• Journal of Korea Water Resources Association
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• v.46 no.9
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• pp.885-896
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• 2013

SEMMA (Soil Erosion Model for Mountain Areas) should be revised to apply on mountain watershed of large scale. In this study, the basic structure of original SEMMA and methods to calculate main parameters are reviewed and the revised parameters are presented to expand a range of application. SEMMA-Ic is new model revised by a rate of vegetation cover which is substituted for index of vegetation structure to use specially NDVI for large scale areas. The correlation coefficient and the Nash-Sutcliffe simulation efficiency for the revised model decreased rather than those of original model. However the evaluation of the revised model on watershed showed the approximate simulation with measured sediment yield and the underestimated simulation when sediment yield is large. The additional research for channel erosion is needed so that soil erosion model for hillslopes is used to estimate sediment yield from a watershed.

• Journal of Korea Water Resources Association
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• v.45 no.8
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• pp.795-804
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• 2012

Recently, changes in rainfall intensity and patterns have been causing increasing soil loss worldwide. As a result, the water ecosystem becomes worse and crops yield are reduced with soil loss and nutrient loss with it. Many studies have been proposed to estimate runoff and soil loss to predict or decrease non-point source pollution. Although the USLE has been used for many years in estimating soil losses, the USLE cannot reflect effects on soil loss of changes in rainfall intensity and patterns. The WEPP, physically based model, is capable of predicting soil loss and runoff using various rainfall intensity. In this study, the WEPP model was simulated for sediment yield, runoff and peak runoff using data of 5, 10, 30, 60 minute term rainfall, Huff's method and design rainfall. In case of rainfall interval of 5 minutes and 60 minutes, the sediment and runoff values decreased by 24% and 19%, respectively. The peak rate runoff values decreased by 16% when rainfall interval changed from 5 minutes to 60 minutes, indicating the peak rate runoff values are affected by rainfall intensity to some degrees. As a result of simulating using Huff's method, all values (sediment yield, runoff, peak runoff) were found to be the greatest at third quartile. According to the analysis under various design rainfall conditions (2, 3, 5, 10, 20, 30, 50, 100, 200, 300 years frequency), sediment yield, runoff, and peak runoff of 906.2%, 249.4% and 183.9% were estimated using 2 year to 300 year frequency rainfall data.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.1
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• pp.71-81
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• 2011

Due to increased human activities and intensive rainfall events in a watershed, soil erosion and sediment transport have been hot issues in many areas of the world. To evaluate soil erosion problems spatially and temporarily, many computer models have been developed and evaluated over the years. However, it would not be reasonable to apply the model to a watershed if topography and environment are different to some degrees. Also, source codes of these models are not always public for modification. The ArcGIS model builder provides ease-of-use interface to develop model by linking several processes and input/output data together. In addition, it would be much easier to modify/enhance the model developed by others. Thus, simple model was developed to decide soil erosion hot spot areas using ArcGIS model builder tool in this study. This tool was applied to a watershed to evaluate model performance. It was found that sediment yield was estimated to be 13.7 ton/ha/yr at the most severe soil erosion hot spot area in the study watershed. As shown in this study, the ArcGIS model builder is an efficient tool to develop simple models without professional programming abilities. The model, developed in this study, is available at http://www.EnvSys.co.kr/~sateec/toolbox for free download. This tool can be easily modified for further enhancement with simple operations within ArcGIS model builder interface. Although very simple soil erosion and sediment yield were developed using model builder and applied to study watershed for soil erosion hot spot area in this study. The approaches shown in this study provides insights for model development and code sharing for the researchers in the related areas.

• Analytical Science and Technology
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• v.22 no.2
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• pp.136-140
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• 2009

To improve the carbon recovery yield of chemical pretreatment in soil and sediment for $^{14}C$ age dating using AMS (Accelerator Mass Spectrometry), we have developed ultrasonic method in chemical pretreatment to replace with stirring method which has been generally used in each step of humic acid extraction for soil and sediment samples. Extraction conditions such as ultrasonic power, temperature and reaction time have been optimized. Six times higher carbon recovery yield could be obtained from low carbon content samples using ultrasonic method. We also compared the dating results by AMS obtained using ultrasonic method with the ages of samples treated by the stirring method. It was found that this new method could be applied to the pretreatment process of low carbon content samples for AMS age dating without effects on the dated ages, and with highly improved carbon recovery yields.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.995-1009
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• 2010

Accelerated soil erosion due to extreme climate change, such as increased rainfall intensity, and human-induced environmental changes, is a widely recognized problem. Existing soil erosion models are generally based on the gross erosion concept to compute annual upland soil loss in tons per acre per year. However, such models are not suitable for event-based simulations of erosion and deposition in time and space. Recent advances in computer geographic information system (GIS) technologies have allowed hydrologists to develop physically based models, and the trend in erosion prediction is towards process-based models, instead of conceptually lumped models. This study aims to propose an effective and robust distributed rainfall-sediment yield-runoff model consisting of basic element modules: a rainfall-runoff module based on the kinematic wave method for subsurface and surface flow, and a runoff-sediment yield-runoff model based on the unit stream power method. The model was tested on the Cheoncheon catchment, upstream of the Yongdam dam using hydrological data for three extreme flood events due to typhoons. The model provided acceptable simulation results with respect to both discharge and sediment discharge even though the simulated sedigraphs were underestimated, compared to observations. The spatial distribution of erosion and deposition demonstrated that eroded sediment loads were deposited in the cells along the channel network, which have a short overland flow length and a gentle local slope while the erosion rate increased as rainfall became larger. Additionally, spatially heterogeneous rainfall intensity, dependant on Thiessen polygons, led to spatially-distinct erosion and deposition patterns.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.353-358
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• 1998

