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ダッカ市の都市域および周辺域における水マネジメントに関するいくつかの考察および水環境分野の環境教育の可能性
誌名誌名 環境科学会誌 = Environmental science
ISSNISSN 09150048
巻/号巻/号 222
掲載ページ掲載ページ p. 91-102
発行年月発行年月 2009年3月
農林水産省 農林水産技術会議事務局筑波産学連携支援センターTsukuba Business-Academia Cooperation Support Center, Agriculture, Forestry and Fisheries Research CouncilSecretariat
環境科学会誌22(2) : 91-102 (2009)
Technical Note Some Consideration on Water Management in
Urban and Peri幽 UrbanAreas of Dhaka City， Bangladesh， and Possibility of Environmental Education on
Water Environment
Yoshiaki TSUZUKI本， Faruque AHMEDネ*and MD Mafizur RAHM却***
Abstract
Based on the field survey results in urban and peri-urban water areas of Dhaka
City， Bangladesh， conducted in 2006， and the literature review of the existing literatures，
desirable direction of water environment management especially on water quality
is roughly discussed in this paper. Flood and drought management and arsenic
contamination in drinking water are the most common issues among water related
problems in Bangladesh. Conservation and improvement of surface water quality is also
important in urban and peri-urban area of Dhaka， considering the drinking water sources.
Groundwater is currently most important water supply source occupied around 85 % of
total water supply in Dhaka City， while surface water consists of around 15 %. Groundwater
withdrawal is increasing annually and groundwater level depletion around 1.0…3.0 m
per year has been observed in Dhaka City. The Shitalakhya River is one of the surface
water sources and the water quality measurement results suggested the water quality is
influenced by that of the Balu River. Even in the upper section of the intercourse of the
two rivers， water quality can be influenced because of the existing river flow fluctuation
derived from tidallevel fluctuation. Water resource management is conducted by some
specified institutions for the national benefits using mathematical model. However， most
information is stiU not publicly available. Possibility of public participation is discussed in
the fie1d of water environment including environment information dissemination.
Key Words: ambient water; Dhaka City; domestic wastewater treatment; environmental
education; water quality
91
1. Introduction
百leMi11ennium Development Goals α1DGs) in the field of water and sanitation target the reduction
of population without appropriate water and
sanitation facilities， which was estimated as 1.1 and
2.4 billions at the beginning of 21 century to half
by 20151) . The aims of the sanitation in the MDGs
focus on health and hygiene. One more purpose of
sanitation is to improve water quality by reducing
pollutant discharges. The reduction of pollutant
discharges from major pollutant sources using
“hardware measurements" following “software
measurements" with community involvements have
2007年 8月27日受付， 2008年 12月17日受理
* Toyo University， Izumino 1-1-1， Itakura叩 achi，Ohra司gun，Gunma Pref. 374-0193， ]apan; and Research Center for Coastal Lagoon Environments， Shimane University， Nishikawatsu 1060， Matsue-shi， Shimane Pref. 690-8055，]apan
* * Integrative Environmental Sciences， Graduate School of Life and Environmental Sciences， Tsukuba University， Tennoudai 1-1-1， Tsukuba-shi， Ibaraki Pref. 305…8572，]apan
* * * Department of Civil Engineering， Bangladesh University of Engineering and Technology， Dhaka 1000， Bangladesh
92 TSUZUKI， AHMED and RAHMAN
been conducted by organizations inc1uding national
and local governments in ]apanJ).
For the “software measurements " ，
environmental accounting housekeeping (EAH)
books as efficient tools for ordinary citizens to
understand complicated aspects of water quality
parameters and their contributions to the pol1utant
loads in the receiving water were proposedJ). Spatial
regression analysis between pollutant discharge
per capita (PDC) and the economic development
indicator in developing countries showed the
original Kuznets relationships between income and
equi匂，2). Therefore， PDC increase is supposed with
economic development in developing countries
inc1uding Bangladesh， one of the least developed
countt・les.
