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INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES

Volume 6, No 2, 2015

© Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0

Research article ISSN 0976 – 4380

Submitted on September 2015 published on November 2015 1556

Assessment of river encroachment and land- use patterns in Dhaka city

and its peripheral rivers using GIS techniques Md. Ashraful Islam Chowdhury 1, Mohammed Amir Hossain Bhuyain1 and Mohammad

Mahbub Kabir1

Department of Environmental Sciences, Jahangirnagar University, Savar, Dhaka-1342

[email protected]

ABSTRACT

After 70’s decade Dhaka city started as a densely populated mega city with high land scarcity

for its ever growing population. Some opportunistic people take this advantage and make

illegal constructions over the bank of river. These illegal constructions are increasing day by

day and now turn into a sore called river encroachment. As a result, Dhaka city has been

suffering from many socio-environmental problems including flooding, water logging and

other related problems. The present study was conducted to assess the areas of illegal

intrusion of navigable rivers and its canals over the period of 2001 to 2014, and unsupervised

image classification was performed over the area of 200 meters by using the Arc GIS 10.1

and Google earth software, which is focused on different criteria. Rapid river encroachment

has been observed in many places of Dhaka city and its peripheral river’s corridor. The order

of encroached rivers was: Turag (Abdullahpur > Gabtoli), 120.7943 acres > Buriganga

(Kamrangirchar > Bosila), 97.1697 acres > Sitallakhya (Katchpur > Narayangang), 23.8315

acres > Balu (Demra > Nandipara), 8.8424 acres within an area of 5.7581 miles, 7.4120

miles, 3.5679 miles and 4.2032 miles respectively. By ISO unsupervised image classification

it was observed that the area was mostly encroached by human settlement and infrastructure.

It was alarming that the infrastructure level in the study area of 2014 was several times higher

when it is compared to the infrastructure level of 2001. The greatest percentages of

infrastructures were built on the bank of Buriganga River in Bosila (56.10%) and the lowest

percentages of infrastructures were built on the Balu River in Nandipara (1.77%). Not only

these rivers, but also the Turag, and Sitallakhya River are also narrowing day by day. Due to

the rising of illegal infrastructures and human settlement, the water bodies, barren lands,

croplands and vegetation decreased significantly in the encroached areas.

Keywords: Illegal constructions, river encroachment, GIS, land-use, Dhaka.

1. Introduction

An unlawful invasion or illegal intrusion of navigable river with or without obstruction is

called encroachment and it is not a newly converted word. Since the prehistoric time, rive is

the main attractive thing for the people for its charming beauty and waste disposal facility, for

this reasons the human settlement, industries and the city was built near the river course. The

most intensive interactions between human beings and the environment take place in cities

and their peripheries (Raihan and Kaiser, 2012).

The ever increasing population increases the pressure on land and makes the demand of land

which results people to be influenced to break the law of encroachment. Dhaka is expanding

apace, at an average rate of 4.24% per year and is projected to be the third largest megacity in

the world by the year 2020 (Dewan and Yamaguchi, 2009).Encroachment and Pollution make

the mega city Dhaka poisonous, and these are the reciprocal practice of Dhaka city which

Assessment of river encroachment and land- use patterns in Dhaka city and its peripheral rivers using GIS

techniques

Md. Ashraful Islam Chowdhury et al.,

International Journal of Geomatics and Geosciences

Volume 6 Issue 2, 2015 1557

make the mega city unloving. The mighty river of Dhaka, the Buriganga that serves Dhaka

city by conveying its waste and the drainage system are now reached into a serious

hydrological and ecological destruction.

The two main canals of Buriganga River namely Kamrangirchar and Bosila are now facing

the question of existence. The other peripheral rivers of Dhaka city also faced in a question of

appearance. Wetland encroachment is a very common practice in Dhaka city. According to

Islam et al., 2010, the first step of encroachment is the building of structures along the banks

of wetlands and furthers out on the wetlands itself, to do this, rows and bamboo posts are

positioned and fixed on the water bodies bed along the bank and extending into the main

body of the wetland and then huts and shops are built on these stilts. The owners of these

structures are then start reclaiming land by earth fills and dumping garbage.

