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The Theis equation is an important mathematical model used for analyzing drawdown data obtained from pumping tests to estimate aquifer parameters. Since the Theis model is a nonlinear equation, a complex graphical procedure is employed for fitting this equation to pump test data. This graphical method was originally proposed by Theis in the late 1930s, and since then, all the groundwater textbooks have included this fitting method. Over the past 90 years, every groundwater hydrologist has been trained to use this tedious procedure for estimating the values of aquifer transmissivity (T) and storage coefficient (S). Unfortunately, this mechanical procedure does not provide any intuition for understanding the inherent limitations in this manual fitting procedure. Furthermore, it does not provide an estimate for the parameter error. In this study, we employ the public domain coding platform Python to develop a script, namely, PyTheis, which can be used to simultaneously evaluate T and S values, and the error associated with these two parameters. We solve nine test problems to demonstrate the robustness of the Python script. The test problems include several published case studies that use real field data. Our tests show that the proposed Python script can efficiently solve a variety of pump test problems. The code can also be easily adapted to solve other hydrological problems that require nonlinear curve fitting routines.
Sun Chang; Sama Memari; T. Clement. PyTheis—A Python Tool for Analyzing Pump Test Data. Water 2021, 13, 2180 .
AMA StyleSun Chang, Sama Memari, T. Clement. PyTheis—A Python Tool for Analyzing Pump Test Data. Water. 2021; 13 (16):2180.
Chicago/Turabian StyleSun Chang; Sama Memari; T. Clement. 2021. "PyTheis—A Python Tool for Analyzing Pump Test Data." Water 13, no. 16: 2180.
Climate change and anthropogenic activities are necessitating accurate diagnoses of seawater intrusion (SWI) to ensure the sustainable utilization of groundwater resources in coastal areas. Here, vulnerability to SWI was assessed by classifying the existing GALDIT into static parameters (groundwater occurrence (G), aquifer hydraulic conductivity (A), and distance from shore (D)) and dynamic parameters (height to groundwater-level above sea-level (L), impact of existing status of seawater intrusion (I), and aquifer thickness (T)). When assessing the vulnerability of SWI based on observational data (2010–2019), 10-year-averaged data of each month is used for GALDIT dynamic parameter for representing the seasonal characteristics of local water cycles. In addition, the parameter L is indicated by the data observed at the sea-level station adjacent to the groundwater level station. The existing GALDIT method has a range of scores that can be divided into quartiles to express the observed values. To sensitively reflect monthly changes in values, the range of scores is divided into deciles. The calculated GALDIT index showed that the most vulnerable month is September, due to relatively low groundwater level. The proposed method can be used to apply countermeasures to vulnerable coastal areas and build water resources management plan considering vulnerable seasons.
Il Kim; Il-Moon Chung; Sun Chang. Development of Seawater Intrusion Vulnerability Assessment for Averaged Seasonality of Using Modified GALDIT Method. Water 2021, 13, 1820 .
AMA StyleIl Kim, Il-Moon Chung, Sun Chang. Development of Seawater Intrusion Vulnerability Assessment for Averaged Seasonality of Using Modified GALDIT Method. Water. 2021; 13 (13):1820.
Chicago/Turabian StyleIl Kim; Il-Moon Chung; Sun Chang. 2021. "Development of Seawater Intrusion Vulnerability Assessment for Averaged Seasonality of Using Modified GALDIT Method." Water 13, no. 13: 1820.
Augmenting water availability using water-harvesting structures is of importance in arid and semi-arid regions (ASARs). This paper provides an overview and examines challenges and prospects of the sand dam application in dry riverbeds of ASARs. The technology filters and protects water from contamination and evaporation with low to no maintenance cost. Sand dams improve the socio-economy of the community and help to cope with drought and climate change. However, success depends on the site selection, design, and construction. The ideal site for a sand dam is at a transition between mountains and plains, with no bend, intermediate slope, and impermeable riverbed in a catchment with a slope greater than 2°. The spillway dimensioning considers the flow velocity, sediment properties, and storage target, and the construction is in multi-stages. Recently, the failure of several sand dams because of incorrect siting, evaporation loss, and one-stage construction were reported. Revision of practitioners’ manuals by considering catchment scale hydrological and hydrogeological characteristics, spillway height, and sediment transport are recommended. Research shows that protected wells have better water quality than open wells and scoop holes. Therefore, the community should avoid open defecation, pit latrines, tethering of animals, and applying pesticides near the sand dam.
