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Dr. Jaehak Jeong
BREC, Texas A&M AgriLife Research, Department of Biological and Agricultural Engineering, Texas A&M University, Temple, Texas, USA

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0 Climate Change
0 Drainage
0 Irrigation
0 Salinity
0 Water

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Water Quality
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Climate Change
Drainage
Salinity
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Sustainable water use

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Journal article
Published: 18 August 2021 in Sustainability
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Agricultural expansion and urban development without proper soil erosion control measures have become major environmental problems in Cambodia. Due to a high population growth rate and increased economic activities, land use and land cover (LULC) changes will cause environmental disturbances, particularly soil erosion. This research aimed to estimate total amounts of soil loss using the Revised Universal Soil Loss Equation (RUSLE) model within a Geographic Information System (GIS) environment. LULC maps of Japan International Cooperation Agency (JICA) 2002 and Mekong River Commission (MRC) 2015 were used to evaluate the impact of LULC on soil erosion loss in Stung Sangkae catchment. LULC dynamics for the study periods in Stung Sangkae catchment showed that the catchment experienced a rapid conversion of forests to paddy rice fields and other croplands. The results indicated that the average soil loss from the catchment was 3.1 and 7.6 t/ha/y for the 2002 and 2015 periods, respectively. The estimated total soil loss in the 2002 and 2015 periods was 1.9 million t/y and 4.5 million t/y, respectively. The soil erosion was accelerated by steep slopes combined with the high velocity and erosivity of stormwater runoff. The spatial distribution of soil loss showed that the highest value (14.3 to 62.9 t/ha/y) was recorded in the central, southwestern and upland parts of the catchment. It is recommended that priority should be given to erosion hot spot areas, and appropriate soil and water conservation practices should be adopted to restore degraded lands.

ACS Style

Nareth Nut; Machito Mihara; Jaehak Jeong; Bunthan Ngo; Gilbert Sigua; P.V. Vara Prasad; Manny R. Reyes. Land Use and Land Cover Changes and Its Impact on Soil Erosion in Stung Sangkae Catchment of Cambodia. Sustainability 2021, 13, 9276 .

AMA Style

Nareth Nut, Machito Mihara, Jaehak Jeong, Bunthan Ngo, Gilbert Sigua, P.V. Vara Prasad, Manny R. Reyes. Land Use and Land Cover Changes and Its Impact on Soil Erosion in Stung Sangkae Catchment of Cambodia. Sustainability. 2021; 13 (16):9276.

Chicago/Turabian Style

Nareth Nut; Machito Mihara; Jaehak Jeong; Bunthan Ngo; Gilbert Sigua; P.V. Vara Prasad; Manny R. Reyes. 2021. "Land Use and Land Cover Changes and Its Impact on Soil Erosion in Stung Sangkae Catchment of Cambodia." Sustainability 13, no. 16: 9276.

Journal article
Published: 01 June 2021 in Environmental Modelling & Software
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APEX (Agricultural Policy/Environmental eXtender) is an oft-used agroecosystem model but has limited use in groundwater-driven watersheds due to a simplistic representation of groundwater processes. This paper presents the linkage of APEX and the groundwater flow model MODFLOW into a single modeling code. The mapping of recharge, groundwater head, and groundwater-surface water interactions are handled internally via subroutines. The APEX-MODFLOW model is applied to three watersheds in the United States for testing code accuracy and hydrologic state variables and fluxes: the Animas River Watershed, Colorado and New Mexico (3543 km2); the Price River Watershed, Utah (4886 km2); and the Middle Bosque River Watershed, Texas (470 km2). Whereas the hydrology of the Animas River and Price River watersheds is driven by snowmelt and spring runoff, the hydrology of the Middle Bosque River Watershed is driven by summer thunderstorms. The model can be used for scenario analysis in groundwater-driven watersheds.

ACS Style

Ryan T. Bailey; Ali Tasdighi; Seonggyu Park; Saman Tavakoli-Kivi; Tadesse Abitew; Jaehak Jeong; Colleen H.M. Green; Abeyou W. Worqlul. APEX-MODFLOW: A New integrated model to simulate hydrological processes in watershed systems. Environmental Modelling & Software 2021, 143, 105093 .

AMA Style

Ryan T. Bailey, Ali Tasdighi, Seonggyu Park, Saman Tavakoli-Kivi, Tadesse Abitew, Jaehak Jeong, Colleen H.M. Green, Abeyou W. Worqlul. APEX-MODFLOW: A New integrated model to simulate hydrological processes in watershed systems. Environmental Modelling & Software. 2021; 143 ():105093.

Chicago/Turabian Style

Ryan T. Bailey; Ali Tasdighi; Seonggyu Park; Saman Tavakoli-Kivi; Tadesse Abitew; Jaehak Jeong; Colleen H.M. Green; Abeyou W. Worqlul. 2021. "APEX-MODFLOW: A New integrated model to simulate hydrological processes in watershed systems." Environmental Modelling & Software 143, no. : 105093.

