Geospatial assessment of Coral and Mangrove ...

Indexed in Scopus Compendex and Geobase Elsevier, Chemical Abstract Services-USA, Geo-Ref Information Services-USA, List B of Scientific Journals, Poland, Directory of Research Journals www.cafetinnova.org

ISSN 0974-5904, Volume 07, No. 01

February 2014, P.P.275-279

Geospatial assessment of Coral and Mangrove Environs of the Andaman Islands MAHENDRA R S1, MOHANTY P C1, BISOYI H2 AND SRINIVASA KUMAR T1 1 2

Indian National Centre for Ocean Information Services (INCOIS), Hyderabad – 500 055 Central Institute of Fisheries Nautical & Engineering Training, Vishakhapatnam- 530001 Email: [email protected]

Abstract: An archipelago island system of Andaman is consisting of several hundreds of islands. The coastal environs of these islands are rich in bio-diversity. Most of the islands rimed with fringing corals and healthy mangroves observed near the creeks/streams in the coastal zones. The Sumatra Earthquake occurred on December 26, 2004 recorded a 9.3 Mw not only generated devastating tsunami, but also created lot of tectonic disturbances in the Andaman region. As result of this, northwestern parts of the land got uplifted above a meter from the earlier position. This resulted in the lot of spatial disturbances in the coastal environment. The shallow depth corals were exposed and degraded permanently. Moreover, the mangroves in the up streams were also degraded. A case study from the Interview Island in the northern Andaman was selected to assess the changes. The study was carried out using the Landsat Enhanced Thematic Mapper (ETM) and Indian Remote Sensing (IRS) Linear Imaging Self Scanning Sensor (LISS)-III data were used to infer the spatial changes in the coral and mangrove environments. The assessment was carried out using the Remote Sensing and GIS techniques. The results of the study reveal that the total coral reef area of 17. 82 km2 degraded. The mangrove also showed the same tendency of degradation of total 4.48 km2 area. The techniques and the data were used in the study were given useful insight. The results help in understanding the spatial extent and the distribution of the damage caused due to this natural calamity on the coral and mangrove environment. Key words: Coastal Zone, Remote Sensing, GIS, earthquake, fringing reef, mortality. 1.

Introduction:

Coastal resources are crucial factor to support life of coastal community. It is very essential that the sustainable use of coastal resources to meet the present and future needs. The important coastal natural resources which are very much useful are Mangroves, Coral Reefs, useful Seaweeds, Wetlands, Minerals, Hydrocarbon and other organisms (Walters et al. 1998; Jin et al. 2002). The majority of human population (more than 60%) lives along the coastal zones and most of communities and industries are depending on local resources for their livelihood. Mangrove and coral ecosystems are extremely important coastal resources. They are coastal ecosystems providing shelter for diverse habitats from different species and serves as a source of food, medicines, and forestry products. In addition to these mangrove and coral ecosystem, they also indirectly support to economic activity through nutrient recycling, water purification, and flood control. Coral Reefs and mangroves buffer along the specific coastlines act as a natural barrier for coast to protect from storm surges, Tsunamis, cyclones, floods, sea level rise, wave action and coastal erosion.

The mangrove and coral reef are the important natural resources need the immense attention towards the sustainable conservation. The remote sensing is one such powerful tool to map these resources in order to assess the spatio-temporal changes. Besides, the Geographic Information System (GIS) facilitates to extract the vital information out of the spatial datasets. There are several such works were carried out on mangroves (Srinivasa Kumar et al. 2011; Blasco et al. 1998; Giri et al. 2007; Kathireshan and Rajendran 2005; Danielsen 2005) and coral reefs (Bahuguna et al. 2008; Mahendra et al. 2008; Mahendra et al. 2010; Rajendran et al. 2008) monitoring using the geospatial techniques. However, the work on the exact quantification in terms of space and time was not brought out in this area. Hence present study aims at the demonstrating the technology to decipher the spatio-temporal changes in the coral and mangrove cover due to 2004 Sumatra earthquake and tsunami in the Interview Island Andaman. This study has brought out the accurate changes those caused in the island due to 2004 tectonic disturbances with the aid of the satellite data from Landsat Enhanced Thematic Mapper (ETM) and Indian

#02070138 Copyright ©2014 CAFET-INNOVA TECHNICAL SOCIETY. All rights reserved.

Geospatial assessment of Coral and Mangrove Environs of the Andaman Islands

Remote Sensing Satellite (IRS) P6 Linear Imaging Selfscanning Sensor (LISS) III. 2.

