Community-Based Flood Early Warning System

MONOJ GOGOI

FEWS Parts

A Flood Early Warning System contains following parts;

• Transmitter end:

Transmitter Box: it contains a circuit with small chips. These chips use for decoding signals.

Sensors: Sensors are use for detecting the level of water. As water enters the sensor lead, former pushes the later which leads to generate signals on transmitter box.

Sensor pipe: It is long plastic pipe fixed with sensors. It has holes which help during cleaning the interior part of sensor pipe.

Antenna: a small antenna needs to fix with the transmitter end to send the signal to receiver part.

Battery: a small battery of 6Volt needs to fix with transmitter box. It supply power to the whole transmitter end.

Solar panel: a small solar panel needs to fix with transmitter box which supply power to charge the battery.

Bamboo pole: one bamboo pole is use to fix whole system along with sensor pipe, transmitter box, solar panel and antenna.

• Receiver Part:

Receiver end has to fix in the caretaker’s house. Following parts are includes in receiving part of FEWS

Receiving Box: Receiving box contains one circuit which needs to decode the signals, coming from transmitter part. There are 5 indicators (with light of different colors) attached to this box. Green light indicates the supply of power to the system. Light red indicates the network connection between transmitter and receiver end. Yellow one indicate the level 1 or normal level of water during monsoon season and orange light indicates the pre alarm or warning level for downstream community. Dark red light indicates the most danger level of water for downstream communities. When Orange light started to blink the siren attached to the system started to buzz sounds for 3 times. And when dark red light started to blink, the siren buzzes sounds continuously. To turn off this sound, a switch is attached to the receiver box. This switch use to control supply of power to the receiver box. Therefore after receding of water, operator has to on the switch. 

Siren: One siren with long wire connects with receiver box to produce sounds when water level touches second sensor and third sensor.

Solar charge controller: this device controls the supply of charges to the system. It has 3 sets of terminals (a set consists of a positive and a negative terminal). Solar charge controller connects with solar panel (supplier of power), Battery (two 6 volt batteries with a parallel connection) and a load (in this case load is Siren). Solar charge controller has 3 indicators which imply the level of charging. If the weather is cloudy for a long spell then automatically red light will started to blink. Once there is sunny weather the green light will started to blink, which is an indication of charging of battery. Once this green light become static it indicates the full charging of the batteries.

Battery: 2 numbers of batteries (of 6 volt) are required to functionalize the receiver end. These batteries are use to charge by solar panel through solar charge controller. Both the batteries should connect within a parallel circuit.

Solar panel: A big solar panel required to supply power to the receiver end.

Antenna: to receive signals from transmitter end, an antenna required.

Miscellaneous items: In case of transmitter end, all the above mentioned parts needs to fixed on a bamboo pole. This bamboo has to erect on river bed, so that water touches the sensor gauge. Few other bamboos need to erect in around main bamboo (where transmitter parts are fixed), so that debris flowing with river could not damage the sensor gauge. A bamboo need at receiver end to fix the antenna outside the caretaker’s house. Good amount of wires required to fix the parts strongly.

Step follows during installation of Flood Early Warning System

1. Site selection:

FEWS needs to install on the upper catchment of the river. As much the altitude the downstream community will get more lead time for rescue. But it is mandatory to remember the following points before selecting a site:

                                            (Transmitter end of the CBFEWS)

• Availability of households within 500 meters from river bank
• Availability of mobile service network

2. Fixation of Sensor:

FEWS is a sensor based instrument. Sensor needs to fix to a pipe/gauge. Before fixing sensor one should know about the level of water at that location which can be danger level for downstream. Deciding the level of sensor is a critical one. In most of the cases it is difficult to find secondary flood level data. Therefore one need to discuss with elderly people of that upstream community about the history of flood levels at their locations.

Next topic of discussion is about the time taken by water to reach downstream location (preferably 10 kms from FEWS installation point) from that particular upstream location which also termed as “Lead Time”. Accuracy of lead time is one of the major factors for successful result from the machine.

Level of sensor measured from river bed. 1st level of sensor indicate the normal water level during rainy season, 2nd level of sensor indicate danger level for downstream. Sensor at this level fix such a way that, downstream people will get a lead time of 2 hours at least to move to safe places with their valuable belongings. 3rd level indicates a possibility of disaster at downstream. For some locations it may also indicate a danger level for that upstream, where machine is installed.

3. Charging of batteries:

All the batteries (maximum 3 batteries) need to be charged before installation finish.

4. Fixation of transmitter box:

Transmitter box need to fix with transmitter antenna, sensor gauge and solar panel. Before the transmitter lid fix, battery (6 volt) has to insert.

5. Fixation of transmitter part :

While erecting the bamboo with all transmitter parts, following points needs to remember,

• Antenna needs to align on the direction with receiver antenna.
• Solar panel: it needs to fix at 45° inclination to the bamboo and towards Southern direction.

(Receiver end of CBFEWS, during a visit by Dr David Molden, Director General of International Centre for Integrated Mountain Development (ICIMOD)

6. Fixation of receiver end:

Antenna needs to fix outside the caretaker’s house. It needs to connect with transmitter box placed in the house. Solar charge controller needs to fix with solar panel, batteries and load (siren). Two 6 volts batteries need to connect with receiver end via solar charge controller. There are 3 ports on receiver box. These are dedicated to battery panel, antenna and siren.