• The Korean Journal of Zoology
• /
• v.9 no.1
• /
• pp.1-6
• /
• 1966

Frequently , large masses of the young short necked clam, Tapes japonica , die at their tidal flats in summer and this phenomenon has not been explained clearly. The purpose of the present investigation is to study the thermal condition and the chlorinity level of tidal flats in which the young clam appears to be injured. A study is also mad efor the burrowing organism in the lower layer of the esturay over which the fresh water flow during the low tide. Observation are made at five places of the tidal flat near Ikawazu Fixheries Laboratory of Tokyo University during the ebb and flow tide period of the spring tide. The diurnal and monthly changes of tidal temperatures and chlorinities are measured. Results of the study are ; 1. The surface temperature of the tidal flat increases with the ebb tide, reaches the highest between 12-14PM, and gradually decreases thereafter. The temperatures of tidal flat below 5 and 10 cm increase gradually until the flow tide reaches the surface. 2. At the spring tide in summer , the diurnal change of surface of the tidal flat temperature is very extensive ; it reaches 37-39$^{\circ}C$ in August. At the depths of 5 and 10 cm the temperature remains at 33 $^{\circ}C$ and 31$^{\circ}C$ , respectively. 3. The chlorinity of the tidal flat is higher during May through June and lower July through August, and this seems to be related to the amount of rainfall. 4. The chlorinity of the surface of tidal flat increases slightly during the ebb and flow tide periods. The observed higher chlorinity of surface of the tidal flat was 18.82% Cl. 5. At near the esturay, the fresh water that overflows the tidal flat affects the chlorinity of the surface but no such influence to the depth of the flat. 6. From above observations, it is assumed that the young short necked clam in the tidal flat could be exposed to the severe change of environmental conditions. The high temperature of the tidal flat in summer and the low chlorinity of it at flood period may be considered as the change in environment.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.12 no.3
• /
• pp.202-208
• /
• 2009

In order to understand the circulation of nutrient between muddy tidal flat and the surrounding coastal area, tidal time-scale variations in nutrient concentrations were seasonally investigated at the entrance of Hampyeong Bay. The results show that the temperature was higher in ebb tide and lower in flood tide during the summer, but it was lower in ebb tide and higher in flood tide during the autumn/winter. The salinity was higher in flood tide and lower in ebb tide during the summer/winter because of the inflow of external sea water resulting from the increase in the tide level. By contrast, the salinity was lower in flood tide and higher in ebb tide during the autumn. Salinity difference was lower than 0.3 psu between flood tide and ebb tide during survey period. Meanwhile, all nutrient concentrations observed in Hampyeong Bay was lower in flood tide and higher in ebb tide during the summer, and by contrast, it was higher in flood tide and lower in ebb tide during the winter. Characteristically, no clear variation of concentrations was found depending on the tide level during the autumn. This tidal variations imply that the muddy tidal flat of Hampyeong Bay supplies nutrients to the seawater in summer and removes nutrient from the seawater in winter. During tidal cycle, seasonal variation of nutrient concentration in seawater is considered as the result of complex interactions between the mud flat and external sea water.

• Atmosphere
• /
• v.27 no.4
• /
• pp.399-409
• /
• 2017

The impact of land cover changed by tidal flats on local meteorology in Gyeonggi Bay was quantitatively evaluated based on a numerical modeling approach during 18 days (21 June to 9 July 2013). The analysis was carried out using three sets of simulation scenarios and the land cover of tidal flats for each simulation was applied as follows: (1) the herbaceous wetland representing coastal wetlands (i.e., EXP-BASE case), (2) the barren or sparsely vegetated representing low tide (i.e., EXP-LOW case), (3) the water bodies representing high tide (i.e., EXP-HIGH case). The area of tidal flats was calculated as about $552km^2$ (the ratio of 4.7% for analysis domain). During the daytime, the change (e.g. wetlands to water) of land cover flooded by high tide indicated the decrease of temperature (average $3.3^{\circ}C$) and the increase of humidity (average 13%) and wind speed (maximum $2.9m\;s^{-1}$). The changes (e.g. wetlands to barren or sparsely vegetated) of land cover induced by low tide were smaller than those by high tide. On the other hands, the effects of changed land cover at night were not apparent both high tide and low tide. Also, during the high tide, the meteorological change in tidal flats affected the metropolitan area (about 40 km from the tidal flat).

