• Magazine of the Korean Society of Agricultural Engineers
• /
• v.24 no.2
• /
• pp.49-55
• /
• 1982

The purpose of this study is to classify the factors influenced on the damages of head works suffered from the storm flood occurred on July 22 1980 in both Musim and Bochong rivers and to find out an integral counter measures against the causes influenced on the disaster of head works in the engineering aspect of planning, design, construction and maintenance. In this survey, number of samples was taken 25 head Works, and the counter measures against the causes of their disasters summarized was as follows, 1. In the aspect of planning a. As the flood water level after the establishment of head works is more increased than the level before setting of head works owing to having more gentle slope of river bed between the head works than nature slope of river bed. Number of head works should be reduced for the appropriate annexation of them b. In the place where head works is established on the curved point of levee, the destruction of levee becomes severe by the strong deflective current. Therefore the setting of head works on the curved point should be kept off as long as possible and in case of unavoidable circumstances the construction method such as reinforced concrete wall or stone wall filed with concrete and anchored bank revetments should be considered. 2. In the aspect of design a. As scoring phenomena at up stream is serious around the weir Where the concentration of strong current is present in such a place, up stream apron having impermeability should be designed to resist and prevent scoring. b. As the length of apron and protected bed is too short to prevent scoring as down stream bed, the design length should be taken somewhat more than the calculated value, but in the case the calculated length becomes too long to be profitable, a device of water cushion should be considered. c. The structure of protected river bed should be improved to make stone mesh bags fixed to apron and to have vinyl mattress laid on river bed together with the improvement for increasing the stability of stone mesh bags and preventing the sucked sand from the river bed. d. As the shortage of cut-off length, especialy in case of the cutoffs conneting both shore sides of river makes the cause of destruction of embankment and weir body, the culculation of cut-off length should be taken enough length based on seepage length. 3. In the aspect of design and constructions a. The overturing destruction of weir by piping action was based on the jet water through cracks at the construction and expansion joints. therefore the expansion joint should be designed and constructed with the insertion of water proof plate and asphalt filling, and the construction joint, with concaved shape structure and steel reinforcement. b. As the wrong design and construction of the weep holes on apron will cause water piping and weir destruction, the design and construction of filter based on the rule of filter should be kept for weep holes. c. The wrong design and construction of bank revetment caused the severe destruction of levee and weir body resulting from scoring and impulse by strong current and formation of water route behind the revetment. Therefore bank revetment should be designod and constructed with stone wall filled with concrete and anchored, or reinforced concrete wall to prevent the formation of water flow route behind the wall and to resist against the scoring and impulse of strong stream. 4. In the aspect of maintenance When the damaged parts occurred at head works the authorities and farmers concerned should find and mend them as soon as possible with mutual cooperation, and on the other hand public citizen should be guided for good use of public property.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2011.05a
• /
• pp.476-476
• /
• 2011

