Bangladesh:
Arsenic Poisoning
and Water
Supply
Dr
Md. Abdul
Ghani
|
Introduction
The river
system that flows
through Bangladesh
is the third largest
source of fresh-water
discharge to the
world's oceans.
The annual volume
of flows passing
below the confluence
of the Ganges
and the Brahmaputra
is about 795,000
cubic meters,
which is equivalent
to about 5.5 meters
of depth over
the country. In
addition to that
the country receives
on an average
about 2 meter
rainfall annually.
Therefore, hypothetically
the country will
be under about
7.5 meter water
if there was no
flow to the Bay
of Bengal. Still
Bangladesh faces
shortages of water
every year for
crop production
and even for home
consumption during
summer months
especially during
February to May.
This contrasting
situation is mainly
due to regulation
of flows of the
major rivers outside
Bangladesh and
uneven or skewed
distribution of
rainfall over
the year (Table
1 --- recent and
long term data
show similar pattern).
Table
1: Average Monthly
Rainfall Data
of Bangladesh
for 1986 to 1998
Period (in mm)
Year |
Jan |
Feb |
Mar |
Apri |
May |
June |
July |
Aug |
Sept |
Oct |
Nov |
Dec |
Average |
1986 |
3 |
1 |
14 |
116 |
146 |
363 |
438 |
315 |
497 |
189 |
131 |
5 |
185 |
1987 |
1 |
5 |
4 |
148 |
113 |
237 |
779 |
450 |
320 |
93 |
31 |
16 |
183 |
1988 |
2 |
41 |
58 |
122 |
336 |
551 |
474 |
429 |
236 |
164 |
98 |
2 |
209 |
1989 |
2 |
13 |
7 |
76 |
203 |
344 |
526 |
134 |
289 |
237 |
0 |
3 |
153 |
1990 |
0 |
50 |
121 |
133 |
245 |
334 |
586 |
206 |
253 |
238 |
60 |
30 |
188 |
1991 |
7 |
19 |
33 |
58 |
274 |
461 |
378 |
341 |
460 |
268 |
3 |
52 |
196 |
1992 |
8 |
54 |
4 |
21 |
187 |
264 |
398 |
254 |
274 |
150 |
9 |
3 |
136 |
1993 |
22 |
57 |
109 |
124 |
367 |
599 |
464 |
434 |
341 |
148 |
18 |
0 |
224 |
1994 |
11 |
27 |
106 |
157 |
183 |
407 |
280 |
309 |
164 |
90 |
8 |
0 |
145 |
1995 |
6 |
28 |
23 |
47 |
216 |
416 |
366 |
392 |
238 |
268 |
45 |
0 |
170 |
1996 |
10 |
23 |
68 |
118 |
211 |
337 |
583 |
357 |
446 |
27 |
12 |
18 |
184 |
1997 |
27 |
19 |
121 |
113 |
223 |
299 |
559 |
3018 |
277 |
29 |
7 |
22 |
393 |
1998 |
28 |
39 |
101 |
150 |
251 |
219 |
697 |
657 |
117 |
161 |
86 |
0 |
209 |
Normal |
8 |
15 |
42 |
111 |
265 |
506 |
537 |
429 |
304 |
186 |
35 |
9 |
204 |
| Source:
Bangladesh
Meteorological
Department,
2000. |
The
country depends
on intensive withdrawal
of groundwater
for irrigation
and household
purposes during
the summer months.
Quality deterioration
of groundwater
during the recent
years due to arsenic
contamination
has reduced safe
water availability
for drinking and
irrigation purposes
all over the country.
However, fortunately
the quantity of
groundwater pumped
and used during
the dry months
-- November to
May -- is fully
recharged during
the rainy season
-- June to October
-- except in Dhaka,
where withdrawal
rate is higher
than possible
recharge rate.
Bangladesh receives
plenty of rainwater
during the monsoon,
which mostly coincides
with the period
of the year when
it receives huge
volume of water
from the catchments
outside the country.
Therefore,
an unfavourable
water environment,
due to drought
during February
to May and frequent
floods during
June to October,
is created. During
the dry months
ground water level
goes down at many
places beyond
suction limit
(>25 feet or
about 10 m), arsenic
content in ground
water becomes
high and crosses
safe limit (>
0.05 ppm) for
irrigation and
domestic consumption
and coastal water
(both surface
and ground) becomes
saline in many
places. Bangladesh,
therefore, needs
better management
of water resources
for crop production
and human consumption.
