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| It is either too much
water or too little. Every year, with the heavy monsoon downpours, the rivers of northern
India get swollen with huge quantities of water. They spill their banks and flood the
surrounding areas. And in the hot summer they dry up. Almost to a trickle. Is a flood
always a bad thing? Can modern engineering ever hope to contain the power of these rivers?
This time we examine floods. There is more to it than paper boats. It’s life or death
for hundreds. |
T he Ganga begins as a
glacial stream from Gangotri high in the Himalayas and tumbles down the mountains, flowing
majestically through the Indo-Gangetic plains. Along the way, many tributaries — big
and small — meet the Ganga. They contribute to the vast volumes of water that the
river finally empties into the Bay of Bengal. As the legend goes, Ganga is the daughter of
Lord Shiva, and has seven tributaries — seven sister rivers. This is a story of one
of the naughtiest, the river Kosi. It flows in a curve, draining the mountains of Nepal
into the plains of North Bihar, and joins the Ganga after travelling more than 400 km.
The Kosi is very mischievous. Every year during monsoons she causes havoc in the plains
of North Bihar. She swells up to several times her normal size and breaches her banks,
flooding peoples’ fields and homes. She gushes down the fragile mountain slopes like
an uncontrolled coil of water, carrying all the monsoon water that rains on these lands,
eroding the soil and causing landslides. Rocks, boulders and lands are pounded and smashed
to smithereens and, along with the top soil, are washed away. Despite her bad behaviour,
the people living along her banks in the hot, moist plains of Bihar welcome these muddy,
silt-laden floodwaters every year. They create fertile alluvial plains on which bumper
crops grow. They have learnt to live with this unpredictable river. A river that has
jumped and shifted its course on more occasions than can be remembered.
Who can control this wild river? Legend has it that a daredevil once tried. Kosi was
said to be a very beautiful and attractive young woman. A huge and mighty demon called
Rannu Sardar got attracted by her beauty and fell in love with her. Bewitched, he asked
Kosi to marry him. Kosi was amused and surprised. She obviously had no
intentions of marrying him. So she very cleverly put forth a condition that if he could
contain her (the river) between the Himalayas and her confluence with the Ganga in one
nights’ time, she would accept. But, if he failed then the demon would be killed.
The demon agreed and set about his task. With an enormous spade that weighed more than
a ton, he began cutting the banks of the river to contain her flow. Without a break he
went on working through the night. As the work progressed Kosi got nervous seeing the pace
of the demons’ work. It was midnight and he had already finished half the work. So,
she went running to her father in the Himalayas and explained her plight. He told her not
to worry. Agreeing to help her and save the situation, he went, disguised as a rooster, to
the place where the demon was working and started crowing. The demon got nervous on
hearing the rooster and thought that morning was approaching. Fearing for his life, he
threw his spade and ran away. And the Kosi has since continued her unruly flow unchecked.
Even today, the boat people on the Kosi believe that Rannu Sardar is trying to achieve
his task in the hope of marrying Kosi one day. That’s how they explain the
continuous erosion of the sand banks of the fast flowing river.
This is merely a myth. But even today, there are Rannu Sardars — in the form of
modern engineers, who are
trying to contain the Kosi and her erratic ways. Their intentions may be good — to
harness her waters and save people from floods — but in trying to tame the river,
they have caused more problems than they can solve. Should we try to conquer nature or
learn to live in harmony?
 Floods are a part of
the river’s life cycle. Imprison a river, try to ‘control’ its natural
tendency to flood, and the move will surely backfire
| THE GBM NGA-BRAHMAPUTRA-MEGHNA)
BASIN |
| The Indian
monsoon strengthens two giant glacier-fed rivers that originate in the Himalayas –
the Ganga and the Brahmaputra. The Meghna-Barak joins them at Dhaka, forming the GBM
(Ganga-Brahmaputra-Meghna) Basin. The GBM system carries the most water after the Amazon
and the Congo basins. More than half a billion people, nearly a tenth of all humans,
reside in this basin, amongst the most fertile in the world. 
