• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.185-185
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• 2023

Agricultural water demand is considered as the major sector of water withdrawal due to irrigation. The majority part of the global agricultural field depends on various irrigation techniques. Therefore, a timely and sufficient supply of water is the most important requirement for agriculture. Irrigation is implemented in different ways in various land surface models, it can be modeled empirically based on observed irrigation rates or by calculating water supply and demand. Certain models can also calculate the irrigation demand as per the soil water deficit. In these implementations, irrigation is typically applied uniformly over the irrigated land regardless of crop types or irrigation techniques. Whereas, the latest version of Community Land Model (CLM) in the Community Terrestrial Systems Model (CTSM) uses a global distribution map of irrigation with 64 crop functional types (CFTs) to simulate the irrigation water demand. It can estimate irrigation water withdrawal from different sources and the amount or the areas irrigated with different irrigation techniques. Hence, we set up the model for the simulation period of 16 years from 2000 to 2015 to analyze the global irrigation demand at a spatial resolution of 1.9° × 2.5°. The simulated irrigation water demand is evaluated with the available observation data from FAO AQUASTAT database at the country scale. With the evaluated model, this study aims to suggest new sustainable scenarios for the ratios of irrigation water withdrawal, high depending on the withdrawal sources e.g. surface water and groundwater. With such scenarios, the CFT maps are considered as the determining factor for selecting the areas where the crop pattern can be altered for a sustainable irrigation water management depending on the available withdrawal sources. Overall, our study demonstrate that the scenarios for the future sustainable water resources management in terms of irrigation water withdrawal from the both the surface water and groundwater sources may overcome the excessive stress on exploiting the groundwater in major river basins globally.

• Journal of Korean Society of Water and Wastewater
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• v.14 no.4
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• pp.311-317
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• 2000

The operation of flocculation process and the evaluation thereof have been mainly based on G, t and $G{\times}t$ values which are available from design guidelines and texts. However, their suggested ranges are too wide to find the optimum condition specific to a particular water treatment plant and none of the existing method can be used to evaluate and suggest the optimum operational condition. Recently, a commercially available particle counter is found to be useful in determining the flocculation process based on the particle dynamics. The optimum condition is defined as one that best suits the purpose of flocculation; the number of small particles should decrease, while that of large particles should increase. The experiments were performed at two conventional water treatment plants in Korea, one with horizontal mechanical flocculators, and another with vertical type mechanical flocculators. In this paper, experiences to evaluate the flocculation process and to suggest the optimum operation condition will be presented. Although particle counting method is found to be beneficial compared to any other existing methods, the optimum condition is very much site-specific and should be evaluated at each water treatment plant for different conditions.

• Journal of Environmental Impact Assessment
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• v.9 no.1
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• pp.13-24
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• 2000

This paper presents a study of water quality model applications in environmental impact statements which were submitted during recent years in Korea. Most of the applications have reported that the development projects would have significant impacts on the water quality, especially, of streams and rivers. The water quality models, however, were hardly used as an impact prediction tool. Even in the cases where models were used, calibration and verification studies were not performed and thus the predicted results would not be reliable. These poor model applications in environmental impact assessment can be attributable to the fact that there were no available model application guidelines as well as no requirements by the review agency. In addition, the expected waste loads were improperly estimated in most cases, especially in non-point sources, and the predicted parameters were not good enough to understand water quality problems expected from the proposed plans. The effects of mitigation measures were not analyzed in most cases. Again, these can be attributed to no formal guidelines available for impact predictions until now. A brief guideline is described in this paper, including model selection, calibration and verification, impact prediction, and analysis of effects of mitigation measures. The results of this study indicate that the model application should be required to overcome the current improper predictions of environmental impacts and the guidelines should be developed in detail and provided.

