CORE Metadata, citation and similar papers at core.ac.uk Provided by International Institute for Science, Technology and Education (IISTE): E-Journals Journal of Environment and Earth Science www.iiste.org ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol.7, No.10, 2017 Mapping Urban Encroachment in the Rivers around Dhaka City: An Example from the Turag River Muhammad Selim Hossain Program Officer (JCM), Department of Environment, Agargaon, Dhaka-1207 Abstract Dhaka, the capital city of Bangladesh, is one of the fastest growing and the most densely populated cities in the world. The city has 4 rivers all around which were once lifelines to it for economy and ecology. Being expanded rapidly in an unplanned way with the phenomenal increase of population, land scarcity and land price, the city’s peripheral zone reached the banks of the rivers. Consequently, an ill-motivated section of people began to use the riverbanks in a variety of ways leading to river encroachment. Gradual encroachment is narrowing down the rivers putting their existence to threat. This study was conducted to find out the major encroachment points, estimate the area and document the land use of each encroachment point in the Turag River, particularly from the Buriganga Third Bridge (Shaheed Budhijibi Bridge) at Bashila to Tongi Bridge. The study was carried out through field survey with Dhaka City (rivers) map and GPS. The field survey was supported by discussion with focus group of 60 people aged over 70 experiencing changes in the Turag River for over last 50 years. Encroachment map showing the location of encroachment points has been prepared through application of GIS and satellite image. During field survey, the area and land use of each encroachment site was estimated and noted down respectively on sketch map. However, the study found out 51 points where about 1.5 acre of the riverbanks have been grabbed and are being used mainly for trade and commerce as well as housing purposes. Keywords: Dhaka, Economy, Ecology, River encroachment, GPS, GIS. 1. Introduction Dhaka, the capital city of Bangladesh, is one of the fastest developed and the most densely populated cities in the world. In Bangladesh, Dhaka is the largest city with a municipal area of 590 sq. miles that homes to more than one-third urban population of the country. The total population of the city is nearly 14 million with a growth rate of around 7% over the last three decades and projected to turn out to be the 6 th biggest megacity in the Asia- Pacific region by 2020 with an approximate population of 20 million (UN-Habitat, 2010; Mohit, 2012; World Bank, 2012). In the municipal area of the city, about 45,000 people live per sq. km. leading to one of the highest densities in the world ( Cox, 2012 ). It is a distinct primate city in the national and regional hierarchy and the nucleus of economy, administration and culture of Bangladesh. Geographically, Dhaka City is located at the center point of the flat deltaic plain of the three major river systems including the Ganges, the Brahmaputra and the Meghna. In particular, the city is surrounded by the distributaries of these rivers. They are the Balu and the Shitalakhya on the east, the Turag on the west and north and the Buriganga on the south. Over centuries, these rivers have been lifelines to the city for both of its economy and ecology. History says that rivers have always shown to have enormous effects on urban economy in a variety of ways. Once, the rivers were the main sources of fish supply to Dhaka City. The city used river water for a variety of purposes as the quality of water satisfied environmental quality standard. The city dwellers would go to the rivers on vacations with family members for recreational purposes. Apart from the above, the rivers supplied fresh air to the city. Before Mughals reign, Dhaka was a small Hindu trading centre. In Pakistan Period (1947-1971), the city of Dhaka experienced a momentous. In 1947, Dhaka restarted its life as the capital of East Pakistan. Again in 1971, Dhaka became the capital of the independent state ‘Bangladesh’. This additional factor as well as the initiatives of the private sectors led to Dhaka’s phenomenal growth since 1971 (Chowdhury and Faruqui, 1991) and started having detrimental effects on the rivers as the urbanization in terms of population and areal extension took place in a rapid but unplanned way. One of the effects is the beginning of urban encroachment in the city surrounding rivers. Despite all odds mentioned thereof, to meet the increasing population pressure, the government took a large project entitled “Dhaka Metropolitan Development Planning (DMDP)” and further expanded the city. According to this project, the total area of Dhaka City is about 1528 sq. km. Although the city was first developed on the bank of the Buriganga River utilizing its multifaceted services, with