Waiting for assistance in the floods, Assam, India / by OXFAM 2012

Flood Early Warning System in Assam: a mechanism for effective disaster risk reduction

Flood Early Warning System (FLEWS) is a system by which flood induced hazards can be minimized and prevented. Currently different organizations are working on flood forecasting and early warning at national, continental and global scale.

Case Study

Flood Early Warning System in Assam (India): a mechanism for effective disaster risk reduction.

HFA Priority

HFA Priority 2: Identifying, assessing and monitoring disaster risks and enhancing early warning systems.

The set of capacities needed to generate and disseminate timely and meaningful warning information to enable individuals, communities and organisations threatened by a hazard to prepare and to act appropriately and in sufficient time to reduce the possibility of harm or loss” (UNISDR, 2009)

Abstract

Flood Early Warning System (FLEWS) is a system by which flood induced hazards can be minimized and prevented. Currently different organizations are working on flood forecasting and early warning at national, continental and global scale. 

In a flood early warning system the most important input is real time hydro-meteorological observations provided by weather radar satellites and automatic hydro-meteorological station network (Billa et al., 2006; Budhakooncharoen, 2004).

This real time data can be used in various ways to evaluate flood risks and issues of flood warning. Apart from real time data, probabilistic weather forecasts (Numerical Weather Prediction-NWP) are also playing an important role in providing input for hydrological models to generate warnings scenarios (Burger et al.2009; Thielen et al., 2010). In addition to having forecasts of the most important input (precipitation), a model needs to be selected that characterizes and simulates the catchment responses for flood early warning.

The primary motivator for the FLEWS initiative in Assam was to alleviate the suffering of the local population from floods. The government of Assam felt the inadequacy of not having an effective early warning system to alert the administration and the population from the probable occurrence of a flood and not taking necessary measures to minimize the loss of human lives as well as mitigate against property damage.

Context

Assam, the gateway to northeastern India, extending from 22019’ to 28016’ north and 89042’ to 96030’ east, is situated between the foothills of the eastern Himalayas and the Patkai and Naga ranges. Bhutan and Arunachal Pradesh border Assam in the north and east. Along the south lie Nagaland, Manipur and Mizoram. Floods have been an age-old phenomenon in the riverine areas of this region.

Flooding is an annual event in Assam. More than 40 percent of its land surface is susceptible to flood damage. The total flood-prone area in the Brahmaputra Valley is about 3.2 Mha. (Goswami, 2001). The Brahmaputra valley experienced major floods in 1954, 1962, 1966, 1972, 1974, 1978, 1983, 1986, 1988, 1996, 1998, 2000, 2004 and 2007 & 2012, which clearly shows that floods are an annual event in the State. This affects a large section of the people of the riverine areas leaving them to cope with their annual losses.

Assam, despite of suffering from annual floods, unfortunately did not have a system of early warning mechanisms that would alert the concerned communities about the occurrence of a disaster. The existing disaster management mechanism is primarily focused on strengthening rescue and relief arrangements during and after major floods. Little work has been done in a scientific context on minimizing the incidence and extent of flood damage.

To minimize flood damage the basic approach is to prevent floodwaters from reaching the vulnerable centres. The Central Water Commission (CWC) under the Ministry of Water Resources issues flood forecasts and warnings.

CWC, however, only gives the water level of the major rivers of the state, which does not indicate the areas/villages where the flooding would occur and leaves the administrative machinery clueless as to which village or revenue circle should be warned /evacuated. The government felt the inadequacy in the early warning system and therefore thought about the development of a flood early warning system and/or decision tools which rely on hydrological modeling and the use of near real time data and consulted different stakeholders to find a solution to the problem.

Location

Lakhimpur, Barpeta, Dhemaji, Baksa, Goalpara, Nalbari, Cachar, Karimganj, Dhubri, Morigaon, Sonitpur, Sivsagar, Darrang and Hailakandi districts of Assam, India.

How was the problem addressed?

