• The Journal of Engineering Geology
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• v.14 no.4 s.41
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• pp.391-400
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• 2004

Excess pumping on the river bank filtration well causes the over drawdown in the protected area of bank, which may make many problems such as soil water contents, Pumping head in the irrigated land, and it needs more irrigation and development of the deeper irrigating well. In this study the installation of the artificial recharging well was suggested to reduce the excess draw down in the protected land. Artificial recharging wells were applied at the bank filtration site of Changwon city by using Visual-MODFLDW. The optimized conditions are calculated that the recharging well is located about loom apart from the pumping well, and the recharging rate is $5\%$ of the pumping yield.

• The Journal of Engineering Geology
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• v.20 no.1
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• pp.61-70
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• 2010

In case of groundwater recharge estimation using water table fluctuation method, specific yield affects the accuracy and confidence level of recharge rate. Nevertheless, there have been few studies on the method for the accurate estimation of specific yield in Korea. Specific yield estimated from the relationship between rainfall and groundwater levels is reasonable compared to the other methods. However, lots of factors such as artificial pumping, evapotranspiration by the plants, and a sudden increase in water levels by a heavy rainfall can affect the pattern of groundwater levels' fluctuation and make an over-estimated or under-estimated specific yield. This study obtained a reasonable specific yield by using a daily or 12 hourly average of rainfall and groundwater levels measured in a dry season.

• Journal of Korea Water Resources Association
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• v.37 no.6
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• pp.499-507
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• 2004

In this study, the fully coupled SWAT-MODFLOW model is developed by using the type of embedment MODFLOW in SWAT. Since SWAT model has semi distributed features, its groundwater component can't consider distributed parameters such as hydraulic conductivity, storage coefficient and spatially variable natures such as distribution of groundwater heads and pumping rate and so forth. The main purpose of this study is to overcome these limitations. This linkage is completed considering the interaction between stream network and aquifer to reflect boundary flow. To correspond HRU in SWAT to grid in MODFLOW, HRU-GRID conversion tool using DEM is newly suggested. As groundwater recharge of MODFLOW can be estimated accurately by SWAT model, the reliability of groundwater discharge and total runoff of watershed could be greatly enhanced.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.244-244
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• 2015

Managed Aquifer Recharge (MAR) in the form of Aquifer Storage and Recovery (ASR) systems are being applied for numerous water augmentation projects both in developed and developing countries. Given the onset of Climate Change and its influence on weather patterns and land use, it has been acknowledged the utilization of this technology will be ever increasing. This technique like all others does have its drawbacks or disadvantages, whereby to overcome these drawbacks or disadvantages it is recommended that logical planning process be followed. In this study, we developed a decision framework known as "Decision framework for the planning, designing, construction/testing and implementation of subsurface water storage system" to further standardize the planning and design process of subsurface water storage system to increase the probability of having a successful ASR/ASTR project. The formulation of this framework was based on earlier frameworks, guidelines, published papers and technical reports which were compiled into a data collection database. The database of which consider both qualitative and quantitative aspect for example recharge objectives, site location, water chemistry of the native, source and recovered water, aquifer characteristics(hydraulic conductivity, transmissivity, porosity), injection/pumping rate, ecological constraints, societal restrictions, regulatory restrictions etc. The assimilation of these factors into a singular framework will benefit the broad spectrum of stakeholder as it maps the chronological order under which ASR project should be undertaken highlighting at each stage the feasibility of the project. The final stage of which should result in fully operational ASR system. The framework was applied to two case studies and through the application of a modified ASR site selection suitability index (Brown et al., 2005) a score was derived to identify the performance of each site. A high score of which meant a maximize chance of success given the reduce presence of project constraints.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.11-18
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• 2018

The climate change impacts on hydrological components and water balance in Jeju Island were evaluated using multiple climate models and watershed model, SWAT-K. To take into account the uncertainty of the future forecast data according to climate models, climate data of 9 GCMs were utilized as weather data of SWAT-K for future period (2010-2099). Using the modeling results of the past (1992-2013) and the future period, the hydrological changes of each year were analyzed and the precipitation, runoff, evapotranspiration and recharge were increasing. Compared with the past, the change in the runoff was the largest (up to 50% increase) and the evapotranspiration was relatively small (up to 11% increase). Monthly results show that the amount of evapotranspiration and the amount of recharge are greatly increased as the amount of precipitation increases in August and September, while the amount of evapotranspiration decreases in the same period. January and December showed the opposite tendency. As a result of analyzing future water balance changes, the ratio of runoff, evapotranspiration, and recharge to rainfall did not change much, but compared to the past, the runoff rate increased up to 4.3% in the RCP 8.5 scenario, while the evapotranspiration rate decreased by up to 3.5%. Based on the results of other researchers and this study, it is expected that rainfall and runoff will increase gradually in the future under the assumption of present climate change scenarios. Especially summer precipitation and runoff are expected to increase. As a result, the amount of groundwater recharge in Jeju Island will increase.

• Journal of Environmental Science International
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• v.22 no.5
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• pp.523-531
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• 2013

In this study, a method of simulating ephemeral stream runoff characteristics in Jeju watershed is newly suggested. The process based conceptual-physical scheme is established based on the SWAT-K and applied to Cheonmi-cheon watershed which shows the typical pattern of ephemeral stream runoff characteristics. For the proper simulation of this runoff, the intermediate flow and baseflow are controlled to make downward percolation should be dominant. The result showed that surface runoff simulated by using the modified scheme showed good agreement with observed runoff data. In addition, it was found that the estimated runoff directly affected the groundwater recharge rate. This conceptual model should be continuously progressed including rainfall interception, spatially estimated evapotranspiration and so forth for the reasonable simulation of the hydrologic characteristics in Jeju island.

