• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.77-87
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• 2008

Wooden model erosion control dam was made with pitch pine, of which the strength properties was evaluated. Wooden model erosion control dam was made with diameter 90 mm of pitch pine round posts treated with CUAZ-2 (Copper Azole), changing joint in three different types. In each type, erosion control dam was made in nine floor (cross-bar of five floors and vertical-bar of four floors), of which the hight was 790 mm. And then strength properties were investigated through horizontal loading test and impact strength test, and the deformation of structure through image processing (AICON 3D DPA-PRO system). In horizontal loading test of wooden model erosion control dam using round post of diameter 90 mm, whether there was stone or not did not affect strength much when using self drill screw, but strength was decreased by 23%. In monolithic type of erosion control dam using screw bar, strength was increased by 1.5 times and deformation was decreased when filling with stone. When reinforcing with screw bar that ring is connected to self drill screw, strength was increased by 4.8 times. In impact strength test of wooden model erosion control dam made with round post of diameter 90 mm, the erosion control dam connected with self drilling screw not filling with stone was totally destroyed by the 1st impact, and the erosion control dam using screw bar was ruptured at cross-bar at which 779 kgf of impact was loaded in the 1st impact. In the 2nd impact, the base parts were ruptured, and reaction force was decreased to 545 kgf. In the 3rd impact, whole base parts were destroyed, and reaction force was decreased to 263 kgf.

• Spatial Information Research
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• v.14 no.4 s.39
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• pp.363-377
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• 2006

Mean annual soil loss was calculated and critical soil erosion areas were identified for the Congaree River Basin in South Carolina, USA using the Revised Universal Soil Loss Equation (RUSLE) model. In the RUSLE model, the mean annual soil loss (A) can be calculated by multiplying rainfall-runoff erosivity (R), soil erodibility (K), slope length and steepness (LS), crop-management (C), and support practice (P) factors. The critical soil erosion areas can be identified as the areas with soil loss amounts (A) greater than the soil loss tolerance (T) factor More than 10% of the total area was identified as a critical soil erosion area. Among seven subwatersheds within the Congaree River Basin, the urban areas of the Congaree Creek and the Gills Creek subwatersheds as well as the agricultural area of the Cedar Creek subwatershed appeared to be exposed to the risk of severe soil loss. As a prototype model for examining future effect of human and/or nature-induced changes on soil erosion, the RUSLE model customized for the area was embedded into ESRI ArcGIS ArcMap 9.0 using Visual Basic for Applications. Using the embedded model, users can modify C, LS, and P-factor values for each subwatershed by changing conditions such as land cover, canopy type, ground cover type, slope, type of agriculture, and agricultural practice types. The result mean annual soil loss and critical soil erosion areas can be compared to the ones with existing conditions and used for further soil loss management for the area.

• Journal of Environmental Impact Assessment
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• v.15 no.6
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• pp.357-372
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• 2006

The excessive land activities in farming can cause soil erosion, inundation by a flood, and fallow. So far land evaluation has been analyzed using the land use limitation derived from the excessive land activities. This study was done for evaluating the agricultural fields by using 3 land use limitations, inundation potential, soil erodibility potential, and fallow potential. The study area is Ibang-myeon, Changnyeong-gun, Gyeongnam-province, Korea. A logistic regression model was applied to recognize the inundation potential by a flood in the Nakdong river basin. And potential soil erodibility index (PSEI) was derived from USLE model to analyze the soil erodibility potential. And a probability model from a logistic regression model was applied to detect the fallow potential. Therefore, we found 220.7ha for the 4th grade and 86.1ha for the 5th grade was analyzed as water damage potential. Large area near Nakdong river have problem to grow the rice due to the damage by water inundation. And 213.6ha for the 3rd grade and 103.3ha for 4th grade was detected as a result of the analysis of soil erosion potential. The soil erosion potential was high when within-field integrity of soil was not stable, or the kinetic energy was high or the slope length was long due to a steep slope of a specific land. And 869.1ha for 3rd grade, 174.9ha for 4th grade, and 110.6ha for 5th grade was detected to be distributed having the fallow potential. Especially, a village, having a steep mountain, had 249.5ha for the 3rd grade, which was 28.7% of total area showing the 3rd grade. Finally, Three villages, including An-ri, Geonam-ri, Songgok-ri, showed they had largest area of the suitable land in the study area. These villages had similar topographic condition where they were far from Nakdong river, and they had relatively higher elevation and flat lands.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.3
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• pp.65-73
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• 2005