Bisrat Yifru; Min-Gyu Kim; Jeong-Woo Lee; Il-Hwan Kim; Sun-Woo Chang; Il-Moon Chung. Water Storage in Dry Riverbeds of Arid and Semi-Arid Regions: Overview, Challenges, and Prospects of Sand Dam Technology. Sustainability 2021, 13, 5905 .
AMA StyleBisrat Yifru, Min-Gyu Kim, Jeong-Woo Lee, Il-Hwan Kim, Sun-Woo Chang, Il-Moon Chung. Water Storage in Dry Riverbeds of Arid and Semi-Arid Regions: Overview, Challenges, and Prospects of Sand Dam Technology. Sustainability. 2021; 13 (11):5905.
Chicago/Turabian StyleBisrat Yifru; Min-Gyu Kim; Jeong-Woo Lee; Il-Hwan Kim; Sun-Woo Chang; Il-Moon Chung. 2021. "Water Storage in Dry Riverbeds of Arid and Semi-Arid Regions: Overview, Challenges, and Prospects of Sand Dam Technology." Sustainability 13, no. 11: 5905.
In South Korea, groundwater intended for use in greenhouse cultivation is collected from shallow riverside aquifers as part of agricultural activities during the winter season. This study quantified the effects of intensive groundwater intake on aquifers during the winter and examined the roles of nearby rivers in this process. Observation data were collected for approximately two years from six wells and two river-level observation points on the study site. Furthermore, the river water levels before and after the weir structures were examined in detail, because they are determined by artificial structures in the river. The structures have significant impacts on the inflow and outflow from the river to the groundwater reservoirs. As a result, a decline in groundwater levels owing to groundwater depletion was observed during the water curtain cultivation (WCC) period in the winter season. In addition, we found that the groundwater level increased owing to groundwater recharge due to rainfall and induced recharge by rivers during the spring–summer period after the end of the WCC period. MODFLOW, a three-dimensional difference model, was used to simulate the groundwater level decreases and increases around the WCC area in Cheongwon-gun. Time-variable recharge data provided by the soil and water assessment tool model, SWAT for watershed hydrology, was used to determine the amount of groundwater recharge that was input to the groundwater model. The groundwater level time series observations collected from observation wells during the two-year simulation period (2012 to 2014) were compared with the simulation values. In addition, to determine the groundwater depletion of the entire demonstration area and the sustainability of the WCC, the quantitative water budget was analyzed using integrated hydrologic analysis. The result indicated that a 2.5 cm groundwater decline occurred on average every year at the study site. Furthermore, an analysis method that reflects the stratification and boundary conditions of underground aquifers, hydrogeologic properties, hydrological factors, and artificial recharge scenarios was established and simulated with injection amounts of 20%, 40%, and 60%. This study suggested a proper artificial recharge method of injecting water by wells using riverside groundwater in the study area.
Sun Chang; Il-Moon Chung. Water Budget Analysis Considering Surface Water–Groundwater Interactions in the Exploitation of Seasonally Varying Agricultural Groundwater. Hydrology 2021, 8, 60 .
AMA StyleSun Chang, Il-Moon Chung. Water Budget Analysis Considering Surface Water–Groundwater Interactions in the Exploitation of Seasonally Varying Agricultural Groundwater. Hydrology. 2021; 8 (2):60.
Chicago/Turabian StyleSun Chang; Il-Moon Chung. 2021. "Water Budget Analysis Considering Surface Water–Groundwater Interactions in the Exploitation of Seasonally Varying Agricultural Groundwater." Hydrology 8, no. 2: 60.
