환경창을 이용한 다기능보의 친환경 준설시기에 관한 연구

정안철,김성원,유완식,김민석,정관수 한국방재학회 2016 한국방재학회논문집 Vol.16 No.4

본 연구에서는 국내 건설된 16개 다기능보의 친환경 준설시기를 산정하기 위해서 다기능보에서 출현하는 법적보호종 및 대표어종을 중심으로 환경창을 수립하였다. 하나의 다기능보에 대해서 수립된 환경창이 다수일 경우에는 가중치를 적용하여 하나의 통합 환경창을 수립하였으며, 통합 환경창의 환경창 지수와 홍수기를 고려하여 최적 친환경 준설시기를 산정하였다. 그 결과, 대부분의 다기능보에서 봄, 여름보다는 가을과 겨울이 친환경 준설을 위한 시기인 것으로 나타났으며, 약 3~6개월의 친환경 준설기간을 갖는 것으로 나타났다. 기존의 하천 유지·보수 매뉴얼에서 제시된 준설시기가 5월과 10월이었으나, 본 연구에서는 5월은 환경적으로 준설의 부정적인 영향이 가장 큰 것으로 나타났다. 또한, 환경창을 이용하여 친환경 준설시기를 산정하는 경우에는 친환경 준설장비 및 준설기법과 같은 구조적 방법에 비해서 시간과 노력이 상대적으로 적어진다는 장점이 있다. 따라서 본 연구에서 제안한 준설시기 산정방법을 이용한다면 하천 환경 및 생태에 대한 준설의 부정적인 영향을 최소화할 수 있는 준설계획 수립이 가능할 것으로 판단된다. In this study, we established environmental windows for estimation of environmental friendly dredging season considering legal protected species and main fish type at 16 multi-functional weirs in the domestic. If various environmental windows was established at one multi-functional weir, we applied weighting factors for integrated environmental windows. We estimated optimal environmental friendly dredging season by environmental windows index and flood season. As a result, optimal environmental friendly dredging season of most multi-functional weirs is estimated to be fall and winter more than spring and summer. And, environmental friendly dredging duration is estimated approximately 3 to 6 months. The river maintenance manual suggested May and October for optimal dredging season. But, May is most harmful season of dredging activities by newly estimated result in this study. The case of dredging season estimation by non-structural method such as environmental windows can decrease time and cost more than structural method such as development of environmental friendly dredging equipment or construction method. Therefore, through suggested method for estimation of dredging season in this study, it is expected to establish the dredging plan for minimization of negative effect to river environment and ecology due to dredging.

낙동강 유역의 친환경 하천 준설을 위한 환경창 수립 방안

정안철 ( An Chul Jeong ),김성원 ( Seong Won Kim ),김민석 ( Min Seok Kim ),정관수 ( Kwan Sue Jung ) 한국환경정책평가연구원 2015 환경정책연구 Vol.14 No.4