the passage of time it has spread over an extended area almost on all directions especially on the north, the south, and the west. Consequently, the peripheral zone of Dhaka City spread to the banks of the surrounding rivers. Land scarcity and land price in the city, even in its peripheral zone, increased manifolds. An ill-motivated section of people of this fast growing metropolitan city availed the opportunity of its rapid expansion. They started using the riverbanks and even the dried up portion of the river channel in a variety of ways. In practice, initially, they use the riverbanks on temporary basis as the rivers are no under private ownership to be highly taken care of. Thus, they pave the way 79 Journal of Environment and Earth Science www.iiste.org ISSN 2224-3216 (Paper) ISSN 2225-0948 (Online) Vol.7, No.10, 2017 of grabbing the riverbanks. Later when they think that the ownership of the grabbed lands has been vested with them automatically due to illegal occupation for long time, they go for permanent land use eventually leading to river encroachment. River encroachment is an illegal intrusion in a navigable river with or without obstruction (Senthil and Anand, 2016). Gradual riverbank encroachment is narrowing the rivers down putting their very existence to threat. Today, encroachment has become one of the major problems faced by the rivers around Dhaka City. Now, it has become urgent to rethink of addressing the encroachment problem not only to save the rivers but also to ensure innumerable socio-economic and ecological services of the rivers to Dhaka City. A recent study to investigate the river encroachment (Chowdhury, Bhuyain and Kabir, 2015, p. 1556) concluded that rapid river encroachment has been observed in many places of Dhaka city’s peripheral rivers and that Dhaka City has already started suffering from many socio-environmental problems including flooding, water-logging and other related problems due to river encroachment. Again, to solve the encroachment problem, first it is necessary to unveil the true picture of this problem. At this backdrop, the present study took an important part of the Turag River, particularly both banks from the Buriganga Third Bridge (Shaheed Budhijibi Bridge) at Bashila to Tongi Bridge as an area of investigation. In this part of the Turag River, industries, housing projects and different commercial business farms have been developing along both banks. All these types of land uses which are on the rise rapidly, work significantly as positive factors for river encroachment. In addition, so far as the literature reviewed, there is no specific study on finding the exact locations of encroachment and the area of each encroachment site. There are very few studies related to encroachment in Dhaka and its peripheral rivers. For example, Hossain et al . (2014) have focused on overall changes in the wetlands of Dhaka City while Chowdhury, Bhuyain and Kabir (2015) studied the overall encroachment picture in Dhaka City surrounding rivers with the help of GIS and remote sensing. The present study, therefore, spotlighted on finding out the exact encroachment points, estimating the encroached area and documenting the land use practices at each encroachment point in the study area through GPS field survey and focus group discussion. The findings of the study will be highly useful to the Government of Bangladesh, particularly the authorized government agencies to easily locate the encroachment points, take concrete actions to restore the river evicting the existing encroachments and protect the river from further encroachment in future. 2. Methods and Materials 2.1. Selection and description of the study area The study covers about 29 kilometers of the Turag River, particularly from Buriganga Third Bridge (Shaheed Budhijibi Bridge) to Tongi Bridge, as an area of investigation. This area lies between 23˚74ʹ - 23˚88ʹ north latitude and 90˚34ʹ - 90˚40ʹ east longitude. About 20 km length of the river is adjacent to Dhaka City (Table 1). The Turag River is the upper tributary of the Buriganga. The Turag originates from the Bangshi River at Kaliakoir of Tangail District. The Bangshi is an important tributary of the Dhaleshwari River. On the other hand, the Dhaleshwari is also a tributary of the Buriganga (Chowdhury, 2001). It flows through Gazipur and then along the north-western side of Dhaka Metropolitan Area. It joins the Buriganga at Mohammadpur on east and at Shalmasi of Keraniganj on west. Keraniganj and Savar Upazila are on the western side and Tongi Pourosova is situated on the northern side of the river. Again, Uttara and Turag Thana are on the southern side and Mirpur and Mohammadpur are on the eastern side of the Turag River. The river has an average width of about 0.12 km during the dry season covering about 276 ha of water body which increases about 500 ha during the flood season (BWDB, 2004).