The area of Bangladesh is 147，570 km2，
almost one third of ] apan， and population is
about 140 mi11ion in 2003 (Figure 1). Bangladesh
is one of the most densely populated countries
in the world. Environmental pollution
including surface water pollution in Dhaka
City (population: 11 million; area: 1，500 km2，
population density: 7，300 person km叩今 isnow a
major environmental problem in Bangladesh3. 4) •
Water supply sources in Dhaka City rely heavily
on groundwater. Among 1.6 mi11ion m3 per day of
urban water supply amount， 1.5 million m3 or 85 %
of total requirement are withdrawn from tubewel1s
owned by the Dhaka Water Supply and Sewerage
Authority (DWASA) and privately owned tubewel1s
in 20035.6). Groundwater withdrawal is increasing
annually. Averaged groundwater level depletion
in 32 years is more than 1.0 m per year in Dhaka
City， and more than 3.0 m per year was observed
recently in densely populated area. Therefore， to
maintain and improve suitable water quali勿 inthe
river for drinking water sources is necessary.
Coverage area of the only one sewerage
treatment plant in Dhaka City， the Pagla Sewage
Waste Treatment Plant (PSWTP)， was 15 % in 19965)
and 30 % in 20067) • The data sets of environmental
quality inc1uding surface water and lake sediment
quality3. 4) should be useful for better understanding
of the environmental degradation. However，
public1y available data sets on water environment
are very limited in Bangladesh8) •
Regarding water胴relatedfields in Bangladesh，
development of flood forecasting systems were
conducted9. 10)， and pol1utant load analysis in the
Buriganga River System was conducted11l. Kamal
et al.ll) summarized water quality data in the
Buriganga River Systemσable 1) and BOD loading
into the river (Table 2). Biological oxygen demand
(BOD5) in the Buriganga River in the dry season
was reported as 20…30 mg 1 -1， total coliform was
104 - 105 MPN 100ml-l， dissolved oxygen (DO) in
the Buriganga River was estimated to decrease with
the rate of 0.3 mg 1叩 1year -1， and BOD discharge
per capita (PDC-BOD) was estimated as 25 g per
person per dayl2) . Benzene， toluene， ethylbenzene，
xylene and cumene (BTEXC) concentrations in the
Buriganga River were 0.10-0.37μg ml-1 analyzed
with gas-chromatographyI3) .
Overall purposes of the research are to find
the effectiveness and efficiency of such domestic
wastewater pollutant discharge indices as pol1utant
loads per capita flowing into the water body
(PLCwb)J) and PDC， and to prepare and examine the
effectiveness of tools as EAH books of domestic
wastewater for public participation in developing
countries inc1uding Bangladesh. Field surveys
were conducted in urban and peri-urban areas of
Dhaka City， Bangladesh， in October and November，
2006. In the previous publications8. 14. 15) ， pollutat
discharge reduction measurements in Bangkok，
τbailand were focused. In this paper， water quali匂r
profiles in the ambient water based on the field
survey and the existing data are summarized，
which inc1ude unpublished detailed data. Possibility
of“hardware measurements" with wastewater
treatment and “software measurements" with
environmental education for water quality
improvement in Dhaka City area are discussed.
2. Methods
2.1 Descri戸tion01 the research field The Shitalakhya (sometimes called as
Sitalakhya or Lakhya) River， a lower branch of
the Old Brahmaputra River， flows west of Dhaka
City and flows into the Dhaleswari River， then
flows into the Meghana River (Figure 1). Water
supply sources in Dhaka City consist of 83 % of
groundwater and 17 % of surface water in 20067) •
The river is one of the surface water supply sources
in Dhaka City.
Water management and environmental education in Dhaka， Bangladesh 93
ー耐.~
cコ仙胸恥時制
Figure 1 Rivers and lakes in urban and peri-urban areas of Dhaka City， Bangladesh， in which sampling points in
the Shitalakhaya River (from Sl to S5) and Dhanmondi (D1 and D2)， Banani (B1 and B2) and Gulshan
Lakes (Gl and G2) are illustrated. Bangladesh 0巴ft)and Dhaka City area (right) are shadowed.
Samp1ing points in the Shita1akhya River was
in Narayanganj District， with popu1ation density
of about 2，800 person km -2 in 2003， whereas that
of Dhaka District was about 5，900 person km -2 16) •
There are industria1 zones and dense1y popu1ated
areas a10ng the river. There are primitive housing
communities on the right bank and industries on
the 1eft bank of the river around the sampling points
(S2-4).τ'here are power p1ants on both sides of the
river around S5.