베트남은 자연재해로 인해 매년 평균 750명 이상의 사망자가 발생하고 있으며, 경제적인 피해 또한 한해 GDP의 1.5%에 달하고 있다. 저먼워치(Germanwatch)의 2010년 세계기후위험지수(Global Climate Risk Index, GCRI)의 전 지구적 기후재난에 관한 국가별 순위 조사에서 베트남은 4위에 기록되었다. 베트남의 자연재해는 상당 비중이 풍수해에 집중 되어 전체 재해의 86%를 차지하고 있고, 이는 대부분 해안 지대와 강 유역의 홍수 및 범람에서 비롯된 것이다. 베트남 전체인구의 약 70%가 상습적 홍수와 범람 발생 지역인 해안가에 거주하고 있어 재난에 예방 및 복구 관리에 대한 국가 차원의 방안이 시급한 실정이다. 본 연구에서는 과거 30년간의 풍수해 관련 재해에 대한 기록상 추이를 통해 공간적으로 재난에 취약한 지역적 분포를 살펴보고, 그 지역의 지리적 특성을 분석하여 재해에 관한 종합적 고찰을 하였다. 벨기에 루뱅대학 부설 재난역학연구센터(Centre for Research on the Epidemiology of Disasters, CRED)의 EM-DAT를 이용하여 과거 기록상의 개괄적인 재해양상에 관한 추이를 살펴본 결과 대부분의 재난은 풍수해에 집중이 되어 있음을 분석하였고, 베트남 풍수해조정기관인 홍수및폭풍조정중앙위원회(Central Committee for Flood and Storm Control, CCFSC)의 최근 30년간 풍수해에 관련된 통계 자료를 정리하여 상습적 재난 피해지역을 지도상에 표시하였다. 이 때 지구지도제작운영위원회(International Steering Committee for Global Mapping, ISCGM)의 D_WGS_1984 Datum을 바탕으로 한 베트남 shape file을 이용하여 풍수해에 따른 인명피해, 경제적 손실, 발생횟수 등에 관한 사항을 일반화 시켜 재난 취약지역을 지리적으로 분석하였다. Thanh hoa, Quang nam, Binh Dinn, Camau성이 풍수해와 관련된 재난에 취약하게 노출되어 있음을 도출하였다. 재난에 상대적으로 취약한 이들 지역에 대한 현재의 재난 관리는 어떻게 이루어지고 있는지에 관해 현재의 풍수해관리 사업단의 조직적 구조와 그 기능 및 역할을 살펴보고, 국제적 원조 사례를 분석하여 상습적으로 재난의 위험 지역에 대한 지속적인 관리와 복구를 어떻게 이루어 나갈 것인지에 대한 방안 및 제언에 관하여 논의하고자 한다. 베트남의 재난 관리에 관한 지리적인 종합 분석은 기존 양상의 재해에 대한 방안을 구축하는 데 대한 제언뿐만 아니라 기후변화와 관련된 재난을 예측하고 관리 방안을 설정하는 데 기초 자료를 제공할 수 있을 것이다.

• Journal of Wetlands Research
• /
• v.6 no.3
• /
• pp.71-81
• /
• 2004

In recent, the heavy rainfall is frequently occurred and the damage tends to be increased. So, more careful hydrologic analysis is required for the designs of the hydraulic or disaster prevention structures. The time distribution of a rainfall is one of the important factors for the estimation of peak flow in hydrologic and hydraulic designs. This study is to suggest a methodology for the estimation of a rainfall time distribution which can reflect the meteorologic and topographical characteristics of Daejeon area. We collect the 34 years' rainfall data recorded in the range of 1969 to 2002 for Daejeon area and we performed the rainfall analysis with the data in between May and October of each year. According to the Huff method, the collected data corresponds to the first quartile which the rainfall is concentrated in the primary stage but the suggested method shows the different rainfall distribution with the Huff method in time. The reason is that the Huff method determines the quartile in each storm event while the suggested one determines it by estimating the dimensionless distribution of rainfall in duration after the accumulation of rainfall in time. The rainfall distributions estimated by two methodologies were applied to the Gabcheon basin in Daejeon area for the estimation of flood flow. Here we use the SCS method for the effective rainfall and unit hydrograph for the flood discharge. As the results, the peak flow for 24-hour of 100-year frequency was estimated as a $3421.20m^3/sec$ by the Huff method and $3493.38m^3/sec$ by the suggested one. We can see the difference of $72.18m^3/sec$ in between two methods and thus we may carefully determine the rainfall time distribution and compute the effective rainfall for the estimation of the peak flow.

• Journal of the Korean Society of Hazard Mitigation
• /
• v.10 no.5
• /
• pp.149-158
• /
• 2010

Recent rainfall patterns in Korea show that both of the total amount of rainfall and the total number of heavy rain days have been increased. Therefore, the damage resulted from flood disaster has been dramatically increased in Korea. The purpose of the present study is to analyze flooding in an urban area using SWMM linked with FLUMEN. The study area is Suyeong-Mangmi lowland area, Busan, Korea. Suyeong-Mangmi lowland area have been a flooding hazard zone since 1995. The last flooding cases of this area occurred on July 7th and 16th, 2009, and the later flooding case was analyzed in this study. The first step of computation is calculating flow through storm sewers using the urban runoff simulation model of SWMM. The flooding hydrographs are used in the inundation analysis model of FLUMEN. The results of inundation analysis were compared with the real flooding situation of the study area. The real maximum inundation depth was guessed by 1.0 m or more on July 16th. The computation yields the maximum inundation depth of 1.2 m and the result was somewhat overestimated. The errors may be resulted from the runoff simulation and incapability of simulation using FLUMEN for flow into buildings. The models and procedures used in this study can be applied to analysis of flooding resulted from severe rainfall and insufficiency of drainage capacity.