Journal article
Published: 15 March 2021 in Agricultural Water Management
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Over-exploitation of groundwater for agricultural irrigation has attracted worldwide attention because of the rapid groundwater depletion and environmental consequences induced by the current intensified cropping system. The combination of cropping system modeling with field experimentation is a powerful tool to evaluate the long-term consequences of changing water management and cropping systems under inter-annual climate variability. Here, we conducted two field experiments for early maize (EM, 2012–2018) single cropping system and winter wheat – summer maize (WWSM, 2015–2018) double cropping system in the North China Plain (NCP). Field observations were carried out for crop growth, yield, and soil volumetric moisture content (VMC) calibration with the Agricultural Policy/Environmental eXtender (APEX) model. The calibrated APEX model was used to assess the long-term (35 years, 1985–2019) impacts of EM and WWSM cropping systems under four irrigation scenarios on sustainable water and crop productivity using historical weather data. Results showed that the APEX replicated growth, yield, and VMC all reasonably well with R2 > 0.5, percent bias < 25%, and index of agreement > 0.8. The model realistically simulated VMC under full irrigation (FI), while model simulations under reduced irrigation were not that accurate. Neglectable yield losses of EM were observed by changing EM-FI to rainfed (EM-RF) (7.0 vs. 6.8 Mg ha−1) and lower inter-annual yield variability. Shifting WWSM-FI to EM-RF saved 47% evapotranspiration (ET) and 115% net water use (NWU) regardless of the precipitation category years, but caused 54% reduction in yield. Critical irrigation (CI) significantly reduced ET (7%) and NWU (28%) of WWSM, without yield loss, compared to FI, indicating great potentials of water-saving through optimized irrigation strategy. Minimum irrigation (MI) saved ET by 17% and NWU of WWSM by 62%, but led to 15% EY reduction compared with FI. In conclusion, the WWSM cropping system under CI has the potential to maintain yield with less water consumption, while rainfed EM is the best alternative option for mitigating groundwater over-exploitation with a certain extent risk in crop yield losses.

ACS Style

Jie Zhao; Xuepeng Zhang; Yadong Yang; Huadong Zang; Peng Yan; Manyowa N. Meki; Luca Doro; Peng Sui; Jaehak Jeong; Zhaohai Zeng. Alternative cropping systems for groundwater irrigation sustainability in the North China Plain. Agricultural Water Management 2021, 250, 106867 .

AMA Style

Jie Zhao, Xuepeng Zhang, Yadong Yang, Huadong Zang, Peng Yan, Manyowa N. Meki, Luca Doro, Peng Sui, Jaehak Jeong, Zhaohai Zeng. Alternative cropping systems for groundwater irrigation sustainability in the North China Plain. Agricultural Water Management. 2021; 250 ():106867.

Chicago/Turabian Style

Jie Zhao; Xuepeng Zhang; Yadong Yang; Huadong Zang; Peng Yan; Manyowa N. Meki; Luca Doro; Peng Sui; Jaehak Jeong; Zhaohai Zeng. 2021. "Alternative cropping systems for groundwater irrigation sustainability in the North China Plain." Agricultural Water Management 250, no. : 106867.

Editorial
Published: 14 March 2020 in Agronomy
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With the growing population and climate change, increasing demands for water are intensifying competition between agricultural stakeholders. Since the mid-20th century, numerous crop models and modeling techniques have emerged for the quantitative assessment of cropping systems. This article introduces a collection of articles that explore current research in model applications for sustainable agricultural water use. The collection includes articles from model development to regional and field-scale applications addressing management effects, model uncertainty, irrigation decision support systems, and new methods for simulating salt balances. Further work is needed to integrate data science, modern sensor systems, and remote sensing technologies with the models in order to investigate the sustainability of agricultural systems in regions affected by land-use change and climate change.

ACS Style

Jaehak Jeong; Xuesong Zhang. Model Application for Sustainable Agricultural Water Use. Agronomy 2020, 10, 396 .

AMA Style

Jaehak Jeong, Xuesong Zhang. Model Application for Sustainable Agricultural Water Use. Agronomy. 2020; 10 (3):396.

Chicago/Turabian Style

Jaehak Jeong; Xuesong Zhang. 2020. "Model Application for Sustainable Agricultural Water Use." Agronomy 10, no. 3: 396.

Journal article
Published: 20 December 2019 in Soil Systems
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Understanding topography effects on soil properties is vital to modelling landscape hydrology and establishing sustainable on-field management practices. This research focuses on an arable area (117 km2) in Southwestern Ethiopia where agricultural fields and bush cover are the dominant land uses. We postulate that adapting either of the soil data resources, coarse resolution FAO-UNESCO (Food and Agriculture Organization of the United Nations Educational, Scientific and Cultural Organization) soil data or pedo-transfer functions (PTFs) is not reliable to indicate future watershed management directions. The FAO-UNESCO data does not account for scale issues and assigns the same soil property at different landscape gradients. The PTFs, on the other hand, do not account for environmental effects and fail to provide all the required data. In this regard, mapping soil property spatial dynamics can help understand landscape physicochemical processes and corresponding land use changes. For this purpose, soil samples were collected across the watershed following a gridded sampling scheme. In areas with heterogeneous topography, soil is spatially variable as influenced by land use and slope. To understand the spatial variation, this research develops indicators, such as topographic index, soil topographic wetness index, elevation, aspect, and slope. Pearson correlation (r), among others, was used to investigate terrain effects on selected soil properties: organic matter (OM), available water content (AWC), sand content (%), clay content (%), silt content (%), electrical conductivity (EC), moist bulk density (MBD), and saturated hydraulic conductivity (Ksat). The results show that there were statistically significant correlations between elevation-based variables and soil physical properties. Among the variables considered, the ‘r’ value between topographic index and soil attributes (i.e., OM, EC, AWC, sand, clay, silt, and Ksat) were 0.66, 0.5, 0.7, 0.55, 0.62, 0.4, and 0.66, respectively. In conclusion, while understanding topography effects on soil properties is vital, implementing either FAO-UNESCO or PTFs soil data do not provide appropriate information pertaining to scale issues.

