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Debris-flow and flooding hazards associated with the December 1999 storm in coastal Venezuela and strategies for mitigation

Open File Report 01-0144

 

Table 2. Characterization of flood and debris-flow deposition in examined watersheds. Size of drainages is from MARN (2000). Velocity estimates are calculated from evidence of superelevation. Flow depth (*) reported where evidence of deposit had been removed.

 

Drainage

 

 


Camuri Chiquito

 


San Julian


Cerro Grande


Camuri Grande


Q. Alcantarilla


Q. Seca

 


El Cojo


San Jose de Galipan


Osorio

Size

(km2)

 


10.2

 


21.3


25.4


45.3


1.5


3.0

 


6.5


15.0

 


4.7

Sequence and Type of Deposition

(top to bottom)

 


Coarse DF/Fine DF/Flood incision

 


Coarse DF/Flood/Fine DF/Flood incision


Flood/Flood incision


Coarse DF/Hypcon. Flow/Flood incision


Coarse DF/Sandy Flood/Flood incision


Coarse DF/Flood incision

 


Debris Flow/Flood incision


Debris Flow/Flood incision

 


Debris flow/Flood incision

 Deposit Thickness

(m)


3.0-4.0

 


4.0


2.0


3.0-6.0


3.2-4.5


2.5-4.0

 


2.0-3.6


1.0-4.0

 


3.0-6.0*

 

Max. Boulder

  (A-axis)

      (m)


5.1-12.0

 


1.0-5.6


0.2-0.4


2.7-4.1


1.7-2.7


1.8-7.5

 


2.5-9.5


3.2-5.3

 


3.2-7.1

Velocity

(m/s)

 


5.8

 


N/A


4.2-7.0


N/A


3.5-13.6


3.3

 


3.2-5.2


4.4

 


4.1-5.8

Fabric

 

 


Matrix supported-grain to grain support


Grain to grain support


Graded


Grain to grain support


Matrix supported


Grain to grain support, partially imbricated


Matrix supported


Grain to grain support

 


N/A