• Journal of Korean Society of Forest Science
• /
• v.5 no.1
• /
• pp.4-9
• /
• 1966

1. On 13 September 1964 a storm raged for 3 hours and 20 minutes with pounding heavy rainfalls, and precipitation of 287.5 mm was recorded on that day. The numerous landslides were occured in the eroded forest land neighbouring Mt. Chunbo, while no landslides recorde at all on Mt. Jookyup within the premise of Kwangnung Experiment Station, the Forest Experiment Station. 2. Small-scalled Landslides were occured in 43 different places of watershed area (21.97 ha.) in which the survey had already been done, in and around Mt. Chunbo (378 m a.s.l.). The accumulated soil amount totaled $2,146,56m^3$ due to the above mentioned landslides, while soil accumulated from riverside erosion has reached to $24,168.79m^3$, consisting of soils, stones, and pebbles. However, no landslides were reported in the Mt. Jook yup area because of dense forest covers. The ratio of the eroded soil amount accumulated from the riversides to that of watershed area was 1 to 25. On the other hand, the loss and damage in the research area of Mt. Chonbo are as follows: 28 houses completly destroyed or missing 7 houses partially destroyed 51 men were dead 5 missing, and 57 wounded. It was a terrible human disaster However, no human casualties were recorded at all, 1 house-completly destroyed and missing, 2 houses-partially destroyed. Total:3 houses were destroyed or damaged, in The area of Mt. Jookyup 3. In the calculation of the quanty of accumulated soil, the or mula of "V=1/3h ($a+{\sqrt{ab}}+b$)" was used and it showed that 24, 168.79m of soil, sands, stones and pebbles carried away. 4. Average slope of the stream stood 15 at the time of accident and well found that there was a correlation between the 87% of cross-area sufferd valley erosion and the length of eroded valley, after a study on regression and correlation of the length and cross-area. In other works, the soil erosion was and severe as we approached to the down-stream, counting at a place of average ($15^{\circ}1^{\prime}$) and below. We might draw a correlation such as "Y=ax-b" in terms of the length and cross-area of the eroded valley. 5. Sites of char-coal pits were found in the upper part of the desert-like Mt. Chunbo and a professional opinion shows that the mountain was once covered by the oak three species. Furthermore, we found that the soil of both mountains have been kept the same soil system according to a research of the soil cross-area. In other words, we can draw out the fact that, originally, the forest type and soil type of both Mt. Chunbo (378m) and Mt. Jookyup (610m) have been and are the same. However, Mt. Chunbo has been much more devastated than Mt. Jookyup, and carried away its soil nutrition to the extent that the ratios of N. $P_2O_5K_2O$ and Humus C.E.C between these two mountains are 1:10;1:5 respectively. 6. Mt. Chunbo has been mostly eroded for the past 30 years, and it consists of gravels of 2mm or larger size in the upper part of the mountain, while in the lower foot part, the sandy loam was formulated due to the fact that the gluey soil has been carried and accumulated. On the hand, Mt. Jookyup has consitantly kept the all the same forest type and sandy loam of brown colour both in the upper and lower parts. 7. As for the capability of absorbing and saturating maximum humidity by the surface soil, the ratios of wet soil to dry soil are 42.8% in the hill side and lower part of the eroded Mt. Chunbo and 28.5% in the upper part. On the contrary, Mt. Jookyup on which the forest type has not been changed, shows that the ratio in 77.4% in the hill-side and 68.2% in the upper part, approximately twice as much humidity as Mt. Chunbo. This proves the fact that the forest lands with dense forest covers are much more capable of maintaining water by wood, vegitation, and an organic material. The strength of dreventing from carring away surface soil is great due to the vigorous network of the root systems. 8. As mentioned above, the devastated forest land cause not only much greater devastation, but also human loss and property damage. We must bear in mind that the eroded forest land has taken the valuable soil, which is the very existance of origin of both human being and all creatures. As for the prescription for preventing erosion of forest land, the trees for furtilization has to be planted in the hill,side with at least reasonable amount of aertilizer, in order to restore the strength of earth soil, while in the lower part, thorough erosion control and reforestation, and establishments along the riversides have to be made, so as to restore the forest type.