ACS Style

Gebiaw T. Ayele; Solomon S. Demissie; Mengistu A. Jemberrie; Jaehak Jeong; David P. Hamilton. Terrain Effects on the Spatial Variability of Soil Physical and Chemical Properties. Soil Systems 2019, 4, 1 .

AMA Style

Gebiaw T. Ayele, Solomon S. Demissie, Mengistu A. Jemberrie, Jaehak Jeong, David P. Hamilton. Terrain Effects on the Spatial Variability of Soil Physical and Chemical Properties. Soil Systems. 2019; 4 (1):1.

Chicago/Turabian Style

Gebiaw T. Ayele; Solomon S. Demissie; Mengistu A. Jemberrie; Jaehak Jeong; David P. Hamilton. 2019. "Terrain Effects on the Spatial Variability of Soil Physical and Chemical Properties." Soil Systems 4, no. 1: 1.

Journal article
Published: 27 September 2019 in Agronomy
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Cultivation of highly salt-tolerant plants (i.e., halophytes), may provide a viable alternative to increase productivity compared to conventional salt-sensitive crops, increasing the economic potential of salt-affected lands that comprise ~20% of irrigated lands worldwide. In this study the Agricultural Policy/Environmental eXtender (APEX) model was adapted to simulate growth of the halophyte quinoa, along with salt dynamics in the plant-soil-water system. Model modifications included salt uptake and salt stress functions formulated using greenhouse data. Data from a field site were used to further parameterize and calibrate the model. Initial simulation results were promising, but differences between simulated and observed soil salinity and plant salt values during the growing season in the calibration suggest that additional improvements to salt uptake and soil salinity algorithms are needed. To demonstrate utility of the modified APEX model, six scenarios were run to estimate quinoa biomass production and soil salinity with different irrigation managements and salinities. Simulated annual biomass was sensitive to soil moisture, and root zone salinity increased in all scenarios. Further experiments are needed to improve understanding of crop salt uptake dynamics and stress sensitivities so that future model updates and simulations better represent salt dynamics in plants and soils in agricultural settings.

ACS Style

Nicole Goehring; Paul Verburg; Laurel Saito; Jaehak Jeong; Manyowa N. Meki. Improving Modeling of Quinoa Growth Under Saline Conditions Using the Enhanced Agricultural Policy Environmental eXtender Model. Agronomy 2019, 9, 592 .

AMA Style

Nicole Goehring, Paul Verburg, Laurel Saito, Jaehak Jeong, Manyowa N. Meki. Improving Modeling of Quinoa Growth Under Saline Conditions Using the Enhanced Agricultural Policy Environmental eXtender Model. Agronomy. 2019; 9 (10):592.

Chicago/Turabian Style

Nicole Goehring; Paul Verburg; Laurel Saito; Jaehak Jeong; Manyowa N. Meki. 2019. "Improving Modeling of Quinoa Growth Under Saline Conditions Using the Enhanced Agricultural Policy Environmental eXtender Model." Agronomy 9, no. 10: 592.

Journal article
Published: 10 August 2019 in Agronomy
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Spring peanut is a valuable alternative crop to mitigate water scarcity caused by excessive water use in conventional cropping systems in the North China Plain (NCP). In the present study, we evaluated the capability of the Agricultural Policy Environmental eXtender (APEX) model to predict spring peanut response to sowing dates and seeding rates in order to optimize sowing dates, seeding rates, and irrigation regimes. Data used for calibration and validation of the model included leaf area index (LAI), aboveground biomass (ABIOM), and pod yield data collected from a field experiment of nine sowing dates and seeding rate combinations conducted from 2017 to 2018. The calibrated model was then used to simulate peanut yield responses to extended sowing dates (5 April to 4 June with a 5-day interval) and seeding rates (15 plants m−2 to 50 plants m−2 with a 5 plants m−2 interval) using 38 years of weather data as well as yield, evapotranspiration (ET), and water stress days under different irrigation regimes (rainfed, one irrigation before planting (60 mm) or at flowering (60 mm), and two irrigation with one time before planting and one time at flowering (60 mm each time) or at pod set (60 mm each time)). Results show that the model satisfactorily simulates pod yield of peanut based on R2 = 0.70, index of agreement (d value) being 0.80 and percent bias (PBIAS) values ≤4%. Moreover, the model performed reasonably well in predicting the emergence, LAI and ABIOM, with a R2 = 0.86, d = 0.95 and PBIAS = 8% for LAI and R2 = 0.90, d = 0.97 and PBIAS = 1% for ABIOM, respectively. Simulation results indicate that the best combination of sowing dates and seeding rates is a density of 35–40 plants m−2 and dates during early-May to mid-May due to the influence of local climate and canopy structure to the growth and yield of peanut. Under the optimal sowing date and plant density, an irrigation depth of 60 mm during flowering gave a pod yield (5.6 t ha−1) and ET (464 mm), which resulted in the highest water use efficiency (12.1 kg ha−1 mm−1). The APEX model is capable of assessing the effects of management practices on the growth and yield of peanut. Sowing 35–40 plants m−2 during early-May to mid-May with 60 mm irrigation depth is the recommended agronomic practice for peanut production in the water-constrained NCP.