On 14th June, 2008 a devastating flash flood occurred in Lakhimpur district of Assam affecting more than 300,000 persons and more than 75,000 hectares of land thereby bringing untold suffering and misery downstream. This event drove the government to consult different organisations like the Indian Meteorological Department (IMD), Brahmaputra Board, CWC, Assam Remote Sensing Application Centre (ARSAC), Assam Water Resources Department (AWRD) and North Eastern Space Application Centre (NESAC) about developing a model which could provide location specific flood early warning advisories. Finally NESAC and Shillong decided to develop an effective flood early warning system as they were already working on the development of a flow forecasting system for the Ranganadi Dam on a pilot basis for the North Eastern Electric Power Corporation Limited (NEEPCO).

Major Technical Components of Project

(1)    The meteorological components comprise of two major sub components of the WRF model for grid-based rainfall prediction through numerical schemes and multi-parametric (CTT, CMV, vorticity etc.) synoptic weather monitoring for overall probability of rainfall in a particular basin.

(2)    The hydrological component comprises of a hybrid approach of a lumped grey box model known a rationale model in combination with a quasi distributed hydrological model known as the HEC-HMS in an Arc-GIS platform. While the first approach provides the forecast of the peak value for a river basin, the distributed model provides the forecast for the daily hydrograph for that basin. When one compare both the forecast with the established flooding thresholds for the river, a flood warning can be issued if necessary.

(3)    The third component is the post flood identification of embankment breaches and general monitoring of embankments.

Methodology Disseminating Flood Alerts to Districts

Once the flood warning alert is received at state HQ, the same is disseminated to the district deputy commissioners and the district project officer (disaster management) for alerting the concerned circle officers, Water Resource Department, Public Works Department, through SMS, phones/mobiles and personnel messengers.

Stakeholders Involved

FLEWS is an integrated efforts with different stakeholders such as IMD, CWC, NEEPCO, AWRD, NESAC and Assam State Disaster Management Authority (ASDMA) to achieve the common goal of effective flood management in Assam. ASDMA took the lead role in bringing all the stakeholders together on a common platform to develop the system. Prior to development of FLEWS each stakeholder was working independently within their own flood management domain. ASDMA was the catalyst to get all on board and also brought in NESAC to develop the location specific FLEWS model. Since then each department has been contributing significantly to effective implementation of FLEWS and thereby making it a success.

Strategies Adopted for Bringing About the Transformation and Its Impact

The first strategy in the establishment of FLEWS is consideration of the flood prone districts in a basin or catchment area. The early warning system has been viewed in the context of a river basin approach where upstream, midstream and downstream activities affect the time of concentration and volume of runoff as reflected in the shape of the hydrograph. Given the fact that most flood prone communities are aware that heavy rainfall upstream may result in flooding downstream area, FLEWS will enhance the existing coping mechanisms of communities.

The second strategy adopted in FLEWS is providing location specific early warning advisory bulletins. The warnings issued by NESAC provide information about the revenue circles and the probable villages that may be affected due to flood. This information is of great help to the administrative machinery for preparedness and response activity. The flood alert is also disseminated to the community through revenue circle officers and gaon buras.

The third strategy is the involvement of all the stakeholders under FLEWS as without their active participation the Flood Early Warning System could have never have been a success. To keep the stakeholders participation and involvements at an optimum level, stakeholders are continuously engaged in periodic reviews, meetings both at State and District levels.

Uniqueness of Project

           I.     This methodology of flood warning has probably been tried out for the first time in the country.

         II.     The project is an integrated approach to develop the Flood Early Warning System. All stakeholders, namely the IMD, CWC, NEEPCO, Brahmaputra Board, NESAC are part of the system.

        III.     The FLEWS provides early warning for floods: magnitude (severity); location (revenue circle/group or cluster of villages); and probable time (within 12-24 hours range).  

        IV.     It also provides heavy rainfall warnings with location and time; pre and post monsoon status of embankment in various flood-causing rivers etc.

         V.     The alert for a possible flood situation in a district/revenue circle level is given with a lead-time of seven to 18 hours.

Effectiveness of Flews

Since CWC only gives the water levels of major rivers in the State, leaving out tributaries that contribute to flooding, the administrative machinery clueless about issuing warnings to the specific revenue circles or villages.