In the beginning of the urbanization period of Bangladesh (1978), about 29 km2 of rivers and

canals and about 130.17 km2 of wetlands were found in Dhaka city and its peripheral areas.

In 2009, only 10.28 km2 of rivers and canals and 53.6 km2 of wet-land is existed which is

about 21% of Dhaka metropolitan area (Mahmud et al., 2011). Turag was once an affluent

100-metre wide river, which has now turned into a narrow canal to only 30- 40 feet in width

in some places, and grabbing still continues in full swing (Dhaka Mirror, 2009). More or less

the Sitallakhya and Balu rivers are also encroached by group of elite people who are

motivated by some Government broker. The encroachments of river are mainly by

infrastructure, bazar, shop, mobile tower, and industries. There is no specific documentation

regarding river encroachment at Dhaka city in Bangladesh. Some research reports have

focused only the overall changes that occurred in the wetlands of Dhaka city (Hossain et al.,

2014). The present study, thus, investigated the identification of river encroachment of

Dhaka city and its peripheral areas and to measure the actual area of encroached so that, the

Government of the People’s Republic of Bangladesh can take proper initiatives to protect the

illegal constructions as well as manage the environmental conditions of Dhaka city in a

sustainable way.

2. Study area

The Buriganga River is a tide-influenced river originates from the Dhaleshwari River near

Kalatia, northwest of Dhaka City, the capital of Bangladesh (Banglapedia, 2009). The study

area for Buriganga River was Kamrangirchar and the Bosila. Kamrangirchar is located at

23.716274°N and 90.378913°E (Figure 1). Bosila is located at 23.715278°N and

90.373611°E (Figure 1).The Turag River is the upper tributary of the Buriganga River, a

major river in Bangladesh. The Turag originates from the Banghi River the latter an

important tributary of the Dhaleshwari River, flows through Gazipur district and joins the

Buriganga at Mirpur thana in Dhaka district (Banglapedia, 2009) .Study area for Turag River

was Abdullahpur and Gabtoli. Abdullahpur is located at 23.883294°N and 90.392491°E

(Figure 1). Gabtoli is located at 23.789884°N and 90.339178°E. Balu River runs mainly

through the extensive swamp of beel belai and the east of Dhaka, joining the Sitallakhya near

Demra thana.

It has a narrow connection through the Suti River near Kapasia upazila with the Sitallakhya,

and also by way of the Tongi khal with the Turag River; there is also a link with the

Sitallakhya near Kaliganj upazila (Wikipedia, 2012). Study area for Balu River was

Nandipara and Demra. Nandipara is located at 23.775329°N and 90.480523°E (Figure 1).

Demra is located at 23.732739°N and 90.496283°E (Figure 1). Sitallakhya River is a


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distributary of the Brahmaputra, in its initial stages; it flows in a southwest direction and then

east of the city of Narayangang in central Bangladesh until it merges with the Dhaleswari

River near Kalagachhiya (Wikipedia, 2012). The study area for Sitallakhya was Narayangang

and Katchpur. Narayangang is located at 23.611929°N and 90.506936°E and Katchpur is

located at 23.675673°N and 90.531624°E (Figure 1).

Figure 1: Location of the study areas

Figure 2: Study areas with digital elevation model (DEM) value (meter), basin boundary,

and watershed and Thana boundary.

3. Methodology

3.1 Data used and software


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Now a day, GIS is an extraordinary ultimate tools for natural resource modeling. Google

earth images were used to conduct the study. Geo-referencing and map projection is one of

the most widely used GIS tool. Geo-referencing was performed to render real world

coordinates to the images to avoid geometric distortion (Sultana et al., 2009).The study has

been carried out under the frame work of Geographic Information System (GIS) and Google

earth Software. The image processing and digitizing have been carried out by using Arc GIS

10.1 software. Data on the river encroachment has been extracted from Arc GIS10.1 image

processing software. The ISO unsupervised image classification tool was used to image

classification and percentage of feature are measured. Google earth software was used to

extraction of images of the rivers of the study area.

3.2 Data generation and analysis

Data generation and analysis was carried out by the Arc GIS 10.1 software and the flow chart

of data generation, analysis and the processing are in (Figure 3).

