Journal of Science and Technology, 7(1 & 2): 1-15, December 2017 MONITORING URBAN EXPANSION OF JHENAIDAH MUNICIPALITY, BANGLADESH THROUGH LULC CHANGE DETECTION BY REMOTE SENSING AND GIS TECHNIQUES MD. MUJIBOR RAHMAN* and MD. GOLAM AZAM Environmental Science Discipline, Khulna University, Khulna-9028, Bangladesh Abstract Monitoring urban expansion or sprawl through change detection is now much easier, accurate and cost-effective with the use of remote sensing and GIS. In order to perform change detection, this study used Landsat satellite images belonging to 1975, 1995 and 2015. Different image enhancement procedures have been adopted to visualize the surface covers of study area followed by the classification of features. Five land use land cover classes were used to perform the maximum likelihood algorithm of supervised classification system. Urban and environmental change rate, trend and magnitude have been determined by the change detection statistics from classified images. The Land Use and Land Cover (LULC) mapping have also been extracted from the classified images using GIS tools via vector shape files. The study shows that the process of urbanization thrusting other land covers. From last 40 year’s land cover analysis, the rate of increase in urban areas 0.25 km2/year leading the agriculture and vegetation to a decline of 0.14 km2 and 0.06 km2 per year respectively. The overall accuracy (96.02%) and kappa coefficient (0.84) shows that the classification quality is reliable. Key words: Urban expansion, LULC, change detection, remote sensing, GIS. Introduction One of the most significant human induced causes of the loss of arable land, habitat destruction, and the decline in natural vegetation cover is urban expansion resulting from rapid population growth (Lopez et al., 2001; Alphan, 2003). Apparently, the urban population has grown exponentially. By 2017, the developing world is likely to have become urban in character than rural; therefore, the vast majority of urban growth is now occurring in the developing world (UN-Habitat, 2003). It is very much true in case of India, China, and Bangladesh where urbanization is going on at a high environmental cost. Land use and land cover are distinct yet closely linked characteristics of the Earth’s surface. The use to which we put land could be grazing, agriculture, urban development, logging, and mining among many others (Meyer, 1995). The term land cover originally referred to the kind and state of vegetation, such as forest or grass cover but it has broadened in subsequent usage to include other things such as human structures, soil * Corresponding author: [email protected] 2 Rahman & Azam. type, biodiversity, surface and ground water (Meyer, 1995). Changes in land cover by land use do not necessarily imply degradation of the land. However, many shifting land use patterns driven by a variety of social causes, result in land cover changes that affects biodiversity, water and radiation budgets, trace gas emissions and other processes that come together to affect climate and biosphere (Riebsame et al., 1994). In some instances, land use land cover change may also result in social and economic impacts of greater damage than benefit to the area. Hence, in order to use land optimally, it is not only necessary to have the information on existing land use land cover but also the capability to monitor the dynamics of land use resulting out of both changing demands of increasing population and forces of nature acting to shape the landscape (Olorunfemi, 1983). Conventional ground methods of land use mapping are labor intensive, time consuming and seldom. These maps soon become outdated with the passage of time, particularly in a rapid changing environment. In fact, monitoring changes and time series analysis is quite difficult with traditional method of surveying (Olorunfemi, 1983; Shosheng et al., 1994). In the past decade, different remote sensing database of both fine and coarse detail forms an important component for preliminary studies on urbanization and environmental studies (Zomer and Ives, 2002). Remote sensing along with GIS is a powerful and cost effective tool for assessing the spatial and temporal dynamics of LULC (Lillesand and Kiefer, 2000). Remote sensing data provide valuable and spatiotemporal data on the processes and patterns of LULC change, and GIS is useful for mapping and analyzing these patterns (Taubenbock et al., 2009). Xiaomei and Rongqing (1999) noted that information about change is necessary for updating land cover maps and the management of natural resources. The information may be obtained by visiting sites on the ground and or extracting it from remotely sensed data. Change detection is the process of identifying differences in the state of an object or phenomenon by observing it at different times (Singh, 1989). Change detection is an important process in monitoring and managing natural resources and urban development because it provides quantitative analysis of the spatial distribution of