**This year also we will have floods. The question is about the intensity of flood. Chances are that we may be hit by flood of higher intensity.

Bangladesh has an area of 144.000 Sq Km lying in the delta of the world's three great rivers — the Ganges, the Brahmaputra and the Meghna. These river systems drain an area of 1.72 million Sq Km in China. India. Nepal. Bhutan and Bangladesh.

Floods in Bangladesh is a recurring phenomenon. About 60 per cent of the country is flood Be while 25 per cent of the is inundated in monsoon in a normal year. Bangladesh experienced worst flood in 1988 when more than 60 per cent of the land was flooded and 50 per cent of the population was affected.

Floods in the South Asian region is also a regular phenomenon in Nepal and India. Flooding in South Asian region is caused by a combination of several factors:

a) Natural: Huge flows generated by rainfall occurring in a short span of time in the upstream catchment and consequent over bank spilling of the main rivers: Runoff generated by heavy local precipitation that cannot be drained out due to high stages in the outfall rivers; Land slides and glacier lake outbursts that result in high sedimentation in the rivers' courses: High tides in the Bay of Bengal coupled with windset up caused by southwesterly monsoon winds that obstruct drainage of upland discharge. and Synchronization of the peak flows of the major rivers.

b) Man Made: Deforestation in the upper catchment; Drainage congestion due to uncoordinated development activities.

Floods in South Asian region countries vary in nature, time and duration. The damage caused by floods in the three countries are colossal.

In Nepal, the floods experienced in the Himalaya and the mountains are mainly due to glacier lake outburst or cloud burst, heavy precipitation and land slides. The three main

rivers, the Sapt Kosi. the Gan-d.iki and the Karnali originate in the Himalaya are snow and glacier feed. A large part of the drainage area is covered by snow and glacier throughout the year and play a significant role In the hydrological regime of the river systems. These three rivers received monsoon floods from June to September where about 85 per cent total precipitation falls The estimated damage due to floods and land slides has increased from US 81 million to US $ 100 million over the year.

In India, almost all the major rivers carry heavy run-off during monsoon due to intensive and heavy rainfall in their catchments. Floods in India in the Ganges Basin are caused by the three factors; inundation due to over bank spilling, erosion of river bank and changing rivers courses.

In the Brahmaputra basin *"1ous floods occur due physiographic conditions, meteorological situation, earth quake, land slides, erosion of rivers banks and encroachment of river areas. After the earthquake in 1950. the regime of the Brahmaputra rivers tn the upper catchment changed and the depth, duration and flooded area have increased due to heavy slltation of the river bed. Floods in India during 1954, 1962, 1966. 1972. 1973. 1974. 1983. 1984. 1987, 1988, 1993, 1994 and 1995 were very serious.

Floods in India due to monsoon generally occur from June to September. The average flood affected area in India is 7.9 million ha of which 3.69 million ha is cropped. The estimated annual loss is about US $ 500 million.

Flooding in Bangladesh is a recurring phenomenon. The

country experiern ed severe floods in 1954. 1955. 1961, 1962, 1964, 1970, 1974. 1987. 1988, 1993 and 1995.

Bangladesh through its intricate network of rivers system drains a catchment of about 1.72 million Sq Km of which only 7 per cent lies in the country. Owing the to the geographi cal location about 90 per cent of the stream flow with high sediment load from upstream passes through Bangladesh. Flood problem in the Ganges basin area in Bangladesh is mainly due to overbank spilling. The flood situation deteriorates when Brahmaputra in spate forces backwater into the Ganges.

The Ganges begin to rise in May and the period of maximum flood is in July and August. Occasionally September could be a month of severe flooding.

Flooding in Brahmaputra is characterized by large scale inundation of its banks, erosion at various places, conveyance of heavy silt load from upstream. The Meghna in the north east Eart of the country is controlled y high water level of the

Padma during flood season.

The area prone to flood in Bangladesh is 6.14 million ha which is 42 per cent of the whole countiy. The loss caused by floods in a normal year is about US $ 175 million. In extreme case, it may exceed US 8 1 billion.

The Ganges, the Brahmaputra and the Meghna basins cover an area of 141.24 million ha of which 109.48 million ha is in India. 14 million ha in Nepal and 12.90 million ha in Bangladesh. Basin wise distribution of area in the three river basins are given below:

Of the total area of the three river basins 62.9 per cent lies in India, 8.02 per cent in Nepal. 7.39 per cent in Bangladesh. 2.5 per cent in Bhutan and the rest in Tibet (China). The flood and drought are twin problem of the three rivers basins. Every year colossal damages occur due to flood in Nepal. India and Bangladesh. The situation in the upper riparian countries are different from Bangladesh. Bangladesh has to give passage to the floods of all the three rivers.

Nepal's worst flood occurred in 1993 which claimed more than 2.000 lives. More than half a million cropped areas were damaged, in India worst flood occurred in 1993 in the northern part of India. The death tool was more than 1100 and it caused extensive damage to crops, homesteads and infrastructures.

The flooding in Bangladesh in 1993 caused extensive damage to crops, houses and infrastructures. About 9.3 million people were affected and 162 lives were lost.

Drought is another factor which concerns India and Bangladesh. Inadequate rainfall. climate change and short-

age of dry season flow often create drought affecting crop production

The floods of 1995 in the northern region of Bangladesh devastated lives and properties, washed away development programmes. economic achievements and growth. It destroyed standing crops, houses and disrupted transportation. Flooding reached unprecedented level particularly in the Naogaon district in September. 1997. The flooding in 1995 between June and October affected about 32.000 Sq Km including 18.000 Sq Km in the north west region.

The Ministry of Water Resources prepared a report on Hoods in North Bengal in 1955. According to the report, floods of 1955 occurred in four waves: First wave from June 13-14. second wave in July 2-20 and the third wave in August 11-16. fourth wave from September 28 to October 15.

The Floods in 1996 in Bangladesh started in June and continued till August. About 46 districts were affected. The loss of lives was 47 but crop damages, houses, livestock were extensive including heavy damage to roads and embankments.

Meteorologist. of Bangladesh have noticed some deviaUon in the weather pattern thia year from normal. They predicted higher rainfall by 20 per cent more than the normal Bangladesh experience higher than normal rainfall at cycle of two to five years. Last gear's monsoon rainfall eras

This year also we will have Hoods. The question is about the intensity of flood. Chances are that we may be hit by flood of higher intensity. Hoods also affect both Nepal and India in varying intensity.

Presently, each country has it plans and programmes for flood control. Long history of floods and other natural events has shown that individual efforts are not enough to mitigate floods even in their own country. There is now a greater need for regional cooperation for lasting solution of the twin problems of flood and drought.

Recent developments in Improving the bilateral and re-Bonal cooperation by India, epal and Bangladesh is encouraging. The Indian Prime Minister during his visit to Dhaka in January, 1997. called for joint efforts to improve water management, flood control and irrigation for the benefit of the people of both countries.

The reports prepared by Bangladesh. Nepal. Bhutan and India on flood mitigation in 1989 and 1990 are now in cold storage. It is time to look at them again with a fresh mind.

Flood is a national problem and a dialogue with Nepal. India and Bangladesh is urgently needed for a holistic development and management of the international river basins to overcome the adverse effects of floods and disasters for the benefit of millions of people in Nepal. India and Bangladesh.

The writer is former Chairman. Bangladesh Water Development Board.