Groundwater is the largest freshwater resource available on Earth, and many coastal regions are depending on groundwater as a primary freshwater source. For example, in Busan and Incheon, two of the largest coastal cities in South Korea, 5.7% and 7.0% of freshwater uses are from groundwater while only 1.8% is from groundwater in Seoul, the capital of the country. Globally, groundwater availability is diminishing primarily by population increase, and especially in coastal regions, this problem is exacerbated by overexploitation and seawater intrusion, which causes groundwater contamination and further reduces its availability. Here, we view the groundwater system and its management for sustainability as a complex problem that is associated with various social, economic, and environmental factors. By adopting the City Blueprint Approach (CBA), which has been used extensively for assessing the sustainability of integrated water management of numerous cities on the globe, we identify water management factors that potentially have direct and indirect links and feedbacks with groundwater variables. We selected Busan and Incheon as case studies for coastal cities that are facing the risk of groundwater salinization by seawater intrusion. This study aims to 1) assess City Blueprint (CB) of selected coastal cities, 2) identify major factors for coastal groundwater management through correlation analysis, and 3) suggest management options regarding identified factors for sustainable groundwater management of the study areas. Our results on CB indicate that the groundwater quality and quantity of the selected cities are currently in ‘good’ status. Also, from the correlation analysis, we identified heat risk and freshwater scarcity as the major factors that potentially can affect groundwater quantity. For groundwater quality, the factors of voice and accountability, regulatory quality, and rule of law and control of corruption, most of which had not been explicitly considered for groundwater management, were identified as the major factors. Some of these factors were assessed from ‘little concern’ to ‘very concern’ for both cities. These results indicate that, regarding the linkages between groundwater variables and other factors in concern, more actions beyond environmental factors should be taken for sustainable groundwater management. This study helps to understand how non-conventional factors could contribute to coastal groundwater, and can provide extensive options for sustainable groundwater management.
Acknowledgement: This research was supported by the Development program of Minimizing of Climate Change Impact Technology through the National Research Foundation of Korea (NRF), funded by the Korean government (Ministry of Science and ICT) (NRF-2020M3H5A1080775).
Khawon Lee; Sun Woo Chang; Jeryang Park. Assessing groundwater management sustainability of coastal cities by utilizing the City Blueprint Approach . 2021, 1 .
AMA StyleKhawon Lee, Sun Woo Chang, Jeryang Park. Assessing groundwater management sustainability of coastal cities by utilizing the City Blueprint Approach . . 2021; ():1.
Chicago/Turabian StyleKhawon Lee; Sun Woo Chang; Jeryang Park. 2021. "Assessing groundwater management sustainability of coastal cities by utilizing the City Blueprint Approach ." , no. : 1.
The feasibility of the lumped approach for reactive transport of 12 organic compounds in mixtures through simulated aquifer sands with different organic carbon content (foc) within soil columns was evaluated. From direct measurements of effluent samples and temporal and spatial pore-water concentration profiles within soil columns, 12 organic compounds in mixtures were sorbed to different extents due to the different dependence of sorption on foc. Considering the tradeoff between accuracy and simplicity, four, five, and six pseudocompounds were determined for simulated aquifer sands with foc of 0.006%, 0.051%, and 0.221%, respectively, to approximate the reactive transport of 12 organic compounds in mixtures. Each pseudocompound presented obviously different reactive transport behavior in terms of both sorption capacity and nonlinearity, indicating that each pseudocompound contained components with relatively similar sorption capacities and nonlinearity. Similar to the results from batch equilibrium sorption tests, log Koc can be used as the a priori grouping criterion, although the relative contributions of different forces to the overall sorption may differ for different composition of organic mixtures and foc values of aquifer sands. Finally, the assignment of the Freundlich sorption parameters of pseudocompounds using averages of Freundlich sorption parameters of their components led to reasonable prediction for reactive transport of organic compounds in mixtures through the soil columns. Further study is warranted to evaluate the effective coupling between lumped approach and reactive transport model using complex multicomponent mixtures within heterogeneous subsurface systems.
Jin Chul Joo; Hee Sun Moon; Sun Woo Chang. Lumped Approach for Reactive Transport of Organic Compound Mixtures through Simulated Aquifer Sands in Lab-Scale Column Tests. Water 2020, 12, 3103 .
