• Title/Summary/Keyword: sediment volume change

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Effect of Sirikit Dam Operation Improvement on water shortage situations due to the land use and climate changes from the Nan Basin

  • Koontanakulvong, Sucharit;Suthidhummajit, Chokchai
    • Proceedings of the Korea Water Resources Association Conference
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    • 2015.05a
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    • pp.232-232
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    • 2015
  • Land use and climate changes are the important factors to determine the runoff and sediment loads from the watershed. The changes also affected to runoff volume/pattern to the dam operation and may cause flood and drought situations in the downstream area. Sirikit Dam is one of the biggest dams in Thailand which cover about 25 % of the runoff into the Central Plain where the Bangkok Capital is located. The study aims to determine the effect of land use change to the runoff/sediment volume pattern and the rainfall-runoff-sediment relationship in the different land use type. Field measurements of the actual rainfall, runoff and sediment in the selected four sub-basins with different type of land use in the Upper Nan Basin were conducted and the runoff ratio coefficients and sediment yield were estimated for each sub-basin. The effect of the land use change (deforestation) towards runoff/sediment will be investigated. The study of the climate change impact on the runoff in the future scenarios was conducted to project the change of runoff volume/pattern into the Sirikit Dam. The improvement of the Sirikit Dam operation rule was conducted to reduce the weakness of the existing operation rules after Floods 2011. The newly proposed dam operation rule improvement will then be evaluated from the water shortage situations in the downstream of Sirikit Dam under various conditions of changes of both land use and climate when compared with the situations based on the existing reservoir operation rules.

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Seasonal Patterns of Sediment Supply to Coastal Foredune of Seungbong Island, Korea

  • Woo, Han-Jun;Seo, Jong-Chul;Kweon, Su-Jae;Je, Jong-Geel
    • Ocean and Polar Research
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    • v.24 no.1
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    • pp.39-45
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    • 2002
  • The seasonal patterns of sediment supply were investigated during the period of June 1999 to June 2000 on a coastal foredune of Seungbong Island, Korea. Sediment supply was determined from measurements of geomorphic changes in the foredune and beach along six lines. Most sands were deposited on the dunefoot and foredune area during the winter and spring, from November to April. The largest amount of sands was deposited along the lines 5 and 6 near the sea-dike in the southern tip of the dune area. In general, the sand on the beach was gradually eroded in spring, summer and fall but deposited in winter. Total sediment accumulation over the study period was $484m^3$ for the foredune and $345m^3$ for the beach. The volume of the foredune increased in the winter and spring, whereas the volume of beach increased in the winter. Variation in sediment deposition appears to be controlled primarily by variations in the seasonal wind regime.

Prediction of sediment flow to Pleikrong reservoir due to the impact of climate change

  • Xuan Khanh Do;ThuNgaLe;ThuHienNguyen
    • Proceedings of the Korea Water Resources Association Conference
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    • 2023.05a
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    • pp.38-38
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    • 2023
  • Pleikrong reservoir with a concrete gravity dam that impound more than 1 billion cubic meter storage volume is one of the largest reservoir in Central Highland of Vietnam. Sedimentation is a major problem in this area and it becomes more severe due to the effect of climate change. Over time, it gradually reduces the reservoir storage capacity affecting to the reliability of water and power supply. This study aims to integrate the soil and water assessment tool (SWAT) model with 14 bias-corrected GCM/RCM models under two emissions scenarios, representative concentration pathway (RCP) 4.5 and 8.5 to estimate sediment inflow to Pleikrong reservoir in the long term period. The result indicated that the simulated total amount of sediment deposited in the reservoir from 2010 to 2018 was approximately 39 mil m3 which is a 17% underestimate compared with the observed value of 47 mil m3. The results also show the reduction in reservoir storage capacity due to sedimentation ranges from 25% to 62% by 2050, depending on the different climate change models. The reservoir reduced storage volume's rate in considering the impact of climate change is much faster than in the case of no climate change. The outcomes of this study will be helpful for a sustainable and climate-resilient plan of sediment management for the Pleikrongreservoir.