GRASS-AGNPS model integrated with GIS was applied to rural watersheds having complex land use characteristics and evaluated for its applicability through calibration using observed data. The analyses of raster encoding accuracy and model behavior to runoff, sediment yields and nutrient loads for different cell-size showed that 150 m cell size indicated reasonable applicability of the model. Simulated runoff was in a good agreement with the observed data and simulated peak runoff rate was larger than the observed data. The sediment yield simulated by modified AGNPS model using irregular cell for forest area were less than that of the regular cell method. In predicting sediment yields, the result showed a different trend at each representative rural watershed. Nutrient loads simulated by the model were significantly different from the observed data.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2009.04a
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• pp.269-270
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• 2009

This study builds a sediment rating curve using the measured sediment yield and the simulated soil erosion by a GIS-embedded empirical model. Then the structured sediment rating curve is used to determine the SDR on a basin scale in southern Korea. The whole data(year of 2002-2008) are divided into two groups and the first group(year of 2002-2005) is used for calibration, while the other is used for validation. Two cases(rainfall amount and rainfall intensity) are analyzed to consider the rainfall runoff erosivity factor in simulating soil erosion. The results show the derived SDR provides reasonable accuracy and rainfall intensity gives better performance in calculating soil erosion than rainfall amount.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.6
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• pp.865-871
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• 2016

This study investigated the quality characteristics of Yanggaeng added with lentil bean sediment. Yanggaeng was prepared by addition of 0, 25, 50, and 75% (w/w) lentil bean sediment to white bean basic formulation. For the proximate composition measurement, lentil bean sediment consisted of 15.63% moisture, 17.31% crude protein, 0.92% crude ash, and 0.31% crude fat. The sediment yield of lentil beans was 54.25%. The moisture content of Yanggaeng significantly increased with increasing lentil bean sediment content. The total soluble solid content ($^{\circ}Brix$) of Yanggaeng significantly decreased with increasing lentil bean sediment content, whereas the pH was not significantly different between the control and experimental groups. The lightness of Yanggaeng significantly decreased with increasing lentil bean sediment content, whereas redness and yellowness significantly increased with increasing lentil bean sediment content. The springiness, gumminess, and chewiness of Yanggaeng decreased with increasing lentil bean sediment content, whereas hardness and cohesiveness was not significantly different between the control and experimental groups. The total phenolic content and 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity significantly increased with increasing lentil bean sediment content. Yanggaeng containing 25% lentil bean sediment had acceptable sensory properties, such as taste, texture, and overall preferences. Thus, our results suggest that Yanggaeng containing 25% lentil bean sediment could improve the sensory properties and antioxidant activities of Yanggaeng.

• Journal of Korean Society on Water Environment
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• v.32 no.1
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• pp.108-114
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• 2016

Sediment-laden water leads to water quality degradation in streams; therefore, best management practices must be implemented in the source area to control nonpoint source pollution. Field monitoring was implemented to measure precipitation, direct runoff, and sediment concentrations at a control plot and straw-applied plot to examine the effect on sediment reduction in this study. A hydrology model, which employs Curve Number (CN) to estimate direct runoff and the Universal Soil Loss Equation to estimate soil loss, was selected. Twenty-five storm events from October 2010 to July 2012 were observed at the control plot, and 14 storm events from April 2011 to July 2011 at the straw-applied plot. CN was calibrated for direct runoff, and the Nash-Sutcliffe efficiency and coefficient of determination were 0.66 and 0.68 at the control plot. Direct runoff at the straw-applied plot was calibrated using the percentage direct runoff reduction. The estimated reduction in sediment load by direct runoff reduction calibration alone was acceptable. Therefore, direct runoff-sediment load behaviors in a hydrology model should be considered to estimate sediment load and the reduction thereof.

• The Korean Journal of Quaternary Research
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• v.19 no.1
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• pp.41-46
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• 2005

This study discusses the soil erosion on hillslopes and sediment deposition in lakes within catchments in South Korea. In order to determine seasonal variations of sedimentation in Yeongcheon and Seondong lakes, the sediment traps were set in the deep part of both lakes and lake sediments have been sampledmonthly from July 2004 to August 2005. Some properties such as highmineral content, fine particle size and high particle density in the Yeongcheon Lake indicate intensive soil erosion, sediment transportation and deposition throughout the catchment for a long time. The high sediment yield in the Seondong Lake is related with higher weathering intensity and extreme soil erosion by running water due to higher seasonal rainfall amount. Rates of erosion and sedimentation in the Seondong Lake are estimated to be higher than those of the Yeongcheon Lake, suggesting that the Seondong Lake is associated with higher precipitation, smaller catchment area, and extreme soil vulnerability to ephemeral erosion by overland flow during the heavy rainfall event. Consequently, both catchments are characterized by different erosion and sedimentation processes, as well as different geomorphic factors (bedrock, soil structure, rainfall intensity and catchment area).