• Title/Summary/Keyword: Hydraulic diffusivity

Search Result 19, Processing Time 0.032 seconds

A Study on Estimation of Vertical Diffusivity in Fractured Bedrock Aquifer (단열암반 대수층에서 수직분산도 추정에 관한 연구)

  • 이진용;이강근;정형재;배광옥
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
    • /
    • 2000.11a
    • /
    • pp.247-250
    • /
    • 2000
  • This study focused on developing a convolution solution for estimating vertical diffusivity of a less permeable hydrogeologic unit in a bedrock aquifer. The diffusivity and corresponding hydraulic conductivity were estimated using the developed convolution equation. An application case was presented in this study.

  • PDF

Estimation of Hydraulic Characteristics and Prediction of Groundwater Level in the Eastern Coastal Aquifer of Jeju Island (제주도 동부 해안대수층의 수리특성 산정과 지하수위 예측)

  • Jo, Si-Beom;Jeon, Byung-Chil;Park, Eun-Gyu;Choi, Kwang-Jun;Song, Sung-Ho;Kim, Gi-Pyo
    • Journal of Environmental Science International
    • /
    • v.23 no.4
    • /
    • pp.661-672
    • /
    • 2014
  • Due to tidal force, it is very difficult to estimate the hydraulic parameters of high permeable aquifer near coastal area in Jeju Island. Therefore, to eliminate the impact of tidal force from groundwater level and estimate the hydraulic properties, tidal response technique has been mainly studied. In this study we have extracted 38 tidal constituents from groundwater level and harmonic constants including frequency, amplitude, and phase of each constituent using T_TIDE subroutine which is used to estimate oceanic tidal constituents, and then we have estimated hydraulic diffusivity associated with amplitude attenuation factor(that is the ratio of groundwater level amplitude to sea level amplitude for each tidal constituent) and phase lag(that is phase difference between groundwater level and sea level for each constituent). Also using harmonic constants for each constituent, we made the sinusoidal wave and then we constructed the synthesized wave which linearly combined sinusoidal wave. Finally, we could get residuals(net groundwater level) which was excluded most of tidal influences by eliminating synthesized wave from raw groundwater level. As a result of comparing statistics for synthesized level and net groundwater level, we found that the statistics for net groundwater level was more insignificant than those of synthesized wave. Moreover, in case of coastal aquifer which the impact of tidal force is even more than those of other environmental factors such as rainfall and groundwater yield, it is possible to predict groundwater level using synthesized wave and regression analysis of residuals.

Diffusion Characteristic of Ocean Dumping Material in the Southeaster Coastal Waters of Korea (동해 남동해역 해양투기물질의 확산 특성)

  • 홍도웅;김종규;류청로
    • Journal of Ocean Engineering and Technology
    • /
    • v.16 no.1
    • /
    • pp.16-22
    • /
    • 2002
  • The diffusion characteristics of an ocean dumping material in the south-eastern East/Japan Sea related to regulate the physical characteristics with the observation and the hydraulic experiment are investigated. The main results are as follows; (1) Spying CTD observation result of the area of Jung in the East/Japan Sea, the ocean dumping area had influenced the Tsushima Warm Current of high temperature and salinity. Horizontal turbulent diffusivity is 1.913$\times$10$^{7}$ by drogue tracking. (2) From the experiment of settling, the initial settling velocity of each material is 1.0~2.7 cm/sec according to the specific gravity and initial concentration. In the pycnocline, particles didn't settle under the pycnocline any more and accumulated. It is signified that calculation of the sedimentation rate of the ocean dumping material including of vertical diffusion must be regard the pynocline in the ocean area have well-developed pycnocline. (3) Vertical turbulent diffusivity were 2.219$\times$10$^{-8}$ ~8.874$\times$10$^{-4}$ cm$^2$/sec from the experiment of settling. And, the pycnocline influenced the vertical turbulent diffusivity.