AMA StyleJin Chul Joo, Hee Sun Moon, Sun Woo Chang. Lumped Approach for Reactive Transport of Organic Compound Mixtures through Simulated Aquifer Sands in Lab-Scale Column Tests. Water. 2020; 12 (11):3103.
Chicago/Turabian StyleJin Chul Joo; Hee Sun Moon; Sun Woo Chang. 2020. "Lumped Approach for Reactive Transport of Organic Compound Mixtures through Simulated Aquifer Sands in Lab-Scale Column Tests." Water 12, no. 11: 3103.
Jeju Island is the largest island in South Korea. Recently, extensive groundwater abstraction has been reported from the shallow aquifer in the northeast region of the island. This study simulated the freshwater resources of the aquifer to estimate the sustainability of groundwater use on Jeju Island in terms of its vulnerability to seawater intrusion. Three-dimensional finite-difference numerical groundwater models were simulated using the MODFLOW-family code SEAWAT. Precise and recent groundwater level and multi-depth salinity data obtained from the study site were used for model calibration; the simulated results showed good agreement with the observed data. SEAWAT was used to delineate the current seawater-freshwater interface to quantitatively estimate the coastal fresh groundwater resources. Future stress scenarios were also simulated in response to increased pumping and various changes in the recharge. The results showed that current groundwater use in the coastal aquifer did not induce seawater intrusion in the coastal aquifer, but seawater intrusion will occur if the dry season continues for the next ten years. The vulnerability assessment based on the predicted groundwater levels and ion concentrations using numerical simulations suggests future vulnerability in the aquifer; therefore, continuous assessment and visualization of the aquifer sustainability is vital. Future projections by the integrated SEAWAT simulation and GALDIT assessment showed that an increase in groundwater pumping may escalate the vulnerability status of coastal groundwater resources from moderate to high in some areas of the study site, by inducing lateral seawater intrusion in deeper areas of the unconfined aquifer.
Sun Woo Chang; Il-Moon Chung; Min-Gyu Kim; Bisrat Ayalew Yifru. Vulnerability assessment considering impact of future groundwater exploitation on coastal groundwater resources in northeastern Jeju Island, South Korea. Environmental Earth Sciences 2020, 79, 1 .
AMA StyleSun Woo Chang, Il-Moon Chung, Min-Gyu Kim, Bisrat Ayalew Yifru. Vulnerability assessment considering impact of future groundwater exploitation on coastal groundwater resources in northeastern Jeju Island, South Korea. Environmental Earth Sciences. 2020; 79 (22):1.
Chicago/Turabian StyleSun Woo Chang; Il-Moon Chung; Min-Gyu Kim; Bisrat Ayalew Yifru. 2020. "Vulnerability assessment considering impact of future groundwater exploitation on coastal groundwater resources in northeastern Jeju Island, South Korea." Environmental Earth Sciences 79, no. 22: 1.
Numerical models are employed widely to evaluate the hydrological components of a watershed but, traditionally, watershed models simplify either surface or subsurface flow module. In this setup, as a bridge between groundwater and surface water regimes, aquifer recharge is the most affected segment of the water balance. Since the watershed processes are increasingly changed, the need for a comprehensive model with detailed conceptualizing capacity of both groundwater and surface water flow systems is growing. This work focuses on the spatiotemporal groundwater recharge assessment in gauged and ungauged agro-urban watersheds in South Korea using the updated SWAT-MODFLOW model, which integrates the Soil and Water Assessment Tool (SWAT2012) and Newton–Raphson formulation for Modular Finite Difference Groundwater Flow (MODFLOW-NWT) in a single executable code. Before coupling, the setup, calibration, and verification of each model were performed separately. After integration, irrigation pumps and drain cells mapping to SWAT auto-irrigation and subbasins were initiated. Automatic calibration techniques were used for SWAT and MODFLOW-NWT models, but a manual calibration was used for the integrated model. A physical similarity approach was applied to transfer parameters to the ungauged watershed. Statistical model performance indicators revealed that the low streamflow estimation was improved in SWAT-MODFLOW. The spatiotemporal aquifer recharge distribution from both the stream seepage and precipitation showed a substantial change, and most of the aquifer recharge occurs in July–September. The areal annual average recharge reaches about 18% of the precipitation. Low-lying areas receive higher recharge consistently throughout a year. Overall, SWAT-MODFLOW exhibited reasonable versatility in evaluating watershed processes and produced valuable results with reasonable accuracy. The results can be an important input for policymakers in the development of sustainable groundwater protection and abstraction strategies for the region.
