developing a community based early warning system in ... #6/1_bravo... · mass flows cuenca alta...

Developing a Community BasedEarly Warning Systemin Vargas State, Venezuela

Lelys Bravo de Guenni1, Rafael Hernández 2, Isabel Llatas1 and Abraham Salcedo2

1Universidad Simón Bolívar, Caracas, Venezuela2Universidad Central de Venezuela, Caracas, Venezuela.

Outline

The problem and the locationAdaptation and Mitigation Measures to Hidrometeorological extremesComponents of the Early Warning SystemExperiences with the CommunityFurther research

CARACASCARACASCERRO EL AVILA

ODIF IED FROM IKONO S

PROYECTO CARACAS

Massive Debris Flows – Vargas, December 1999

Deposit of sediments and rocks from debris flows, December 1999

Mass flows

Cuenca alta San José de Galipan

Cuenca alta Camuri Chico

Cuenca media Qda. TacaguaCuenca baja Río Cerro Grande

Cuenca media Qda. Alcantarilla

Study Area: 15,000 inhabitants, located 45 minaway from Caracas

Naiguatá CamuríGrande

Event of 2005

Camurí Grande

Extreme events in the past

Source: Andressen y Pulwarty, 2003

Years with very wet Nov-Feb periods: 1951, 1976, 1986, 1992, 2000, 2005.

Table 2. Registered rainfall amounts during the wet years Year Location Amount (mm) Date 1950-1951 Maiquetia 193 16/02/1951 1975-1976 Los Caracas 100.6 17/02/1976 1985-1986 Macuto

Los Caracas Los Caracas Maiquetía-Aerop.

130.21 106.8 159.0 118.7

04/12/1985 01/11/1985 07/12/1985 04/12/1985

1991-1992 Macuto Los Caracas Maiquetía-Aerop.

152.95 157.0 98.7

26/11/1991 19/11/1991 24/11/1991

1999-2000 Maiquetía-Aerop. 410.4 15/12/1999 2004-2005 Puerto Cruz

La Guitarrita Los Caracas Los Caracas

130.9 103.6 249.5 162.6

09/02/2005 07/02/2005 08/01/2005 08/02/2005

Most events occurred during November-February

Adaptation and Mitigationmeasures to floods and debrisflows

Structural measures- Erosion control- Bed-flow stabilization- Retention and storage of sediments- Flow control channels- Improving Infrastructure

Non structural measures- Monitoring hydrometeorological variables including

sediments- Risk mapping- Land use regulations- Early warning systems- Contingency planning- Population awareness program- Insurance cover- Strengthening institutions governance

Open Dams (slotted):

a) Reinforced concrete in Qda. Guanape

b) Simple concrete in Qda. Curucuti

c) Gavions dam in El Cojo

a) b)

c)

Structural MeasuresCivil works for retention and storage of sediments

d) Gavions open dam (window type) in Camuri Chico.

f) Gavions closed dam in Macutoe) Slotted open dam

(steel tubular) inTacagua

g) Open dam (slotted), reinforced concrete in San

Julián

H = 11 mH = 11 m

Dams in SeriesQUEBRADA PIEDRA AZUL

Dam NDam N°°2 (h= 5 m) 2 (h= 5 m)

Dam NDam N°°1 (h= 5 m)1 (h= 5 m)

Dam NDam N°°3 (h= 4 m)3 (h= 4 m)

Non structural measures: Early WarningSystems (EWS)

EWS

MONITORING: Identify critical

levels

RISK ASSESSMENT:Risk components

analysis

COMUNICATION:Liason among

the community andreponse institutions

PREPARATION:Capacity building,Acting protocols

Maskrey (1997)

Community based early warning system: Example of Camurí Grande and NaiguatáBasins

For each community the following tasks are developed: Evaluation of existing hazards General information about mitigation measuresEstablishing a local risk task force Developing a local risk and emergency plan To define the role of the communityCommunal early warning system tools (portable radios, alarms,

communal rain and water level gages)Promotion activities (workshops, posters, fliers, broadcasting

etc.)Simulations (evacuation drill)

CommunalCommunal RainRain GagesGages

Container

Funnel

External Cover

CommunalCommunal RainRain GageGage

PVC Pipe 4”

Plastic Funnel

Upper Lid

Soda PlasticBottle 2 litters

Lower Lid

Community based hazard map: Camurí Grande

Community based hazard map: Naiguatá

Workshops with the Communities: Six workshops during January-June 2010

Further work

Hydrological modeling of floods and sediments in real timeDetermination of the limiting rainfall thresholds to be used by the communities for alert purposesDeveloping indicators to measure the EWS effectiveness

THANK YOU!!!!

Photos: courtesy of Prof. Arlenys Brito