• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.6 no.5
• /
• pp.59-69
• /
• 2003

Most denuded mountain areas in Korea were completely stabilized by the successful work of the 1st and 2nd 10-year Forest Development Plans which targeted the reforestation of denuded forest lands. The objectives of this study are (1) to estimate the depth of organic horizon in the soil profile, (2) to investigate the change of vegetation structure, (3) to estimate the change of biomass in the erosion controlled and rehabilitated mountain areas with the passage of time. This study was carried out as the 5th times. The first study began in the year of 1985, the second study was in the year of 1988, the third study was in the year of 1992, 4th was in the year of 1998 and 5th was in the year of 2002. The first study started in the study sites which elapsed 9 years after erosion control works. The results of the study were as follows : The increase rate of soil thickness was estimated to $Y_{(cm)}=2.906log_{(yr)}-3.2476(r^2=0.917)$ during 26 years after erosion control works. The important value of pines decreased to 14.7% on upper layer. But, the important value of alders. which did not plant on erosion control work increased to 27.1%. The decrease of whole crown projection indicates that pines. and alders were heavily injured by pine leaf gall midge in the year of 1993, 1995 years and Agelastica coerulea Baly in the year of 1986, 1987 years at Yoju-gun. The young growth of pines and alders not appeared on the soil surface which elapsed 26 years after erosion control works. On the lower layer, oaks occupied over 50% in I.V, RD, RC, RF. In process of years, the increase of biomass estimated to be $Y_{(t/ha)}={0.7505X_{(yr)}}^{1.6335}\;(r^2=0.9712)$ for 26 years after erosion control works.

• Journal of Korean Society of Forest Science
• /
• v.20 no.1
• /
• pp.51-60
• /
• 1973

The trend and achievments of soil erosion control research in Japan were investigated through observation tours and reference work and following facts were found to be important aspects which should be considered in the soil erosion control research program in Korea. Experiments on forest and water relations, and ground water phenomena at the water source zone in Tokyo University. Studies on land-slides and erosion control dam in Kyoto University. Studies on mud-flow and snow avalanches in Hokkaido University. Studies on sanddune fixation and disaster damage prevention forests in Kyushu University. Studies on forest denudations in Nagoya University. Studies on Greening-works and soil erosion prevention chemicals in Tokyo Agriculture University. Training on planning of erosion control works and prevention of disaster damages in Forest Research Institute. Experiments on soil erosion phenomena and infiltration in Tohoku Branch, FRI. Experiments on erosion and surface stratum failure of steep slopes and their prevention methods in Railway Technical Research Institute.

• Journal of agriculture & life science
• /
• v.50 no.5
• /
• pp.111-120
• /
• 2016

The objective of this study was to provide basic information for selecting the right timing and the right place of erosion control of stream on Gyeongsangnam-do. In order to achieve this objective, a total of 526 erosion control dams and 230 mountains stream conservation facilities on the constructed places and construction planned places for the erosion control were investigated on site, forest physiognomy, and hydrologic conditions. The erosion control dams and mountain stream conservation facilities were mostly constructed in the area, which has the sedimentary rock, 200-400m of altitude, a slope of 21~30°, and II of landslide hazard map. Among the forest environmental factors, it was only similar to the construction frequency in the areas that have small diameter class, III age class. Also, we investigated the hydrological environmental factors that determine the size and numbers of erosion control dam. The places constructed to the highest frequency were below 50ha in the area, 2.1~4.0km/㎢ of drainage density, longitudinal water system, 61~90mm of maximum precipitation per hour, and 201~300mm of day maximum precipitation. As the results, the sites and floodgate conditions between the constructed places and stream conservation facilities for the erosion control showed to be very similar. Therefore, these results indicate that the erosion control of the stream of the areas, which have the disruption of mountain peaks and the high erosion risk areas, should be used on both the erosion control dam and stream conservation facilities.

• 한국방재학회:학술대회논문집
• /
• 2007.02a
• /
• pp.509-512
• /
• 2007

The fire area need management to prevent enlargement of collapes and sinkage. and it need that repair Vegetation sack work, Soil arresting structure, Terrace-sodding works, Direct seeding works in greening works and Water cushion in erosion control dam. The whole of the Concrete stream grade stabilization structures were broken, it need to be repair. As pass the time, a lot of structures were abandoned. Therefore, it need to reorganize erosion control structures and the method of construction in the fire area

• Journal of Korea Water Resources Association
• /
• v.41 no.10
• /
• pp.983-993
• /
• 2008

In recent times, sea level increasing caused by abnormal weather and global warming, sea-sand dredging and complex development causes various kind of erosion damages onto the coastal area in the world. The various types of erosion control and protection methods are applied but there are no signs of fruitful effectiveness. The PC concrete protection block for shore protection structure is practically installed in globally but most of structures in the present day became villainous because of bad accessability. In this study, hydrophilic revetments for control and protection of coastline erosion will be developed in order to make up for a faculty of the shore erosion protection block with better accessibility and excellent protection ability. Experimental measurements were researched to insure for the capacity and facility on reflection coefficient, overtopping volume, and overtopping height characteristics of newly developed shore erosion protection block in model tests. As the result, hydraulic model tests show much excellent than the general step block. Field tests were carried out also to verify through vegetative test on an affinity and construction work test of control-protection on coastline erosion with actual utilization. In the latter case, deposition of sand accumulation occurred in fairly short time at the established reaches and then we can be confirmed to utilize for newly developed block as the revetments for control and protection of coastline erosion.