Figure 3: Process of data generation and analysis

3.3 Detection procedure of river encroachment

The study was conducted at different rivers of Dhaka city and its peripherals. The river

encroachment was detected from Google earth by using the Arc GIS 10.1 software. The study

was conducted to show the differences of encroachment in different places. The Google earth

images were collected directly by using the Google Earth software and downloaded directly

to the computer. The images of the previous years were also collected from the Google earth

clock tool. The available image for the Buriganga, Turag, Balu and Sitallakhya River was of

2001-2014and 2002-2014. Every image was Geo-referenced and projected with UTM. After

then the river images were digitized and edited.

By using the Arc Catalog different layers of different features were generated through the

creation of different shape file; such as, polygon for encroached area and poly line for river.

Digitized image was also created by using the Arc map of Arc GIS 10.1 using the editing

toolbar. Then two river data were added in same layer and the area was regarded as


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encroached area. The area was measured from attribute table in acres (Table 3).The figures (4

to 7) indicate the river encroachment where the necessary information is indicated by legend.

Figure 4: Encroachment in Buriganga River canal.

Figure 5: Encroachment in Turag River.


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Figure 6: Encroachment in Balu River.

Figure 7: Encroachment in Sitallakhya River.

Table 1: Area encroached in different places at several years.

Name of the river Place Encroached area

in Acres Year

Length of

study

(miles)

Buriganga

Buriganga

Turag

Turag

Balu

Balu

Sitallakhya

Sitallakhya

Kamrangirchar

Bosila

Gabtoli

Abdullahpur

Demra

Nandipara

Katchpur

Narayangang

67.819647

29.342332

41.354336

79.441066

6.814914

2.009378

12.769376

11.061646

2001-2014

2001-2014

2001-2014

2004-2014

2002-2014

2002-2014

2002-2014

2002-2014

5.036849

2.375213

2.860067

2.898093

1.647296

1.903298

2.29768

1.922839

* Starting year (3rd column) for different places are different because of lacking of data

unavailability.


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3.4 Image classification

A version of Arc GIS 10.1 software was used for image classification. This latest version of

Arc GIS enabled to perform the land cover classification without creating any signature files,

which was primitive for the older versions (Mamun et al., 2013).The Google earth images

were Geo-referenced and projected. The projections were done by WGS 1984 and UTM. By

using the Arc GIS the image was edited and digitized. The buffer area from the river was 200

meters and the images were clipped. ISO unsupervised image classification was used to

classify the images and then converted into raster to polygon. The image was also dissolved.

There were four land use types have been mainly identified; infrastructure, vegetation, barren

land and water body. The percentages of areas were measured in acres firstly from attribute

table by grid code of every specific type of land use. The data that obtained from the attribute

table were converted into the percentage of area within 200 meters from the river represented

in (Table 3).

Table 2: Land use image classification outline

Land use types Description

Infrastructure

Vegetation

Water body

Barren land

Resident, Industries, Brick kiln, Mobile tower,

Road, Transportation, Market, Shop,

Boat, Ferry, Ship etc.

Crop land, Trees, Grass land, Agricultural field,

Vegetable field etc.

River, Canal, Pond, Drain.

Exposed land, Exposed soil, unfruitful land, and

Sand deposition.

Figure 8: Image classification of Buriganga River.


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Figure 9: Image classification of Turag River

Figure 10: Image classification of Balu River.

Figure 11: Image classification of Sitallakhya River.


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Table 3: Percentages of different land use patterns within 200m from those rivers at different

years.

Land use

within 200

meters from

the River

Year (2001) Year (2002) Year (2004) Year (2014)

Area (%)

Area (%)

Area (%)

Area (%)