국내의 하천 환경은 4대강 사업 이후로 많은 변화가 예상되며, 이 과정에서 하천관리기법 역시 변화가 요구되고 있다. 준설이 그 대표적 예라고 할 수 있지만 준설은 2차 환경피해의 우려가 있다. 이를 위해서 준설의 사회·환경적으로 미치는 부정적인 영향을 최소화하기 위하여 미국의 환경창 제도를 한국에 적용시켜보았다. 자료의 부족을 극복하기 위해 통계학적 기법을 이용한 방안을 제시하였으며, 낙동강 강정고령보 하류부에 적용해보았다. 그 결과, 1개월 동안준설하는 경우에는 3월에 수행하는 것이 최적으로 나타났으며, 8개월 동안 준설하는 경우에는 8월에 수행하는 것이 최적인 것으로 나타났다. 여기에 홍수기를 고려했을 경우에는 8개월 동안 준설에 대해서 10월에 시작하는 것이 최적인 것으로 나타났다. 환경창 제도와 같이 비구조적 방법은 친환경 준설장비를 개발하는 등의 구조적 방법보다 제도만 잘 정비된다면 단기간에 효과를 볼 수 있으며, 친환경 준설장비를 개발하면서 소요되는 막대한 예산을 절감할 수 있다는 장점이 있으므로 환경창을 준설규정을 수립하는 데 있어서 참고할 수 있을 것으로 판단된다. 환경창의 국내적용은 하천준설에 대한 연구가 미비했던 국내에 기초자료로써 제공될 수 있을 것으로 판단된다. The river environment in Korea has changed significantly after the completion of the Four Major Rivers Project due to the outdated river management methods and thus, it is necessary to modify the current river management process. A typical example of this management is dredging but it is a method that usually results in socio-environmental side effects. Therefore, in order to minimize the socio-environmental impacts of dredging, Korea is currently applying the Environmental Windows, a management practice currently being used in the United States that eliminates the risk of potentially harmful impacts of dredging. The use of statistical methods was suggested to address the issue of data insufficiency and this methodology was applied in the downstream part of the Gangjeong-Goryeong weir located within the Nakdong river basin. The results show that when performing a month of dredging, the optimal period is March whereas the optimal month to start dredging is August in case of an eight-month dredging project. If Korea’s flood season is also considered for an eight-month dredging process, then October is the optimal month to start dredging. Non-structural methods such as the Environmental Windows reduce maintenance costs and also bring only short-term side effects to the environment, as opposed to structural methods such as the development of environmentally-friendly dredging machine. Given that few studies have explored this topic in Korea, the findings and suggestions could serve as basic data in studying river dredging in the future.

Framework of the Approximate Cost Estimating Model for River Dredging Construction

이정윤,이시욱,우성권,신도형 대한토목학회 2011 KSCE JOURNAL OF CIVIL ENGINEERING Vol.15 No.1

Recently, construction on the Four River Restoration Project began in South Korea. The project includes the maintenance of river embankments, the development of river areas, and river dredging. Accordingly, considerable attention is being paid to the necessary budget and estimation of construction costs. However, only a few studies have been carried out for the cost estimation of construction projects for river development or maintenance. In particular, approximate construction cost estimations for river dredging have not been studied. The lack of sufficient studies on estimating the approximate construction cost of river dredging has caused some doubt about the validity of the project’s estimated construction cost. This study proposes a framework of an approximate cost estimating model for river dredging construction. For this purpose, the construction operation process, type of river section, and the combination of equipment employed for river dredging were analyzed from the historical data of river dredging projects conducted in South Korea. The appropriateness of the analysis was examined through interviews with experts in the field. The framework of the approximate cost estimating model for river dredging construction proposed in this study provides a basis from which to develop a more accurate construction cost estimation of river dredging at the planning stage.

생태계 보호를 고려한 남북공동수로의 친환경 준설시기 분석

정안철,김성원,최미경,정관수 한국방재학회 2019 한국방재학회논문집 Vol.19 No.3

Recently, a survey was conducted of the waterway shared by South Korea and North Korea. In the Han River Estuary, the need for dredging emerged due to serious riverbed aggradation. Dredging is the most efficient way to remove deposited sediment. However, it is expensive and has negative impacts on society and the environment. The negative impacts of dredging occur both in water and on land, causing huge disturbances to ecosystems. In this study, an environmentally friendly dredging season was proposed using the non-structured method of environmental windows to minimize the negative impacts of dredging. To establish environmental windows, the growth stages of six species in the Han River Estuary were used. Results showed that dredging in November could minimize its negative impacts and that dredging between October and December would be appropriate when it had to persist for more than two months. The negative perception of dredging has been increasing from the Four Rivers Project. This study will be applied to this situation, to mitigate the negative impacts of dredging, provide basic data pertaining to river construction considering the ecosystem, and support decision-making. 최근 남북공동수로 조사가 마무리되면서 하상상승이 심각한 한강하구에 대한 준설 필요성이 대두되고 있다. 준설은 퇴적된 유사를 가장 확실하게 제거할 수 있지만, 비경제적이고 사회·환경적인 측면에서 부정적인 영향이 큰 건설공사로 알려져 있다. 준설의 부정적인 영향은 수역은 물론 육역에서도 발생하며 생태계에 매우 큰 교란요소로 작용하게 된다. 준설의 부정적인 영향을 최소화하기 위해서 본 연구에서는 환경창이라는 비구조물적 방법을 이용하여 친환경 준설시기를 제시하였다. 환경창 수립을 위해서 한강하구에 서식하는 것으로 알려진 6분류군의 생물종의 성장단계를 이용하였다. 그 결과, 11월에 준설하는 것이 준설의 부정적인 영향을 최소화할 수 있으며, 2개월 이상 준설 시에는 10월에서 12월 사이에 준설하는 것이 적절할 것으로 판단된다. 4대강 살리기 사업부터 시작하여 준설에 대한 부정적인 인식이 증가하고 있는 상황에서 본 연구는 준설의 부정적인 영향을 완화하고 생태계를 고려한 하천공사에 대한 기초자료 제공 및 의사결정 지원 등에 활용될 것으로 판단된다.

