• Water Engineering Research
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• 제5권4호
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• pp.185-193
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• 2004

Estimates of annual actual evapotranspiration are needed in water balance studies, water resources management projects, and many different types of hydrologic studies. This study validated a set of 5 empirical equations of estimating annual actual evapotranspiration with climate data on 11 watersheds, and evaluated the further applicability of these forms in estimating annual runoff on watershed level. Five empirical equations generally overestimated annual evapotranspiration, with relative errors ranging $3.3\%$ to $47.2\%$. The results show that Schreiber formula can be applicable in determining annual evapotranspiration in sub-humid region that is classified by aridity index, while Zhang equation gave better results than the remaining methods in humid region. The mean differences for annual evapotranspiration bias over 11 watersheds are Zhang, Schreiber, Budyko, Pike, and Ol'dekop formula from lowest to highest. The empirical equations provide a practical tool to help water resources managers in estimating regional water resources on ungauged large watershed.

• 한국수자원학회논문집
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• 제50권11호
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• pp.795-802
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• 2017

본 연구는 지하댐에 의한 수자원 개발량을 평가하는 방법론을 제시한다. 연구 대상지역으로 선택한 쌍천 지하댐은 동해안 쌍천유역 하구에 위치하며 비피압 충적 대수층을 형성하고 있다. 동해안에는 지형적으로 유사한 지하댐 후보지가 여러 개 존재한다. 본 연구에서는 대수층의 지하수위를 평면 2차원 FDM 모형으로 산출하였으며, 여기서 유역 유출은 대수층 표면에 침투항으로서 입력된다. 3개의 유역 유출모형의 평균으로서, 기저유량은 $0.5m^3/sec$로 산출되었다. 그리고 이 기저유량 근처의 유입량을 갈수기 유입으로 간주하여, 유입량 및 양수량 변화에 따른 지하수위를 산출하는 방법으로 수자원 개발량을 평가하였다. 구체적으로는 현재 속초시 생활용수를 공급하고 있는 실제 양수량($28,000m^3/day$)을 적용하여, 우물 수위가 대수층 바닥에 도달하거나 지하수위가 대수층 표면을 상회하여 지표수 흐름이 발생하는 유입량을 추정하였다. 또한 수자원 개발량을 증대시키기 위하여 우물의 양수량을 증가시키거나 추가 우물을 설치하는 상황을 재현하고, 극심한 갈수기에 가능한 양수량을 산출하였다.

• 한국농공학회지
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• 제45권7호
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• pp.94-106
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• 2003

A pilot study was performed to examine the feasibility of UV disinfection system and the reactivation of indicator microorganisms (TC, FC, E. coli) after UV irradiation for agricultural reuse of reclaimed water. Photoreactivation and dark repair enable UV-inactivated microorganisms to recover and may reduce the efficacy of UV inactivation, which might be drawbacks of the UV disinfection method. The effluent of biofilter for 16-unit apartment house was used as input to the UV disinfection system, and average SS and BOD concentration were 3.8 and 5.7 mg/L, respectively, and the mean level of total coliform was in the range of $1.0\times10^4$ MPN/100mL. UV disinfection was found to be effective and it reduced mean concentration of indicator microorganisms (total coliform, fecal coliform, and E. coli) to less than 100 MPN/100mL within 60s exposure using 17, 25, and 40W lamps. Two UV doses of 6 and 16 mW$\cdot$s/$\textrm{km}^2$ were applied and microorganisms reactivation was monitored under the dark, photoreactivating light, and solar irradiation. Microorganisms reactivation was observed in the UV dose of 6 mW$\cdot$s/$\textrm{km}^2$, and numbers increased up to 5% at the photoreactivating light and 1% at the dark. However, microorganisms were inactivated rather than reactivated at the solar radiation and numbers decreased to non-detectible level about below 2 MPN/100mL in 4 hours. In the case of 16 mW$\cdot$s/$\textrm{km}^2$, microorganism reactivation was not observed indicating that UV dose might affect the reactivation process such as photoreactivation and dark repair. Therefore, concerns associated with microorganism reactivation could be controlled by sufficient UV dose application. Agricultural reuse of reclaimed water might be even less concerned due to exposure to the solar irradiation that could further inactivate microorganisms. The pilot study result is encouraging, however, sanitary concern in water reuse is so critical that more comprehensive investigation is recommended.

