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National Institute for Land and Infrastructure Management (NILIM) Coastal, Marine and Disaster Prevention Department Coastal Zone Systems Division Tomoya.

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Presentation on theme: "National Institute for Land and Infrastructure Management (NILIM) Coastal, Marine and Disaster Prevention Department Coastal Zone Systems Division Tomoya."— Presentation transcript:

1 National Institute for Land and Infrastructure Management (NILIM) Coastal, Marine and Disaster Prevention Department Coastal Zone Systems Division Tomoya Kataoka Hirofumi Hinata Lunchtime Discussion at IPRC20 February 2013

2 Kurochio current  Risk caused by plastic debris  Threats to marine animals ex. Ingestion of plastics, Entangled sea turtles  Pollution by toxic chemicals in plastic debris ex. Lead that leach into beach (Nakashima et al., EST, 2012)  Transportation of plastic debris  Outflow from sources  Washing ashore  Returning to ocean  Washing ashore … To Pacific ocean Jean Wash ashore Outflow Return offshore Wash ashore Return offshore To Pacific ocean Outflow

3  Transportation process in East Asian Seas  Monitoring quantity of debris at multiple sites  Webcam monitoring (Low cost and Few labor)  Simulating drifting debris  Ocean circulation model and its quantity at multiple site  Beaching process in nearshore (included returning process offshore)  Movement of debris on beach  Investigation in situ Today’s First Topic Today’s Second Topic

4 (e) Ishigaki (a)Tsushima(b)Wajima (c)Tobishima ) (d) Wakkanai (i) Shiriya (h)Niijima(g)Muroto (f)Tanegashima Nine monitoring sites Tsushima current : 4 sites Tsushima current: 4 sites Kuroshio current: 4 sites Tsushima current: 4 sites Kuroshio current: 4 sites Oyashio: 1 site 【 Today’s topic 】 Tsushima Current: 4 sites

5 The webcam monitoring system Webcam Control box Storage batteries Our laboratory in NILIM Transmission via the Internet Time Photographs Solar panels Operating time  every two hours from 7:00 to 15:00 (i.e., five operations every day) Taking photographs  five photographs every operating time Daily number of photographs  25 photographs (i.e., 5 (operations)× 5 (photos)=25) Saving in a built-in Local storage (SDHC card, 32GB)

6 Tobishima December 2010

7 1. Generation of color references Color references for detecting pixels of plastic debris are generated using CIELUV color space. CIELUV color space: This space is one of three-dimensional color spaces Colors are expressed by ( L *, u *, v * ). 2. Detection of plastic debris pixels using the color references Plastic debris pixels are detected using color references and a composite method. v*v* u*u* u * -v * coordinate v*v* u*u* L * -v * coordinate L * -u * coordinate L*L* L*L* 1) T. Kataoka et al.(2012), MPB, 64,

8 , C Color distribution of plastic debris “C” in the CIELUV color space. Color references, which are generated from webcam images at Tobishima. Three ellipses form the ellipsoid body Ellipsoid body in the CIELUV color space  Color references G E A H D F B a Periods: p1, November 21-27, 2010; p2, December 14-21, 2010; p3, February 16-22, 2011; p4, April 1-7, 2011; p5, May 18-24, 2011

9 , 【 Detection of plastic debris using a single photograph 】 Plastic debris with various colors  detection e.g., Driftwoods  misdetection Detection using one photograph misdetected Composite method: ( L *, u *, v * ) of the pixel is frequently located in the ellipsoid body of a certain color using photographs for three days.  Plastic debris pixels Not plastic debris For 3 days Plastic debris Using one photo Plastic debris  white Using photos for three days Driftwood Plastic debris

10 Projective transformation 1) 1) S. Magome et al.(2007),JO,63, ( X, Y ): Geographic coordinate ( x, y ): Photographic coordinate Coefficients A = N × a N : Number of plastic pixels a : Area of a single pixel Covered area A Beached plastic debris quantity  Covered area GPS Webcam image Converted image Error of computed area: within5.0% m

11 clean-up Err.: 19%, Corr.: 0.93 Err.: 12%, Corr.: 0.81 Err.: 20%, Corr.: 0.94 Err.: 21%, Corr.: 0.73 Time series of daily covered areas  Short-term fluctuations depended on changes in the weather conditions (e.g., amount of sunlight, wind). Removing the short-term fluctuations  Time series of 30-day moving averages (bold line).

12 Period:1month (April, 2011) Time: 7:00, 9:00, 11:00, 13:00, 15:00 Plastic Debris: Three type (Tank (Blue), Cylinder Buoy (White), Cube Buoy (White)) Cylinder Side Cylinder Top Cube Top Cube Side Tank Top Tank Side Calculate average value and standard deviation of (L, u, v)

13 Blue (Tank)White (Cube)White(Cylinder) EW Morning EW EW Afternoon Noon

14 Wakkanai 2010/10/9 Tobishima 2010/11/5 Wajima 2010/12/5 Tsushima 2010/11/22 Webcam sites Wind obs. sites Wind Q in : Quantity of debris washed ashore Q out : Quantity of debris returned offshore Factors for variability of debris quantity Q in > Q out  Increase Q in < Q out  decrease Q in = Q out  not change Near shore current Wave Wind

15 【 Major conclusion for webcam monitoring 】 Succeeded Sequential monitoring of quantity of debris at multiple sites  Succeeded not only vary by intensification of westerly wind but also by other factors Debris quantity  not only vary by intensification of westerly wind but also by other factors  At Wajima and Tsushima  increase according to intensification westerly wind for Nov – Mar  At Wakkanai and Tobishima  Not vary despite intensification of westerly wind  At Tsushima  Increase greatly despite no westerly wind Strong dependence on sunlight angle Factor of the underestimation  Strong dependence on sunlight angle Measurement error can be minimized Using only photographs on certain time when variability of debris color is the lowest  Measurement error can be minimized 【 Major conclusion for Investigation in situ 】 Found seasonal variation of movement and quantity of debris Found seasonal variation of movement and quantity of debris Established residual function of debris Established residual function of debris Estimated residence time on Wadahama beach Estimated residence time on Wadahama beach  152 days (Three type buoys)  98 days (PET bottle) Obtained system characteristics on Wadahama beach Obtained system characteristics on Wadahama beach


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