• 한국환경과학회지
• /
• 제17권9호
• /
• pp.1039-1052
• /
• 2008

The SWAT model developed by the USDA-Agricultural Research service for the prediction of rainfall run-off, sediment, and chemical yields in a basin was applied to Jeju Island watershed to estimate the amount of runoff. The research outcomes revealed that the estimated amount of runoff for the long term on 2 water-sheds showed fairly good performance by the long-term daily runoff simulation. The watershed of Chunmi river located the eastern region in Jeju Island, after calibrations of direct runoff data of 2 surveys, showed the similar values to the existing watershed average runoff rate as 22% of average direct runoff rate for the applied period. The watershed of Oaedo river located the northern region showed $R^2$ of 0.93, RMSE of 14.92 and ME of 0.70 as the result of calibrations by runoff data in the occurrence of 7 rainfalls.

• 환경위생공학
• /
• 제11권3호
• /
• pp.9-12
• /
• 1996

Polychlorinated biphenyl (PCBs) is one of major toxic pollutants in marine environments, This artificial chlorinated compound has been found in freshwater, seawater, soil, sediments and organismes living in various environments. Because of its toxicity and degradability, its uses in industrial processes have been banned after 1984 in Korea. Coastal area is an important environment for agriculture, industry, transportation, reduction of pollution loads through biogeochemical processes, cycling of nutrients and recreation. Input of pollutants from land and freshwater has been occurring through runoff, rivers and estuaries. Concentrations of PCBs were determined with GC-ECD. Concentrations of PCBs were in the range of 1.0 - 19.2 ng/g-dry weight of sediment(g-d.w.) at Ulsan, 4.5 -8,2 ng/g-d.w. at Onsan, 2.7 - 33.5 ng/g-d.w. at Masan and 4.0 - 60.7 ng/g-d.w. in Kwangyang, In Inchon area, PCBs were not detected in sediments. In sediments of Nakdong estuary, the distribution of PCBs' concentrations was 0.19 - 303 ng/g-d.w.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2021년도 학술발표회
• /
• pp.150-150
• /
• 2021

Soil erosion due to climate change is one of the global environmental issues. Especially, Korea is vulnerable to soil erosion as the frequency of extreme rainfall events and rainfall intensity are increasing. Soil erosion causes various problems such as reduced farmlands, deterioration of water quality in rivers, etc. To these severe problems, understanding the process of soil erosion is the first process. Then, it is necessary to quantify and analyze soil ersoion using an erosion model. Soil erosion models are divided into empirical, conceptual, and physics-based models according to the structures and characteristics of models. This study used GSSHA (Gridded Surface Subsurface Hydrologic Analysis), the physics-based erosion model, running on WMS (Watershed Modeling System) to analyze soil erosion vulnerability of the CheonCheon watershed. In addition, we compared the six sediment transport capacity formulas provided in the model and evaluated the equations fir on this study site. Therefore, this result can be as a primary tool for soil conservation management.

• 대한토목학회논문집
• /
• 제31권4B호
• /
• pp.361-367
• /
• 2011

하천 정비 및 하천 복업사업의 기준유량이 되는 하도형성유량 산정은 안정하도 설계시 반드시 선행되어야 하는 것이다. 국내의 경우 하도형성유량 산정방법에 대한 연구가 많이 수행되지 않아 특정패턴을 도출하기가 어려운 실정이다. 국내하천의 경우 외국의 주요하천과 비교하여 하상계수가 크게 나타나는 특성으로 인해 외국사례를 국내에 적용하기에 어려움이 있다. 따라서 현재 구하도 복원이 진행 되고 있거나 계획되어 있는 만경강, 청미천, 함평천을 대상으로 하도형성유량 산정을 위해 만제유량, 특정 재현기간별 유량, 유효유량을 산정해보고 각각의 상호관계를 분석하여 하상계수가 큰 국내하천에 적용 가능한 하도형성유량을 제안하고자 한다. 만제유량은 대상유역의 지형자료를 이용한 HEC-RAS 모의를 통해 산정하였으며 특정 재현기간별 유량과 유효유량은 대상구간의 유량, 하상토, 유사 자료를 이용하여 산정하였다. 산정결과 하상계수가 큰 하천에서는 유효유량이 만제유량보다 크게 나타났으며 하상계수와 관련하여 특정 재현기간별 유량은 일관성 있는 특징이 없는 것으로 나타났다.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2015년도 학술발표회
• /
• pp.237-237
• /
• 2015