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Natural and Artificial Bed Change Analysis through Sediment Budget Analysis of Nakdong River Channel (before the Four Rivers Restoration Project) (낙동강 하도의 유사수지 분석을 통한 자연적 그리고 인위적 하상변동 분석(4대강살리기 사업 이전))

  • Son, Kwang Ik;Ji, Un
    • Journal of Korea Water Resources Association
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    • v.48 no.1
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    • pp.1-8
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    • 2015
  • General features of sediment budget for the Nakdong River before the Four Rivers Restoration Project were analyzed using surveying, dredging, and mining data for the past 20 years, as well as sediment data measured from the tributaries, and numerical modeling, etc. As a result of the sediment budget analysis of the Nakdong River before the Four Rivers Restoration Project, sediment inflow supplied from the watershed is $2,100,000m^3/yr$ and sediment outflow including mining and dredging volumes is $10,180,000m^3/yr$. Therefore, the bed change volume estimated by the sediment budget analysis is $-8,080,000m^3/yr$ of the bed erosion volume which is similar to the analysis result ($-8,300,000m^3/yr$) of natural and artificial bed changes using the surveyed data.

Runoff Characteristics Change of a Basin under Urbanization (도시화 진행에 따른 유역 유출특성 변화에 관한 연구)

  • Son, Kwang-Ik;Kim, Min-Chol
    • Journal of the Korean Society of Hazard Mitigation
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    • v.10 no.4
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    • pp.89-93
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    • 2010
  • It is well known that the drastic change of hydrological characteristics of an urbanized basin causes severe runoff, sediment yield, and peak flow. High vulnerability of urban flood disasters is caused by land-use change and development of a basin. A typical site suffering urbanization was selected and the experimental site has being operated last three years. Hydrological and hydraulic characteristics of the urbanizing basin were examined by observation of runoff, sediment loads and precipitation with T/M. The effects of land-use change were analyzed by examination of the hydrological characteristics, such as run-off ratio (runoff volume/rainfall volume), sediment yields. Runoff coefficient of rational equation was increased as basin was urbanized. Suspended sediment yields due to a urban development activities were raised almost 10 times compare to undisturbed condition for small runoff less than 1 cms. Meanwhile, no big change could be detected for bed loads.

An Experimental Study on Engineering Characteristics of Wet Dredged Soil and Dry Dredged Soil after Chemical Treatment (습윤준설토와 노건조준설토의 약품처리 후 공학적 특성에 관한 실험적 연구)

  • Chang, Yongchai;Park, Kiyoun;Park, Jongcheol;Lee, Ingyu
    • Journal of the Korean GEO-environmental Society
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    • v.13 no.3
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    • pp.71-76
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    • 2012
  • Since sediment in a stable state is disturbed during the process from sediment in a natural state to dredged soil, the turbidity of water is not good. When the dredged soil settles again, the volume change in the sediment occurs. Coagulant and flocculant are added for turbidity mitigation of the water and faster settling process of suspended solid, and the amount of the substances affects the characteristics of the dredged soil. This study is to investigate the characteristics of the dredged soil depending on the amount of three chemical products added to the wet dredged soil and the dry dredged soil through measuring the suspended solids (SS), volume change and sedimentation velocity. The experimental measurements show that the SS decreased, the volume change rate increased, and the sedimentation velocity increased, as the chemical amount increased. In addition, it was found that the dry dredged soil reacted even with little quantity of the chemicals because derelict and microorganism are removed due to the drying process at $100{\pm}5^{\circ}C$.

The Change of Beach Sediment Composition and Geography by Typhoon (Naa Beach, East Sea) (태풍에 의한 해빈 퇴적물 조성 및 지형 변화(동해, 나아해빈))

  • Lee, Yeon-Gyu;Shin, Hyeon-Ok;Lee, Jeong-Sup;Park, Il-Heum;Choi, Jeong-Min
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.8 no.3
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    • pp.122-133
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    • 2005
  • The change of surface sediment composition, shoreline and transection of geography were studied to investigate the Typhoon(Maemi) effect in Naa Beach located in the south area of East sea. In the backshore the volume of gravel is do creased, and increased in the volume of sand. The erosion in the sediment occurred to 4 m in the thickness and effected to 10 m in depth. And the coastline retreated to 12 m after typhoon. During typhoon conditions, higher amplitude waves deepen the wave base, causing much of the lower beach face and the offshore. The upper beach face is extensively eroded during typhoon and sand sediment is redeposited.

