• The Journal of Engineering Geology
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• v.26 no.3
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• pp.361-370
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• 2016

This study was performed in order to evaluate the efficiency of groundwater well installed in alluvial aquifer that has filter layers, using laboratory experiment. We manufactured test equipment that can simulate dual filter layer and single filter layer and evaluated the initial volume of water intake, pumping efficiency, and long term stability using the experiment and analysis. In an early stage within 60 minutes, the case that took the dual filter showed an increase of 19.4 % in the initial volume of water intake compared to the case without it. It was found that after 24 hours of the test, the well installed with the dual filter showed higher than 68.9% compared to the well with single filter. It was calculated that it took 1.35 days to reach the point corresponding to the half of the water intake in case of single filter while it took 38.66 days to do so in case of dual filter. Therefore, it is highly recommended that the well with dual filter is much more favorable in the long term stability.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.1-6
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• 1983

The results of COLE(Coefficient of Linear Extensibility) measurement on various paddy soils in Korea are summarized as follows; 1. The COLE values of paddy soil in Korea varied from 0.024 to 0.094 in the surface soil while in the sub-surface soils those were ranging from 0.022 to 0.115. The poorer the relative drainage and the finer the texture caused, the greater the COLE values. 2. The matured clayey soils on fluvio-marine plains and local alluvium derived from the Tertiary materials have COLE values more than 0.09 which is demonstrated that the necessity of COLE measurement throughout profiles so that could be considered the characteristic in the characteristic of those soils. 3. The clay content has the highest positive correlation (r=0.81~0.76) values. The content of organic matter, water content at 1/3 bar, Atterberg limits, water stable aggregate etc. also have significant positive correlation with COLE values while the context of sand and silt show negative correlation. 4. Although the COLE values measured on horizontal linear bases were slightly greater than those measured on volume bases practicability was for granted. For more accurate measurement of COLE, it is reasonable to have the average values of COLE calculated from the horizontal and vertical bases.

• Economic and Environmental Geology
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• v.37 no.5
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• pp.459-475
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• 2004

The geology of the Kualakulun area in Middle Kalimantan, Indonesia comprises Permian to Carboniferous Pinoh Metamorphic Rocks and Cretaceous Sepauk Plutonics of the Sunda Shield, late Eocene Tanjung Formation, Oligocene Malasan Volcanics, Oligocene to early Miocene Sintang Intrusives and Quaternary alluvium. Sepauk Plutonic rocks are classified as the calc-alkaline series and the S-type granite. Sintang Intrusive rocks are basic-intermediate and intermediate rocks, and consists of basalt, basaltic andesite, basaltic trachyandesite and trachyandesite. The Malasan Volcanics are characterized by intermediate dacitic pyroclasticl and minor lavas and belong to the subalkaline (calc-alkaline and tholeiitic) series. The whole-rock K-Ar ages of the fine-grained biotite granites and medium-grained granitoids were determined to be 100.5-106.5 Ma and 91.9-102.6 Ma, respectively. The whole-rock K-Ar age of the diorite is 89.1 Ma. K-Ar ages of the Malasan Volcanics and Shintang intrusives show 31.5-36.8 Ma and 24.6-34.5 Ma, respectively, and correspond to the Tertiary time.

• Magazine of the Korean Society of Agricultural Engineers
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• v.25 no.4
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• pp.50-60
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• 1983

305 samples of alluvial deposit in inland and harbour districts were selected and consolidation charateristics of the alluvium were put in order statiscally. The correlations between them were as follows. 1. The relationships between LL(liguid limit) and Cc (compression index) were explained as Cc=0. 03(LL-21. 7) in case of inland district soil and as Cc=0. 019(LL-19) in case of harbour district soil. As compared with formular proposed by Skernpton, the gradient of this linear line was slight steep. 2. The relationships between PI(plastic index) and Cc were explained as Cc=0. 063 PI-0. 52 in case of inland district soil and Cc=0. 043 PI-0. 31 in case of harbour district soil. 3. As void ratio and natural moisture content were increased, Cc was increased, and as wet density was increased, Cc was decreased with a gentle curve. 4. As LL and P1 increased, mv(coefficient of volume compressibility) was increased but if LL and P1 was increased beyond a certain extend, mv has a tendency of constant value, that is, mv show a tendency to take constant value in the very soft clay. and mv in P=2. 5kg/cm$^2$ was about l${\times}$ l0-$^1$cm$^2$/kg in case of land district soil and 6x 10-$^1$crn$^2$/kg in case of harbour district soil lower than that in P=0. 25kg/crn2. 5. Cv(coefficient of consolidation) was a tendency to decrease with a gentle curve as LL was increased, and Cv in P=0. 25kg/crn2 was about 3x l0-$^1$crn$^2$/min larger than that in P=2. 5kg/crn$^2$. 6. Relationships between Py(pre-consolidation pressure) which is included over consolidation soil and ∑r1h(effective over-burden pressure) were explained as Py=l. 12 ∑r'h in case of land district soil and as Py=l. l5∑r'h in case of harbour district soil. 7. Some of the properties show good correlations between them, practical and effective applications of these correlations are expected in the planning and excution of soil investigation and also in the evaluation of the results.

