INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 6, No 2, 2015

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1 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 Assessment of river encroachment and land- use patterns in Dhaka city and its peripheral rivers using GIS Md. Ashraful Islam Chowdhury 1, Mohammed Amir Hossain Bhuyain 1 and Mohammad Mahbub Kabir 1 Department of Environmental Sciences, Jahangirnagar University, Savar, Dhaka-1342 sagorchowdhury6996@gmail.com 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), acres > Buriganga (Kamrangirchar > Bosila), acres > Sitallakhya (Katchpur > Narayangang), acres > Balu (Demra > Nandipara), acres within an area of miles, miles, miles and 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 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 Submitted on September 2015 published on November

2 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 km 2 of rivers and canals and about km 2 of wetlands were found in Dhaka city and its peripheral areas. In 2009, only km 2 of rivers and canals and 53.6 km 2 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 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 N and E (Figure 1). Bosila is located at N and 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 N and E (Figure 1). Gabtoli is located at N and 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 N and E (Figure 1). Demra is located at N and E (Figure 1). Sitallakhya River is a 1557

3 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 N and E and Katchpur is located at N and 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 1558

4 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 and 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 1559

5 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. 1560

6 Figure 6: Encroachment in Balu River. Name of the river Buriganga Buriganga Turag Turag Balu Balu Sitallakhya Sitallakhya Figure 7: Encroachment in Sitallakhya River. Table 1: Area encroached in different places at several years. Place Kamrangirchar Bosila Gabtoli Abdullahpur Demra Nandipara Katchpur Narayangang Encroached area in Acres Year Length of study (miles) * Starting year (3 rd column) for different places are different because of lacking of data unavailability. 1561

7 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. 1562

8 Figure 9: Image classification of Turag River Figure 10: Image classification of Balu River. Figure 11: Image classification of Sitallakhya River. 1563

9 Table 3: Percentages of different land use patterns within 200m from those rivers at different years. Land use within 200 meters from the River Percentage (%) of Infrastructure Percentage(%) of Vegetation Percentage(%) of Barren land Percentage(%) of Water body Percentage(%) of unidentified object Percentage(%) of Barren land + Vegetation Year (2001) Year (2002) Year (2004) Year (2014) Area (%) Area (%) Bosila Gabtoli Bosila Gabtoli Bosila Gabtoli Bosila Gabtoli Gabtoli-9.40 Nandipara-0 Katchpur Narayangang Nandipara Katchpur Narayangang Nandipara Katchpur Narayangang * Where indicate missing data, not nill. 4. Results and discussion Area (%) Abdullapur Demra Abdullapur Abdullapur Abdullapur Demra Demra Area (%) Bosila Gabtoli Abdullapur Nandipara-1.77 Demra Katchpur Narayangang Bosila Gabtoli Abdullapur Bosila Gabtoli-2.93 Abdullapur Bosila Gabtoli Abdullapur Nandipara-24.6 Demra Katchpur Narayangang Gabtoli Nandipara Demra Katchpur Narayangang

10 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 km 2, which was depicted to be 67 km 2 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 highrise buildings and factories being built on rivers. From Figure 12 and Table 1, it has been found that, the highly encroached areas were Abdullahpur ( acres), which is followed by Kamrangirchar ( acres), Gabtoli ( acres), and for Bosila ( acres). The least encroached river was Balu in Nandipara ( acres). At Katchpur, in Sitallakhya River, it was ( acres) and for Narayangang, it was ( 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). 1565

11 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 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 % to % 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 socioenvironmental 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. 1566

12 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 , Environmental Monitoring and assessment, 150, pp 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), pp 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 Lambin E. F., (1997), Modeling and monitoring land-cover change processes in tropical regions, Progress in physical geography, 21, pp 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 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 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 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), pp 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