• Proceedings of the KSEG Conference
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• 2002.04a
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• pp.275-284
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• 2002

서울 북부지역에 위치하는 북한산 일대의 지역단위 지하수 함양량 산정에 대하여 물수지 분석법과 SCS-CN방법을 이용하였다. 물수지분석법에는 Coutagne 공식과 Turc 공식을, SCS-CN방법에는 직접유출율과 누가침투율을 계산하여 평균 지하수 함양량을 산정하였다. 물수지분석법인 Coutagne 공식과 Turc 공식에서 평균 21.36%가 지하수 함양량으로 산출되었다. SCS-CN 방법에서는 직접유출율과 침투율을 계산하여 산정한 결과 지하수함양량은 30.07%로 추정되었다. 여기서 북한산 일대의 기반암을 경계로 상당량이 기저유출(baseflow)의 형태로 유출되기 때문에, 기저유출량 10.9%을 제외한 19.17%를 순수 지하수함양량으로 결정하였다. 누가침투율을 이용한 지하수함양량은 약22.0%로 산정되었다. 물수지분석법과 SCS-CN 방법들을 이용하여, 북한산 지역의 지하수 함양량을 산출한 결과 평균 약 20.84%로 산정되었다.

• ETRI Journal
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• v.37 no.4
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• pp.804-812
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• 2015

Energy harvesting (EH) technology in the field of wireless sensor networks (WSNs) is gaining increasing popularity through removing the burden of having to replace/recharge depleted energy sources by energy harvester devices. EH provides an alternative source of energy from the surrounding environment; therefore, by exploiting the EH process, WSNs can achieve a perpetual lifetime. In view of this, emphasis is being placed on the design of new medium access control (MAC) protocols that aim to maximize the lifetime of WSNs by using the maximum possible amount of harvested energy instead of saving any residual energy, given that the rate of energy harvested is greater than that which is consumed. Various MAC protocols with the objective of exploiting ambient energy have been proposed for energy-harvesting WSNs (EH-WSNs). In this paper, first, the fundamental properties of EH-WSN architecture are outlined. Then, several MAC protocols proposed for EH-WSNs are presented, describing their operating principles and underlying features. To give an insight into future research directions, open research issues (key ideas) with respect to design trade-offs are discussed at the end of this paper.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.428-432
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• 2012

SWAT모형을 이용하여 악근천, 호근천, 동흥천을 대표 3개 유역으로 구분하여 1990년 토지이용상태에 1980년부터 1999년까지의 기상자료를 사용하였고 2000년 토지이용상태에 2000년부터 2010년까지의 기상자료를 적용하여 분석한 결과, 적용 기간 평균 지하수 함양률은 30%로 분석되었다. 이러한 연구결과는 기존의 제주지역 지하수 함양량 분석연구에서 나타난 40-50%보다 훨씬 적은 값으로 나타나고 있음을 알 수 있었다. 이 결과는 투수성 다공질 지층이 제주지역의 지질특성을 고려하더라도 개발형태가 비투수성 포장형태이고, 개발된다면 육지지역과 같은 지하수함양특성과 비슷할 수 밖에 없음을 알 수 있었다. 또한 Markov-chain을 이용하여 장래토지이용상태를 분석한 결과 장래의 토지이용은 2000년 현재에 비해 산림 3.4%감소, 농경지 0.2% 증가, 수계 1.0% 증가, 도심지 0.5%증가 하는 것으로 나타났다. 토지이용상태에 따른 SWAT모형 분석을 비교한 결과 현재에 비해 유출량은 평균 22mm 증가하였으며, 증발산량은 평균 5mm감소, 함양량은 평균15mm감소하여 0.7% 정도 감소하는 것으로 토지이용상태가 함양량에 영향을 미치는 것으로 분석되었다.

• Proceedings of the Korea Water Resources Association Conference
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• 2018.05a
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• pp.275-275
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• 2018

본 연구의 목적은 지표수-지하수 통합 모델을 통해 모델 영역과 시설농업단지(밀양들)의 지표수/지하수 유동을 모의하고 모델 영역의 물수지 분석을 통해 지하수 함양량을 산정하는 것이다. 지표수 유동 모델 결과에서는 밀양강 상류(북동쪽)에서 하류(남동쪽)로 약 1~5 m의 수심으로 지표수가 유동하고 있으며, 모델지역 상류의 M01 지점에서는 지표수 유량 관측값과 모델값이 일치하고, 모델지역 하류의 M02 지점에서의 지표수 유량은 1% 정도의 차이를 보인다. 지하수 유동 모델에서는 지하수 심도가 하천에서는 표고와 유사하며 산림 지역으로 갈수록 높아지고, 지하수 양수를 고려한 지하수 심도는 모델값이 관측값보다 1.5 m 이내의 범위로 높게 나타난다. 지표수지하수 통합모델에서는 지하수의 함양 면적이 모델 면적의 90% 정도이고, 지하수 함양량은 $1.92{\times}105m^3/day$인 것으로 나타난다. 연평균 물수지 분석에서는 단위 면적당 지하수 함양량이 503.9 mm/year로서 연평균 강우량의 39% 정도로 추정된다.