2.2 Field Survey methods
The existing data and information collection
was conducted in regard to domestic wastewater
and water・ qua1ityand quantity in the ambient
water in urban and peri-urban area in Dhaka
City， Bang1adesh. Fie1d surveys were conducted
on October 23 and 26， and November 20， 20068 14)
Water qua1itymeasurements in the
Shita1akhya River and three 1akes in Dhaka
City， Dhanmondi， Banani and Gu1shan Lakes
were conducted in October (Figure 1). Water
quality was measured with a water qua1ity data
10gger， Compact-CTD⑧ (A1ec E1ectronics，
J apan) ， and a water quality measurement kit，
Pack Test ⑧ (Kyoritsu Chemica1 LaboI・atory，
J apan). Parameters measured with the data
10gger were water depth， water temperature，
sa1inity， EC25 (e1ectricity ca1ibrated at water
temperature of 25'C )， densi勿， ch10rophyll同a(Ch1-a)
and turbidity， and with the water qua1ity
measurement kit were CODMn and P04-p. Water
qua1ity measurements with data 10gger were
conducted twice at S5.
In the fie1d survey in November， flow rate， pH，
c010r， turbidity， BOD5， CODcro DO， T-N， T-P， tota1
coliform and feca1 coliform were measured in the
fie1d (S4) as well as in the 1aboratory.
3. Resu1ts
3.1 Field survey results
In the Shita1akhya River， CODMn at Sl and
S2 ranged from 10 to 20-50 mg 1 ¥ increased to
50-100 mg 1ぺ atS3 and S4， and decreased to 13
20 mg 1 1 at S5 (Figure 2 JJ)). The ranges of the
measurements resu1ts of the water qua1ity kit
indicated the reaction c010rs were between the
indicator・c010rs(Figure 2). CODMn in the inner-city
1akes in Dhaka City was from 5-10 to 50-100 mg 1-1•
P04-P at Sl and S2 were 0.066-0.165 mg 1 -1
and 0.066 mg 1 1， remained as 0.066…0.165 mg 1 -1
at S3， increased to 0.165-0.33 mg 1ぺ atS4， and
decreased to 0.165 mg 1-1 at S5. P04-P in the inner-
94 TsuzU!G， AHMED and RAHMAl'l
Table 1 Summary of water quali匂Tdata for the Buriganga River System in early 1990' s (mg 1 -1).11)
Water quality Turuga River Buriganga River Dhaleswari River parameter Minimum Maximum Data rangea Minimum Maximum Data range" Minimum Maximum Data range"
DO 0.1 8.2 0.1-5.0 0.1 17.2 0.1-4.0 2.8 22.7 4.0-8.0
BOD5 l 150 NA 2.5 430 NA 200 NA
CODcc 4 382 NA 8 540 NA 4 530 NA
NH3-N 。 14.53 NA 。 15.2 NA O 0.11 NA
NH4-N O 109 NA O 114 NA O 0.76 NA
E. coli. b 75 7，500 NA 10 55，000 NA 4 4，000 NA
Total coli. b 25 20，000 NA 125 80，0∞ NA 50 6，500 NA
TSS 9 80 NA 10 42 NA 10 35 NA
N03-N O 6.7 NA O 8.9 NA O 4.58 NA
PO，，-p 0.06 5.36 NA 0.45 15.22 NA 0.78 11.54 NA
Cr O 0.016 NA O 0.014 NA O 0.01 NA
a: Data range of mostly dat丑;b: Units of E. coli and Total coli are numbers 100 ml -1; NA means not available Original data source: Department of Environment のOE)，Bangladesh.
Table 2 BOD loading estimation from domestic and industrial wastewater into the Buriganga River system in
early 1990' s (kg d -1). 11)
8-4a 8-5a 8-6 8-7 Eト8 8-9 8-10
BODloading 1，470 3，480 1，080 21，080 1，860 220 1，380
Measurement points Dholai K.b PSWTpc Ci句Tdrain Kashipur K.b
BODloading 29，980 6，000 7，950 365
a: 8-4 and 8-5 are different from S4 and S5 in Fig. 1; b: Khal (canal); c: Pagla Sewage Waste Treatment Plant (PSWTP).
city lakes in Dhaka City was from non detective
( < 0.066 mg 1 -1) to 0.66-1.65 mg 1-1.