Groundwater is
contaminated by
natural arsenic
in 60 out of 64
districts in Bangladesh.
Out of 640 upazillas
(sub-districts),
268 are affected
by arsenic contamination
(personal communication
with a senior
manager of the
Department of
Public Health
Engineering, DPHE).
However, the extent
of contamination
varied from area
to area and entire
area of a district
or sub-district
is not affected.
High concentration
of arsenic is
found in water
from thousands
of wells across
the country and
an estimated 30
million out of
130 million people
are at risk (DPHE
2000).
However, the extent
of contamination
level varies from
area to area.
The extent of
problem and its
impact on health
and production
are still unknown,
but millions of
people are threatened.
Information on
arsenic contamination
in groundwater
does not cover
all areas of potential
contamination
and is not always
reliable or conclusive.
However, in recent
years arsenic
contamination
has become an
additional problem
and is becoming
a major concern
both from human
consumption and
irrigation points
of views. It is
a complex problem
in Bangladesh
which needs to
be dealt with
scientifically.
Careful investigation
is also required
to find out impact
of using arsenic
contaminated water
on crop production,
its effects in
the food chain
as well as arsenic
build-up in the
soil.
The coastal area
of Bangladesh
consists of about
2.8 million hectare
(Mha),
which is over
20% of the country.
Due to suspected
salinity problem,
people in this
area are forced
to use costly
tube-wells of
over 300 meter
depth for avoiding
pumping saline
water.
In view of the
above situation,
Bangladesh should
develop strategies
for addressing
salinity and arsenic
contamination
to ensure supply
of clean water
for agriculture
and household
use. Since 25
per cent of the
country is suspected
salinity prone
and about another
25 per cent affected
by arsenic contamination,
Bangladesh cannot
afford to leave
almost 50 per
cent of the country
unattended. The
impact of this
situation on human
health, production,
social and natural
environments needs
to be assessed
so that professionals
can assist in
developing research
programmes for
mitigating the
problems.
Bangladesh has
excess water from
June to October,
which causes floods
carrying debris,
dirt and sediments.
Therefore, physical
cleanliness is
a visible problem
in addition to
the chemical contamination
of water, which
makes it unsuitable
for drinking unless
purified. Salinity
and arsenic contamination
are problems for
coastal and affected
areas respectively
for agricultural
and human consumption
purposes in the
dry seasons.
Improvement
Strategy
Water
availability over
the year indicates
that the country
should not face
problem in supplying
adequate water
for human consumption
and agricultural
production. In
addition to deep
and shallow tube-wells
mainly used for
irrigating about
4 million hectares
in recent years,
about 8 million
hand tube-wells
and about 1500
production wells
(deep tube-wells
of different capacities
used for urban
water supply)
are in operation
for drinking water
supply all over
the country (Personal
communication
with concerned
DPHE
high management
2005).
Water
Availability
Water
for drinking is
not scarce in
Bangladesh. The
document on national
water management
plan confirms
that the requirements
for domestic and
industrial supplies
are only to the
extent of 0.7
per cent and is
assured while
planning agricultural
water demand for
the country (MPO
1991).
However, its quality
is the limiting
factor at places
and during a certain
period of the
year. With possible
low cost treatment/purification,
this can be solved
specially during
the rainy season
(May to
Table
2: Agro ecological
Regime and Surface
and Ground Water
Availability Situation
in Bangladesh
Sl.No. |
Region |
Water
Availability |
|
1. |
Old
Himalayan
Piedmont Plain |
Limited
surface water
Ample groundwater
|
|
2. |
Active
Tista Floodplain |
No
dependable
surface water
Ample groundwater
|
|
3. |
Tista
Meander Floodplain |
Limited
surface water
Ample groundwater
|
|
4. |
Koratoya-Bangali
Floodplain
|
Limited
surface water
Ample groundwater
except in
some locations.