• Journal of Animal Science and Technology
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• 제53권6호
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• pp.517-523
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• 2011

The experiment was conducted with 144 broiler chicks from day-old to 5 weeks of age to investigate the efficacy of a water additive in broiler production. The chicks were randomly distributed into four different treatments namely T1 (control), T2 (water additive as per recommendation level), T3 (25% less than recommendation) and T4 (25% more than recommendation). Body weight of control group was higher in 2nd week of age, but at the end of the experiment additive groups showed higher values compare to control (p<0.05). Body weight gain was increased and feed conversion ratio was improved in the additives groups during the finishing and total period, although feed intake was different among the additive groups (p<0.05). When the hematological parameters were evaluated, packed cell volume and total erythrocytes counts were increased in the additive group that received 25% more than recommendation, and hemoglobin in 25% less than recommendation group. Mean cell volume and mean cell hemoglobin of the additive groups showed lower (p<0.05) values compare to the control, but other parameters were not affected. Sales price and profit were significantly higher in the additive groups compare to the control, although total production cost was increased in the additive groups (p<0.05). All levels of water additive increased profit in comparison with the control but 25% less than recommendation level appeared to be most profitable and cost effective. It also suggests that any additive considered for poultry, must undergo trial for determining efficacy as well as its cost effectiveness for application.

• Ocean and Polar Research
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• 제27권4호
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• pp.433-441
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• 2005

To investigate the characteristics of tidal currents and water circulation in the coastal waters off the Taean Peninsula, tidal currents and sea levels were measured at the study area from 1998 to 2004. In the central waterway to the south of Changan Sand Ridge, mean speed of tidal currents and residual currents were 74.0cm/s, 17.8cm/s respectively; the dominant residual currents flowed northeastward, and the amplitudes of semi-diurnal components $(M_2,\;S_2)$ were larger than diurnal components $(O_1,\;K_1)$. The flood and ebb tidal currents were northeastward and southwestward, respectively, and each period was about 6 hours for them, which was consistent with the period of sea levels at the study area. In the coastal region near Hakampo, Taean, mean velocities of tidal currents and residual currents were 46.1cm/s, 30.8cm/s respectively, and the dominant residual currents flowed southwestward. The amplitudes of shallow water constituents $(M_4,\;MS_4)$ were relatively laige, which were weaker to the northeastern coastal region off Mineodo. The northeastward flow continued for about $2{\sim}3$ hours, while the southwestward flow continued for about $9{\sim}10$ hours near Hakampo during the tidal period. Tidal currents flowed northeastward in the central area of the waterway during the period from the Low Water Level (LWL) to the High Water Level (HWL). While the currents in the coastal region flowed northeastward for the first 3 hours after the LWL, southwestward counter-currents flowed between 3 and 6 hours after the LWL. During the period from the HWL to the LWL, the dominant currents flowed southwestward in the study area except to the northeastern coastal region off Mineodo. Along the shorelines, the counter-currents flowed northward between 4 and 6 hours after the HWL. It seems that the counter-currents near the coastal region are caused by the topography and the geography of the shorelines at the study area.

• 산업경영시스템학회지
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• 제37권1호
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• pp.91-95
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• 2014

During a flood season, Bo region could be easily exposed to flood due to increase of ground water level and the water drain difficulty even the water amount of Bo can be managed. GFI for the flood risk is measured by mean depth to water during a dry season and minimum depth to water and tangent degree during a flood season. In this paper, a forecasting model of the target variable, GFI and predictors as differences of height between ground water and Bo water, distances from water resource, and soil characteristics are obtained for the dry season of 2012 and the flood season of 2012 with empirical data of Gangjungbo and Hamanbo. Obtained forecasting model would be used for keep the value of GFI below the maximum allowance for no flooding during flooding seasons with controlling the values of significant predictors.

• 한국물환경학회지
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• 제30권6호
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• pp.673-682
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• 2014

A watershed model was constructed using Hydrological Simulation Program Fortran to predict the water temperature at major tributaries of Nakdong River basin, Korea. Water temperature is one of the most fundamental indices used to determine the nature of an aquatic environment. Most processes of an aquatic environment such as saturation level of dissolved oxygen, the decay rate of organic matter, the growth rate of phytoplankton and zooplankton are affected by temperature. The heat flux to major reservoirs and tributaries was analyzed to simulate water temperature accurately using HSPF model. The annual mean heat flux of solar radiation was estimated to $150{\sim}165W/m^2$, longwave radiation to $-48{\sim}-113W/m^2$, evaporative heat loss to $-39{\sim}-115W/m^2$, sensible heat flux to $-13{\sim}-22W/m^2$, precipitation heat flux to $2{\sim}4W/m^2$, bed heat flux to $-24{\sim}22W/m^2$ respectively. The model was calibrated at major reservoir and tributaries for a three-year period (2008 to 2010). The deviation values (Dv) of water temperature ranged from -6.0 to 3.7%, Nash-Sutcliffe efficiency(NSE) of 0.88 to 0.95, root mean square error(RMSE) of $1.7{\sim}2.8^{\circ}C$. The operational water temperature forecasting results presented in this study were in good agreement with measured data and had a similar accuracy with model calibration results.