Analysis for the Effectiveness of Sediment Dredging in the Approach Channel at the Nakdong River Estuary Barrage

박상길,지운,여운광,김도훈 대한토목학회 2013 KSCE JOURNAL OF CIVIL ENGINEERING Vol.17 No.6

The upstream channel of the Nakdong River Estuary Barrage (NREB) has experienced sedimentation problems requiring annual dredging operation after the construction. The main purpose of sediment dredging is to prevent flooding during late summer. Numerical simulation and volume analysis using field surveying data for the Lower Nakdong River have been conducted to quantify the bed changes with and without dredging operation and to analyze the effectiveness of dredging at the NREB. As a result, it is presented that the bed change rate (sedimentation rate) after dredging is much faster than the bed condition without dredging. The water surface rising of the maximum 10 cm was generated in case the dredging was not considered in the modeling. Volumetric analysis of bed changes using field surveying data presented that 41 percent of total sediment erosion was eliminated by natural flushing and 59 percent was dredged in the field. Because it is noticeable that dredged section is redeposited rapidly after dredging during low flow through the 2D simulation, it is expected that most of total sediment erosion (at least more than 41% of total sediment erosion) is caused by natural flushing due to the floods. Therefore, it is highly recommended to use natural flushing or intentional sluicing techniques for sedimentation control methods at the NREB.

III분과 : 사방댐 준설이 계류의 지형변화에 미치는 영향-지상 LiDAR 자료를 이용하여-

서준표 ( Jun Pyo Seo ),우충식 ( Choong Shik Woo ),이창우 ( Chang Woo Lee ),김경하 ( Kyong Ha Kim ),이헌호 ( Heon Ho Lee ) 한국임학회 2014 한국산림과학회지 Vol.103 No.3

본 연구는 사방댐의 준설작업이 퇴사선내 계류의 지형변화에 미치는 영향을 알아보기 위해서 준설을 시행한 사방댐과 준설을 시행하지 않은 사방댐을 대상으로 지상 LiDAR 측량을 실시하고 경사도 및 체적의 지형변화를평가하였다. 지상 LiDAR 장비는 사용자의 숙련도에 영향을 받지 않고 쉽게 지형변화를 관측할 수 있는 장점이 있다. 본 연구결과, 경사도 변화는 토양침식 유발의 위험이 높은 경사도(20°~40°)가 차지하는 비율은 준설을 시행한 사방댐 지역보다 준설을 시행하지 않은 사방댐에서 수치적으로는 더 높게 나타났지만, 우기후 위험구역은 준설을 시행하지 않은 사방댐에서 더 감소하는 것으로 나타났다. 체적변화는 준설을 시행한 사방댐에서 침식과 퇴적이 규칙적인 양상으로 나타났지만, 준설을 시행하지 않은 사방댐에서는 침식과 퇴적이 불규칙적으로 나타났다. 그리고 정량적 분석결과 준설을 시행하지 않은 사방댐에 비해 준설을 시행한 사방댐에서 우기후 m2당 1.7배 더 많은 토사가 유입되었다. 조사대상지의 강우량 차이는 토사유출량에 미치는 영향이 없는 것으로 나타났다. 따라서, 준설을 시행한사방댐에서는 준설을 시행하지 않은 사방댐에서보다 우기를 지나면서 토양침식의 위험이 높은 경사도 분포가 증가하고, 준설작업을 시행한 지역의 상류계류에서 토사가 많이 유입된 것으로 나타났다. This research was carried out to understand the impact of mountainous torrent on topographicalchange of slope and sediment volume within a deposit line by dredging of soil erosion control dam. TerrestrialLiDAR surveys were conducted at dredged and non-dredged sites. Terrestrial LiDAR has an advantage ondetecting topographical changes easily without demanding workmanship and technical skill for users. Thedistribution of erodible slope (20o-40°) was higher in non-dredged site than that of dredged site. However, thedistribution was higher in dredged site than that of non-dredged site after rainy season. Erosion and depositionappeared regularly in a dredged site, but those occurred irregularly in the non-dredged site. The inflow of soilper square meter was 1.7 times higher in dredged site than that of non-dredged site after rainy season. Thedifference of rainfall in each site did not affect to soil erosion. The distribution of erodible slope was increasedin dredged site than that of non-dredged site after rainy season due to inflow of soil from upper stream causedby dredging.