Bisrat Yifru; Il-Moon Chung; Min-Gyu Kim; Sun Chang. Assessment of Groundwater Recharge in Agro-Urban Watersheds Using Integrated SWAT-MODFLOW Model. Sustainability 2020, 12, 6593 .
AMA StyleBisrat Yifru, Il-Moon Chung, Min-Gyu Kim, Sun Chang. Assessment of Groundwater Recharge in Agro-Urban Watersheds Using Integrated SWAT-MODFLOW Model. Sustainability. 2020; 12 (16):6593.
Chicago/Turabian StyleBisrat Yifru; Il-Moon Chung; Min-Gyu Kim; Sun Chang. 2020. "Assessment of Groundwater Recharge in Agro-Urban Watersheds Using Integrated SWAT-MODFLOW Model." Sustainability 12, no. 16: 6593.
In several parts of the world, groundwater potential information gap limits the development and management of the resource. GIS-based multi-criteria decision analysis (MCDA) plays an important role in this regard. This work presents the groundwater potential mapping in a data-scarce region of Main Ethiopian Rift (MER) using Soil and Water Assessment Tool (SWAT) and GIS-based MCDA. SWAT was used to model the spatiotemporal variation of groundwater recharge. The calibration and validation results show the applicability of the model in the study area. The estimated monthly average recharge varies from 2.78–164 mm. The recharge, geomorphology, lithology, soil, land use/land-cover, and DEM derived topographic characteristics were analyzed using GIS-based MCDA to evaluate the groundwater potential. The result is classified into low, moderate, and high zones and validated using the wells and springs information available in the region. More than 61% of the area has moderate groundwater potential and less than 22% of the area has high groundwater potential.
Bisrat Ayalew Yifru; Dereje Birhanu Mitiku; Mesfin Benti Tolera; Sun Woo Chang; Il-Moon Chung. Groundwater Potential Mapping Using SWAT and GIS-Based Multi-Criteria Decision Analysis. KSCE Journal of Civil Engineering 2020, 24, 2546 -2559.
AMA StyleBisrat Ayalew Yifru, Dereje Birhanu Mitiku, Mesfin Benti Tolera, Sun Woo Chang, Il-Moon Chung. Groundwater Potential Mapping Using SWAT and GIS-Based Multi-Criteria Decision Analysis. KSCE Journal of Civil Engineering. 2020; 24 (8):2546-2559.
Chicago/Turabian StyleBisrat Ayalew Yifru; Dereje Birhanu Mitiku; Mesfin Benti Tolera; Sun Woo Chang; Il-Moon Chung. 2020. "Groundwater Potential Mapping Using SWAT and GIS-Based Multi-Criteria Decision Analysis." KSCE Journal of Civil Engineering 24, no. 8: 2546-2559.
Seawater intrusion (SWI) is a major environmental threat to groundwater resources in coastal regions. GALDIT is an index-based SWI vulnerability model that is increasingly being used in many parts of the world to identify regions that are vulnerable to various types of SWI based on six major parameters. In this study, we conducted a vulnerability assessment of Jeju Island to SWI based on several years of collected groundwater level data and hydrogeological values where the objectives of the study were to visualize the distribution of recent SWI, to increase the reliability of the GALDIT assessment method by improving current GALDIT techniques, and to respond effectively to diagnoses of SWI on Jeju. To improve the GALDIT assessment method to fit the Jeju model, the possibility of electrical conductivity was explored instead of standard GALDIT parameters that represented the existing impact of SWI. Improvements to the GALDIT vulnerability assessment method made it clear that groundwater became increasingly vulnerable to SWI in the existing high-vulnerability group. The results of this research may be used to develop a quantitative index for rational decision-making on policies and suggest the need for further improvements in groundwater management, with a stronger focus on easing groundwater use.