• Journal of Korea Water Resources Association
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• v.41 no.1
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• pp.27-34
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• 2008

Groundwater development in coastal areas induces saltwater intrusion. In many cases amount of groundwater resources available for development is limited by a pre-specified limit of additional saltwater intrusion. In this paper a simple equation is developed to assess available groundwater resources which depends on the constraint of acceptable additional saltwater intrusion. Strack#s single-potential analytical solution is used to derive the equation. Available groundwater increases as more additional intrusion is allowed. However, critical points limit both the maximum pumping rate and the allowed saltwater intrusion limit. The equation is presented in the form of design curves from which the maximum pumping rate can be read off quickly. The equation and the design curves are suitable for preliminary estimation of available groundwater resources in coastal areas.

• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.2
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• pp.181-187
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• 1984

Lysine is known as a limiting amino acid in rice. In addition, it is considered to be important in that it is easily non-activated by the browning reaction during processing or storage. The present study was designed to utilize a kinetic approach to analyse the effect of temperature and water activity on available lysine loss in rice. Simplified kinetic models were used to obtain the various kinetic parameters for available lysine loss in rice subjected to accelerated shelf-life tests (ASLT). These kinetic parameters were then used to predict protein quality loss under the non-steady state storage. The predicted losses were compared to the actual losses. As expected, available lysine loss was increased with increased temperature and water activity. The activation energies and $Q_{10}$ values for available lysine loss ranged from 4.03 to 5.10 Kcal/ mole and 1.22 to 1.27, respectively, The shelf-lives at $25^{\circ}C$, the time to reach 25% loss of the available lysine, which was derived from the accelerated shelf-life tests showed 67 to 107 days according to $a_w$'s. The amount of loss for the fluctuating condition was greater than that occurring at the mean temperature of $45^{\circ}C$. Actually, the differences in effective temperature for the fluctuating storage were between about 4 and $6^{\circ}C$. In predicting the extent of loss using constant state data, the predicted shelf-lives were 2 to 7 days shorter than the actual storage values.

• Korean Journal of Soil Science and Fertilizer
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• v.37 no.2
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• pp.55-58
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• 2004

The objective of this study was to get information about water retention characteristics of horticultural substrates used in Korea determined by European standard method. Water retention curves were prepared at water volume (v/v, %) in relation to -10 cm, -50 cm, -100 cm water pressure head. Water retention curves showed different properties depending upon the type, the place of origin, particle size, and manufacturing processes of substrates. Peat and coir had easily available water content in the range of 30-40% and showed high water holding capacity, water buffering capacity, and aeration for plant growth. However, bark, sawdust and rice hull showed low water holding capacity about below 10%. The easily available water content of perlite and clay ball was low about 0.1-13.8%, whereas that of vermiculite and rockwool granulate was high about 25.9-52.0%. Understanding water retention characteristics of growing substrates is very important in cstablisliing optimum condition for plant growth. Further study on water retention curves for more substrates, mixture and growing media is needed.

• Korean Journal of Soil Science and Fertilizer
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• v.23 no.3
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• pp.167-172
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• 1990

Some of soil properties already known were selected for the determination of their effect on soil moisture characteristics. Total number of 2,808 representative samples from all over Korea with the exception of Jeju Island were investigated. 1. Available water contents were 4.7 for S, 7.7 for LS, 13.2 for SL, 17.7 for L, 19.2 for SiL, 15.9 for CL, 14.5 for SCL, 18.7 for SiCL, 17.3 for SiC, and 14.9% for C, respectively. 2. Simple regression analysis showed that field capacity and available water content were most strongly associated with sand content in coarse-textured soils, and with organic matter content in fine-textured soils, whereas permanent wilting point was closely associated with clay content. 3. Available water was strongly associated with silt content and also significantly with field capacity, but either not at all or negatively with permanent wilting point. 4. Prediction equations for available water and field capacity were drown out from known soil properties, which can be used for each textural class.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.1
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• pp.41-50
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• 2003

