Modern Environmental Science and Engineering (ISSN 2333-2581) 2017, Volume 3, No. 6, pp. 419-423 Doi: 10.15341/mese(2333-2581)/06.03.2017/007 Academic Publishing Company, 2017

Two and Half Century’s Changes of Largest : A Geo-informatics Based Study on Mangrove Forest, ,

Nur Hussain1, Rozina Khanam2, and Ebadullah Khan1 1. , Bangladesh 2. of Professionals, Bangladesh

Abstract: largest mangrove forest Sunderbans is located the southern coastal zone of Bangladesh and India. The ecologically rich world site (UNESCO-1997) Sundarbans have been playing important role to protect the . The economic importance of mangrove is remarkable for Bangladesh and India both . The mangrove bio-diversity and ecosystem of Sundarbans have created world famous tourist . During the demographic growth the Sundarbans have been decreasing. This research focused on geo-spatial charge of this mangrove forest during last 244 . Historical maps Geo-informatics tools and techniques specifically Remote Sensing (RS), Geographical Information System (GIS) have been used to explore these changes. About 56.48% of total Mangrove forest have been lost during last two and half century with 0.23% yearly trend. The last half century it have lost 0.62% per . The decreasing rate of Indian part more than Bangladeshi part. That is dangerous for Natural disaster protect, economy, Mangrove ecosystem and bio-diversity.

Key words: world heritage, natural disaster, remote sensing, GIS, mangrove ecosystem

loosed by the areal changes of Sundarbans. The 1. Introduction Sundarbans have been declining at an alarming The mangrove frost is grown up by the land- rate perhaps even more rapidly than inland tropical interface tidal ecosystem. The Approximately 10,000 forests due to pollutants and nutrients as well as km2 the Sundarbans in the Northern Bay of is conversion into development activities such as sea the largest contiguous mangrove forest on earth [1]. It level raise, change, , aquaculture protect coastal against and tsunamis (mainly farms), salt extraction and such as Sedor 2007, Aila 2009. The are also infrastructure development, all of which contribute to of great economic value [2-8]. The mangrove the degradation and process [11, 12]. In ecosystem is very developed because it provide this circumstance the research paper explores the important and unique ecosystem and services to changes of Sundarbans from 1773 to 2016 about two society and coastal and marine systems [9]. The and half centuries. The historical map or cartographical Sundarbans is primarily known as a reserve. The evidence, the remote sensing technology is used to tiger stands at the pinnacle of both the aquatic and the detect the land use and land cover change [13-16]. The terrestrial food chain [10]. The amount of tiger is “Chart of Sundarbans ” of Jamse Rennell (1773) is the first details map of Sundarbans have used as base

map. The Landsat Operational Land Image (OLI) Corresponding author: Nur Hussain, M.Sc., Researcher, research areas/interests: Geo-informatics, GNSS and (2016) have used to explore present status of this environmental management. E-: [email protected].

420 Two and Half Century’s Changes of World Largest Mangrove Forest: A Geo-informatics Based Study on Sundarbans Mangrove Forest, Bangladesh, India mangrove forest. The historical maps and images have been used in Geographic Information System (GIS) and Remote Sensing (RS) technology to estimate the Historical changes of Sundarbans during last two and half centuries.

2. Study Area

The Sundarbans is situated on the delta of Bangladesh and Sundarbans delta of India, both are located in the north coast of . These deltas have formed by the and deposited loads the upstream rivers carry from their Himalayan headwaters [17]. Tidal amplitude within the is between 3.5 and 4 m, with seasonal variation between 1 and 6 meters in Sundarbans [18]. Fig. 1 Location map of Sundarbans.

The Sundarbanss have situated within 21°31′ to Table 1 Data and methods. 22°30′N and 88°15′ to 90°6′E [19] covers an of Objective Data Methods Output approximately 10,000 km2, of which 62% lies within Area of Articles, Remote sensing, Location, Sundarbans. Maps, Spatial analysis, Distribution, Size, Bangladesh and 38% in India [20]. The Sundarbans is Satellite Geographic Shape and Area. characterized by a tropical climate with a dry season Images. Information System. Image between and and a wet monsoonal Interprets. period over the rest of the year. The total annual Spatial Maps, Remote sensing, Dynamics changes Changes Satellite Geographic of Mangrove amount of precipitation is between 1500 and 2000 mm. Image. Information forest. During the season, tropical cyclones and System. Geo-spatial smaller tidal events regularly hit the area, causing analysis, Excel. severe flooding and damage [21]. There are in Trend of GIS Excel, Correlation and and seasonal mean minimum and changes Data set. SPSS-analysis. comparison of dynamic changes. maximum temperatures vary from 12°C to 24°C and 25°C to 35°C, respectively [22]. Table 2 Sources of data. Year Data Sources 3. Material and Methods 1773 Historical Chart of Sundarbans Rivers 1773 (24 Map Paragana, Nodya and ) [23] This research has been flowed on objective base 1873 Historical The of 24 Paragana, Map Nodiya and Jessore-1873. [24] systematic approach (Table 1). The historical 1973 Satellite Landsat MSS, (147/44,148/44, 147/45, maps, Landsat multispectral sensor (MSS) and Images 148) 1973 [25] 2016 Satellite Landsat OLI, ( 137/44, 138/44, 137/45, operational land image (OLI) satellite data have been Images 138/45) 2016 [25] used (Table 2). These data was used to detect changes in Data Process: Assessment of Mangrove distribution the mangrove-covered area over 245 years. Step by step and diversity Geographic Information System (GIS), objective based methods of analysis and output have Remote Sensing (RS) and Image Analysis Technology been developed these have been mentioned in Table 1. (Erdas Imagine14) have been used. SPSS and Excel The relevant data is collected from Secondary source have been used for statistical analysis. Historical (Map) sources. These have been noticed in Table 2. Data and Remote sensing Data have been processed for