This problem was resolved with the initiation of the FLEWS project as the flood warnings are location specific i.e. the revenue circle/cluster of villages that are likely to be inundated due to flood is identified. Apart from the location specific information, the water level of minor tributaries monitored by different organisations are also taken into consideration. This combined information helps the administrative machinery to alert the revenue circle officers and concerned gaon buras about the rivers that are likely to cause floods so that necessary precautions can be taken in advance for preparedness and response activities for people residing in those areas.

Results

1)   Alerts for possible floods in districts/circles with the best possible lead-time has been sorted out.

2)   Submission of annual periodic report on status of existing embankments has been done.

3)   Joint participation among all stakeholders has created a workable product to manage floods in Assam.

4)   Optimum methodology has been developed for rainfall predictions from satellite based weather monitoring and numerical weather prediction models, which is supported by ground data have been developed.

5)   There are now river specific rainfall-runoff models for flood forecasting.

6)   Inundation simulation for flood plain zoning has been developed .

Measuring Success

Though FLEWS was implemented on a pilot basis in Lakhimpur district during 2009 with only four major rivers, major flood events during July-August, 2009 were forecasted successfully.

In 2010, FLEWS became operational in Lakhimpur. In four other districts namely, Dhemaji, Barpeta, Baksa and Nalbari FLEWS was taken up on a pilot basis. The success rate improved from 25% to about 51%.

With five operational districts, the three new Barak Valley districts of Cachar, Karimganj and Hailakandi were added as pilots in 2011 taking the total to eight districts. Despite the increasing number of districts, the success rate further improved to about 60%.

In 2011, most of the flood events were forecasted accurately. Out of 24 flood alerts issued during the 2011 flood season in from all 8 districts, the water rise was recorded 19 time, 4 times when actual flood inundation took place, and only once when no flooding condition was reported.

With the increasing demand from District Administration of other districts FLEWS was further extended to six more flood prone districts i.e. Sivasagar, Sonitpur, Darrang, Morigaon, Goalpara and Dhubri districts during 2012, thereby extending the FLEWS project to 14 districts (8 operational and 6 pilots). Success rate further improved to about 65%. Altogether 64 flood alerts were disseminated during 2012, 42 of which were actual floods.

The State Government has recognized the benefits of the FLEWS project and as it is an effective tool for decision-making. The project is being expanded to the entire State of Assam. Special funds are being earmarked from the current year to enhance FLEWS operations in all the flood prone districts.

Relevance to HFA

The HFA stresses the need for, “identifying, assessing and monitoring disaster risks and enhancing early warning systems.”

Following this project/agreement, efforts were underway to incorporate early warning systems as an integral component of any nation’s disaster risk management (DRM) strategy, enabling governments and communities to take appropriate measures towards building community resilience to disasters.

EWS are increasingly recognized at the highest political level as a critical tool that saves lives and livelihoods, and there are increasingly more investments by national and local governments, international development agencies, and bilateral donors to support such systems.

The initiative is relevant to the HFA2 Priority Action 1: Understanding disaster risk and Priority Action 4: Enhancing preparedness for effective response, and building back better in recovery and reconstruction as described in the Zero draft. It is recommended that HFA2 advocate for a more meaningful and functional early warning systems that works at the grassroots level. Example such as this can guide similar initiatives for more effective results.

Potential for Replication

The whole of Lakhimpur district i.e. the rivers other than Ranganadi were taken up as a pilot exercise. This activity was implemented in project mode and was named Flood Early Warning System (FEWS) until the 2010 monsoon. During a review meeting held on the 16 June 2010 the NDMA pointed out that FEWS is an already existing terminology in UN Disaster Management Programme which stands for Famine Early Warning System. The project name was changed to FLEWS.

Further, the project which started with one district in 2009 was extended to another district in upper Assam namely Dhemaji and three districts of lower Assam namely Barpeta, Nalbari & Baksa in 2010. With the achievement of some success, the project was further extended to Cachar, Karimganj and Hailakandi districts of Barak Valley in 2011. With the increasing demand from the district administrations of other districts the project was further extended to six more districts of Assam namely Dhubri, Goalpara, Morigaon, Sonitpur, Sivasagar and Darrang districts in2012. The total coverage as of now is 14 districts.

Contribution

Assam State Disaster Management Authority, Government of Assam

E-mail: asdmaghy@gmail.com