the population of interest. Macleod and Congation (1998) list different aspects of change detection, which are important when monitoring natural resources. The basis of using remote sensing data for change detection is that changes in land cover result in changes in radiance values. Techniques to perform change detection with satellite imagery have become numerous because of increasing versatility in manipulating digital data and increasing computer power. A wide variety of digital change detection techniques have been developed over the last two decades. Singh (1989) and Coppin and Bauer (1996) summarized different change detection algorithms. The State of Maryland Health Resources Planning Commission used all seven bands of Landsat TM data to create a 21-class land cover data set for inclusion in their Maryland Geographic Information (MAGI) database (EOSAT, 1992).In 1985, the U.S.G.S produced 1:250,000 land cover maps for Alaska using Landsat MSS data Monitoring Urban Expansion of Jhenaidah Municipality 3 (Fitzpatrick et al., 1987). In addition, in 1992, the Georgia Department of Natural Resources mapped the entire State of Georgia to identify and quantify wetlands and other land cover types using Lands at TM data (ERDAS, 1992). The State of southern Carolina Lands Resources Conservation Commission developed a detailed land cover map composed of 19 classes from multi temporal and multi spectral TM data (EOSAT, 1992). Pandy and Nathawat (2006) carried out a study on land use land cover mapping of Panchkula, Ambala and Yamunanger districts, Hangana State in India. A study of LULC change in Indonesia (Dimyati, 1995) shows the use of remote sensing to calculate the index of changes, superimposing land use land cover images of 1972, 1984 and land use maps of 1990. Daniel et al. (2002), in their comparison of land use land cover change detection methods, made use of five methods resulting nine land use land cover classes. They observed that there are merits to each of the five methods examined, and that, at the point of their research, no single approach can solve the land use change detection problem. According to Population and Housing Census 2011 of Bangladesh (BBS, 2011), 35094684 (adjusted) persons live in urban areas, which contribute 23.43% of the total population from 2.43% in 1901. The proportion of urban population was almost similar during the period 1901-1921 after that it started increasing and the rate of increase was relatively high during 1961-1974 (137.6%), 1974-1981 (115.8%) and 1981-1991 (65.9%) Though the urban population shows substantial rise during the last three decades even then Bangladesh by and large continues to be predominantly a rural country having about 76.57% of its population living in villages (BBS, 2014). As urban population increases, the demand of land for various urban activities also increases. In Bangladesh, the process of urbanization gained momentum with the start of industrial revolution and globalization way back in 1970s. After the War of 1971, the process of urbanization accelerates. Forests, grasslands, wetlands and croplands were encroached upon under the influence of expanding cities, yet never as fast as in the last two decades. Various studies have revealed that main basis of urbanization is the socio-economic transformations and in particular the growth of secondary and tertiary occupation in urban areas. Jhenaidah municipality has become a very important place due to its geographic location. According to different statistics from the office of Jhenaidah Municipality and the author’s observation in this decade, the city is facing a very speedy process of urbanization. Therefore, the present study is aimed at assessing the urbanization in Jhenaidah over the period of 40 years (1975-2015) using remote sensing technology and spatial functionalities technique in Geographical information system (GIS). The aim of the study is to monitor urban expansion of Jhenaidah municipality over time with three specific objectives; to prepare multi-temporal LULC map of Jhenaidah Municipality; to assess the multi-temporal LULC change pattern of Jhenaidah Municipality and to evaluate the LULC changes between 1975 and 2015; and to determine the LULC change rate, trend and magnitude of the study area. 4 Rahman & Azam. Materials and Methods Jhenaidah municipality is the only urban area of Jhenaidah sadar upazila consisting of 9 wards, 34 mahallas and 1 adjoining mouja, which altogether occupy an area of 32.42 km2. The study area is located in between 89.130E, 23.590N and 89.200E, 23.500N. The City is a plain land with high altitude (12-16m). The river Nabaganga is the only river running through Jhenaidah city. Due to the geographic location, the city is almost free of risks of flood as well as other natural hazards. Fig. 1. Location of the study area in the context of Bangladesh and Jhenaidah district Jhenaidah municipality started its journey in 1958 and became a town committee in 1960 under the municipal administration ordinance of 1960.