The feasibility as floricultural crops and water garden plant materials of Korean native water plants was investigated. Propagation type, growing and flowering time were observed for development as water garden, interior aquarium plant and water purification materials. Flowering time of the water plant was 7 species in May, 28 species in June, 49 species in July, 55 species in August, 47 species in September, and 17 species in October. Beautiful flowering water plants were Nymphaeaceae, Nymphoides peltata, Nymphoides indica, Monochoria korsakowii, Iris pseudacorus, Iris laevigata, and etc. Ornamental leafy water plants were Ceratopteris thalictroides, Ludwigia ovalis, Myriophyllum verticillatim, Limnophila sessiliflora, Blyxa aubertii, Blyxa echinosperma, Vallisneria asiatica, Hydrilla verticillata and Eleocharis acicularis etc. Isoetes japonica, Isoetes coreana and Isoetes sinensis were propagated by spore. Blyxa aubertii, Blyxa echinosperma, Myriophyllum verticillatim, Nuphar japonicum, Nelumbo nucifera, Ottelia alismoides, Sagittaria aginashi, Trapa japonica, and Trapa natans were propagated by seed. Persicaria amphibia, Ceratophyllum demersum (hornwort), Myriophyllum verticillatim, Myriophyllum spicatum, Oenanthe javanica, Potamogeton crispus, Hydrilla verticillata and Acorus calamus were propagated by division. And Vallisneria asiatica, Hydrilla verticillata and Phragmites japonica were propagated by runner. Ceratophyllum demersum (hornwort), Myriophyllum verticillatim, Myriophyllum spicatum, Limnophila sessilifera were propagated by adventitious bud. Ceratopteris thalictroides was propagated by leaf cutting. The 35 genera, 68 species of water plants were available for horticultural use. The 45 species such as Iris laevigata, Eleocharis acicularis, Menyanthes trifoliata, Nymphaea minima, Nuphar pumilum, Nymphoides coreana, Nymphoides peltata, Nymphoides indica, Nymphaea tetragona (water lily), and Typha latifolia could be use for water garden plant. The 21 species such as Limnophila sessilifera, Vallisneria asiatica, Ceratophyllum demersum and Hydrilla verticillata available for indoor aquarium. The 19 species such as Ottelia alismoides, Oenanthe javanica, Limnophila sessilifera and Blyxa echinosperma could be culture in container. The 27 species such as Trapa japonica, Trapa incisa, Phramites commuris (reed), Phragmites japonica, and Zizania latifolia were usable for water purification plant materials.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.2244-2248
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• 2008

This study was focused on estimated Stream Maintenance Flow and performed for simulate securing Stream Maintenance Flow in New town development area. Tributary streams were made of 6 small streams, joined Gong-ji Stream and Eu-am lake finally. For estimate Stream Maintenance Flow used Kajiyama and SWAT models for calculate available flow in study area. As a result the annual average stream flow dry years were $2,300{\sim}136,000\;m^/day3$, the annual average stream flow wet years were $4,800{\sim}136,031\;m^3/day$. The coefficient of determination($R^2$) and Nash-sutcliffe coefficient(EI) for comparison between Kajiyama and SWAT models were 0.88, 0.78 respectively.

• Water for future
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• v.16 no.1
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• pp.49-56
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• 1983

A STUDY ON THE ESTIMATION OF THE AVAILABLE WATER RESOURCES IN KOREA The purpose of this study is to present the estimated the total amount of runoff in Korea. The annual mean runoff is estimated by cumulating daily discharges that obtaine from daily stages on the rating curve. The selected five major gaging stations(Indogyo, Gyuam, Jindong, Naju, and Songjeong) to take the daily discharges stand for the five major streams such as the Han River, the Geum River, the Nokdong River, the Yeongsan River and the Seomjin River. The results of this study are as follows; 1) The maximum quantity of the total available water resources is estimated at 26,900 million cubic meters, the minimum is 24,300 million, and the annual mean quantity is 25,600 million 2) The annual mean rate of runoff is evaluated about 58 percent in the five major basins. 3) The annual mean rate of runoff over inland is estimated about 57 percent as a result of assuming the runoff rate of 5 zone about 80 percent, the annual mean rate of runoff is estimated about 56 percent except for V-zone in analysis.