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.2 no.3
• /
• pp.1-9
• /
• 1999

This paper described the results of the characteristics of the near-bottom flow and field analysis of the tidal flats sediment. It was the aim of this paper to grasp current flow of tidal flat's environment and influence factor for environmental change forecast of tidal flats. Field measurement of water velocity, water elevation, bed materials test, and temperature distribution of tidal flat were conducted. Thereafter, current flow, turbidity and temperature distribution of tidal flat sediment have been discussed. The field research results showed that the fluctuating velocity near the seabed before and after its appearance at low tide was strongly affected by the wind wave. The resuspension of the sea-bottom sediment took place with great intensity before and after the appearance of the seabed at low tide. Both the sea water level and the weather condition were a significant influential factors. Such as, temperature and turbidity just on the surface and the shallow layer of seabed sediments were varied largely with time and weather conditions, but that its deeper layers was almost constant. Temperature on the seabed sediments was strongly influenced by irradiance and water depth. The temperature variation of the tidal flat and the variation characteristics of the current flow and turbidity depend greatly on the inhabiting environment of the tidal flat benthic organism.

• Korean Journal of Remote Sensing
• /
• v.8 no.2
• /
• pp.131-145
• /
• 1992

A low cost personal computer and image processing S/W were empolyed to derive Digtal Elevation Model(DEM) of tidal flat from multitemporal LANDSAT TM images, and to create three-dimensional(3D) perspective views of the tidel flat on Komso bay in west coasts of Korea. The method for generation of Digital Elevation Model(DEM) in tidal flat was considered by overlapping techniques of multitemporal LANDSAT TM images and interpolations. The boundary maps of tidal flat extracted from multitemporal images with different water high were digitally combined in x, y, z space with tide in formation and used as an inputcontour data to obtain an elevation model by interpolation using spline function. Elevation errors of less than $\pm$0.1m were achived using overlapping techniques and a spline interpolation approach, respectively. The derived DEM allows for the generation of a perspective grid and drape on the satellite image values to create a realistic terrain visualization model so that the tidal flat may be viewed from and desired direction. As the result of this study, we obtained elevation model of tidal flats which contribute to characterize of topography and monitoring of morphological evolution of tidal flats. Moreover, the modal generated here can be used for simulation of innudation according to tide and support other studies as a supplementary data set.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.21 no.6
• /
• pp.453-461
• /
• 2009

Camera monitoring of topographical changes of intertidal flat was performed at Daehang-ri mud flat outside Semangeum sea dike No. 1, where creation of mud flat was reported after sea dike construction. Ground survey on the mud flat is often limited only to points or few line surveys because of difficulty of walking and limitation of working hours by flood/ebb. This study uses natures of tide that the water lines moving on the intertidal flat during a flood indicate depth contours between low and high tide. Ground coordinates for the water lines extracted from the consecutive images of intertidal flat are calculated and information of topography is acquired by integrating all the water line data. Analysis of 6 camera monitoring data between September 2005 and September 2009 shows 0.127 m deposition per year on the average and variation of deposition/erosion in space and time.

