INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 3, No 2, 2012

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1 INTERNATIONAL JOURNAL OF GEOMATICS AND GEOSCIENCES Volume 3, No 2, 2012 Copyright by the authors - Licensee IPA- Under Creative Commons license 3.0 Research article ISSN Landuse / Landcover change study of Jharkhali Island Sundarbans, West Bengal using Remote Sensing and School of Oceanographic Studies, Jadavpur University, Jadavpur, Raja S.C. Mallick Road, Kolkata , West Bengal, India samanta.kaberi@gmail.com ABSTRACT Jharkhali, an island in the Sundarbans, is situated between two mighty rivers, Matla (on the west) and Bidya (on the east) covering an area of about 161 sq.km (2009). The landuse / landcover maps of the Jharkhali island have been prepared from the satellite data and field checking. The time series analysis of land use / land cover changes of this area for the period reveals a virtual disappearance of the mangroves of Namkhana Reserve Forest. A forest area of km 2 has been found to be converted into aquaculture farms or agricultural fields. Others changes involve conversion of small waterbodies and marginal erosion of the western blank of the island. A further conversion of km 2 agricultural land into settlements is attributed to the growing population pressure in this Biosphere reserve area, World heritage site, and proposed Ramsar Site. Key words: Sundarban, Landuse change, Population pressure, Deforestation, Aquaculture. 1. Introduction Landuse is the human modification of natural environment or wilderness into built environment such as fields, pastures and settlements. Landcover is the physical material at the surface of the earth. These two terms are very interrelated as landcover is the type of features that exist on the earth and landuse is the economic utilization of land (Lillesand and Keifer, 1994). Knowledge of landuse and landcover change is important for many perspective planning and natural resource management initiative. Change detection analysis using multitemporal satellite data attempts to discriminate areas of landcover change between dates of imaging. Remote Sensing data have been widely used in change detection analysis. Various methods are developed for this type of study and the most commonly used technique is image differencing, principal component analysis and post classification comparison. In this paper the later technique has been used. In recent years the spectral mixture analysis, artificial neural networks and integration of geographical information system and remote sensing data have become important techniques for change detection applications. Research is still going on to find out the best and effective way of change detection technique (Lu et.al., 2004). Though landuse categories identified on ground do not undergo significant changes within short time, dynamic changes are inevitable over a longer time window. These changes may be due to natural causes, catastrophic disturbances, and also due to human interventions. The present study area as shown in figure 1 is an island in the Sundarbans (21º59'34.25"N - 22º13'23.98"N latitude and 88º37'23.96"E - 88º48'38.88"E longitude.), the largest mangrove ecosystem in India, located at the estuary of the Hugli-Matla-Ichamati river system. It is found that the mangroves of this region has been cut down to utilize it to some economic activities specially aquaculture farms. The case study area is unique in the sense that it Submitted on Septmeber 2012 published on November

2 comprises the Reserve forest (Namkhana) area under Biosphere Reserve Programme of the Sundarbans, yet stands as an evidence of the most recent anthropogenic deforestation event. 2. Materials and methods This paper aims to evaluate the magnitude and direction of landuse change in a partially protected environment of Sundarbans, and to identify the natural or anthropogenic factors responsible for such changes. The analysis has been done with the help of Remote Sensing data with relevant field verifications. The area calculations have been done in the environment. The first data was Landsat TM digital satellite imagery (date of acquisition 19 th January, 1986) and the second one was IRS P6 LISS III digital satellite imagery (date of acquisition 8 th February, 2009). The study was based on digital as well as vector based analysis in ERDAS IMAGINE 9.0 and ARCVIEW software. Multidated (Jan 1986 and Jan 2009) digital satellite data of Landsat TM sensor and Indian Remote sensing satellite IRS P6 Linear imaging Self Scanning sensor (LISS III) acquired from NRSC (National Remote Sensing Centre, Hyderabad) were used for this study. The satellite data were compared with topographical map of Survey of India (SOI). Analysis and interpretation of satellite data was done by digital image processing using ERDAS imaging and ARC software. Accuracy test was also performed by ERDAS imaging software to confirm the procedure / classification (Manonmani and Mary Divya Suganya, 2010; Mahdavi et.al., 2010). The satellite data procured were of similar tidal condition for the scale of the map and this helped in assessing the erosion and accretion of the Jharkhali island. Distribution of the landuse / landcover features (Dense Forest, Settlement with vegetation, agricultural land, aquaculture farm, mudflats) were cross checked during the field survey conducted in Extent of change in landuse pattern was evaluated by classification of satellite imagery of 1986 and Demographic data of the 1981, 1991 and 2001 census were used in this study. Figure 1: Location map of the study area 300

3 3. Results and discussions During the area which remained unchanged was about km², the erosion was about km² and accretion accounted to be about km². A Supervised Classification by Maximum Likelihood Classifier is operated on each dataset by marking the training sets. There is a possible relationship between increasing trend of population with rising settlement with vegetation area, decline in the forest cover, shifting of economy from agriculture to aquaculture. Figure 2: Landuse / Landcover map of Jharkhali Island (1986) Figure 3: Landuse / Landcover map of Jharkhali Island (2009) 301

4 Figure 4: Variation in area of different Landuse / landcover categories ( ) Table 1: Table showing the Landuse/ Landcover classes and area in sq kms of Jharkhali Island for the years 1986 and 2009 Sl.No Landuse / Landcover Area in sq.kms Area in sq kms classes (1986) (2009) 1 Dense Forest Settlement with Vegetation Agricultural Land / Other vegetation Aquaculture Farm Water Body / Marsh / Swamp Mud Flats Deforested Land Total Table 2: Table showing the land transformation matrix between