For almost al1 the parameters measured with
the data logger in the Shitalakhya River (Table
3)， the water quality in the vertical direction were
almost constant8. 14)， besides small amount of
gradual increase with depth were observed for
density and turbidity. Figure 3 shows horizontal
water quality profiles in the Shitalakhya River.
Depth of the river was from 6.5 to 13.0 m. Water
quality of measured parameters were almost
constant along the river.
Chl-a was 3.1…10.7μg 1-1 in Dhanmondi Lake，
27.5-44.6μg 1-1 in Banani Lake and 23.9-55.9，u g 1-1
in Gulshan Lake with the da匂 loggermeasurement
(Table 4). Turbidity was 3.5-6.6 FTU in Dhanmondi
Lake， 14.3-16.5 FTU in Banani Lake and 13.4-35.5
FTU in Gulshan Lake.
Some turbidity values for the bottom layer are
not given in Tables 3 and 4， because extraordinary
large values suggested the instrument discharged
the bottom sediment of the sampling points3) •
In regards to the laboratory analysis results on
Nov. 20 (Table 5)， larger concentrations of organic
carbon， nutrient and bacterial parameters were
observed.
3.2 Existing publicized wαter quality and quαntiか
informαtion
In the overall environment topics in
Bangladesh， water-related topics focus on seasonal
flooding and arsenic pollution in the drinking
water17). Researches on water quality are also
conducted. The surface water quality in Dhaka
City is deteriorating every year18). DO in the
Shitalakhya River decreased to less than 2 mg 1-1 in
1997 comparing to more than 5 mg 1-1 before 1995.
In the Shitalakhya River， influence of the Balu River
was observed. The water quali匂Tof the Balu River is
one of the most deteriorated in the peripheral rivers
of Dhaka City. Water quality deterioration in the
lower section of the Shitalakhya River in 2010 was
predicted especial1y in the dry season.
BOD discharge into the peripheral river
systems around Dhaka City (Figur・e1) was
95
二三ム」口問A A
Sampling poi.nt
Water management and environmental education in Dhaka， Bangladesh
(同PO，・F伊'ackT1品。1.8
1.6
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2 0五0.4
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Figure 2 Water quality measurement results with the water quality measurement kit in the Shitalakhya River
and the three lakes in urban and peri-urban areas of Dhaka， Bangladesh. The reaction color of the
water samples of the water quality measurement kits sometimes indicated between the standard
color indications. The vertical bars indicate that the reaction color were between the standard color
indications. (Modified from Tsuzuki et al.， 2008a，b)
一宇一Depth(m)
一+一、.vatertemp. (OC)
一ー-Salinity (UNESCO unit) 一合司EC25(mS m~l)
向。-Chlorophyll-a (ppb)
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提 D釘1SityCkg m-3)
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5
0
5
0
5
0
5
0
3
3
2
2
1
i
(bzzωで。=昔話ω)bzsrsc孟
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Shitalakhya River measured with the water
quality data logger.
estimated as 162 t-BOD day 1， 15 t-NH3-N day山 l
and 4.7ιP01-P day -1 in 1990 and 245ιBOD day-l，
24 t-NH3-N day -1 and 7.3 t-PO.rP day -1 in 20005. 19).
Mathematical modeling has been app1ied
in ur・banwater management by organizations
inc1uding the Institute ofWater Modeling (IWM)鉛)
IWM is conducting water modeling researches
in the fields of flood management， coastal
engineering， hydrology， water and sediment quality，
integrated water resource management， urban
water management， ground water management and
nver engmeenng.
was possible that water quality at 83 and 84 was
influenced by that of the Balu River.