사방댐 준설이 저서성 대형무척추동물 군집에 미치는 영향

김봉성 ( Bong Sung Kim ),이창우 ( Chang Woo Lee ),서을원 ( Eul Won Seo ),이종은 ( Jong Eun Lee ) 한국임학회 2012 한국산림과학회지 Vol.101 No.3

본 연구는 사방댐의 준설이 저서성 대형무척추동물 군집에 미치는 영향을 파악하기 위해 경북북부지역 예 천, 영주, 봉화의 산간계류에 위치한 사방댐을 대상으로 준설 전·후로 조사하였다. 조사는 실험수계 3곳과 대조수 계 2곳의 사방댐을 기준으로 상류와 하류로 설정하여 2011년 5월부터 8월까지 이루어졌다. 실험수계에서 준설 전 4 문 6강 11목 31과 56종이 출현하였으나, 준설 후 4문 5강 10목 27과 51종으로 감소하였다. 이와 같이 사방댐 준설 후 발생한 저서성 대형무척추동물의 미소서식처 파괴는 종수 및 개체수의 감소로 이어졌으며, 특히 실험수계의 상 류지점에서는 종수가 평균 38% 감소하였다. 전반적으로 준설 후 실험수계에서 종풍부도지수와 종다양도지수가 감소 했지만, 우점도지수는 증가하였다. 실험수계의 상류지점에서 미소서식처의 파괴와 정수역이 형성되었으며, 유속이 감 소하고 하상구조는 모래나 실트로 단순해졌다. 그에 따라 상류지점의 섭식기능군과 서식기능군의 종조성은 단순해졌 으며, 상·하류 군집의 차이가 커졌다. 또한 상류지점에서는 유속이 느리거나 정수역을 선호하는 깔따구류(Chironomidae spp.), 부채장수잠자리류(Gomphidae spp.), 하루살이류(Ephemeridae spp.)의 개체수 비율이 크게 증가하였으며, 군집의 균형성을 나타내는 EPT/C 지수가 감소하였다. This study was conducted for determining the influence of Sediment Control Dam dredging on benthic macroinvertebrate communities in mountain stream of Gyeongsangbuk-do. The sediment control dams were surveyed before and after dredging from mountain streams of Yecheon, Yeongju and Bonghwa in Northern part of Gyeongsangbuk-do. Sampling was taken at upper and down from 3 experimental sites and 2 control sites during May to August 2011. The identified species before dredging were 56 belonged to 31 families, 11 orders, 6 classes and 4 phyla, but after dredging it has decreased to 51 species belonged to 27 families, 10 orders, 5 classes and 4 phyla. The microhabitat damage of benthic macroinvertebrates occurred at experimental sites after dredging of sediment control dams led to reduction of the number of species and individuals. Especially, upper stream of experimental sites showed the reduction of an average of 38% species. In general, species diversity indices and species richness indices decreased after dredging; however, dominance indices increased at experimental sites. In the upper stream of experimental sites, the microhabitat damaged and became pool due to dredging. Also, velocity of flow decreased and the river bed became simply due to the sedimentary matter being finer than sand and silt. As a result, composition of functional feeding groups and functional feeding groups were relatively simpler at upper stream and the degree of community differences was greater between upper and down stream. Also, Chironomidae spp., Ephemeridae spp., and Gomphidae spp. to prefer where slow velocity of flow and lentic increased in a greater rate, and the EPT/C index to indicate the balance of the community decreased.

