ from those previously reported; the latter only applying to atmospheric conditions of neutral stability. The saltating sand reaches a greater height under non‐neutral stability than under neutral stability, while the maximum horizontal distance is greater under unstable conditions and is smaller under stable conditions than under conditions of neutral stability.  相似文献   

Field observations of waves generated by passing ships: A note     

A.F. Velegrakis  M.I. VousdoukasA.M. Vagenas  Th. KarambasK. Dimou  Th. Zarkadas 《Coastal Engineering》2007

This short contribution reports the results of a field study on the nearshore characteristics of waves generated by both conventional and high speed passenger ferries. The field observations took place in the late summer of 2005, at a beach close to the port of Mytilene (Island of Lesbos, Greece), and involved the visual observation of ship waves, using digital video recordings and image processing techniques. The results showed that passage of the fast ferry was associated with a longer, more complex and energetic nearshore event; this event not only did include higher nearshore waves (up to 0.74 m) and was organised in different wave packets, but it was also an order of magnitude longer (∼ 680 s) than the conventional ferry event. Regarding the effects on beach sediment dynamics, the fast ferry waves were estimated to be very efficient in mobilising the nearshore sediments in contrast to those of the conventional ferry. The fast ferry service appears to generate daily prolonged nearshore events, which contain waves with higher energy than those expected from the normal summer wind wave regime of the area; these events also include some high and very steep waves, which can be particularly erosive. Therefore, fast ferry wakes may have considerable impacts on the seasonal beach sediment dynamics/morphodynamics and the nearshore benthic ecology, as well as they may pose significant risks to bathers, affecting the recreational use of the beaches exposed to fast ferry traffic. Finally, the study has shown that satisfactory field observations of the nearshore characteristics of ship-generated (and wind) waves can be obtained using inshore deployments of calibrated poles, digital video cameras and appropriate image processing algorithms.  相似文献   

A Computational Model for Velocity Separation in Shallow Sea   总被引：1，自引：0，他引：1  

SONG  Zhiyao 《中国海洋工程》2002,16(3):407-413

Based on the hydrodynamical feature and the theoretical velocity profiles of tidal flow and vvind-induced flow in shal-low sea, a computational model is established for the first time, which can separate observed velocity into tidal velocity and wind-induced velocity by use of the least square method. With the model, not only the surface velocities of tidal flow and vvind-induced flow are obtained, but also the bed roughness height is determined and the wind velocity above the wa-ter surface is estimated. For verification of the model, the observed velocity in the Yellow River Estuary and the laborato-ry test is separated, then it is applied to the Yangtze River Estuary. All the results are satisfactory. The research results show that the model is simple in method, feasible in process and reasonable in result. The model is a valid approach to analysis and computation of field dala, and can be applied to separate the observed velocity in shallow sea; at the same time, reasonable boundary conditions of th  相似文献   

沃克环流上升区赤道低空强西风带的分析     

李若钝  于惠苓  刘丽惠  孙瑞本  井传才  苏新锁 《热带海洋学报》1995,(1)

采用ＴＯＧＡ／ＣＯＡＲＥ国际合作考察期间（１９９２年１０月─１９９３年２月）获得的２６７次定点（２°Ｓ，１５５°Ｅ）定时高空大气探测资料，进行计算分析，发现１９９２年１２月─１９９３年２月低空存在一支西风急流，有两次分别持续半月之久，而１９９２年１１月的两次赤道西风急流，因无赤道高空急流配合，仅持续２ｄ便消失。本文还指出：（１）赤道低空西风急流是各种海－气指数产生ＥＮＳＯ异常的重要信息；（２）赤道高空急流有滞后赤道低空急流２ｄ左右的响应关系；（３）赤道低空急流是纬向水汽输送的狭窄通道。  相似文献   

Formation of Equilibrium Beach Profile of the Abandoned Yellow River Delta Coast in North Jiangsu     

XU  Min 《中国海洋工程》2001,(1):139-146

The abandoned Yellow River Delta coast is a typical erodible silty and muddy coast in China. The paper analyses the marine dynamic characteristics and the mechanism of beach erosion of this area. Analysis and calculation show that in this sea area wave and tidal current action should be considered. Based on the above analysis, an equilibrium beach profile calculation model is developed, in which the wave-current interaction is considered while sediment supply and sediment re-deposition are neglected. The model consists of four parts: (1) calculation of wave parameters, (2) calculation of velocity due to wave-current interaction at different water depth, (3) calculation of friction velocity and shear stress at different water depths, and (4) calculation of the amount of sediment erosion, erosion intensity and variation of beach profile. Calculated results are in good agreement with observed data. Finally, the evolution tendency is discussed and the equilibrium beach profile of this coast is calculated. B  相似文献