ACS Style

Jie Zhao; Qingquan Chu; Mengjie Shang; Manyowa N. Meki; Nicole Norelli; Yao Jiang; Yadong Yang; Huadong Zang; Zhaohai Zeng; Jaehak Jeong. Agricultural Policy Environmental eXtender (APEX) Simulation of Spring Peanut Management in the North China Plain. Agronomy 2019, 9, 443 .

AMA Style

Jie Zhao, Qingquan Chu, Mengjie Shang, Manyowa N. Meki, Nicole Norelli, Yao Jiang, Yadong Yang, Huadong Zang, Zhaohai Zeng, Jaehak Jeong. Agricultural Policy Environmental eXtender (APEX) Simulation of Spring Peanut Management in the North China Plain. Agronomy. 2019; 9 (8):443.

Chicago/Turabian Style

Jie Zhao; Qingquan Chu; Mengjie Shang; Manyowa N. Meki; Nicole Norelli; Yao Jiang; Yadong Yang; Huadong Zang; Zhaohai Zeng; Jaehak Jeong. 2019. "Agricultural Policy Environmental eXtender (APEX) Simulation of Spring Peanut Management in the North China Plain." Agronomy 9, no. 8: 443.

Journal article
Published: 23 March 2019 in Water
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The Agricultural Policy/Environmental eXtender (APEX) model has been widely used to assess changes in agrochemical loadings in response to conservation and management led by US Department of Agriculture (USDA). However, the existing APEX model is limited in quantification of wetland water quality functions. This study improved the current model capacity to represent wetland water quality functions by addition of a new biogeochemical module into the APEX model. The performance of an enhanced APEX model was tested against five observed outgoing water quality variables (e.g., sediment, organic N, NO3, NH4 and PO4) from a wetland within the Eastern Shore of Maryland. Generalized Likelihood Uncertainty Estimation (GLUE) was implemented to assess model uncertainty. The enhanced APEX model demonstrated that it could effectively represent N and P cycling within the study wetland. Although improvement of model performance was limited, the additions of wetland biogeochemical routines to the APEX model improved our understanding of inner mass exchanges within N and P cycling for the study wetland. Overall, the updated APEX model can provide policymakers and managers with improved means for assessment of benefits delivered by wetland conservation.

ACS Style

Amirreza Sharifi; Sangchul Lee; Gregory W. Mccarty; Megan W. Lang; Jaehak Jeong; Ali M. Sadeghi; Martin C. Rabenhorst. Enhancement of Agricultural Policy/Environment eXtender Model (APEX) Model to Assess Effectiveness of Wetland Water Quality Functions. Water 2019, 11, 606 .

AMA Style

Amirreza Sharifi, Sangchul Lee, Gregory W. Mccarty, Megan W. Lang, Jaehak Jeong, Ali M. Sadeghi, Martin C. Rabenhorst. Enhancement of Agricultural Policy/Environment eXtender Model (APEX) Model to Assess Effectiveness of Wetland Water Quality Functions. Water. 2019; 11 (3):606.

Chicago/Turabian Style

Amirreza Sharifi; Sangchul Lee; Gregory W. Mccarty; Megan W. Lang; Jaehak Jeong; Ali M. Sadeghi; Martin C. Rabenhorst. 2019. "Enhancement of Agricultural Policy/Environment eXtender Model (APEX) Model to Assess Effectiveness of Wetland Water Quality Functions." Water 11, no. 3: 606.

Preprint
Published: 13 September 2018
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The recent increase in global consumption of rice has led to increased demand for sustainable water management in paddy cultivation. In this study, we propose an enhanced paddy simulation module to be introduced to Soil and Water Assessment Tool (SWAT) to evaluate the sustainability of paddy cultivation. The enhancements added to SWAT include: (1) modification of water balance calculation for impounded fields, (2) addition of an irrigation management option for paddy fields that are characterized by flood irrigation with target water depth, and (3) addition of a puddling operation that influences the water quality and infiltration rate of the top soil layer. In a case study, the enhanced model, entitled SWAT-Paddy, was applied to an agricultural watershed in Japan. The results showed that the SWAT-Paddy successfully represented paddy cultivation, water management, and discharge processes. Simulated daily discharge rates with SWAT-Paddy (R2 = 0.8) were superior to the SWAT result (R2 = 0.002). SWAT-Paddy allows the simulation of paddy management processes realistically, and thus can enhance model accuracy in paddy-dominant agricultural watersheds.

ACS Style

Ryota Tsuchiya; Tasuku Kato; Jaehak Jeong; Jeffrey G. Arnold. Development of SWAT-Paddy for Simulating Lowland Paddy Fields. 2018, 1 .

AMA Style

Ryota Tsuchiya, Tasuku Kato, Jaehak Jeong, Jeffrey G. Arnold. Development of SWAT-Paddy for Simulating Lowland Paddy Fields. . 2018; ():1.