Because the geological features of Imha basin are composed of clay and shale layer, much soil particle flows into reservoir in shape of muddy water when it rains a lot. Therefore, turbidity data can be indirect-index to estimate the soil erosion of Imha basin. This study evaluated annual soil erosion using GIS-based soil erosion model and applied rainfall weighting value method by time-series rainfall data to estimate monthly soil erosion. In view of 2003 turbidity data, monthly soil erosion with rainfall weighting value is more efficient than monthly soil erosion with rainfall data.

• Proceedings of the Korea Water Resources Association Conference
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• 2006.05a
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• pp.908-912
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• 2006

Geology and terrain of Imha basin has a very weak characteristics to soil erosion, so much soil particles flow into Imha reservoir and bring about high density turbid water when it rains a lot. Especially, since the agricultural area of Imha basin is mainly located in river boundary, Imha reservoir has suffered from turbid water by soil erosion. Therefore, it is important to estimate the influence of soil erosion to establish efficient management of water-pollutant buffering zone for the reduction of turbid water. By applying GIS-based RUSLE model, this study can acquire 12.23% that is the ratio of soil erosion in water-pollutant buffering zone and is higher than area-ratio (9.95%) of water-pollutant buffering zone. This is why the area-ratio of agricultural district (27.24%) in water-pollutant buffering zone is higher than the area-ratio of agricultural district (14.96%) in Imha basin. Also as the result of soil erosion in sub-basin, Daegok basin shows highest soil erosion in water-pollutant buffering zone, second is Banbyeon_10 basin and last is Seosi basin.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.7
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• pp.3-14
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• 2006

The objective of this study was to develop a GIS-based decision support system (GIS-USLE system) to estimate soil erosion and evaluate its effect on concentrated upland plots in Godang district, Korea. This system was developed for the ArcView environment using A VENUE script. Three modules were used in the GIS-USLE system, namely pre-processing, the USLE factors calculator module, and post-processing. This system benefits from a user friendly environment that allows users with limited computer knowledge to use it. This system was applied to 1,285 individual upland plots ranging from 0.005 to 1.347 ha in size with an average slope steepness of 14 %. The rainfall distributions were estimated using the three methods, namely Mononobe and Yen-Chow with Triangle and with Trapezoid type, and then used to calculate the rainfall erosivity factor. The soil erosion amounts from the 1,285 individual plots in the study area by 2 year return period with a 24h maximum rainfall amount of 154.6 mm were estimated at 5 tons/ha on average. Slope appeared to be the most important factor affecting soil erosion estimation, as expected. The prototype model was applied to the project area, and the results appeared to support the practical applications. By examining many fields simultaneously, this system can easily provide fast estimation of soil erosion and thus reveal the spatial pattern of erosion from fields in a region. This study will help estimate and evaluate soil erosion in concentrated upland districts and identify the best management practices.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.341-347
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• 2006

Geographically Imha basin is adjacent to Andong basin, but the occurrence of turbid water in each reservoir by storm events shows big differences. Hence, it is very important to identify the reason for these large differences. This study compared and analyzed soil erosion using the semi-empirical soil erosion model, RUSLE for both Imha and Andong basin, especially with emphasis on high-density turbid water. The agricultural district, which is the most vulnerable to soil erosion, was intensively analyzed based on land cover map produced by Ministry of Environment. As a result, the portion of the agricultural area is 11.88% for Andong basin, while it is 14.95% for Imha basin. Also all RUSLE factors excepts practice factor turned out to be higher for Imha basin. This means that the basin characteristics such as soil texture, terrain, and land cover for Imha basin is more vulnerable to soil erosion. Estimation of soil erosion by RUSLE for Andong and Imha basin is 1,275,806 ton and 1,501,608 ton, respectively, showing higher soil erosion by 225,802 ton for Imha basin.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2D
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• pp.335-340
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• 2006