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Prediction of reservoir sedimentation: A case study of Pleikrong Reservoir

  • Thu Hien Nguyen;XuanKhanh Do
    • Proceedings of the Korea Water Resources Association Conference
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    • 2023.05a
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    • pp.36-36
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    • 2023
  • Sedimentation is a natural process that occurs in all reservoirs. Sedimentation problem reduces the storage capacity of the reservoir and limits its ability to provide water for various uses, such as irrigation, hydropower generation, and flood control. Therefore, predicting reservoir sedimentation is important for ensuring the efficient operation and sedimentation management of a reservoir and . In this study, the HECRAS model was applied to predict longitudinal distribution of deposited sediment in the Pleikrong reservoir to 2050. Different scenarios was considered: (i) no climate change, (ii) climate change (under two emissions scenarios, RCP4.5 and RCP8.5), and (iii) climate change and land use change (followed land use planning of the watershed). The computation results with different scenarios were analyses and compared. The results show that the reservoir reduced storage volume's rate and sedimentation proceed toward to the dam in the case of climate change is faster than in the case of no climate change. Analyses also indicates that following the land used planning could also improve the long-term problem of the reservoir sedimentation. The outcomes of this study will be helpful for a sustainable plan of sediment management for the Pleikrong reservoir.

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The Experimental Study for Variance of Depositation Due to Sediment Volume Concentration of Debris Flow (토석류의 토사체적농도에 따른 퇴적 특성 변화에 관한 실험 연구)

  • Choi, Youngdo;Kim, Sungduk;Lee, Hojin
    • Journal of Korean Society of Disaster and Security
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    • v.15 no.3
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    • pp.15-21
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    • 2022
  • The purpose of this study is to investigate the sedimentation area and runout distance in the downstream when debris flow occurred on a mountain slope through an experimental performance. Super typhoons and torrential rains caused by climate change cause large-scale debris flow disasters in the downstream areas of mountainous areas, mainly where sediments are deposited and flowed downstream. To analyze the characteristics of the sediment deposited downstream, the disposition area and runout distance were investigated through experiments in the case of a straight channel and channel with berm, respectively. As experimental conditions, changes in sediment volume concentration and channel slope, and channel with or without berm, reduction rates in sedimentation area and runout distance were investigated. In the straight channel, the steeper the channel slope and the lower the sedimentation concentration, the sedimentation area and runout distnace were increased. In a channel with berm, the runout distance and sediment area increased as the slope became steeper and the sediment area decreased.

The Effective Wind Velocity and the Patterns of Morphological Change in the Coastal Dune Area (해안사구에서의 유효풍속과 지형변화)

  • Sea, Jong-Cheol
    • Journal of the Korean association of regional geographers
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    • v.10 no.3
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    • pp.667-681
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    • 2004
  • This research is aimed to investigate the relationship of the effective wind velocity and the morphological change in coastal dune at Sindu-ri in Korea. Sediment flux was estimated by the measurement of elevation change along eight transects deployed in the study area from July 1999 to July 2000. The results of this study indicated that. first. based on the occurrence of morphological change and winds effective for sand movement. two distinct seasons were identified: a season of deposition and that of erosion. During the depositional season, spanning from November to April, effective winds were dominant and sand accumulation occurred mainly in foredunes and sequentially in dune plains. During the erosional season, from May through October, volume change was small and erosion or sand loss occurred mostly at the dunefoot of foredunes. Secondly, the research revealed that the sediment budget of Sindu coastal dune turned out to be surplus on the whole, but there are some regional differences. Deficit budgets were observed partly in secondary dunes. The utmost northern part of Sindu coastal dune was provided with abundant sand, whereas the central and northern parts were poorly supplied.

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