5 During the area which has remain unchanged is about km², the erosion was about km² and accretion accounted to be about km². Figure 5: Population density map of Jharkhali Island (Basanti Block) Year Figure 6: Population density map of Jharkhali Island (Basanti Block) Year

6 Figure 7: Year wise Population growth with settlement ( ) Figure 8: Year wise decline of agricultural land with increasing settlements ( ) Figure 9: Year wise Population growth with depletion of forest cover ( ) 304

7 3.1 Erosion and accretion From the above Table no 1 and 2 it is apparent that the erosion is greater than accretion and it is observed at particular stretches of the island which is otherwise protected by landmasses from the sea. The erosion is amounting to be about km 2 and accretion is about km 2 within the time frame of 23 years. In Table no. 2 the land transformation matrixes between two existing baseline years have been detailed. 3.2 Forest cover changes The most significant change that has been noticed in this area is partial deforestation of the existing forest area at the southern part of the island and this portion is identified as deforested land. Later this deforested area has been reutilized as settlement area, aquaculture farm and agricultural land. From Figure. 2 & Table. 1 it is observed that Mangroves were prevalent at the southeastern edges all along the Jharkhali Island and a considerable patch existed at the southern part of the island as a remnant of Namkhana Reserve Forest. By the year km 2 of Namkhana Reserve Forest of 1986 has been entirely converted to deforested land as observed from the Figure. 9. The deforested area has increased from km² to km² during , leaving behind km² remnant of the previous reserve forest. This has been done apparently not in conformity with the Forest Conservation Act (1980/1988) and the Coastal Regulation Act (1991). However there is also an addition of kms 2 of forest area as some mudflats have been colonized by mangroves There is also some positive sign that some of the amounting to an addition of to forest area. The amount of regeneration of mangrove in the Jharkhali island is about kms 2 from 1986 to Changing settlement with vegetation and agricultural land with population pressure The population pressure is increasing at a faster rate than the increase in the settlement area which is quite prominent from the Figure. 7. The maximum change in the island is noticed in the agricultural sector which involves conversion of kms 2 of agricultural land into settlement with vegetation. The history behind this conversion of forest area into agricultural land and settlements can be traced back to the refugee rehabilitation program during The swampy areas of kms 2 have been well utilized by settlement in due course of time. The census report portrays that in 1991 the population was about while it increased to during 2001 (Census of India 1991 and 2001). Population has played a significant role in reduction in the agricultural area (Figure 8) from km² to km² ( ) while the settlement has increased to km² from km² ( ). The decrease in the agricultural sector leads to the reduction in the per capita availability of agricultural land. The percentage share of agricultural land and settlement with vegetation was about and respectively in the year 1986 while it became nearly in the recent years. From the HDI report prepared by Govt. of West Bengal, it is understood that the area under total foodgrains was about ( 000 hect) in the year while it came down to ( 000 hect) in the year for South 24 Pgs (Human Development Report 2007), where Jharkhali has a significant contribution. 3.4 Aquaculture farms Aquaculture Farm areas have been found to be increasing and it is presently about 5.04 km² (2009). The matrix ( Table 2) shows Aquaculture Farms have grown at the expense of the 305

8 Namkhana Reserve Forest. There are numerous small aquaculture farms all over the island. Aquaculture farms which were left as dry are made economically viable in recent years. From field observations it has been found that brick kilns which have become more profitable in the recent years have started coming up along the fringes of the aquaculture farms. There is a notable decrease of Water Body / Marsh areas from km² to km². 4. Conclusions The landuse change dynamics of Jharkhali island indicate prolonged anthropogenic pressure on a fragile ecological niche of the World Heritage Site (UNESCO, 1989) of the Sundarbans. There are other areas in Gosaba and Hingalganj where similar changes have taken place in recent times. Of late, serious conservation efforts have resulted in partial regeneration of mangroves in mudflats, as evidenced from recent satellite images. However among the erstwhile 9600 km 2 forested area of Sundarbans, only 4225 km 2 forest area remains, which have restricted access to mankind. 5. References 1. Lillesand, T.M., and Keifer, R.W., (1994), Remote Sensing and Image Interpretation (5th Edition), John Wiley and Sons Inc. 2. Lu, D., Mausel, P., Brondizio, E., and Moran., E., (2004), Change Detection techniques, International Journal of Remote Sensing, 25(12), pp Manonmani, R., and Mary Divya Suganya G., (2010), Remote Sensing and Application in Change Detection Study In Urban Zone Using Multi Temporal Satellite.,, 1(1), pp Mahdavi, A., (2010), IRS-1C image data applications for landuse / landcover mapping in Zagros region, Case Study: Ilam Watershed, West of Iran., Caspian Journal of Environmental Sciences, 8(1), pp Forest Conservation Act (1980), with Amendments Made in 1988, Ministry of Environment and Forest, available at accessed during June Notification under Section 3(1) and Section 3(2)(v) of the Environment (Protection) Act, 1986 and Rule 5(3) (d) of the Environment (Protection) Rules, 1986 Declaring Coastal stretches as Coastal Regulation Zone (CRZ) and Regulating Activities in the CRZ, New Delhi, 1991 (as amended up to 3rd October 2001), available at accessed during June Census of India, Ministry of Home Affairs, Government of India, available at accessed during June Human Security and Vulnerability, Human Development Report, Chapter 7, (2007) available at pgssouth/ Chapter% 2007.pdf, accessed during June