Chicago/Turabian Style

Ryota Tsuchiya; Tasuku Kato; Jaehak Jeong; Jeffrey G. Arnold. 2018. "Development of SWAT-Paddy for Simulating Lowland Paddy Fields." , no. : 1.

Journal article
Published: 11 September 2018 in Sustainability
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The recent increase in global consumption of rice has led to increased demand for sustainable water management in paddy cultivation. In this study, we propose an enhanced paddy simulation module to be introduced to Soil and Water Assessment Tool (SWAT) to evaluate the sustainability of paddy cultivation. The enhancements added to SWAT include: (1) modification of water balance calculation for impounded fields, (2) addition of an irrigation management option for paddy fields that are characterized by flood irrigation with target water depth, and (3) addition of a puddling operation that influences the water quality and infiltration rate of the top soil layer. In a case study, the enhanced model, entitled SWAT-Paddy, was applied to an agricultural watershed in Japan. The results showed that the SWAT-Paddy successfully represented paddy cultivation, water management, and discharge processes. Simulated daily discharge rates with SWAT-Paddy (R2 = 0.8) were superior to the SWAT result (R2 = 0.002). SWAT-Paddy allows the simulation of paddy management processes realistically, and thus can enhance model accuracy in paddy-dominant agricultural watersheds.

ACS Style

Ryota Tsuchiya; Tasuku Kato; Jaehak Jeong; Jeffrey G. Arnold. Development of SWAT-Paddy for Simulating Lowland Paddy Fields. Sustainability 2018, 10, 3246 .

AMA Style

Ryota Tsuchiya, Tasuku Kato, Jaehak Jeong, Jeffrey G. Arnold. Development of SWAT-Paddy for Simulating Lowland Paddy Fields. Sustainability. 2018; 10 (9):3246.

Chicago/Turabian Style

Ryota Tsuchiya; Tasuku Kato; Jaehak Jeong; Jeffrey G. Arnold. 2018. "Development of SWAT-Paddy for Simulating Lowland Paddy Fields." Sustainability 10, no. 9: 3246.

Article
Published: 15 August 2018 in Environmental Monitoring and Assessment
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Monitoring the health and condition of wetlands using biological assessments can serve as an effective tool for environmental managers to better evaluate and monitor the status and trends of their wetland ecosystems. Woody species can be used as conspicuous biological assessment tools due to their direct response to environmental change, such as hydrologic alteration. The purpose of this study is to use field-measured morphological measurement indices to develop and optimize tree growth parameters and growth curves using multi-model combination approach to improve tree biomass estimations. Field morphological investigations were conducted for two common wetland tree species in Texas. A range of morphological characteristics including leaf area index, height, and biomass was measured for black willow (Salix nigra Marsh) and green ash (Fraxinus pennsylvanica) sampled from 15 sites in a wetland near Cameron, Texas. The measured morphological parameters were used to optimize tree growth and development with the ALMANAC model. The developed tree growth parameters and growth curves were subsequently used in the APEX model to simulate tree biomass at the catchment scale. Both models accurately simulated biomass of trees growing in the wetland. This accurate biomass prediction will be useful to advance science to better monitor and assess wetland health on a large scale (e.g. national or global).

ACS Style

Su Min Kim; Jaehak Jeong; Dan Keesee; James R. Kiniry. Development, growth, and biomass simulations of two common wetland tree species in Texas. Environmental Monitoring and Assessment 2018, 190, 521 .

AMA Style

Su Min Kim, Jaehak Jeong, Dan Keesee, James R. Kiniry. Development, growth, and biomass simulations of two common wetland tree species in Texas. Environmental Monitoring and Assessment. 2018; 190 (9):521.

Chicago/Turabian Style

Su Min Kim; Jaehak Jeong; Dan Keesee; James R. Kiniry. 2018. "Development, growth, and biomass simulations of two common wetland tree species in Texas." Environmental Monitoring and Assessment 190, no. 9: 521.

Journal article
Published: 13 August 2018 in Agricultural Systems
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Limited field studies have been performed to evaluate the impacts of conservation agriculture (CA) on crop yields and soil organic carbon sequestration in tropical conditions. In this study, we used the Environmental Policy Integrated Climate (EPIC) model to evaluate the impact of CA and conservation tillage (CT) on crop yields in tropical conditions for unique upland rice, soybean, and cassava cropping systems in Cambodia. New crop parameters were developed and tested for cassava, sesame, banana, sunn hemp, stylo, and congo grass. The results show that EPIC successfully replicated crop yields of soybean, upland rice, maize, and cassava based on R2 statistics ranging from 0.62 to 0.88 and percent bias (PBIAS) values ≤10%. However, it cannot be concluded that the model can accurately capture the biomass for all the individual crops due to limitations in the observed biomass data. The cassava and maize biomass were simulated satisfactorily, resulting in R2 values of 0.81 and 0.75, respectively. However, the computed PBIAS for the biomass estimates of the two crops were >25%. In contrast, the predicted rice and soybean biomass met PBIAS criteria (≤23%) but resulted in weak R2 statistics of ≤0.20, indicating inaccurate replications of the measured biomass. Similarly, the cover crop mean biomass and PBIAS statistics were acceptable but the R2 values were not. Overall, the model tended to overestimate the measured crop biomass. No significant difference was found in the simulated crop yields between the CA and CT treatments. However, the predicted rice and soybean results reflect an increased yield trend over time for the CA treatments, versus no discernible trend for the cassava and maize yields.