Geology and terrain of Imha basin has a very weak characteristics to soil erosion, so much soil particles flow into Imha reservoir and bring about high density turbid water when it rains a lot. Especially, since the agricultural area of Imha basin is mainly located in river boundary, Imha reservoir has suffered from turbid water by soil erosion. Therefore, it is important to estimate the influence of soil erosion to establish efficient management of water-pollutant buffering zone for the reduction of turbid water. By applying GIS-based RUSLE model, this study can acquire 12.23% that is the ratio of soil erosion in water-pollutant buffering zone and is higher than area-ratio (9.95%) of water-pollutant buffering zone. This is why the area-ratio of agricultural district (27.24%) in water-pollutant buffering zone is higher than the area-ratio of agricultural district (14.96%) in Imha basin. Also as the result of soil erosion in sub-basin, Daegok basin shows highest soil erosion in water-pollutant buffering zone, second is Banbyeon_10 basin and last is Seosi basin.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.17-17
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• 2011

As a method of countermeasure to bed degradation and armoring phenomena of bed material in the downstream area of dam reservoirs, sediment augmentation (replenished sediment) has been carried out in many Japanese rivers. In general, bed of the replenished sediment site is composed of rocks, because the site is located in the downstream area of the dams and sediment supply is very small. Bed deformation process has been researched by many researchers. As a method of countermeasure to bed degradation and armoring phenomena of bed material in the downstream area of dam reservoirs, sediment augmentation (replenished sediment) has been carried out in many Japanese rivers. In general, bed of the replenished sediment site is composed of rocks, because the site is located in the downstream area of the dams and sediment supply is very small. Bed deformation process has been researched by many researchers. However, most of them can treat movable bed only and cannot be applied to the bed deformation process of sediment on rocks. If the friction angle between the sediment and the bed surface is assumed to be the same as the friction angle between the sediment and the sediment, sediment transport rate must be smaller without sediment deposition layer on the rocks. As a result, the reproduced bed geometry is affected very well. In this study, non-equilibrium transport process of non-cohesive sediment on rigid bed is introduced into the horizontal two dimensional bed deformation model and the model is applied to the erosion process of replenished sediment on rock in the Nakagawa, Japan. Here, the Japanese largest scale sediment augmentation has been performed in the Nakagawa. The results show that the amounts of the eroded sediment and the remained sediment reproduced by the developed numerical model are $56300m^3$ and $26800m^3$, respectively. On the other hand, the amounts of the eroded sediment and the remained sediment measured in the field after the floods are $56600m^3$ and $26500m^3$, respectively. The difference between the model and field data is very small. Furthermore, the bed geometry of the replenished sediment after the floods reproduced by the developed model has a good agreement with the measured bed geometry after the floods. These results indicate that the developed model is able to simulate the erosion process of replenished sediment on rocks very well. Furthermore, the erosion speed of the replenished sediment during the decreasing process of the water discharge is faster than that during the increasing process of the water discharge. The replenished sediment is eroded well, when the top of the replenished sediment is covered by the water. In general, water surface level is kept to be high during the decreasing process of the discharge during floods, because water surface level at the downstream end is high. Hence, it is considered that the high water surface level during the decreasing process of the water discharge affects on the fast erosion of the replenished sediment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.7
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• pp.713-723
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• 2023

Climate change is significantly affecting coastal areas, and its impacts are expected to intensify. Recent studies on climate change adaptation and risk assessment in coastal regions increasingly integrate the concepts of recovery resilience and vulnerability. The aim of this study is to develop a measurement model for coastal hazard recovery resilience in the context of climate change adaptation. Before constructing the measurement model, a comprehensive literature review was conducted on coastal hazard recovery resilience, establishing a conceptual framework that included operational definitions for vulnerability and recovery resilience, along with several feedback mechanisms. The measurement model for coastal hazard recovery resilience comprised four metrics (MRV, LRV, RTSPV, and ND) and a Coastal Resilience Index (CRI). The developed indices were applied to domestic coastal erosion cases, and regional analyses were performed based on the index grades. The results revealed that the four recovery resilience metrics provided insights into the diverse characteristics of coastal erosion recovery resilience at each location. Mapping the composite indices of coastal resilience indicated that the areas along the East Sea exhibited relatively lower coastal erosion recovery resilience than the West and South Sea regions. The developed recovery resilience measurement model can serve as a tool for discussions on post-adaptation strategies and is applicable for determining policy priorities among different vulnerable regional groups.