The district of Marlborough has had more than its share of river management projects over the past 150 years, each one uniquely affecting the geomorphology and flood hazard of the Wairau Plains. A major early project was to block the Opawa distributary channel at Conders Bend. The Opawa distributary channel took a third and more of Wairau River floodwaters and was a major increasing threat to Blenheim. The blocking of the Opawa required the Wairau and Lower Wairau rivers to carry greater flood flows more often. Consequently the Lower Wairau River was breaking out of its stopbanks approximately every seven years. The idea of diverting flood waters at Tuamarina by providing a direct diversion to the sea through the beach ridges was conceptualised back around the 1920s however, limits on resources and machinery meant the mission of excavating this diversion didn't become feasible until the 1960s. In 1964 a 10 m wide pilot channel was cut from the sea to Tuamarina with an initial capacity of $700m^3/s$. It was expected that floods would eventually scour this 'Wairau Diversion' to its design channel width of 150 m. This did take many more years than initially thought but after approximately 50 years with a little mechanical assistance the Wairau Diversion reached an adequate capacity. Using the power of the river to erode the channel out to its design width and depth was a brilliant idea that saved many thousands of dollars in construction costs and it is somewhat ironic that it is that very same concept that is now being used to deal with the aggradation problem that the Wairau Diversion has caused. The introduction of the Wairau Diversion did provide some flood relief to the lower reaches of the river but unfortunately as the Diversion channel was eroding and enlarging the Lower Wairau River was aggrading and reducing in capacity due to its inability to pass its sediment load with reduced flood flows. It is estimated that approximately $2,000,000m^3$ of sediment was deposited on the bed of the Lower Wairau River in the time between the Diversion's introduction in 1964 and 2010, raising the Lower Wairau's bed upwards of 1.5m in some locations. A numerical morphological model (MIKE-11 ST) was used to assess a number of options which led to the decision and resource consent to construct an erodible (fuse plug) bank at the head of the Wairau Diversion to divert more frequent scouring-flows ($+400m^3/s$)down the Lower Wairau River. Full control gates were ruled out on the grounds of expense. The initial construction of the erodible bank followed in late 2009 with the bank's level at the fuse location set to overtop and begin washing out at a combined Wairau flow of $1,400m^3/s$ which avoids berm flooding in the Lower Wairau. In the three years since the erodible bank was first constructed the Wairau River has sustained 14 events with recorded flows at Tuamarina above $1,000m^3/s$ and three of events in excess of $2,500m^3/s$. These freshes and floods have resulted in washout and rebuild of the erodible bank eight times with a combined rebuild expenditure of $80,000. Marlborough District Council's Rivers & Drainage Department maintains a regular monitoring program for the bed of the Lower Wairau River, which consists of recurrently surveying a series of standard cross sections and estimating the mean bed level (MBL) at each section as well as an overall MBL change over time. A survey was carried out just prior to the installation of the erodible bank and another survey was carried out earlier this year. The results from this latest survey show for the first time since construction of the Wairau Diversion the Lower Wairau River is enlarging. It is estimated that the entire bed of the Lower Wairau has eroded down by an overall average of 60 mm since the introduction of the erodible bank which equates to a total volume of $260,000m^3$. At a cost of $$0.30/m^3$ this represents excellent value compared to mechanical dredging which would likely be in excess of $$10/m^3$. This confirms that the idea of using the river to enlarge the channel is again working for the Wairau River system and that in time nature's "excavator" will provide a channel capacity that will continue to meet design requirements.