A Study on Characteristic of Diffusion of the Ocean Dumping Material (해양투기물질의 확산 특성에 관한 연구)

  • 홍도웅;류청로
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
    • /
    • 2001.05a
    • /
    • pp.180-185
    • /
    • 2001
  • In order to regulate the physical characteristics of an ocean dumping material in the south-eastern East Sea, the diffusion characteristics with the observation, hydraulic experiment and numerical experiment data are investigated. The main results are as follows; (1) Spying CTD observation result of the area of Jung in the East Sea, the ocean dumping area had influenced the Tsushima warm current of high temperature and salinity. Horizontal turbulent diffusivity is 1.913${\times}$10$^{7}$ $\textrm{cm}^2$/sec by drogue tracking. (2) From the experiment of settling, the initial settling velocity of each material is 1.0∼2.7 cm/sec according to the specific gravity and initial concentration. In the pycnocline, particles didn't settle under the pycnocline any more and accumulated. It is signified that calculation of the sedimentation rate of the ocean dumping material including of vertical diffustion must be regard the pycnocline in the ocean area have well-developed pycnocline. (3) Vertical turbulent diffusivity were 2.219${\times}$10$^{-8}$∼8,874${\times}$10$^{-4}$ $\textrm{cm}^2$/sec from the experiment of settling. And, the pycnocline influenced the vertical turbulent diffusivity. (4) From the result of diffusion simulation in the East Sea, the co-concentration line of 0.05 ppm and 0.1 ppm are limited at dumping area after 200 days. The constant concentration line of 0.01 ppm is distributed to the vicinity of Ulleungdo and Tokdo, but isn't distributed to the coastal area of East Sea and southern area of Jung in the East Sea.

  • PDF

Pore Size Distribution and Chloride Diffusivity of Concrete Containing Ground Granulated Blast Furnace Slag

  • Moon Han-Young;Kim Hong-Sam;Choi Doo-Sun
    • Journal of the Korea Concrete Institute
    • /
    • v.16 no.2 s.80
    • /
    • pp.277-282
    • /
    • 2004
  • In a hardened concrete, diffusion of oxygen, carbon dioxide, aggressive ions, and moisture from the environment to the concrete takes place through the pore network. It is well known that making dense cement matrix enhances the durability of concrete as well as all the characteristics including strength of concrete. In this paper,9 mix concretes with water to cementitious material ratio (40,45, and $50\%$) and replacement ratio of GGBFS (40 and $60\%$ of cement by weight) were studied on the micro-pore structure by mercury intrusion porosimetry and the accelerated chloride diffusion test by potential difference. From the results the average pore diameter and accelerated chloride diffusivity of concrete were ordered NPC > G4C > G6C. It is concluded that there is a good correlation between the average pore diameter and the chloride diffusivity, and the mineral admixtures has a filling effect, which increases the tortuosity of pore and makes large pores finer, on the pore structure of cement matrix due to the latent hydraulic reaction with hydrates of cement.

Analysis of Hydraulic Gradient at Coastal Aquifers in Eastern Part of Jeju Island (제주도 동부지역 해안대수층의 조석에 의한 수리경사 변화 연구)

  • Kim, Kue-Young;Shim, Byoung-Ohan;Park, Ki-Hwa;Kim, Tae-Hee;Seong, Hyeon-Jeong;Park, Yun-Seok;Koh, Gi-Won;Woo, Nam-Chil
    • Economic and Environmental Geology
    • /
    • v.38 no.1
    • /
    • pp.79-89
    • /
    • 2005
  • Groundwater level changes in coastal aquifers occur due to oceanic tides, where the properties of oceanic tides can be applied to estimate hyadraulic parameters. Hydraulic parameters of coastal aquifers located in eastern part of Jeju island were estimated using the tidal response technique. Groundwater level data from a saltwater intrusion monitoring well system was used which showed tidal effects from 3 to 5 km. The hydraulic gradient was assessed by utilizing the filtering method from 71 consecutive hourly water-level observations. Calculated hydraulic diffusivity ranged from 2.94${\times}10^7m^2d^{-1}$ to 4.36${\times}10^7m^2d^{-1}$ . The hydraulic gradient of the coastal aquifer area was found to be ~$10^{-4}$, whereas the gradient of the area between wells Handong-1 and 2 was found to be ~$10^{-6}$, which is very low comparatively. Analysis of groundwater monitoring data showed that groundwater levels are periodically higher near coastal areas compared to that of inner land areas due to oceanic tide influences. When assessing groundwater flow direction in coastal aquifers it is important to consider tidal fluctuation.