Sun Woo Chang; Il-Moon Chung; Min-Gyu Kim; Mesfin Tolera; Gi-Won Koh. Application of GALDIT in Assessing the Seawater Intrusion Vulnerability of Jeju Island, South Korea. Water 2019, 11, 1824 .
AMA StyleSun Woo Chang, Il-Moon Chung, Min-Gyu Kim, Mesfin Tolera, Gi-Won Koh. Application of GALDIT in Assessing the Seawater Intrusion Vulnerability of Jeju Island, South Korea. Water. 2019; 11 (9):1824.
Chicago/Turabian StyleSun Woo Chang; Il-Moon Chung; Min-Gyu Kim; Mesfin Tolera; Gi-Won Koh. 2019. "Application of GALDIT in Assessing the Seawater Intrusion Vulnerability of Jeju Island, South Korea." Water 11, no. 9: 1824.
Saltwater intrusion refers to a process where saline seawater naturally intrudes into a freshwater coastal aquifer. This process will often naturally degrade groundwater quality in coastal aquifers, an impact which can be further exacerbated by climate change effects and other human activities. This chapter summarizes recent modeling and experimental advances pertaining to saltwater intrusion research. The discussions presented in this chapter include an in-depth and expansive summary of experimental and modeling efforts recently completed in our research group, along with a review of all pertinent literature information relevant to these efforts. The first section of this review chapter describes the mathematical details of the sharp interface Ghyben–Herzberg model and various analytical solutions that are based on this model. These discussions are subsequently extended to develop more comprehensive, fully-coupled, variable-density flow model equations, as well as a classic steady-state solution, known as the Henry solution, to these equations. Later, a detailed numerical solution to transient variable-density flow equations is presented. In published literature, the Henry solution is often used as a standard benchmark for testing numerical solutions. The boundary condition and the dimensionless parameters used in the classic Henry problem are carefully reexamined and an alternate Henry solution, which is a worthier benchmark for testing steady-state numerical solutions, is presented. Thereafter, the results of a series of experimental studies that have investigated transient Henry-type problems involving both constant head and constant flux boundary conditions are summarized. These experimental datasets are better benchmarks for testing transient density-coupled codes used for modeling saltwater intrusion processes.
Sun Woo Chang; T. Prabhakar Clement. Perspectives on Modeling Saltwater Intrusion Processes in Coastal Groundwater Aquifers. Advances in Coastal Hydraulics 2018, 73 -109.
AMA StyleSun Woo Chang, T. Prabhakar Clement. Perspectives on Modeling Saltwater Intrusion Processes in Coastal Groundwater Aquifers. Advances in Coastal Hydraulics. 2018; ():73-109.
Chicago/Turabian StyleSun Woo Chang; T. Prabhakar Clement. 2018. "Perspectives on Modeling Saltwater Intrusion Processes in Coastal Groundwater Aquifers." Advances in Coastal Hydraulics , no. : 73-109.
Availability of reliable meteorological data for watershed modeling is one of the considerable challenges in the Awash River Basin in Ethiopia. To overcome this challenge, the Climate Forecast System Reanalysis (CFSR) global weather data was evaluated and compared with the limited conventional weather data available in the Upper Awash Basin. The main objective of this study was to search for an optional data source for hydrological modeling, instead of using the limited available data, and for data-scarce areas of the basin. The Soil and Water Assessment Tool model was used to compare the performance of the two weather datasets at simulating monthly streamflow. For calibration, validation, and uncertainty analysis, the sequential uncertainty fitting algorithm was used. The model evaluation statistics showed that the CFSR global weather data performed similarly to the conventional weather data for simulating the observed streamflow at Melka Kunture. At Keleta, where the conventional data is scarce, the CFSR performed better. The CFSR performance at the two sub-basins indicated that it performed better for the large sub-basin, Melka Kunture. Generally, the CFSR weather data are a good addition to the dataset for areas where no reliable weather data exists for hydrological modeling in the basin. The precipitation data of the CFSR are slightly higher than that of the conventional data, which also resulted in a relatively higher water balance components.