ACS Style

Kieu N. Le; Jaehak Jeong; Manuel R. Reyes; Manoj K. Jha; Philip W. Gassman; Luca Doro; Lyda Hok; Stéphane Boulakia. Evaluation of the performance of the EPIC model for yield and biomass simulation under conservation systems in Cambodia. Agricultural Systems 2018, 166, 90 -100.

AMA Style

Kieu N. Le, Jaehak Jeong, Manuel R. Reyes, Manoj K. Jha, Philip W. Gassman, Luca Doro, Lyda Hok, Stéphane Boulakia. Evaluation of the performance of the EPIC model for yield and biomass simulation under conservation systems in Cambodia. Agricultural Systems. 2018; 166 ():90-100.

Chicago/Turabian Style

Kieu N. Le; Jaehak Jeong; Manuel R. Reyes; Manoj K. Jha; Philip W. Gassman; Luca Doro; Lyda Hok; Stéphane Boulakia. 2018. "Evaluation of the performance of the EPIC model for yield and biomass simulation under conservation systems in Cambodia." Agricultural Systems 166, no. : 90-100.

Journal article
Published: 07 August 2018 in Science of The Total Environment
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Terrestrial fate and transport processes of E. coli can be complicated by human activities like urbanization or livestock grazing. There is a critical need to address contributing sources of bacterial contamination, properly assess the management of critical sources, and ultimately reduce E. coli concentrations in impaired water bodies. In particular, characterization of wildlife animal contributions and other “background” input sources of microbial pollution are highly uncertain and data are scarce. This study attempts to identify critical sources of E. coli and the efficacy of conservation practices for mitigating E. coli concentrations in the Arroyo Colorado watershed, Texas, using a process-based hydrologic and water quality model. We propose to incorporate a bacterial source tracking assessment into the modeling framework to fill the gap in data on wildlife and human contribution. In addition, other sources identified through a GIS survey, national census, and local expert knowledge were incorporated into the model as E. coli sources. Results suggest that simulated distribution of E. coli sources significantly improved after incorporating this enhanced data on E. coli sources into the model (R2 = 0.90) compared to the SWAT result without BST (R2 = 0.59). Scenario assessments indicate that wildlife contributions may remain significant despite land use change and urbanization, expected to mostly occur in agricultural and range lands. A combination of nonpoint source management measures, voluntary implementation of advanced treatment by wastewater plants where possible, and installation of aerators in the zone of impairment were demonstrated to be effective measures for restoring the recreation and aquatic life uses of the Arroyo Colorado.

ACS Style

Jaehak Jeong; Kevin Wagner; Jaime J. Flores; Tim Cawthon; YoungGu Her; Javier Osorio; Haw Yen. Linking watershed modeling and bacterial source tracking to better assess E. coli sources. Science of The Total Environment 2018, 648, 164 -175.

AMA Style

Jaehak Jeong, Kevin Wagner, Jaime J. Flores, Tim Cawthon, YoungGu Her, Javier Osorio, Haw Yen. Linking watershed modeling and bacterial source tracking to better assess E. coli sources. Science of The Total Environment. 2018; 648 ():164-175.

Chicago/Turabian Style

Jaehak Jeong; Kevin Wagner; Jaime J. Flores; Tim Cawthon; YoungGu Her; Javier Osorio; Haw Yen. 2018. "Linking watershed modeling and bacterial source tracking to better assess E. coli sources." Science of The Total Environment 648, no. : 164-175.

Journal article
Published: 29 July 2018 in Sustainability
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Will soil organic carbon (SOC) and yields increase for conservation management systems in tropical zones in response to the next 100 years? To answer the question, the Environmental Policy Integrated Climate (EPIC) model was used to study the effects of climate change, cropping systems, conservation agriculture (CA) and conservation tillage management practices on SOC and crop productivity in Kampong Cham, Cambodia. The EPIC model was successfully calibrated and validated for crop yields, biomass, SOC and nitrogen based on field data from a five-year field experiment. Historical weather (1994–2013) was used for baseline assessment versus mid-century (2046–2064) and late-century (2081–2100) climate projections generated by the Geophysical Fluids Dynamics Laboratory (GFDL) CM2.1 global climate model. The simulated results showed that upland rice yield would increase the most under the B1 scenario in mid-century for all treatments, followed by soybean and maize. Cassava yield only increased under CA treatment when cultivated as a continuous primary crop. Carbon sequestration was more sensitive to cropping systems and crop rotation than climate change. The results indicated that the rotated CA primary crop (maize) systems should be prioritized for SOC sequestration as well as for increasing crop productivity. In addition, rice systems may increase SOC compared to soybean and cassava.

ACS Style

Kieu N. Le; Manoj K. Jha; Jaehak Jeong; Philip W. Gassman; Manuel R. Reyes; Luca Doro; Dat Q. Tran; Lyda Hok. Evaluation of Long-Term SOC and Crop Productivity within Conservation Systems Using GFDL CM2.1 and EPIC. Sustainability 2018, 10, 2665 .

AMA Style

Kieu N. Le, Manoj K. Jha, Jaehak Jeong, Philip W. Gassman, Manuel R. Reyes, Luca Doro, Dat Q. Tran, Lyda Hok. Evaluation of Long-Term SOC and Crop Productivity within Conservation Systems Using GFDL CM2.1 and EPIC. Sustainability. 2018; 10 (8):2665.