• 대한토목학회논문집
• /
• 제9권2호
• /
• pp.73-82
• /
• 1989

충적하천(沖積河川)에서 홍수파(洪水波)가 발생할 때 하천은 그 홍수파를 안전하게 소통시키기 위하여 주어진 흐름에 적응(適應)하는 하상변동(河床變動) 구조(構造)를 가지고 있다. 이러한 하상변동(河床變動)의 예측모형(豫測模型)을 개발하기 위하여, 홍수파를 해석하고 그에 따른 하상변동과정(河床變動過程) 대한 수치모형을 홍수추적 및 유사추척을 통하여 구성하였다. 본 하상변동모형으로 홍수파해석, 하상고(河床高)의 변동 및 하상구성토사(河床構成土砂)의 입도분포변화(粒度分布變化)등을 예측할 수 있도록 하였으며, 한강하류부(漢江下流部) 팔당댐으로부터 인도교 수위표지점에 이르는 구간에 본 모형을 적용하여 그 적용성을 확인하였다. 본(本) 모형(模型)의 적용결과 유사운송(流砂運送)이 홍수파의 형상에 미치는 영향은 미소(微小)하였으며, 이는 부정류(不定流)의 흐름변동에 비하여 동일 시간동안의 하상변동량(河床變動量)이 상대적으로 작기 때문이다. 또한 비교적 비슷한 홍수파가 인접하여 발생하는 경우, 하상변동과 유사교환하상층(流砂交換河床層)의 입도분포변화(粒度分布變化)는 전반부 홍수파가 지배적이고 후반부 홍수파의 영향은 상대적으로 작았으며, 하천이 동적평형상태(動的平衡狀態)를 유지하기 위한 거동(擧動)을 하는 것으로 나타났다. 한강하류부 팔당댐으로부터 인도교 지점에 이르는 하상은 세굴(洗掘) 및 조립화현상(粗粒化現像)이 지배적이었다.

• 방사성폐기물학회지
• /
• 제17권1호
• /
• pp.1-13
• /
• 2019

후쿠시마 원자력 발전소의 사고로 인해 일본 동부 지역에 다량의 방사성 핵종이 축적되었다. 이러한 방사성 물질은 숲, 도시, 하천, 호수를 포함한 넓은 범위에서 관측되고 있다. 방사성 세슘의 토양 입자에 강하게 흡착하는 특성 때문에 방사성 세슘은 침식된 토사와 함께 이동하여, 인구가 밀집한 하천 하류지역으로 그리고 연안으로 서서히 이동한다. 본 연구에서는 수생환경의 오염된 토사의 이동을 재현하기 위한 수치모델을 개발하고, 그 성과의 일부를 한국원자력연구원 내에 위치한 침식된 토사 관측 장비에서 관측된 결과와 비교하였다. 수집된 토사 시료의 입경 특성을 분석하기 위해서 표준 체분석과 이미지 분석법을 적용하였다. 수치 모델은 초기 포화도, 강우의 토사 침투율, 멀티 레이어, rain splash 등을 고려하여 현실의 강우에 따른 토사의 이동을 시뮬레이션 할 수 있도록 개발하였다. 2019년 연구에서는 수치모델에 나무에 의한 강우 쉴드 효과, 증발효과, 표면물의 쉴드 효과 등이 추가될 계획이다. 토사 유실 관측 장비를 2018년부터 월성 원전 인근에 설치해 지속적으로 관측 자료를 수집하고 있다. 이러한 관측자료를 기반으로 방사성 핵종의 강우, 하천, 연안으로 이동하는 장기 영향 평가 수치모델을 개발할 계획이다.