Mesfin Benti Tolera; Il-Moon Chung; Sun Woo Chang. Evaluation of the Climate Forecast System Reanalysis Weather Data for Watershed Modeling in Upper Awash Basin, Ethiopia. Water 2018, 10, 725 .
AMA StyleMesfin Benti Tolera, Il-Moon Chung, Sun Woo Chang. Evaluation of the Climate Forecast System Reanalysis Weather Data for Watershed Modeling in Upper Awash Basin, Ethiopia. Water. 2018; 10 (6):725.
Chicago/Turabian StyleMesfin Benti Tolera; Il-Moon Chung; Sun Woo Chang. 2018. "Evaluation of the Climate Forecast System Reanalysis Weather Data for Watershed Modeling in Upper Awash Basin, Ethiopia." Water 10, no. 6: 725.
Coastal freshwater aquifers are highly vulnerable to climate change and other anthropogenic environmental impacts. Therefore, managing coastal freshwater for future use requires critical planning. This is especially true for small barrier islands where, in most cases, groundwater could be the only freshwater resource. In this study, the combined effects of climate change, land-use changes, and increased groundwater pumping on freshwater resources of a barrier island were studied. A case study was completed using the field data available for Dauphin Island, a small barrier island located in Alabama, U.S., and by using the simulation data generated from multiple water-resource-management models. Soil and Water Assessment Tool (SWAT) simulations provided recharge estimates under various future land use/land cover and climate-change scenarios. Downscaled global circulation model provided precipitation and temperature patterns for the period 2011–2030. The recharge estimates from SWAT were then used as input in a numerical groundwater model to evaluate saltwater-intrusion effects and forecast the changes in freshwater storage within the island aquifer system. Various groundwater-management scenarios were simulated using the MODFLOW-family computer code SEAWAT to assess the sensitivity of the groundwater system to increased pumping rates and decreased recharge due to climate change and/or future developments. SEAWAT was used to predict the lateral saltwater-intrusion effects and its impacts on groundwater quality and freshwater volume. The simulation results show that the saltwater wedge would advance laterally under all future climate-change scenarios. These results indicate that the shallow unconfined aquifer might not be able to sustain any significant future population growth, especially under adverse climate-change conditions. Analysis of changes in the volume of freshwater lens provided a broader understanding of the coupled effects of climatic and anthropogenic changes on freshwater storage and this information can be used to better manage Dauphin Island’s unconfined groundwater system.
Sun Woo Chang; Katherine Nemec; Latif Kalin; T. Prabhakar Clement. Impacts of Climate Change and Urbanization on Groundwater Resources in a Barrier Island. Journal of Environmental Engineering 2016, 142, 1 .
AMA StyleSun Woo Chang, Katherine Nemec, Latif Kalin, T. Prabhakar Clement. Impacts of Climate Change and Urbanization on Groundwater Resources in a Barrier Island. Journal of Environmental Engineering. 2016; 142 (12):1.
Chicago/Turabian StyleSun Woo Chang; Katherine Nemec; Latif Kalin; T. Prabhakar Clement. 2016. "Impacts of Climate Change and Urbanization on Groundwater Resources in a Barrier Island." Journal of Environmental Engineering 142, no. 12: 1.
충청북도 청원군의 수막재배지역에서는 동절기 지하수를 시설재배에 이용하기 위해 하천변 천부 대수층에서 지하수를 집중 취수하여 지하수자원의 고갈을 초래하고 있다. 지하수위의 관측을 통하여 1차적인 지하수 고갈을 확인할 수 있으나 실증지역 전체의 지하수 고갈 여부 및 수막재배의 지속가능성을 파악하기 위하여 통합 수문해석에 의한 물수지를 분석을 수행하였다. 청원군의 수막재배 지역을 중심으로 3차원 유한차분모형인 MODFLOW를 구축하였으며, 지하수모형에 입력할 지하수 함양량 시계열 자료는 유역수문모형 SWAT모형이 제공한 시변성 함양량 자료를 이용하였다. 2012년부터 2014년까지 2년 동안의 모의기간 동안 관측정에서 수집한 지하수위 시계열 관측값과 모의값을 비교하여 모델의 타당성을 입증한 후 대수층 중심의 정량적인 물수지 분석을 구현하였다. 마지막으로 인공함양 시나리오를 주입량을 각각 20, 40, 60%로 구분하여 모의한 결과를 바탕으로, 현 실증부지의 하천변 지하수의 수막 용수활용이 지속가능하도록 적정 인공함양 방식을 제안하였다.