Chicago/Turabian Style

Kieu N. Le; Manoj K. Jha; Jaehak Jeong; Philip W. Gassman; Manuel R. Reyes; Luca Doro; Dat Q. Tran; Lyda Hok. 2018. "Evaluation of Long-Term SOC and Crop Productivity within Conservation Systems Using GFDL CM2.1 and EPIC." Sustainability 10, no. 8: 2665.

Journal article
Published: 30 June 2018 in Journal of Climate Change Research
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ACS Style

Soon-Kun Choi; Jaehak Jeong; JaePil Cho; Seung-Oh Hur; Dongho Choi; Min-Kyeong Kim. Assessing the Climate Change Impacts on Paddy Rice Evapotranspiration Considering Uncertainty. Journal of Climate Change Research 2018, 9, 143 -156.

AMA Style

Soon-Kun Choi, Jaehak Jeong, JaePil Cho, Seung-Oh Hur, Dongho Choi, Min-Kyeong Kim. Assessing the Climate Change Impacts on Paddy Rice Evapotranspiration Considering Uncertainty. Journal of Climate Change Research. 2018; 9 (2):143-156.

Chicago/Turabian Style

Soon-Kun Choi; Jaehak Jeong; JaePil Cho; Seung-Oh Hur; Dongho Choi; Min-Kyeong Kim. 2018. "Assessing the Climate Change Impacts on Paddy Rice Evapotranspiration Considering Uncertainty." Journal of Climate Change Research 9, no. 2: 143-156.

Erratum
Published: 11 June 2018 in Water
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Note: In lieu of an abstract, this is an excerpt from the first page.Excerpt The authors wish to make the following correction to their paper [1]: The second author’s name should be changed from “Yihun Dile Taddele” to “Yihun Taddele Dile”

ACS Style

Abeyou Wale Worqlul; Yihun Taddele Dile; Essayas Kaba Ayana; Jaehak Jeong; Anwar Assefa Adem; Thomas Gerik. Erratum: Worqlul, A.W.; et al. Impact of Climate Change on Streamflow Hydrology in Headwater Catchments of the Upper Blue Nile Basin, Ethiopia. Water 2018, 10, 120. Water 2018, 10, 761 .

AMA Style

Abeyou Wale Worqlul, Yihun Taddele Dile, Essayas Kaba Ayana, Jaehak Jeong, Anwar Assefa Adem, Thomas Gerik. Erratum: Worqlul, A.W.; et al. Impact of Climate Change on Streamflow Hydrology in Headwater Catchments of the Upper Blue Nile Basin, Ethiopia. Water 2018, 10, 120. Water. 2018; 10 (6):761.

Chicago/Turabian Style

Abeyou Wale Worqlul; Yihun Taddele Dile; Essayas Kaba Ayana; Jaehak Jeong; Anwar Assefa Adem; Thomas Gerik. 2018. "Erratum: Worqlul, A.W.; et al. Impact of Climate Change on Streamflow Hydrology in Headwater Catchments of the Upper Blue Nile Basin, Ethiopia. Water 2018, 10, 120." Water 10, no. 6: 761.

Book chapter
Published: 23 May 2018 in Arid Environments and Sustainability
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ACS Style

Sumin Kim; Jaehak Jeong; James R. Kiniry. Simulating the Productivity of Desert Woody Shrubs in Southwestern Texas. Arid Environments and Sustainability 2018, 1 .

AMA Style

Sumin Kim, Jaehak Jeong, James R. Kiniry. Simulating the Productivity of Desert Woody Shrubs in Southwestern Texas. Arid Environments and Sustainability. 2018; ():1.

Chicago/Turabian Style

Sumin Kim; Jaehak Jeong; James R. Kiniry. 2018. "Simulating the Productivity of Desert Woody Shrubs in Southwestern Texas." Arid Environments and Sustainability , no. : 1.

Journal article
Published: 11 May 2018 in Sustainability
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This paper studied the impacts of small-scale irrigation (SSI) interventions on environmental sustainability, agricultural production, and socio-economics using an Integrated Decision Support System (IDSS). The IDSS is comprised of a suite of models, namely the Soil and Water Assessment Tool (SWAT), Agricultural Policy/Environmental eXtender (APEX), and Farm Income and Nutrition Simulator (FARMSIM). The IDSS was applied in Dimbasinia watershed in northern Ghana using irrigation water from shallow groundwater. The watershed has a modest amount of shallow groundwater resources. However, the average annual irrigation water requirement exceeded the average annual shallow groundwater recharge. It was found that the current crop yield in Dimbasinia watershed was only ~40% of the potential crop production. This is mainly related to climate variability, low soil fertility, and land-management practices. For example, application of 50 kg/ha urea and 50 kg/ha DAP doubled maize and sorghum yield from the current farmers’ practices. Better income was obtained when irrigated vegetables/fodder were cultivated in rotation with sorghum as compared to in rotation with maize. Investment in solar pumps paid better dividends and also supplied clean energy. The socio-economic analysis indicated that having irrigated dry season vegetables will improve household nutrition. Since shallow groundwater recharge alone may not provide sufficient water for irrigation in a sustainable manner, surface water may be stored using water-harvesting structures to supplement the groundwater for irrigation. Integrated use of the water resources will also reduce depletion of the shallow groundwater aquifer. We conclude that IDSS is a promising tool to study gaps and constraints as well as upscaling of SSI.