|
|
5. |
Lower
Atrai Basin
|
Limited
surface water
Ample groundwater
|
|
6. |
Lower
Purnabhaba
Floodplain
|
Limited
surface water
Uncertain
groundwater
|
|
7. |
Active
Brahmaputra
and Jamuna
Floodplain |
Limited
surface water
Uncertain
groundwater
|
|
8. |
Young
Brahmaputra
and Jamuna
Floodplain |
Ample
surface and
groundwater |
|
9. |
Old
Brahmaputra
Floodplain |
Available
surface water
(exploited)
Ample groundwater
|
|
10. |
Active Ganges
Floodplain |
Limited
surface water
Ample groundwater
|
|
11. |
High
Ganges River
Floodplain |
Limited
surface water
Ample groundwater
|
|
12. |
Low
Ganges River
Floodplain |
Limited
surface and
groundwater
Groundwater
is not available
in some places
|
|
13. |
Ganges
Tidal Floodplain |
Limited
surface water,
satisfactory
groundwater
but with
some dead
zone |
|
14. |
Gopalganj-Khulna
Beels |
Adequate
surface water
but saline
within 500
meter.
Adequate groundwater
but saline
near surface
and
good below
300 meter. |
|
15. |
Atrai
Beel |
Ample
surface and
groundwater
with some
limitation
of
groundwater
in certain
areas. |
|
16. |
Middle
Meghani River
Floodplain |
Ample
surface and
groundwater |
|
17. |
Lower
Meghna Floodplain |
Ample
surface and
groundwater |
|
18. |
Young
Meghana Estuarine
Floodplain |
Ample
surface water
but little
salinity in
dry season.
Groundwater
is good below
300 meter.
|
|
19. |
Old
Meghna Estuarine
floodplain |
Ample
surface and
groundwater
but saline
in some |
|
20. |
Eastern
Surma-Kushiyara
Floodplain |
Surface
and groundwater
are available
but not enough
for the entire
area. |
|
21. |
Sylhet
Basin |
Ample
surface water
Limited groundwater
|
|
22. |
Northern
and Eastern
Piedmont plains |
Surface
and groundwater
are limited |
|
23. |
Chittagong
Coastal Plain |
Limited
surface and
groundwater |
|
24. |
St.
Martins Coral
Islam |
Surface
water is saline
No mention
about groundwater
|
|
25. |
Level
Barind Tract |
Limited
surface water
Good groundwater
|
|
26. |
High
Barind Tract |
Limited
surface water.
Groundwater
is poor but
need detail
investigation
|
|
27. |
North
Eastern Barind
Tract |
Limited
surface water
but groundwater
is good |
|
28. |
Madhupur
Tract |
Limited
surface water
but
Ample groundwater
|
|
29. |
Northern
and Eastern
Hills |
Limited
surface water,
Groundwater
is also limited,
but need detail
surveying.
|
|
30. |
Akhaura
Terrace |
Limited
surface water
Groundwater
is good but
need detail
survey whether
it
is enough
for the entire
area. |
| |
| Source:
Land Resources
Appraisal
of Bangladesh
for Agricultural
Development. |
| |
Report
2, Agro -Ecological
Regions of
Bangladesh,
UNDP &
FAO, Rome,
1988. |
October).
Water pollution
caused by dumping
industrial and
other wastes in
the low-lying
areas, rivers
and other water
bodies will improve
the situation.
Improved management
at local and national
level through
government and
social interventions
can ensure clean
water for all.
Bangladesh has
assessed availability
of groundwater
over the Agro-Ecological
Regions of the
country (UNDP
& FAO 1988).
The country can
a develop plan
for its sustainable
use and quality
improvement using
this information
(Table 2).
The Department
of Public Health
Engineering (DPHE)
confirmed that
there are 11 Zonal
Laboratories in
Bangladesh for
monitoring drinking
water quality.
DPHE
is also setting
up a donor-funded
central laboratory.
Arsenic
Contamination
Groundwater
is contaminated
by naturally occurring
arsenic in 60
out of 64 districts
in Bangladesh.
Technical options
for using groundwater
in the arsenic
contaminated area
will need to be
developed. This
will require analysis
of existing water
supply infrastructure
and options for
alternative supply
and treatment
of water.
Low cost mitigation
of arsenic contaminated
water is available,
which indicates
that through community
participation,
cost effective
methods of supplying
arsenic free water
can be made available
at less than Taka
0.1 (0.2 cent)
per litre (PROSHIKA
2001). Tube-wells
used for irrigation
can also be used
for household
water supply.
(BMDA
