The Interplay between a Mountainous River and NThe Interplay between a Mountainous River and Nearby Submarine Canyon in Southern Taiwans earby Submarine Canyon in Southern Taiwans

Ray T. Hsu and James T. Liu

Institute of Marine Geology and Chemistry, National Sun Yat-sen University, Kaohsiung, Taiwan 804-24

Mediterranean seaMediterranean seaHudson Submarine CanyonHudson Submarine Canyon

Submarine Canyons are Everywhere on This Submarine Canyons are Everywhere on This Planet!Planet!

Kaikoura CanyonKaikoura Canyon

Monterey Monterey Submarine Submarine

CanyonCanyonLa Jolla Submarine CanyonLa Jolla Submarine Canyon

Submarine Canyons Around TaiwanSubmarine Canyons Around Taiwan

Kaoping Kaoping Submarine Submarine

CanyonCanyon

South China SeaSouth China Sea

Taiwan StraitTaiwan Strait TaiwanTaiwan

Pacific Pacific OceanOcean

Study Area

Study Area

Drainage area: 3,275 kmDrainage area: 3,275 km22

Mean annual runoff: 8.46*10Mean annual runoff: 8.46*1099 m m33

Annual sediment discharge: 3.61*10Annual sediment discharge: 3.61*1077 M.T. M.T.

The Annual Mean Runoff of The Kaoping RiverThe Annual Mean Runoff of The Kaoping River

78%

Field SurveyField Survey

-30

-30-40

-50

450

-300

2468000

2470000

2472000

2474000

2476000

2478000

2480000

2482000

2484000

2486000

2488000

2490000

168000 170000 172000 174000 176000 178000 180000 182000 184000 186000 188000 190000 192000 194000 196000 198000 200000 202000 204000

Kao-ping River

TaiwanStrait

Lin-pienRiver

Tung-kangRiver

Ta-ponBay

Easting (m)

Tripod

Legend

Hsiao Liu ChiuIsland

Sediment Trap

June 19 – July 20, 2000June 19 – July 20, 2000

Trap Array and TripodTrap Array and TripodTripodTripod

ResultResult

Observations on The TripodObservations on The Tripod

Suspended Sediments Captured in Traps Suspended Sediments Captured in Traps and SSC Measured from LISST-100)and SSC Measured from LISST-100)

10

12

14

16

18

20

22

-80

-60

-40

-20

0

20

40

60

80

10

12

14

16

18

20

22

-80

-60

-40

-20

0

20

40

60

80

Time

TemperatureN-S Current

195 m

24 5 m

Observation on RCMObservation on RCM

Temperature (Tripod and Trap Array)Temperature (Tripod and Trap Array)

DiscussionDiscussion

Coastal impact by kai-tek typhoon.The sand fraction in the suspended sedimen

t concentration (SSC) in the canyon came from the shelf floor above and has the highest correlation with the river sediment discharge.

Clay composes the largest fraction of SSC in the canyon.

Coastal Impact by Kai-tek TyphoonCoastal Impact by Kai-tek Typhoon

SSC and Wave Field at Kaoping

River Mouth

Sand in The Submarine CanyonSand in The Submarine Canyon

Sand Fall in San Lucas Submarine Canyon

Grain Size Composition of Captured SedimentsGrain Size Composition of Captured Sediments

Conclusion (1)Conclusion (1)High mountainous rivers located in the tropical and

subtropical regions of the world whose runoff and sediment content (sediment load) display:

Distinct dry and flood seasons in their annual hydrological cycle

The range of magnitude can span several orders of magnitude

the extreme values in the runoff and sediment content are controlled by episodic events that mostly occur in the summer (flood season)

Conclusion (2)Conclusion (2)

The largest fraction in SSC in Kaoping Submarine Canyon (KPCY) is from clay to very fine grains.

The role of the KPCY is an important conduit for sediments from the river to the ocean, especially in episodic events, such as typhoons