ACS Style

Abeyou W. Worqlul; Yihun T. Dile; Jean-Claude Bizimana; Jaehak Jeong; Thomas J. Gerik; Raghavan Srinivasan; James W. Richardson; Neville Clarke. Multi-Dimensional Evaluation of Simulated Small-Scale Irrigation Intervention: A Case Study in Dimbasinia Watershed, Ghana. Sustainability 2018, 10, 1531 .

AMA Style

Abeyou W. Worqlul, Yihun T. Dile, Jean-Claude Bizimana, Jaehak Jeong, Thomas J. Gerik, Raghavan Srinivasan, James W. Richardson, Neville Clarke. Multi-Dimensional Evaluation of Simulated Small-Scale Irrigation Intervention: A Case Study in Dimbasinia Watershed, Ghana. Sustainability. 2018; 10 (5):1531.

Chicago/Turabian Style

Abeyou W. Worqlul; Yihun T. Dile; Jean-Claude Bizimana; Jaehak Jeong; Thomas J. Gerik; Raghavan Srinivasan; James W. Richardson; Neville Clarke. 2018. "Multi-Dimensional Evaluation of Simulated Small-Scale Irrigation Intervention: A Case Study in Dimbasinia Watershed, Ghana." Sustainability 10, no. 5: 1531.

Journal article
Published: 15 March 2018 in Hydrology
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Existing methods to estimate stream health are often location-specific, and do not address all of the components of stream health. In addition, there are very few guidelines to estimate the health of a stream, although the literature and useful tools such as Indicators of Hydrologic Alteration (IHA) are available. This paper describes an approach developed for estimating stream health. The method involves the: (1) collection of flow data; (2) identification of hydrologic change; (3) estimation of some hydrologic indicators for pre-alteration and post-alteration periods; and (4) the use of those hydrologic indicators with the scoring framework of the Dundee Hydrologic Regime Assessment Method (DHRAM). The approach estimates the stream health in aggregate including all of the components, such as riparian vegetation, aquatic species, and benthic organisms. Using the approach, stream health can be estimated at two different levels: (1) the existence or absence of a stream health problem based on the concept of eco-deficit and eco-surplus using flow duration curves; and (2) the estimation of overall stream health using the IHA–DHRAM method. The procedure is demonstrated with a case example of the White Rock Creek watershed in Texas in the United States (US). The approach has great potential to estimate stream health and prescribe flow-based goals for the restoration of impaired streams.

ACS Style

Narayanan Kannan; Aavudai Anandhi; Jaehak Jeong. Estimation of Stream Health Using Flow-Based Indices. Hydrology 2018, 5, 20 .

AMA Style

Narayanan Kannan, Aavudai Anandhi, Jaehak Jeong. Estimation of Stream Health Using Flow-Based Indices. Hydrology. 2018; 5 (1):20.

Chicago/Turabian Style

Narayanan Kannan; Aavudai Anandhi; Jaehak Jeong. 2018. "Estimation of Stream Health Using Flow-Based Indices." Hydrology 5, no. 1: 20.

Journal article
Published: 01 February 2018 in Journal of Hydrologic Engineering
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Vegetative filter strips (VFS) are an effective approach to reducing edge-of-field discharge of sediment and pesticide. The web-based Vegetative Filter Strip MODel (VFSMOD) system, developed to assess the trapping efficiency of VFS, has a limited capability in regards to considering the effects of shallow groundwater table, which significantly affects estimation of infiltration and runoff in the VFS. In addition, the system does not simulate the transport of pesticides that can be implemented in agricultural areas. Thus, the web-based VFSMOD system was enhanced in this study by incorporating the groundwater table in simulating soil moisture dynamics and by adding a new water quality module for evaluating the VFS performances effectively. Results show that the trapping efficiencies of sediment (61%) and a pesticide (57%) were simulated with the VFS width of 10 m for a single storm event, improving the VFSMOD performance with a shallow groundwater table. The optimum VFS widths for multiple storm events were found for a given reduction goal.

ACS Style

Kyoung Jae Lim; Youn Shik Park; Min-Kyeong Kim; Jaehak Jeong; Bernard A. Engel; Rafael Munoz-Carpena; Jonggun Kim. Design of Vegetative Filter Strip Using Web-Based System with Groundwater Table and Pesticide Degradation Analysis Modules. Journal of Hydrologic Engineering 2018, 23, 04017061 .

AMA Style

Kyoung Jae Lim, Youn Shik Park, Min-Kyeong Kim, Jaehak Jeong, Bernard A. Engel, Rafael Munoz-Carpena, Jonggun Kim. Design of Vegetative Filter Strip Using Web-Based System with Groundwater Table and Pesticide Degradation Analysis Modules. Journal of Hydrologic Engineering. 2018; 23 (2):04017061.

Chicago/Turabian Style

Kyoung Jae Lim; Youn Shik Park; Min-Kyeong Kim; Jaehak Jeong; Bernard A. Engel; Rafael Munoz-Carpena; Jonggun Kim. 2018. "Design of Vegetative Filter Strip Using Web-Based System with Groundwater Table and Pesticide Degradation Analysis Modules." Journal of Hydrologic Engineering 23, no. 2: 04017061.