• Journal of Korean Society of Forest Science
• /
• v.110 no.3
• /
• pp.419-430
• /
• 2021

This study investigated spatiotemporal trends of sediment-related disasters in North Korea from 1960 to 2019 and post-disaster recovery cases based on a literature review and satellite images. Results showed that occurrence status of sediment-related disasters was initially externally reported in 1995 (during the Kim Jongil era); their main triggering factor was heavy summer rainfall. Furthermore, forest degradation rate was positively correlated with population density (R² = 0.4347, p = 0.02) and occurrence number of sediment-related disasters was relatively high on the west coast region, where both variables showed high values. This indicates that human activity was a major cause of forest degradation and thus, significantly affected sediment-related disasters in mountain regions. Finally, sediment- related disasters due to shallow landslides, debris flow, and slow-moving landslides were observed in undisturbed forest regions and human-impacted forest regions, including terraced fields, opencast mines, forest roads, and post-wildfire areas, via satellite image analysis. These disaster-hit areas remained mostly abandoned without any recovery works, whereas hillside erosion control work (e.g., treeplanting with terracing) or torrent erosion control work (e.g., check dam, debris flow guide bank) were implemented in certain areas. These findings can provide reference information to expand inter-Korean exchange and cooperation in forest rehabilitation and erosion control works of North Korea.

• Journal of Forest and Environmental Science
• /
• v.34 no.2
• /
• pp.192-195
• /
• 2018

To establish a management strategy of sediment-related disasters for adaptation to climate change, it is necessary to 1) understand the specific details and problems about the present status, 2) systematize related technologies by using exact numerical values obtained from physically-based analysis, and 3) ensure the basic guidelines are applied to field elastically. To achieve these successfully, detailed guidelines are required by scientifically considering the utilization and impact of related technology on the field. Here, detailed guidelines should include 1) the development of a basic plan, 2) enhancement of relevant technical instructions, 3) establishment of survey and inspection methods, 4) procedure of erosion control works in urban living sphere, and 5) proactive countermeasures against sediment-related disaster caused by earthquakes.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.34 no.2
• /
• pp.153-159
• /
• 2016

Rivers refer to either natural or artificial structures whose primary functions are flood control and water conservation. Due to recent localized torrential downpours led by climate change, large amounts of eroded soil have been carried away, forming deposits downstream, which in turn degrades the capacity to fulfill these functions. To manage rivers more effectively, we need data on riverbed erosion and deposition. However, environmental factors make it challenging to take measurements in rivers, and data errors tend to prevent researchers from grasping the current state of erosions and deposits. In this context, the aim of the present study is to provide basic data required for river management. To this end, the author made annual measurements with a Real-time Kinematic-Global Positioning System (RTK-GPS) and a total station in Pats Cabin Canyon, Oregon, United States, and also prepared thematic maps of erosion and deposition thickness as well as water depth profiles based on a GIS spatial analysis. Furthermore, the author statistically analyzed the accuracy of three dimensional (3D) measurement points and only used the data that falls within two standard deviations (i.e. ±2σ). In addition, the author determined a threshold for a DEM of Difference (DoD) by installing measurement points in the rivers and taking measurements, and then estimated erosion and deposition thickness within a confidence interval of ±0.1m. Based on the results, the author established reliable data on river depth profiles and thematic maps of erosion and deposition thickness using pre-determined work flows. It is anticipated that the riverbed data can be utilized for effective river management.

• Korean Journal of Environment and Ecology
• /
• v.23 no.4
• /
• pp.353-364
• /
• 2009

This study was conducted to evaluate the effect of erosion control works on the stream ecosystem in a mountain torrential stream. The species composition of benthic macroinvertebrates and biological water quality were investigated before and after construction of erosion control works at 5 sites. The total number of benthic macroinvertebrates before construction was 3,086 individuals including 4 phyla, 6 classes, 11 orders, 22 families, and 25 species, but after construction it has decreased to 1,208 individuals including 4 phyla, 6 classes, 10 orders, 17 families, and 19 species. Especially, the diversity, richness, and evenness indices, which were calculated based on existing number of biological species, have decreased or not produced at the erosion control sites, where biological species were not found or the minimum number of species were found. The results of community analysis of benthic macroinvertebrates and ESB(Ecological Score of Benthic macroinvertebrate community) indicated that the environmental qualities of the stream based on saprobity, environmental condition, and water quality decreased after the construction at all sites: before construction, the top of the stream was satisfactory and some satisfactory, the middle was some defectiveness, and the lower was defectiveness and very defectiveness; after construction, all parts of the stream except some parts of the top were very defectiveness. Moreover, the water quality of torrential stream was rated between I to III before construction, but after construction, it declined to $IV{\sim}V$ except control. The habitat damage of benthic macro invertebrates occurred at all investigation sites after the construction of erosion control works led to reduction of the number of biological species and water quality deterioration. The results reported in this study were collected directly after the construction of erosion control works. Therefore, additional studies are needed to further explore the effect of disaster-prevention of erosion control works and the recovery process of stream ecosystem through long term monitoring.

• Journal of Wetlands Research
• /
• v.18 no.1
• /
• pp.45-57
• /
• 2016

Levee safety is being evaluated using one of the several failure causes including overtopping, infiltration and erosion or 1D hydraulic analysis considering physical characteristics of levee in practical engineering works. However, mentioned evaluation methods are not able to consider various failure causes of levee at the same time and to get reliable results where requires the accurate topographic information. This study proposed the flood hazard index which is able to consider several hazard factors involving overtopping, infiltration and erosion risk simultaneously. The index was generated from results of 2D hydraulic analysis reflecting accurate topographic information. The study areas are the confluences of the Nakdong River and two streams(Gamcheon and Hoecheon). Levee safety was evaluated using results based on 2D hydraulic analysis considering riverbed changes of before and after dredging work in the study area. This study will contribute to estimate the reliable safety evaluation of levee where may have hazards during extreme flood events.