CODMn and P01-P in Banina Lake and Gulshan
Lake were relatively larger concentrations than
those in Dhanmondi Lake (Figure 2)8.14). The
landuse difference around the three lakes was
considered as the reason for the water quality
profile differences8.14) . Another reason for the water
quality differences in the three lakes is considered
that the sampling points in the former two lakes
were near the bridges， where water qua1ity is
assumed to be deteriorated comparing to the center
of the lakes. The reason of the difference of th巴
sampling points was because of the boat availabili勿
in those lakes at that time，出eEid holiday season，
the Muslim holiday after the Ramadan8) .
4. Discussions
4.1 Water quality in the river and the lakes
τne water quality measurement kit was rather
effective to compare the water qua1ity parameters
in the peripheral river and the inner-city lakes
of Dhaka (Figure 2) 11)， one reason for which is
water qua1ity deterioration in some ambient water
bodies. The results showed large concentrations
of organic carbon and phosphorus near 83 and
84. The reasons for the water quality profiles had
been supposed to be wastewater discharge from
community and factories along the river around 82-
4， and organic carbon and phosphorus purification
in the river or dilution between 84 and 85 in the
previous pub1ications8. 11). Water quality of the
Balu River is one of the most deteriorated among
surface water around Dhaka CityI8). Therefore， it
96 TSUZUKI， AHMED and RAHMAN
Table 3 Water qua1i句Tdata of the Shitalakhya River measured with the data logger on Oct. 23， 2006.
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Water management and environmental education in Dhaka， Bangladesh 97
Table 4 Water quality data of the three lakes measured with the data logger on Oct. 26， 2006.
No. Sample StartTime Depth W. temp." Salinity EC25b Density Chl-a< Turbidity
ロ1 。C psu mSm-1 kgm-3 μgl-1 FfU
Dld 12:15 0.0 29.5 0.13 27.4 995.90 6.81 4.0
0.5 29.0 0.13 27.5 996.05 10.67 4.5
1.0 28.8 0.13 27.6 996.12 4.74 4.7
1.5 28.6 0.13 27.4 996.17 4.24 4.3
2.0 28.5 0.13 27.3 996.20 3.10 4.1
2.5 28.5 0.13 27.4 996.22 2.94 4.9
3 Dld 12:25 0.0 28.4 0.13 27.3 996.21 3.58 4.4
0.5 28.4 0.13 27.4 996.22 3.40 5.4
1.0 28.4 0.13 27.3 996.22 3.59 6.6
1.5 28.4 0.13 27.3 996.23 3.45 10.9
4 Dld 12:26 0.0 28.5 0.13 27.3 996.21 4.04 6.1
0.5 28.4 0.13 27.4 996.21 3.64 4.8
1.0 28.4 0.13 27.3 996.22 3.48 6.0
1.5 28.4 0.13 27.3 996.23 3.41 7.7
2.0 28.4 0.13 27.3 996.23 3.45 13.2
5 D2d 12:45 0.0 29.1 0.13 27.7 996.02 8.00 3.6
0.5 28.9 0.13 27.8 996.08 8.08 3.5
1.0 28.7 0.14 27.9 996.15 6.53 3.5
1.5 28.5 0.14 28.0 996.19 4.36 3.3
2.0 28.5 0.14 28.5 996.21 4.12 4.0
2.5 28.5 0.14 28.8 996.22 3.83 4.1
3.0 28.5 0.14 28.7 996.23 3.92 4.0
7 BF 13・23 0.0 31.0 0.15 32.0 995.48 27.52 14.9
0.5 30.9 0.15 32.0 995.48 28.03 16.5
9 Glf 13:40 0.0 31.3 0.17 34.4 995.36 50.48 13.4
0.5 31.3 0.17 35.0 995.38 55.89 13.7
10 Glf 14・06 0.0 32.9 0.16 33.5 994.86 43.14 35.5
11 B2e 14:34 0.0 30.1 0.22 46.3 995.80 44.68 14.3
12 B2e 14:35 0.0 29.5 0.23 46.8 995.96 44.24 64.0
a: Water temperature; b: Electric conductivity at 25 "c ; c: Chlorophyll-a; d: Dhanmondi Lake; e: Banani Lake; f: Gulshan Lake.
Table 5 Field survey results with laboratory analyses in the Shitalakhya River， S4， on Nov. 20， 2006
Flowrate pH Color Turbidity BOD5
m3S-1 Pt. Co. Unit NTU mgl-1
230 7.3 20.0 15.0 18
a: Total coliform; and b: Fecal coliform.