Parameter estimation for identification on cause of drawdown around underground LPG storage cavern (지하 LPG저장공동 주변의 지하수위 강하 원인규명을 위한 파라미터추정)

  • Han, Il-Yeong;Lee, Dae-Hyuck;Lee, Jung-Eun;Jung, Kwang-Pil
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
    • /
    • 1998.11a
    • /
    • pp.76-80
    • /
    • 1998
  • In order to identify the cause of ground water drawdown of a piezometer installed around the LPG storage cavern, parameter estimations were conducted by inverse and forward numerical models. An inverse model, SK-EST developed by SK Engineering & Construction Co., Ltd.(SKEC,1997) was performed to estimate the change of the hydraulic conductivity. It was verified by the commercial forward model, AQUA3D (VATNASKIL,1995). The simulation results showed that the hydraulic diffusivity of the rock mass between the piezometer and the cavern had been increased and the change rate of the hydraulic head had been abruptly increased in response to the change of the operation pressure. Finally the statistical analysis for observed data showed the increase of the change rate of the hydraulic head and thus proved the applicability of SK-EST.

  • PDF

PARAMETER ESTIMATION PROBLEM FOR NONHYSTERETIC INFILTRATION IN SOIL

  • CHO, CHUNG-KI;KANG, SUNGKWON;KWON, YONGHOON
    • Journal of the Korean Society for Industrial and Applied Mathematics
    • /
    • v.4 no.1
    • /
    • pp.11-22
    • /
    • 2000
  • Nonhysteretic infiltration in nonswelling soil is modelled by the Burgers equation under appropriate physical conditions. For this nonlinear partial differential equation the modal approximation scheme is used for estimating parameters such as soil water diffusivity and hydraulic conductivity. The parameter estimation convergence is proved, and numerical experiments are performed.

  • PDF

Soil Water Diffusivity and Soil Water Stress Coefficient Studies Using Weighting Lysimeter Data (토양수분확산계수 측정과 자동측정리이시메타를 이용한 토양수분계수 추정)

  • Oh, Dong-Shig;Ayars, James E.;Soppe, Richard;Eom, Ki-Cheol
    • Korean Journal of Soil Science and Fertilizer
    • /
    • v.32 no.4
    • /
    • pp.344-356
    • /
    • 1999
  • A new and relatively simple equation for the soil water content-pressure head curve, ${\theta}$(h) is described in this paper. The particular form of the equation enables one to derive closed-form analytical expressions for the relative hydraulic conductivity, Kr, when substituted in the predictive conductivity models of Y. Mualem. Hopmans' equation is presented as an experimental method. The experienced method, $ET_a=K_sK_cET_o$ is introduced to estimate the actual evapotranspiration, $ET_a$(or $ET_c$). Using $ET_c$ and coil water data measured automatically in a weighing lusimeter, $K_s$ and $K_c$ values are estimated. Recently, FAO has introduced calculation procedures for the soil water(stress) coefficient, Ks in "Guidelines for computing crop water requirements".

  • PDF

DEVELOPMENT OF THE MULTI-DIMENSIONAL HYDRAULIC COMPONENT FOR THE BEST ESTIMATE SYSTEM ANALYSIS CODE MARS

  • Bae, Sung-Won;Chung, Bub-Dong
    • Nuclear Engineering and Technology
    • /
    • v.41 no.10
    • /
    • pp.1347-1360
    • /
    • 2009
  • A multi-dimensional component for the thermal-hydraulic system analysis code, MARS, was developed for a more realistic three-dimensional analysis of nuclear systems. A three-dimensional and two-fluid model for a two-phase flow in Cartesian and cylindrical coordinates was employed. The governing equations and physical constitutive relationships were extended from those of a one-dimensional version. The numerical solution method adopted a semi-implicit and finite-difference method based on a staggered-grid mesh and a donor-cell scheme. The relevant length scale was very coarse compared to commercial computational fluid dynamics tools. Thus a simple Prandtl's mixing length turbulence model was applied to interpret the turbulent induced momentum and energy diffusivity. Non drag interfacial forces were not considered as in the general nuclear system codes. Several conceptual cases with analytic solutions were chosen and analyzed to assess the fundamental terms. RPI air-water and UPTF 7 tests were simulated and compared to the experimental data. The simulation results for the RPI air-water two-phase flow experiment showed good agreement with the measured void fraction. The simulation results for the UPTF downcomer test 7 were compared to the experiment data and the results from other multi-dimensional system codes for the ECC delivery flow.