• Fisheries and Aquatic Sciences
• /
• 제10권4호
• /
• pp.205-214
• /
• 2007

Surface water and sediment samples collected from the Mokpo coast of Korea were analyzed for molecular markers of organic municipal wastewaters, i.e., 11 fecal sterols including coprostanol (Cop) and nonylphenolic compounds (NPs), to characterize the main routes of these wastewaters to the coast and to assess contamination levels. Concentrations of Cop ranged from 94 to 7,568 ng/L in surface water and from 43 to 38,108 ng/g dry weight in sediments. Concentrations of NPs [nonylphenol (NP) and nonylphenol mono- and di-ethoxylates ($NP_{1-2}EOs$)] ranged from 123 to 4,729 ng/L in surface water and from 4 to 2,119 ng/ng dry weight in sediments. The levels of these compounds were much higher at stations near the rivers that pass through the urban center of Mokpo and the outfall of the wastewater treatment plant (WWTP). The spatial distribution of Cop levels was statistically similar to that of NPs (r=0.809 and 0.982 in surface water and sediments, respectively), indicating that these compounds may have similar discharge points, transport, mixing, and deposition in the study area. These results suggest that considerable amounts of organic wastewater compounds are discharged through rivers and WWTP effluent to the Mokpo coast.

• Ocean and Polar Research
• /
• 제28권3호
• /
• pp.293-303
• /
• 2006

The topography of the sea floor and textural characteristics of surface sediments are documented in areas off sectors 1,2, and 4 of the Saemangeum dyke and inside the dyke. These were investigated during the years 2002 to 2005, when the dyke construction almost came to an end, and were compared with natural topographic analogs before the dyke construction from the maritime maps of 1982 and 1994. Along and across the dyke are a number of erosional troughs formed by intensified currents during the dyke construction. The sea floor off sector 4 has undergone gradual accumulation of sands moving from the north by currents varying in direction from normal to parallel to the dyke. This is in a strong contrast with a slight erosional environment prevailing over the sea floor before dyke construction. off sectors 1 and 2, a topography with an alterative pattern of erosional troughs and sand shoals develops normal to the dyke. Eroded materials from the troughs seem to have added to the sand shoals. As a result, the troughs, former natural tidal channels, have become increasingly deeper, whereas the sand shoals have become somewhat shallower. The sea floor inside the dyke has also been remarkably shallower with expanding tidal flats due to trapping by the dyke of continuous sediment input from the Dongjin and Mangyeong rivers. Sands, all of which are considered to have originated originally from the two rivers, dominate the entire Saemangeum area.

• 한국물환경학회지
• /
• 제26권1호
• /
• pp.71-80
• /
• 2010

We studied the nitrogen behavior and budget of Lake Paldang from March to December 2008. The particulate nitrogen (PN) concentrations ranged from 7 to 13% of the total nitrogen concentration (TN) in the stream inflows, the downstream outflow, and the lake water. The nitrate nitrogen ($NO_3-N$) concentration ranged from 67 to 78% of the TN. In the three rivers of Lake Paldang, Gyeongan River (In3 site) had the highest average of the TN, 5.037 mgN/L, but North Han River (In2 site) had the lowest average TN, 1.683 mgN/L. South Han River (In1 site) had the average TN of 2.399 mgN/L. In the dam discharge, TN showed the average 2.063 mgN/L. In the lake water, L4 site (Gyeongan River area) had the highest average TN, 3.781 mgN/L, but L3 site (North Han River) had the lowest average TN, 1.587 mgN/L. Total input of nitrogen loads to Lake Paldang was about 30,875 ton/year in 2008. Inflow rivers contributed 30,643 ton/year (South Han River: 18,111 ton/year (59%), North Han River: 11,333 ton/year (37%), and Gyeongan River: 1,199 ton/year (4%)). The atmospheric deposition had 135 ton/year, the nitrogen release from the bottom sediments had 88 ton/year, and macrophytes had 9 ton/year. Total output of nitrogen loads from Lake Paldang was about 31,256 ton/year. The downstream from dam contributed 29,877 ton/year, and the sediment deposition was 1,379 ton/year.