• Title, Summary, Keyword: 하천 얼음

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A Study on the Measurement of River Ice Thickness by Using X-band Scatterometer (X-밴드 산란계를 이용한 하천 얼음 두께 측정에 관한 연구)

  • Han, Hyang-Sun;Kim, Bum-Jun;Lee, Hoon-Yol
    • Geophysics and Geophysical Exploration
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    • v.15 no.1
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    • pp.16-22
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    • 2012
  • In this study, we setup a ground-based scatterometer using an antenna of which the center frequency is 9.5 GHz (X-band), and measured radar backscatterings from air/ice and ice/water interfaces to extract ice thickness. Both of air/ice and ice/water interfaces make strong radar backscatterings and so we can clearly identify two peaks in measured data by scatterometer. By using the distance of two peaks and refractive index of ice, we confirmed that it is possible to measure ice thickness. Field survey was performed at the downstream of Jiam River flowing into Chuncheon Lake. We measured radar backscattering from river ice along a survey path and extracted ice thickness. The ice thickness map of the downstream of Jiam River was produced by using kriging which is one of well known interpolation methods. The ice thickness was about 50 cm along the mainstream while ice was thin as 30 ~ 40 cm at a fast-flowing meander. Ice thickness was particularly thinner at some locations than that of surrounding areas even in the mainstream region of constant flow. This was because of impurities in ice or artificially formed refrozen holes after fishing. We expect that this study helps to expand utilization field of X-band SAR and airborne scatterometer system.

과학기술, 그 뿌리와 현주소 - 기상학(상)

  • Hong, Seong-Gil
    • The Science & Technology
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    • v.33 no.2
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    • pp.84-88
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    • 2000
  • 세계의 기상관측시대는 한국으로부터 열렸다고 볼 수 있다. 1441년 세계 최초로 세종때 측우기를 개발하였기 때문이다. 새 천년을 맞아 상당수 과학자들은 대기온난화 등 미래의 지구기후에 관심을 기울이고 있다. 실제로 기온이 3℃ 상승하면서 해수면이 1m 이상 높아지고 바닷물이 지하로 흘러들어 우물이 짠물이 된다. 또 기온이 3℃ 강하하면 지상에 얼음과 눈이 누적되어 해수면이 3~6cm 낮아지고 지하수면도 낮아져 하천과 호수가 바닥을 드러내게 되어 과학자들은 크게 우려하고 있다.

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Feasibility Study of Wetland-pond Systems for Water Quality Improvement and Agricultural Reuse (습지-연못 연계시스템에 의한 수질개선과 농업적 재이용 타당성 분석)

  • Jang, Jae-Ho;Jung, Kwang-Wook;Ham, Jong-Hwa;Yoon, Chun-Gyeong
    • Korean Journal of Ecology and Environment
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    • v.37 no.3
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    • pp.344-354
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    • 2004
  • A pilot study was performed from September 2000 to April 2004 to examine the feasibility of the wetland-pond system for the agricultural reuse of reclaimed water. The wetland system was a subsurface flow type, with a hydraulic residence time of 3.5 days, and the subsequent pond was 8 $m^3$ in volume (2 m ${\times}$ 2 m ${\times}$ 2 m) and operated with intermittent-discharge and continuous flow types. The wetland system was effective in treating the sewage; median removal efficiencies of $BOD_5$ and TSS were above 70.0%, with mean effluent concentrations of 27.1 and 16.8 mg $L^{-1}$, respectively, for these constituents. However, they did often exceed the effluent water quality standards of 20 mg $L^{-1}$. Removal of T-N and T-P was relatively less effective and mean effluent concentrations were approximately 103.2 and 7.2 mg $L^{-1}$, respectively. The wetland system demonstrated high removal rate (92 ${\sim}$ 90%) of microorganisms, but effluent concentrations were in the range of 300 ${\sim}$ 16,000 MPN 100 $mL^{-1}$ which is still high for agricultural reuse. The subsequent pond system provided further treatment of the wetland effluent, and especially additional microorganisms removal in addition to wetland-pond system could reduce the mean concentration to 1,000 MPN 100 $mL^{-1}$ from about $10^5$ MPN 100 $mL^{-1}$ of wetland influent. Other parameters in the pond system showed seasonal variation, and the upper layer of the pond water column became remarkably clear immediately after ice melt. Overall, the wetland system was found to be adequate for treating sewage with stable removal efficiency, and the subsequent pond was effective for further polishing. This study concerned agricultural reuse of reclaimed water using natural systems. Considering stable performance and effective removal of bacterial indicators as well as other water quality parameters, low maintenance, and cost-effectiveness, wetland- pond system was thought to be an effective and feasible alternative for agricultural reuse of reclaimed water in rural area.