Percentage

(%) of

Infrastructure

Kamrangirchar-

29.98

Bosila-11.07

Gabtoli-23.07

Nandipara-0

Katchpur-

44.34

Narayangang-

40.48

Abdullapur-

15.77

Demra-

31.83

Kamrangirchar-

50.28

Bosila-56.10

Gabtoli-43.76

Abdullapur-36.30

Nandipara-1.77

Demra-38.00

Katchpur-47.82

Narayangang-43.60

Percentage(%)

of Vegetation

Kamrangirchar-

24.84

Bosila--------

Gabtoli-22.05

Abdullapur-

24.37

Kamrangirchar-

18.04

Bosila------

Gabtoli-34.77

Abdullapur-10.46

Percentage(%)

of Barren land

Kamrangirchar-

11.70

Bosila-63.09

Gabtoli----------

Abdullapur-

7.88

Kamrangirchar-------

Bosila-31.29

Gabtoli-2.93

Abdullapur-28.06

Percentage(%)

of Water body

Kamrangirchar-

33.45

Bosila-25.89

Gabtoli-45.47

Nandipara-

16.33

Katchpur-

38.91

Narayangang-

38.05

Abdullapur-

51.97

Demra-

24.08

Kamrangirchar-

31.66

Bosila-12.59

Gabtoli-18.54

Abdullapur-25.16

Nandipara-24.6

Demra-28.50

Katchpur-34.78

Narayangang-40.60

Percentage(%)

of

unidentified

object

Gabtoli-9.40 Gabtoli------

Percentage(%)

of Barren land

+ Vegetation

Nandipara-

83.66

Katchpur-

16.74

Narayangang-

21.45

Demra-

44.02

Nandipara-73.75

Demra-33.50

Katchpur-17.39

Narayangang-15.78

* Where “--------”indicate missing data, not “nill”.

4. Results and discussion


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The study of river encroachment of Dhaka city and its peripheral areas was conducted at

different years along the bank side of the river, and the encroached area is presented in Table

1.The river of Dhaka city and its peripherals are badly encroached by a group of people and

most of the encroached areas within Dhaka city was the Kamrangirchar and Bosila;

peripherals river Turag and Sitallakhya were rigorously encroached within the area of

Abdullahpur and Gabtoli and for Sitallakhya river, it is Narayangang and Katchpur, where

Balu river was encroached rigorously by the area of Nandipara and Demra (Figure 4 to 7). In

1968, the total area of marshy and peaty inundated low-lying areas was 133 km2, which was

depicted to be 67 km2 in the year 2001 (Sultana et al., 2009).

The various civil society leaders and human rights organizations have filed summonses for

the protection of rivers in the country. But the land-grabbers are still at work and seen high-

rise buildings and factories being built on rivers. From Figure 12 and Table 1, it has been

found that, the highly encroached areas were Abdullahpur (79.441066 acres), which is

followed by Kamrangirchar (67.819647 acres), Gabtoli (41.354336 acres), and for Bosila

(29.342332 acres). The least encroached river was Balu in Nandipara (2.009378 acres). At

Katchpur, in Sitallakhya River, it was (12.769376 acres) and for Narayangang, it was

(11.061646 acres).

Figure 12: Encroached areas at different places at different years.

Encroachment, earth-filling, and construction of illegal structures on the Buriganga, Turag,

Balu and Sitallakhya rivers have been increased over the year. In the river vicinity, the

encroachment is now standing in a common practice. Land use/cover change analysis is an

important tool to assess global change at various spatial–temporal scales (Lambin, 1997).In

addition, it reflects the dimension of human activities on a given environment (Lopez et al.,

2001).From the image classification ( figure 8 to figure 11) at different rivers in different time

periods, it has been found that in the time of 2001 to 2014 and 2002 to 2014 at

Kamrangirchar, Bosila, Abdullahpur, Gabtoli, Demra, Katchpur and lastly Narayangang the

areas of river’s vicinity were encroached by infrastructure, shop, market, barren land, brick

field and agricultural field (see table 2). For instance, approximately 6,000 hectors of Dhaka-

Narayangang-Demra (DND) project were originally retained for assisting the agricultural

production, which is being converted to residential land apace since 1990s without prior

approval from the government (Islam, 1996).


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Figure 13: Areas of encroached at different years with various Land use types.

From the image classification analysis (Figure 13) and (Table 3), it has been found that in

2001, the percentage of infrastructure at Kamrangirchar was 29.98% and now in 2014, the

percentage is turned into 50.28%. By this time the percentage of the vegetation in 2001 was

24.84% and now decreases into 18.04%. Not only the vegetation is decreased within 200

meters from the river but barren land also decreased, and it is declined from 11.70 to 0

percent. The water bodies and lowlands decreased by 32.57% and 52.58%, respectively

during 1960 and 2008 (Islam et al., 2010).These acts are common in all rivers and canals in

Dhaka city and it’s peripheral. Some areas were more or less mainly encroached by

infrastructure. In some river and canal these encroachments were by the barren land, and by

the agricultural land. For this reasons rivers are narrowing. At Abdullahpur in Turag River,

the areas are encroached mainly by the barren land, where the canal of Buriganga is

encroached by the infrastructure.