Relatively high concentrations of Chl-a and
turbidity in Banani Lake and Gulshan Lake were
observed (Table 4)， which were coincide with the
measurement results of CODMn and P04-P (Figure
2). These results indicated larger water quality
deterioration in仕letwo lakes.
Electrici匂Tmeasured with the data logger was
29.2-30.8 mS m -1 in Dhanmondi Lake， 35.8…51.0
CODc， DO 下N T-P TC" FCb
mgl-1 mgl-1 mgl-1 mgl-1 (100ml)一1(100ml)-1
30.4 0.25 8.35 5.00 1，700 1，000
mS m-1 in Banani Lake and 38.7-39.6 mS m同 1in
Gulshan Lake (Table 4). Electricity measurement
results in Banani 1ぷke，which was called Gulshan
Lake 1 in the reference3l was 51.0-53.2 mS m-1，
and 42.6-51.0 mS m-1 in Gulshan Lake， which was
called Gulshan Lake 2 in the reference (Table 6).
The measured values in this research were smal1er
than the literature values. Their sampling was
98 TSUZUKI， AHMED and RAHMAN
Table 6 Water quali匂Tof Gulshan and Banani Lakes in March， dry season3)
Depth W. temp.a pH Electrici勿 ORP Turbidity TDS 町l 。C
Banani Lake (Gulshan Lake-1)
0.0 28.0 7.5 0.5 27.4 7.4
1.0 27.3 7.4 1.5 27.1 7.4
2.1 27.0 7.2
2.5 26.7 6.9
2.7 26.6 6.6
Gulshan Lake (Gulshan Lake-2)
0.1 27.4 8.4
0.7 26.6 7.8
1.1 26.3 7.6
1.5 26.1 7.4
1.9 24.8 6.8
2.4 22.9 6.5
2.9 22.4 6.5
3.5 22.0 6.5
4.0 21.9 6.5
4.5 21.8 6.5
5.0 21.8 6.5
5.5 21.7 6.5
5.9 21.9 6.5
a: Water temperature.
conducted in March (dry season) and the sampling
points were offshore in the lakes. Sampling in this
study was conducted in October (rainy season)
and the sampling points in the two lakes were
near the bridges as described above. Water quality
deterioration in the dry season was confirmed from
the comparison results.
Direct comparison of organic carbon parameter
measurement with the water quality measurement
kit and laboratory measurement is difficu1t
because of the difference of the parameter， CODMn and CODcr. However， when we compare the COD
values in the field surveys， CODCr concentration
in November could be considered to be almost the
same with CODMn concentration with the water
quality measurement kit in October (Table 5 and
Figure 2).川市atkinds of parameters are appropriate
for monitoring water quality should be considered
based on the available research resources in釦rther
research.
In contrast， larger TP concentration was
observed in Novemberぐrable5) compared to P04-P
51.3
51.1
51.0
51.1
51.6
52.0
53.2
42.6
44.0
44.3
44.6
47.1
49.8
49.8
49.9
50.0
50.1
50.3
50.3
51.0
mV
-30 62 0.33
“96 45 0.33 同99 37 0.33
ー120 35 0.33
162 33 0.33
ー180 31 0.33
ー2∞ 143 0.34
118 48 0.28
151 56 0.29
160 41 0.29
30 45 0.29
ー154 32 0.31 自167 28 0.32
178 25 0.32
-191 28 0.32
-200 26 0.32
-207 28 0.32
-213 28 0.32 同220 29 0.32
-229 70 0.32
wi出 thekit measurement in October (Figure 2). In
the Buriganga River System， larger fluctuation of
water quali匂rwas observed in early 1990' s (Table
1)， which was largely dependent on the seasonal
effects. The water quality fluctuation might be one
of the reasons for the large difference between the
measurement results in this study. Flow rate of the
field survey (Table 5) was within the or・derof the
existing data2U described below.