델파이 기법과 AHP를 이용한 중력식 사방댐 준설 평가지표 및 조사야장 개발

서준표 ( Jun Pyo Seo ),이창우 ( Chang Woo Lee ),우충식 ( Choong Shik Woo ),이헌호 ( Heon Ho Lee ) 한국환경복원기술학회 2014 한국환경복원기술학회지 Vol.17 No.6

A dredging on erosion control dam has been enforced without evaluation the factors that affect the dredging. In addition, there is the negative effect much more than positive effect by dredging on erosion control dam. Therefore, this study was carried out to develop evaluation indicators and to suggest fieldbook in order to determine whether sand deposits at erosion control dam should be dredged up or not. The most important six evaluation indicators that can decide to dredge up at erosion control dam were obtained from three round delphi technique and were selected in the following order: the current sand deposit ratio(0.339), existence of cultivated land and house downstream(0.276), the slope of streambed(0.162), the amount of movable soil and gravel(0.118), the history of any disasters(0.063), the basin area(0.043). The weighted score for each evaluation indicator were acquired from AHP analysis with respect to the degree of importance and then the modified weighted score for actual measurements were classified as three categories: large(2.53), medium(1.60) and small(1.01). Based on delphi technique, erosion control dam dredging evaluation fieldbook introduced the four evaluation indicators out of the total six evaluation indicators and two low effected evaluation indicators were excluded. This results showed that the values for reliability analysis and consistency ratio were acceptable.

Effectiveness of dredging and drains’ treatment on water quality of Rosetta branch

Mohie Eldin M. Omar,Mohamed A. Ghareeb,Shaimaa El Sherbini 대한환경공학회 2022 Environmental Engineering Research Vol.27 No.1

Rosetta Branch of Nile River in Egypt receives drainage water from five agricultural drains deteriorating its water quality. Since the branch is used for irrigation and municipal purposes, its water quality should be enhanced. Hence, the current paper aimed at providing the most effective intervention to improve the branch water quality. Preventing drainage disposal was excluded due its significance to downstream users. The paper investigated the impacts of drains" treatment and branch dredging on hydrodynamics and water quality. The branch was numerically simulated using HECRAS model, and calibrated using measured water levels and quality parameters. The paper selected constructed wetlands as the most suitable method for drainage treatment based on conditions of study area. SUBWET model predicted optimal designs of wetlands achieving the desired treatment efficiency. SUBWET model was calibrated with experimental wetlands at Delta Barrage. Results showed that 1-m dredging dropped water surface elevations by 22 to 50 cm. Dredging had no significant changes in the backwater zone of Edfina Barrage at the branch end except for the maximum flow case. Simulation of dissolved oxygen and ammonium showed that dredging and treatment improved water quality. Drains’ treatment by constructed wetlands with selected designs was much more effective than dredging.

하도준설이 사행하천에 미치는 수리학적 영향 분석

김태형 ( Tae Hyeong Kim ),김병현 ( Byung Hyun Kim ),한건연 ( Kun Yeun Han ) 한국지리정보학회 2015 한국지리정보학회지 Vol.18 No.4

This paper attempted to analyze the hydraulic effects that the dredging can take as an alternative to reduce possible damages of flooding due to the overflow of river levee in meandering rivers, where riverbed aggradation, seepage and erosion may occur. In order to make a hydraulic analysis in a section of meandering rivers, a two-dimensional hydraulic analysis model, RMA-2, was selected. The GIS was applied to construct twodimensional finite element grids to consider the hydraulic conditions before and after dredging. The water surface elevations, depths, velocities, and tractive forces were compared before and after the dredging. The difference of water surface elevation between the inside and outside of river was turned out to be the maximum value of 0.58m under the design flood condition. It could be evaluated that the tractive force at the bank decreased about 42 to 67% on average for all the sections. These results could give valuable information that the dredging of the stream channel at the meandering sections decreased the risk of overflow, seepage and erosion of the banks. The methodologies given in this study will contribute to mitigating the flood damages in the surrounding farmlands.