• 한국농공학회지
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• 제31권1호
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• pp.117-130
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• 1989

In this study, an implicit one-dimensional model, DWRM(Dynamic Wave Routing Model) was developed by using the four-point weighted difference method. By applying the developed model to the Keum River, the parameters were calibrated and the model applicability was tested through the comparison between observed and computed water levels. In addition, the effects of the construction of an estuary dam to the flood wave were estimated as a result of the model application. The results of the study can be summarized as follows; 1. The roughness coefficients were evaluated by comparison between observed and computed water level at Jindu, Gyuam and Ganggyeung station in 1985. The Root Mean Squares for water level differences between observed and computed values were 0.10, 0.11, 0. 29m and the differences of peak flood levels were 0.07, 0.02, 0. 07m at each station. Since the evaluated roughness coefficients were within the range of 0.029-0.041 showing the realistic value for the general condition of rivers, it can be concluded that the calibration has been completed. 2. By the application of model using the calibrated roughness coefficients, the R. M. S. for water level differences were 0.16, 0.24, 0. 24m and the differences of peak flood level were 0.17, 0.13,0.08 m at each station. The arrival time of peak flood at each station and the stage-discharge relationship at Gongju station agreed well with the observed values. Therefore, it was concluded that the model could be applied to the Keum River. 3. The model was applied under conditions before and after the construction of the estuary dam. The 50-year frequency flood which had 7, 800m$^3$/sec of peak flood was used as the upstream condition, and the spring tide and the neap tide were used as the downstream condition. As the results of the application, no change of the peak flood level was showed in the upper reaches of 19.2km upstream from the estuary dam. For areas near 9.6km upstream from the estuary dam, the change of the peak flood level under the condition before and after the construction was 0. 2m. However considering the assumptions for the boundary conditions of downstream, the change of peak flood level would be decreased.

• 대한지리학회지
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• 제33권2호
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• pp.143-163
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• 1998

In order to clarify the depositional environment and sea-level change at Ilsan area including Gawaji and Saemal valley plains, which is located at the right side in downstream of the Han River, boring data, radiocabon dating and diatom analysis were comprehensively investigated. As a result, the palaeogeographies fo this area altered by the transgressions and regressions after 7,000 y. BP could be restored. The high tide sea-level(mean high water level of spring tide) was arrived ca. 7,000y. BP at the valley plain and risen to ca. 5.5m at ca. 5000y. BP. Since then, the sea-level was kept up the same level to ca. 3,200 BP. The descended sea-level to ca. 2,300 BP was risen up to ca. 5.8m in ca. 1,800 y. BP. It is presumed that such a sea-level change as well as the different sediments in quantity supplied from the river basin of the valley plain could be effected to change diversely the depositional environment of the study area and eventually to the prehistoric human life.

• 한국농공학회논문집
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• 제64권3호
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• pp.63-73
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• 2022

A more accurate understanding of the irrigation water supply is necessary for efficient agricultural water management. Although we measure water levels in an irrigation canal using ultrasonic water level gauges, some errors occur due to malfunctions or the surrounding environment. This study aims to apply CNN (Convolutional Neural Network) Deep-learning-based image classification and segmentation models to the irrigation canal's CCTV (Closed-Circuit Television) images. The CCTV images were acquired from the irrigation canal of the agricultural reservoir in Cheorwon-gun, Gangwon-do. We used the ResNet-50 model for the image classification model and the U-Net model for the image segmentation model. Using the Natural Breaks algorithm, we divided water level data into 2, 4, and 8 groups for image classification models. The classification models of 2, 4, and 8 groups showed the accuracy of 1.000, 0.987, and 0.634, respectively. The image segmentation model showed a Dice score of 0.998 and predicted water levels showed R² of 0.97 and MAE (Mean Absolute Error) of 0.02 m. The image classification models can be applied to the automatic gate-controller at four divisions of water levels. Also, the image segmentation model results can be applied to the alternative measurement for ultrasonic water gauges. We expect that the results of this study can provide a more scientific and efficient approach for agricultural water management.