• Journal of the Korean association of regional geographers
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• v.3 no.2
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• pp.19-35
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• 1997

The purpose of this study is to find out the characteristics of landform in Geoje-Do using GIS and DTED data. The characteristics of landform in Geoje-Do are as follows; First, the height-range of Geoje-Do is $0{\sim}580m$, and the average elevation of it is 124m. Volcanic and granite region is mainly appeared at high elevation-region. But, we can't find out outstanding difference of elevation, according to its geology. The second. the slope-range of Geoje-Do is $0{\sim}52$ degree, and the average slope of it is 17.6 degree. The slope of volcanic and granite area is more steeper than any other region. But the results of analysis of the geology in Geojo-Do, don't show outstanding difference of the slope. The third, the area-rate of the aspect of Geoje-Do is almost same in all direction. And the area-rate of south-west direction is the highest. According to the geology of Geoje-Do, granite is distributed the most widely, and the area of volcanic and granite occupy 60% of entire island's area. According to analysis of influence of geology with elevation, geology has little relationship with elevation. According to analysis of geology and drainage network, streams are inclined to be developed well in Alluvium area. Drainage network is well developed throughout the entire island, except southeast area. The highest order of stream is 4 in 1:25,000 topographic map. The density of stream in Geoje-Do is very high, such as 1.6. The bifurcation-ratio of stream is also higher than 4 in all order. The length-ratio of stream is ranged from 1.24 to 3.25. According to the relationship between order and elevation. order is the greater, elevation is the lower. According to the relationship between order and slope, order is the greater, slope is the gentler. In this study, we use DTED Data, and compare it with topographic map data. According to the comparison, there is a little difference between DTED data and topographic map data. Therefore, to use DTED data in landform analysis, it is required coordinate matching process. This process is very important, and take very long time. Thus, if you use DTED in landform analysis, some processes are required. DTED data can be taken very easily, but its using is not simple. Because coordinate adjust is very hard work.

• The Journal of Engineering Geology
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• v.22 no.2
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• pp.195-205
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• 2012

We evaluated the results of pumping tests, the amount of groundwater used by Protected Cultivation with Water Curtain (PCWC), and monthly depth to water table (DTW) at the Wangjeon-ri area, Nonsan City, to elucidate the cause of a decrease in pumping rate during the winter PCWC season. The transmissivity and storage coefficient at eight sites where the major aquifer is alluvium, vary from 119.9 to $388.1m^2/d$ and $1.5{\times}10^{-4}$ to $5.5{\times}10^{-4}$, respectively. The pumping rate for PCWC during three months (Dec. to Feb.) averaged about $8,100m^3/d$ and the maximum water level in the area varied by about 10 m. Groundwater levels had fully recovered by August-five months after pumping for PCWC had ceased. These observations indicate that the pumping rate during the winter PCWC season was excessive compared with groundwater productivity in the area. Groundwater level in the central PCWC area varied from -3.0 to 4.38 m, exceeding the water level of the Nosung Stream for only three months (Aug. to Oct.). This result indicates that Nosung Stream recharges the area during the period from November to July. To solve the problem of reduced pumping rate during the winter PCWC season, it would be necessary to reduce the amount of groundwater used for PCWC or to develop an artificial recharge system using recycled groundwater.