Sunwoo Chang; Il-Moon Chung; Yongchel Kim; Sang-Ho Moon; 장선우. Long-term groundwater budget analysis based on integrated hydrological model for water curtain cultivation site: Case study of Cheongweon, Korea. Journal of the Geological Society of Korea 2016, 52, 201 -210.
AMA StyleSunwoo Chang, Il-Moon Chung, Yongchel Kim, Sang-Ho Moon, 장선우. Long-term groundwater budget analysis based on integrated hydrological model for water curtain cultivation site: Case study of Cheongweon, Korea. Journal of the Geological Society of Korea. 2016; 52 (3):201-210.
Chicago/Turabian StyleSunwoo Chang; Il-Moon Chung; Yongchel Kim; Sang-Ho Moon; 장선우. 2016. "Long-term groundwater budget analysis based on integrated hydrological model for water curtain cultivation site: Case study of Cheongweon, Korea." Journal of the Geological Society of Korea 52, no. 3: 201-210.
Salt wedges divide coastal groundwater flow regime into two distinct regions that include a freshwater region above the saltwater-freshwater interface and a saltwater region below the interface. Several recent studies have investigated saltwater transport in coastal aquifers and the associated flow and mixing processes. Most of these studies, however, have either focused on studying the movement of salt wedge itself or on studying contaminant transport processes occurring above the wedge. As per our knowledge, so far no one has completed laboratory experiments to study contaminant transport processes occurring within a saltwater wedge. In this study, we completed laboratory experiments to understand contaminant transport dynamics occurring within a saltwater wedge. We used a novel experimental approach that employed multiple neutral-density tracers to map and compare the mixing and transport processes occurring above and within a saltwater wedge. The experimental data were simulated using SEAWAT, and the model was used to further investigate the saltwater flow and transport dynamics within a wedge. The laboratory data show that the transport rates active within the wedge are almost two orders of magnitude slower than the transport rates active above the wedge for the small-scale experimental system which is characterized by very low level of mixing. The numerical results, however, postulate that for large-scale systems involving higher levels of mixing (or dispersion) the transport rate active within the wedge could be comparable or even higher than the rates active above the wedge. More field or laboratory studies completed under high dispersion conditions are needed to further test this hypothesis.
Sun Woo Chang; T. Prabhakar Clement. Laboratory and numerical investigation of transport processes occurring above and within a saltwater wedge. Journal of Contaminant Hydrology 2013, 147, 14 -24.
AMA StyleSun Woo Chang, T. Prabhakar Clement. Laboratory and numerical investigation of transport processes occurring above and within a saltwater wedge. Journal of Contaminant Hydrology. 2013; 147 ():14-24.
Chicago/Turabian StyleSun Woo Chang; T. Prabhakar Clement. 2013. "Laboratory and numerical investigation of transport processes occurring above and within a saltwater wedge." Journal of Contaminant Hydrology 147, no. : 14-24.
Sun Woo Chang; T. Prabhakar Clement. Experimental and numerical investigation of saltwater intrusion dynamics in flux‐controlled groundwater systems. Water Resources Research 2012, 48, 1 .
AMA StyleSun Woo Chang, T. Prabhakar Clement. Experimental and numerical investigation of saltwater intrusion dynamics in flux‐controlled groundwater systems. Water Resources Research. 2012; 48 (9):1.
Chicago/Turabian StyleSun Woo Chang; T. Prabhakar Clement. 2012. "Experimental and numerical investigation of saltwater intrusion dynamics in flux‐controlled groundwater systems." Water Resources Research 48, no. 9: 1.