• Title/Summary/Keyword: Height above river bed

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The Geomorphic Characteristics of the Location of the 4 Traditional Settlements in Youngnam District (영남지방 4대 전통취락의 지형적 입지 특성)

  • Choe, Hee-Man
    • Journal of the Korean association of regional geographers
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    • v.9 no.4
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    • pp.413-424
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    • 2003
  • This study aims to interpret the location of 4 traditional settlements in the Youngnam district of Korea in view of geomorphology. For this study, GIS techniques were used to analyse quantitatively the degree of slope, slope aspect and the relation with river/stream of these regions. Yugok is located on pediment in the valley basin. Cheonjeon is located in the end part of the hill. Hahoe is located on the convex natural levee of the flood plain. Yangdong is located on a hillside. Houses are mostly distributed with south, southeast, and southwest aspect, but in Hahoe face all sides. Also, the settlements are located on average $10{\sim}20m$ above river bed. This indicates a safe height above river bed for avoiding an flood damage. These results imply that the location of the traditional settlement is based on a scientific logic and rationale. It is thus argued that the settlements satisfy exellent geomorphic conditions from the perspective of modern theories of residential location.

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The Paleoenvironment of the Northern Part of the Nagdong River Delta (낙동강 삼각주 북부의 고환경)

  • 오건환
    • The Korean Journal of Quaternary Research
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    • v.8 no.1
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    • pp.33-42
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    • 1994
  • The study area is filled up by alluvium which can be classified into lower and upper beds by the facies of deposits and their degree of weathering. The lower bed is not of marine but of fluvial. The upper bed is mainly composed of clay and silt or fine sand beds col-ored dark or dark gray which are of neritic or brackish yielding mollusca fossils. The oyster(Crassostrea ariakensis) obstained from the depth of 3m below the present sea level in the upper bed was dated at 4,100 110Y.B.P. and the veneridae(Meretrix lamarck) 1m height above the present delta plain in the old sand bar was dated at 1,700 85Y,B,P. It is therfore concluded that the study area a small kern col of terrestri-al basin prior to postglacial age had experienced the Holocene transgression. Consequently the study area is considered to have been progressively formed under neritic or brackish circumstance before 1,700Y.B.P.

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Experimental Study of Flow Resistance and Flow Characteristics over Flexible Vegetated Open Channel (개수로 내 식생구간의 흐름저항 및 흐름특성에 관한 실험적 고찰)

  • Yeo, Hong Koo;Park, Moonhyeong;Kang, Joon Gu;Kim, Taewook
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.7 no.6
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    • pp.61-74
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    • 2004
  • Hydraulic engineers and scientists working on river restoration recognize the need for a deeper understanding of natural streams as a complex and dynamic system, which involves not only abiotic elements(flow, sediments) but also biotic components. From this point of view, the role played by riverine vegetation dynamics and flow conditions becomes essential. Hydro-mechanic interaction between flow and flexible plants covering a river bed is studied in this paper and some previous works are discussed. Measurements of turbulence and flow resistance in vegetated open channel were performed using rigid and flexible tube. Measuring detailed turbulent velocity profiles within and above submerged and flexible stems allowed to distinguish different turbulent regimes. Some interesting relationships were obtained between the velocity field and the deflected height of the plants, such as a reduced drag coefficient in the flexible stems. Turbulent intensities and Reynolds stresses were measured showing two different regions : above and inside the vegetation domain. In flexible vegetated open channel, the maximum values of turbulent intensities and Reynolds stresses appear above the top of canopy. Method to predict a flow resistance in flexible vegetated open channel is developed by modifying an analytical model proposed by Klopstra et al. (1997). Calculated velocity profiles and roughness values correspond well with flume experiments. These confirm the applicability of the presented model for open channel with flexible vegetation. The new method will be verified in the real vegetated conditions in the near future. After these verifications, the new method should be applied for nature rehabilitation projects such as river restorations.

Changes in Biomass of Salix subfragilis and S. chaenomeloides with Stand Ages in a Riparian Zone of a Sand-bed Stream (하천 하안대에서 입지 연령에 따른 선버들과 왕버들의 생물량 변화)

  • Cho, Hyung-Jin;Jin, Seung-Nam;Cho, Hyunsuk;Cho, Kang-Hyun
    • Ecology and Resilient Infrastructure
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    • v.4 no.3
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    • pp.149-155
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    • 2017
  • Willow plants are representative biomaterials used in river restoration and main target trees in stream managements. In order to understand the changes in the growth of Salix subfragilis and S. chaenomeloides with their stand ages, we investigated the density, height and basal area of stems and biomass at their different aged stands of the riparian zone of the sand-bed stream, the Nakdong River, Korea. We also developed allometric equations for estimating the biomass of these two species by establishing the relationship between diameter at breadth height and tree height with above-ground biomass. The stem density showed a sharp decrease for 3 years after germination for S. subfragilis and 6 years for S. chaenomeloides, resulting in strong self-thinning. The stem height of the two species increased to 7.5 m in 15 years for S. subfragilis, and to 14 m in 13 years for S. chaenomeloides. Aboveground biomass also increased rapidly at the early stage of growth. The biomass increased to 17 ton DM/ha in 13 years for S. subfragilis and to 1,110 ton DM / ha in 13 years for S. chaenomeloides. It is expected that the allometric equations of two Salix species derived from this study will be applied to the objectively estimating the biomass of willow plants for the management of floodplain trees in streams.