• Economic and Environmental Geology
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• v.53 no.3
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• pp.245-258
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• 2020

In this study, a data-driven response surface method using the results acquired from the numerical simulation is developed to evaluate the potential storage capacity of groundwater due to the construction of a groundwater dam. The hydraulic conductivities of alluvium and basement rock, depth and slope of the channel are considered as the natural conditions of the location for groundwater dam construction. In particular, the probability models of the hydraulic conductivities and the various types of geometry of the channel are considered to ensure the reliability of the numerical simulation and the generality of the developed estimation model. As the results of multiple simulations, it can be seen that the hydraulic conductivity of basement rock and the depth of the channel greatly influence to the groundwater storage capacity. In contrast, the slope of the channel along the groundwater flow direction shows a relatively lower impact on the storage capacity. Based on the considered natural conditions and the corresponding numerical simulation results, the storage capacity estimation model is developed applying an artificial neural network as the nonlinear regression model for training. The developed estimation model shows a high correlation coefficient (>0.9) between the simulated and the estimated storage amount. This result indicates the superiority of the developed model in evaluating the storage capacity of the potential location for groundwater dam construction without the numerical simulation. Therefore, a more objective and efficient comparison for the storage capacity between the different potential locations can be possibly made based on the developed estimation model. In line with this, the proposed method can be an effective tool to assess the optimal location of groundwater dam construction across Korea.

• The Journal of Engineering Geology
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• v.13 no.4
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• pp.457-474
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• 2003

This study aims to elucidate characteristics of groundwater level fluctuation at riverbank filtration sites in Daesan-myeon, Changwon City. Groundwater level fluctuation, river water level change and stream-aquifer interaction are very important to estimate optimal discharge rate of the pumping well. Water level contours from February 2003 to October 2003 show normal decreasing trend toward the Nakdong river with the hydraulic gradient of 0.008. However, flow reversion occurs when groundwater is discharged at the pumping wells or rise of the Nakdong river by rainfall. The fluctuation of the Nakdong river ranges 0 - 10 m msl. Autocorrelation analysis was conducted to the groundwater levels measured on the six monitoring wells (DS1, DS2, DS3, DS4, DS6 and DS7). The analyzed waterlevel data can be grouped into three: group 1 (DS1 and DS3) represents strong linearity and long memory effect, group 2 (DS1 and DS6) intermediate linearity and memory, and group 3 (DS4 and DS7) weak linearity and memory. Waterlevels of group 1 wells are relatively closely related to the change of river-water level. Those of group 2 wells are largely affected by the pumping and the river-water level, and those of group 3 wells are strongly linked to pumping.

• The Journal of Engineering Geology
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• v.16 no.2 s.48
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• pp.125-134
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• 2006

In order to establish the in-situ application of the artificial storage and recovery (ASR) technology which is used the property of the aquifer storage of groundwater. We carried out to the in-situ experiments such as borehole TV logging, pumping test and artificial hydraulic fracturing in volcanic island, Ulleungdo. In-situ experiments were conducted to divide the before- and after-hydraulic fracturing. Pumping test was achieved to confirm the two fracture zones, GL-13m and GL-21m, which are determined by the borehole TV logging. From the results of the before- and after-pumping tests, the hydraulic connectivity was confirmed to locate at GL-13m in the residual deposit zone of pumice media as alluvium. However, in the bedrock tone at GL-21m the hydraulic connectivity could be considered to faulty. Consequently, in this study area the artificial recharge has a little unsatisfied to geo-structural condition and desired to more detail investigation works.

• The Journal of Engineering Geology
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• v.12 no.4
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• pp.471-484
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• 2002

Alluviums in the Keum River watershed cover an areal extent of $3,029{\;}\textrm{km}^2$ and contain about 8.1 billion tons of groundwater. However, the waters are severely polluted by nitrate, possibly due to the application of nitrogen fertilizer (>250 N kg/ha) on agricultural land. This paper aims to elucidate the pollution status and behaviors of nitrate in alluvial groundwaters in the Keum River watershed area, based on regional hydrogeochemical study. Most of the collected samples (n = 186) are polluted by nitrate (average = 42.2 mg/L, maximum = 295 mg/L). About 29% of the samples have the nitrate concentrations exceeding Korean Drinking Water Standard (44 mg/L $NO_3$). The distribution of nitrate concentrations in the study area is largely dependant on geochemical environments of alluvial aquifers. In particular, the decrease of redox potential of alluvial groundwaters showed a good correlation with the decreases of nitrate, iron, and manganese concentrations. Thus, the change of redox state in alluvial aquifers, likely reflecting their sedimentary environments, controls both the behavior and fate of nitrogen compounds and their natural attenuation (denitrification) in aquifers. A carbon-rich, silty layer within alluvium strata forms a reducing condition and possesses a buffering capacity on nitrate pollution.