In 2002, there was 0% of infrastructure at Nandipara in Balu River, but these scenes have

been changed in the year of 2014 and the rising infrastructure level is now 1.77 %. For

Demra, it was found that the rising infrastructure is 31.83 % to 38.00 % respectively. Not

only the percentage of infrastructure increases but also the percentage of water body

increases with the decreasing of barren land and the vegetation (Table 3).The encroachment

of river and canal not always occurs by the infrastructure, but in some areas, it’s occurred by

the vegetation; such as crop land, trees, vegetable field, as in Turag River at Gabtoli, the

vegetation percentage in 2001 was 22.05% and now it is increasing and reaches to 34.77%,

and in the meantime, the water body decreases. In Sitallakhya River at Narayangang and

Katchpur, the encroachment is caused by the infrastructure. But for Narayangang, the river

also encroached by the water bodies.

5. Conclusion

From the present study, it can be concluded that, all the major rivers of Dhaka city and its

peripheral areas are encroached to a greater extent that may poses horrendous socio-

environmental problems to the city dwellers and the reason behind these encroachment is

mainly due to the greediness of the local residents. So, the encroachment of rives in Dhaka

city and its peripherals area must be stopped; besides the illegal structures must be

demolished form the river bank. Government should take strong initiative to protect the eye

sore of river encroachment and make a rule of chain to protect these rivers and sustainable

socio-environmental development of Bangladesh.


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6. References

1. Dewan A.M., Yamaguchi Y.,( 2009), Using remote sensing and GIS to detect and

monitor land use and land cover change in Dhaka Metropolitan of Bangladesh during

1960–2005, Environmental Monitoring and assessment, 150, pp 237–249.

2. Hossain M.W., Ferdaus J., Saha, P.K. and Saifullah, A.S.M.,( 2014), Temporal and

Spatial Changes of Wetlands in the Selected Areas of Dhaka City and Its Impact on

Surrounding Environment,International Journal of Science and Research, 3(7),

pp1043-1050.

3. Islam N., (1996), Dhaka : from city to megacity, perspectives on people, places,

planning, and development issues.

4. Islam, M.S., Rahman, M.R., Shahabuddin, A.K.M, Ahmed R., (2010), Changes In

Wetlands In Dhaka City: Trends and Phisico-Environmental Consequences, Jornal

of.Life and Earth Science, 5, pp 37-42.

5. Lambin E. F., (1997), Modeling and monitoring land-cover change processes in

tropical regions, Progress in physical geography, 21, pp 375-393.

6. Lopez E., Bocco G., Mendoza M. and Duhau E., (2001), Predicting land-cover and

land-use change in the urban fringe: a case in Morelia city, Mexico, Landscape and

urban planning, 55, pp 271-285.

7. Mahmud M.S., Masrur A., Istiaque A., Haider F. and Habiba U., (2011), Remote

Sensing & GIS Based Spatio-Temporal Change Analysis of Wetland in Dhaka City,

Bangladesh, Journal of Water Resource and Protection, 3, pp 781-787.

8. Mamun A. A., Mahmood A. and Rahman M., (2013), Identification and Monitoring

the Change of Land Use Pattern Using Remote Sensing and GIS: A Case Study of

Dhaka City, IOSR Journal of Mechanical and Civil Engineering, 6, pp 20-28.

9. Raihan F, Kaiser N., (2012), Land Use Changing Scenario at Kerniganj Thana of

Dhaka District Using Remote Sensing and GIS,Journal of Environment, 1(3), pp105-

110.

10. Sultana M.S., Islam G. M.T, Islam Z.,( 2009), Pre- and Post-Urban Wetland Area in

Dhaka City, Bangladesh: A Remote Sensing and GIS Analysis, Journal ofWater

Resource and Protection, 1, pp 414-421.

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