The vertical profiles with the measurement
results with the data logger showed vertically
homogenized water quality (Table 3). In the existing
report， hourly flow rate fluctuation in the Lakhya
(Shitalakhya) River in the dry season from Dec. 12，
1989 to Jan. 1， 1990 was observed， which showed
hourly upflow (ebbing: maximum 330 m3 s -1)
and downflow (flooding: maximum 450 m3 s 1)
fluctuation with tidallevel fluctuation2U .τ'here is no
salt intrusion in the section of出eriver. These river
flow conditions might be a reason of the vertically
homogenized water quality8， 14，22) . The possible
reasons for slightly high water temperature at
Water management and environmental education in Dhaka， Bangladesh 99
Photo 1 Water quality measurement with the water quality measurement kits in Dhaka City
S5 are supposed to be the effect of warm water
discharge from power plants near S5， and the
difference of timing of the measurement between
S5 and other sampling points (Table 3).
More water quality and quantity data in
regards to accuracy， frequency and the number
of the monitoring points in the ambient water
and domestic wastewater discharge are required
to evaluate domestic wastewater contribution on
the water quality in the river and lakes in further
research.
4.2 跨Tatermωzagementin Dhαka Ciか
The Shitalakhya River is one of the surface
water sources and the water quality measurement
results suggested the water quality is influenced
by that of白eBalu River. Even in the upper section
of the intercourse of the two rivers， water quality
in the Shitalakhya River can be influenced from
that of the Balu River because of the existing river
flow fluctuation derived from tidallevel fluctuation.
Current water quality prediction results by DWASA
are illustrated daily average bases in dry and rainy
seasons and water quality deterioration in the
lower section of the Shitalakhya River is predicted
in 201019) . The results of this study suggested
possibility of water quality deterioration of the
upper section of the intercourse of the Balu River
and the Shitalakhya River. Therぜ'ore，hourly level
water quality fluctuation should be considered
in the urban water management with surface
water sources， and comprehensive water quality
improvement requirement in the Dhaka City
peripheral river systems should be necessary.
Even in the high class residential areas， highly
deteriorated water and garbage disposed at the
road side was observedl4. 15). BOD loading of the
city drain was estimated as 7，950 kg d -1 7)， which
was comparable to BOD loading of the effluent of
PSWTP of 6，000 kg d日 1(Table 2)21). Around 30 %
of domestic wastewater 1云omtoilet， black water， in
Dhaka Ci勾Twas collected with piped wastewater
collection system and treated at the PSWTP 7) •
Gray water and rain water were discharged directly
into the surface water. To estimate PLCwb， further
water quality and quantity data will be required in
regards to domestic wastewater and ambient water.
Some results on pollutant discharge amounts were
available in the litteratures5. 11) ， however， detailed
estimation methods and base data were unavailable.
In general， in the central or highly populated
areas， some central systems which treat both black
and gray water would be desirable to improve the
water quali勿 inthe surface water23) . In peri-urban
and rural areas， some on-site treatment systems
are considered to be appropriate. The alternatives
include eco-sanitation24)， combined johkasou， a
]apanese on-site wastewater treatment system])，
duckweed-lagoon25)， constructed wetlands26) ， and
so on based on the economic and other conditions.
Original Kuznets relationship of income and
equity was observed in the relationship between
PDC and economic development indicators
including purchase power parity based gross
national income (PPP-GNI) per capita2). In
Bangladesh， currently in the least developed
stage， PDC is supposed to increase wi仕1economic
development up to certain extent of development
leveF) . Therefore， some policy and technical and
institutional measurements should be implemented
in the early stage of the development to reduce
pollutant discharge.
4.3 Possibility 01 enviromnental education on water
environment in Dhakα
The water quality monitoring data with the
water quality measurement kit could illustrate
roughly and effectively the tendency of the
water quality in the river and the lakes， which
suggested possibility of the effectiveness of water
quality measurement activity with simple water
100 TSUZUI<I， AHMED and RAHMAN
measurement kits with community involvement
in Bangladesh. During the field survey， ordinary
people seemed to be interested in our field survey
and sometimes come to see our sampling and
measurement with the water quality measurement
kit (Photo 1). It may be difficu1t to judge the
people's interests in water quality measurement
only from the fact， however， it showed possibility to
let the people to be interested in the water quality
measurement activity with some simple methods
inc1uding tbe water quality measurement kit. When
applying the methods， appropriate disposal of used
measurement kits should be considered in the
existing waste management and disposal system.