• Journal of the Korean earth science society
• /
• v.23 no.7
• /
• pp.565-574
• /
• 2002

Based on previous investigations of aerial photographs and topographical surveys, this study focuses on the sedimentologic features of the Daebudo area including sedimentation processes, sedimentary facies and hydrologic conditions of the erosional coast. A total of 137 surface sediments and one core (by hand auger) sediment were obtained to interpret the depositional environment of the erosional coast in the macro-tidal coast. Surface sediments are distributed from sandy gravel (sG) to silt (Z). Textural parameters are characterized not only by coarse, poorly sorted, positive skewed and multi-modal distribution in the supra-tidal flat, but also finer, relatively well-sorted, symmetric distribution in the intertidal flat. According to the C/M diagram, sediment transport modes of study area are characterized by the mixed mode of suspension and bedload in the upper-, middle-tidal flat and by uniform suspension in the lower-tidal flat due to tidal effect. Vertical sediment distribution of the core, collected near shoreline, shows coarsening-upward, poorly sorted pattern by the input of detritus resulting from coastal erosion. Considering the sedimentological features of the study area, it appears to be composed of a coastal zone changed by not only artificial reclamation, but also by natural processes such as strong wave action due to typhoons and storms during high water level and long/short-term sea level rising. As a result, tide-dominated erosional coasts show that the shore is affected by local, temporal and hydrological conditions near high tide level and that the intertidal flat is represented by a general tide-dominated sedimentary environment.

• Proceedings of the KSRS Conference
• /
• 2004.10a
• /
• pp.148-151
• /
• 2004

In this study the micro landform of tide flat in west Seohan bay. North Korea was classified and the change of this environment was detected by using Landsat TM. FTM+, KOMPAST. For this. ISODATA method of the unsupervised methods was used to classify the micro landform while tasseled cap method was used to detect the change of environment in west Seohan bay, North Korea by passing years. This study shows the possibility that the topography analysis and change especially in unapproachable area could be detected and monitored by using satellite images.

• 한국해양학회지
• /
• v.20 no.1
• /
• pp.43-49
• /
• 1985

The Changgu Bay, a macrotidal coastal embayment of the west coast of Korea, is an area of extensive intertidal sedimentation. Three types of major sediment facies are identified based on grain size analysis: silt, sandy-silt, and silty-sand facies. It is found that intertidal sediment facies comprise a continuum of progressively finer sediments from lower flat to upper one. The X-radiography of the cores in the intertidal zone show a wide variety of physical and biogenic sedimentary structures. The major structures include bioturbation, current ripple and parallel-laminae. Bioturbations are observed in all core samples, especially in the silt flat zone. The degree of bioturbation increases laterally from sandy facies (low tide level) to silt facies (high tide level) due to favorable properties of fine mud for organisms. The ripple laminae, composed of current ripple foresets, characterize the silty-sand and sandy-silt flats. The parallel laminae are extensively bioturbated, and two types of laminae are distinguishable; thick-laminae with a thickness of 1 to 5mm and thin-laminae with a thickness of less than 1mm.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.28 no.1
• /
• pp.51-59
• /
• 1986

Through the hydraulic model test, a more convenient and accurate method of deter- mining discharge coefficients in the sluice type of tide gates can be derived by the use of aubmergence ratio as a parameter. The results obtained are summarized as follows; 1. Discharge coefficients under submerged flow conditions can be obtained by the application of sutmergerice ratio (S) to the free flow equation of the broad-erested we r. 2. The critical submergence ratios (Scr) for the flat basin and the broad-crested types of sill have the same value of 0.8. 3. Under free flow conditions, the discharge coefficient (m) are 0.37 and 0. 35 for the flat basin and the broad-crested types of sill respectively. However, when submerged flow condition exists, the discharge coefficients for both types of sill is given by a regression equation of discharge coefficients (IL) on submergence ratios (8) expressed as; m 1.3- 1. 17S. 4. The relationships between S and Froude number (Fr), for the flat basin and the broad-crested types of sill are Fr=2. 79-2.495 and Fr2.5=5. 7-6.16S respectively. From the above relationships, it can be concluded that m can also be expressed in terms of the Froude number which is a very relevant hydraulic parameter of the open channel hydraulics.