Two and Half Century’s Changes of World Largest Mangrove Forest: A Geo-informatics Based Study on 421 Sundarbans Mangrove Forest, Bangladesh, India area measurement and change detection with same 8537 km2 and 7894 km2 respectively Bangladesh and coordinate system. India (Table 3 & Fig. 3). These areas have been Chlorophyll, the chief photosynthetic in explored by using spatial analysis in Arc GIS. In 1973 plants, strongly absorbs visible light (from 0.4 to the total area of Sundarbans was 10802 km2 which 0.7 µm). The cell structure of the leaves, on the other includes 6525 km2 and 4277 km2 respectively hand, strongly reflects near-infrared light (from 0.7 to Bangladesh and India and in 2016 the area of 1.1 µm) [26]. According to this, The NIR band is more Sundarbans was 9728 km2 which includes 6152 km2 reflected by green chlorophyll and the band is and 3576 km2 respectively Bangladesh and India more absorbed in by green chlorophyll. According to (Table 3 & Fig. 3). These area have been detected by this consideration a model known as the Normalized using NDVI model in Erdas Imagine 14 from Landsat Difference Vegetation Index (NDVI) have been satellite images of both periods. developed. That is used to detect vegetation coverage. Lost Area and decreasing trends: According to Landsat Multi spectral sensor (MSS) have 60 meters characteristics of mangrove formation, function and spectral resolution four [27]. In this satellite ecosystem the forest have been flooded within tidal image the NIR (infrared) is four Band and process. As a result most of the mangrove forest also Band three is Red Band. The Landsat Operational land considered as the tidal . The Sudarbans image (OLI) have 30 meters spectral resolution eleven mangrove forest is consist with rivers and such band [28]. The Band five and band four represent the as net. This is direct connected with Bay of Bengal. NIR (infrared) and red band respectively. This research During last two and half century the total mangrove have used NDVI model to detect the Vegetation forest have been decreasing 12,626 km2 that 56.48% of coverage. This equation has been flowed. total which have included 10695 km2 forest land and NIR band Red band 1931 km2 body (Table 4). The average yearly NDVI NIR band Red band changing rate is 0.23% and 2.34% has been lost each The data process approach (Fig. 2) has been flowed. Table 3 Area of Sundarbans 1773-2016. Area 1973 Area 1873 Area 1973 Area 2016 4. Results and Discussion Country (km2) (km2) (km2) (km2) Total Area of Sunderbans: The area of Sunderbans Bangladesh 12290 8537 6525 6152 has been explored from historical amps of 1773 and India 10064 7894 4277 3576 Total 22354 16431 10802 9728 1873. The total area of Sunderbans was 22354 km2 in

1773 which includes 12290 km2 and 10064 km2 respectively Bangladesh and India. In 1873 the total area of Sundarbans was 16431 km2 which includes

Fig. 3 Map of Sundarbans 1773-2016.

Fig. 2 Data process approaches.

422 Two and Half Century’s Changes of World Largest Mangrove Forest: A Geo-informatics Based Study on Sundarbans Mangrove Forest, Bangladesh, India

Table 4 Trend of spatial decreasing of Sundarbans 1773-2016. Year Mangrove (km2)River (km2) Total (km2) Lost (km2) Per Decade (km2) Percentage per Decade 1773 17309 5045 22354 - - - 1773-1873 12721 3710 16431 5923 592.3 2.65 1873-1973 7495 3307 10802 5629 562.9 3.43 1973-2016 6614 3114 9728 1074 268.5 6.21 decade. The spatial change has occurred in all side of Bangladesh part than Indian part. This trends also Sundarbans. The South part lost due to erosional represent the decreasing rate have more India than activities (Figs. 4 & 5). The others three sides have lost Bangladesh. The average rate of decreasing in India socio-economic aggression. 2.68% more than Bangladesh per decade. Last 46 year, Comparison the decreasing trends between yearly average loss of Bangladeshi part is 0.35% and Bangladesh and India: The trends analysis has 1.02% decrease per year in Indian part (Table 5). represented the total area of Sundarbans is more

Fig. 5 Decreasing trend map of Sundarbans 1773-2016.

Fig. 4 Changing map of Sundarbans 1773-2016.

Table 5 Comparison trend of loss 1773-2016. Total area (km2) Lost area (km2) Per Decade lost (km2) Percentage of lost Year Bangladesh India Bangladesh India Bangladesh India Bangladesh India 1773 12290 10064 ------1773-1873 8537 7894 3753 2170 375.3 217 3.0 2.15 1873-1973 6525 4277 2012 3617 201.2 361.7 2.35 4.5 1973-2016 6152 3576 373 701 93.25 175.25 3.5 10.24 1773-2016 - - 6138 6488 223.25 251.3167 2.95 5.63

“Swatch of no ground” located in near upper part of 5. Conclusion Sundarbans as a result the coastal mangrove forest have The Sundarbans inclusive Sundarban delta (India) lost due to erosional process. The demographic growth and (Bangladesh) have developed during is more in this forest dominated area due to social 5000 to 1800 years [29]. The coastal landform status. The forest dominated society always live below dynamic. This research have found that the south part level so the land price is very lowest than other of Sundarbans lost due to erosional process of Bay of location of country. As a result the settlement, Bengal. The upstream water and sediment supply have structural and development project have been decreasing and the lowest part of Bay of Bengal been increased rapidly and the mangrove area have

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