There are many international and domestic
NGOs working actively in Bangladesh and
community-participation methods have been
studied in the fields including drinking water
pollution with arsenic， rural-development and
fishery27) • Institutional framework and participatory
approach is applied in flooding forecast warning
system28) • Some environmental related information
dissemination systems using internet are operated
inc1uding coastal environment information system
operated by the Chittagong PortAuthority (CPA戸
Dissemination of environmental information in
developing countries wi1l enhance the awareness
of the environment by the ordinary people in the
country， facilitate understanding of the environment
of the developing countries by出eforeign country，
and make overseas development assistance (ODA)
more effective and efficient.
5. Conclusion
Based on the field survey results and existing
data on water quality related researches in
Bangladesh especially in Dhaka City， an urban
water management direction and possibility of
environmental education in the water environment
fields is discussed. When considering water supply
planning with surface water sources in Dhaka City，
comprehensive water quali匂Timprovement in the
Dhaka Ci勿 peripheralriver systems is necessary
because of hourly fluctuation of water quality
derived from tidallevel fluctuation.
Flood and drought management and arsenic
contamination in drinking water are most
important topics among many water related
problems in Bangladesh. At research level， high
quality researches are conducted including
those with mathematical model. Conservation
and improvement of surface water quality is also
important in urban and peri欄urbanarea of Dhaka
Ci勿 Surfacewater usage amount for water supply
sources may be increase in tbe如ture.Thus， water
quality information regarding the pollution status
of the river should be disseminated for effective
and efficient community participation for the water
quality improvement.
Acknowledgements
This study was financially supported by Japan
Education Center of Environmental Sanitation.
Tables 1 and 2 were reprinted from Kamal et al.
(1999) after copyright permission from International
Water Association， and Table 6 was reprinted from
Ahmed et al. (2005) after copyright permission from
Springer-Varlag. Figures 1 and 2 were modified
from Tsuzuki et al. (2008a，b) after copyright
permission from J apan Socie守 ofCivil Engineers
and Japan Education Center for Environmental
Sanitation. Comments from anonymous reviewers
on the previous version of the manuscript enhanced
the quality of the papers. The field survey was
assisted by Mr. Rana Hasan and Mr. Sumon of
BUET at that time.
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つんハUl
TSUZUKl， AHMED and RAHMAN
夕、ツカ市の都市域および
周辺域における水マネジメントに関するいくつかの考察および
水環境分野の環境教育の可能性
都筑 良明*・ファルク・アーメッド**'MDマブイツアー・ラーマン***
(*東洋大学**筑波大学***バングラデシュ工科大学)
摘 要
ダッカ(バングラデシュ)において表流水の水買を中心とする水環境に関するフィール
ド調査と文献調資を 2006年に行ったO バングラデシュにおける水環境の分野では，洪水
と卒魅，欽料水のヒ素汚染が最も重姿な問題となっている O ダッカ周辺においては，都市
水道用水の水源を考えると，表流水の水質保全，水震改善が重要で、あると考えられた。な
ぜならば，ダッカ市の上水道の水源は地下水が約 85%，表流水が約 15%であり，地下水
のくみ上げ最は急激に増加していて，地下水の過剰くみよげにより，ダッカ市の地下水位
は年間約1.0~ 3.0m 低下しているため，水源の表流水への転換等が必要で、あると考えら
れるからである。シタラカヤ川はダッカ市上水道の表流水水源の 1つであり，パル川の水
質の影響を受けている。現地調査結果から合流部の上流の水質もパル川の水質の影響を
受けていることが示唆され，これは潮汐の影響があるためであると考えられるとともに，
水源水質管理のためにはダッカ周辺河川システム全体の水質管理が必要であると考えら
れた。水資源管理の分野では，数理モデルを用いた研究が進められている。しかしながら，
水質等に関する水環境についての情報の多くは公開されていなし、。水環境に関する情報提
供を含めて，水質保全分野における市民参加の可能性について検討が必要でLある O
キーワード:環境水，ダッカ市，生活排水処理，環境教育，水質