Ganga-Brahmaputra discharge
hydrographs
These graphs show how the quantity of
water in the Ganga and the Brahmaputra shoots up (over ten times) between July and
September.
Fortunately, the peak periods are a few weeks
apart. Can you imagine what happens when these peak periods coincide? |
NATURAL
FLOODS:
The mighty Himalayas gets kayoed every year.
KOed. Knocked Out, by the monsoon system. For 4 months in a year, the mountains get a
concentrated battering by two gargantuan blue-grey fists, the Bay of Bengal monsoon
current and the Arabian Sea current. As an opponent, the Himalayas are all phusss,
very big, but not very strong. After all, they once used to be the bottom of the sea, just
sand and slimy sediments!
When the monsoon slams into the Himalayas, it deposits 80 percent of the year’s
rain in a short span of 60 days, from July to September. The Himalayas are soft and
geologically very fragile. Cut and gouged mercilessly by the streams and rivers that flow
off its slopes, these rivers dump their soil when they suddenly come in contact with
flatter land.
Rivers in the GBM Basin experience floods mainly due to:
Loose, crumbly soil in the mountain ranges
where the rivers originate and excessive silt loads in the rivers,
A rainfall pattern peculiar to monsoon lands
i.e. 80 percent of the annual rainfall concentrated in three months of the year, and
Steep slopes that suddenly flatten out. This
causes the river and its tributaries to drop their loads of silt. This raises the level of
the river bed so that its contents spill over onto its banks, causing floods.
FLOODS IN THE HILLS:
Heavy monsoonal rains, sparse vegetation and loose Himalayan soil is a
perfect formula for landslides. Landslides dam the rivers creating massive lakes which
sooner or later burst and send a devastating flood pulse down the river valley.
 In 1893, a landslide dammed the Birahiganga where it meets the Alaknanda creating a
massive lake. The dam burst 10 months later raising the Alaknanda’s level by 50
metres, washing away Srinagar town (In Garhwal, not the one in Kashmir).
Sometimes, nearly 50% of a
Himalayan stream’s load is soil
In its middle course, once a river hits the plains, the slope
is less and the river tends to wander in great S-shaped loops or meanders,
depositing silt. When the floods recede, this land where silt is deposited is known as khadar
or diara land.
| The grass
isn’t greener on the diara side  The
Himalayan rivers come to the plains swollen with silt. They drop their loads as the floods
recede and leave behind huge tracts of land exposed, usually adjacent or as islands in the
river. These are the diara (in Bihar and eastern UP) or khadar (in western
UP) lands. Life is not safe on the diara. Even as it builds diara land on
one bank, it swings around to engulf vast tracts of land on the other.
Diara land is fertile as the sandy veneer recedes away from the river. Precious
cereals and pulses are grown here, as well as melons, pumpkin and bottle gourd. Yet people
have to be prepared to shift with the mood of the river.
Life here is a continuous search for a place to settle. This scarcity of land is a far
more
dangerous opponent than the river itself. People fight and even murder each other to
gain control of these shifting lands. |
We all live downstream
But what if someone upstream used up all the water?
No South Asian security issue affects more poor South Asians today than the issue of
harnessing the great rivers of the Himalayas – the GBM basin. The areas drained by
these rivers’ basins in Nepal, India and Bangladesh, comprises only 0.1 percent of
the earth’s surface. But more than 500 million people live here, including about
one-third of all the poor people in the world. Sharing these waters can become a very
tricky issue indeed.
Nepal hopes to use its hydropower potential by building many dams and earn lots of
‘Hydrodollars’. Bihari politicians point fingers at Nepal and tell them to keep
their waters and not flood Bihar. India hopes to take waters from the Ganga and divert it
to irrigate its fields in more arid parts...leaving some very angry Bangladeshis who feel
cheated. A floody mess!
Can the governments of these countries ever hope to share their water resources
amicably? |
A Down To
Earth Supplement