Satellite

Fig1: Map showing the study area 3.

Table1: Satellite data used for the study

Study Area:

The Andaman and Nicobar group of Islands are an example of archipelagoes system which covers about 350 islands (Bahuguna et al. 2008). Interview Island lies in the northwestern part of Andaman Islands (Figure 1) in the Bay of Bengal. The geographical constraints of the Interview Island are 12.76 N to 13.00N latitudes and 92.64 E to 92.73 E longitudes. The island covers a total geographic area of about 88 km2. The habitation in the island is nil except government and security officials. Andaman falls under tropical climatic condition experiencing a temperature within the range of 23°C to 31°C. There are no severe climate conditions in the region except for tropical storms and rains in late summers and monsoons.

Data Used:

The present study was carried out based on the available remote sensing data given in the Table 1with the aid of the in-situ observations. The Landsat ETM data acquired on February 07, 2000 used as the pre-tsunami and IRS-P6 LISS-III data acquired on the February 06, 2006 was used as the post-tsunami information. The Landsat ETM data acquired on April 10, 2010 to assess the recent changes in the mangrove cover.

276

IRS-P6 (Post Tsunami) Landsat (Recent) Landsat (Pre Tsunami) 4.

Sensor

Date Acquisition

Spatial Resolution

LISSIII

Feb 06, 2006

23.5 m

ETM

Apr 10, 2010

30 m

ETM

Feb 07, 2000

30 m

Methodology:

The spatiotemporal assessment of mangrove and coral reefs involves three main steps viz: pre-processing; processing and post processing. The pre-processing consists of the geo-correction, area selection, radiance conversion and re-sampling. The Landsat ETM Orthorectified data acquired in 2000 and 2010 are downloaded from www.landsat.org website. Resourcesat-1 (IRS P6) LISS-III data of 2006 was obtained from the NRSC. IRS P6 LISS-III digital data of July 22, 2006 was geo-referenced for polynomial order 2 using Landsat ETM data as the reference. A subset of a mangrove and coral reef area were extracted from all the images in order to minimize the classification inaccuracies. The appropriate band selection (Selvam et al. 2003; Brian and Timothy, 1996; Green et al. 1998; Chauhan and Dwivedi, 2007; Srinivasa Kumar et al. 2011) and the radiance conversion techniques (Lunetta, 1999; Chauhan and Dwivedi, 2007; Singh, 1989) were applied on the images before the classification. Then the LISS-III data of spatial resolution 23.5 m has been resample to 30 m in order to be spatially comparable with ETM. The above two steps are making the multi-temporal and multi-resolution satellite data comparable spectrally and spatially respectively. The processing of remote sensing consists of classification and finalization of the classes using contextual editing. Iterative Self Organizing Data Analysis Technique (ISODATA) clustering was performed on individual images to segment them into possible classes each depending upon the spectral signatures in green, red and infra-red bands. Using contextual editing the mangrove cover pertaining to the periods 2000, 2006 and 2010 were separated from other classes. Similarly another step performed in order to classify eco-morphological classes of coral reefs during 2000 and 2006. The final classes of the coral eco-morphology were obtained by contextual editing with the aid of the ground truth information.

International Journal of Earth Sciences and Engineering ISSN 0974-5904, Vol. 07, No. 01, February, 2014, pp. 275-279

277

MAHENDRA R S, MOHANTY P C, B ISOYI H AND SRINIVASA KUMAR T

In order to carryout post-processing using GIS analysis composites of the mangrove and coral eco-morphology composites were converted to Environmental Systems Research Institute (ESRI) shape files by raster to vector conversion techniques. These shape files were analyzed using GIS package ESRI Arc Map to assess the spatiotemporal changes in the coral and mangrove environs. 5.

Results and Discussions:

The catastrophic impact on the shallow corals resulted in the mass coral mortality due to the land uplift resulted in the shallow corals to expose above water permanently. The change in coral eco-morphology (Figure 2B) was carried out using pre-earthquake (data acquired on 2000) and post-earthquake (data acquired on 2006). The results (Figure 3B) reveal that total 17 km2 area of corals were degraded and recorded as exposed coral reefs in 2006. It was the part of the healthy coral environment earlier (2000).

The current study focused on the assessment of the spatiotemporal changes in the coral reef and mangrove of interview Island before and after 2004 Sumatra earthquake. This earthquake has caused lot of tectonic disturbances in the region resulted in the land up lift (Toiba et al. 2006 and Rajendran et al. 2008) up to a meter and half. The earthquake caused devastating tsunami taking the life of several people and resources, which has not left its impact on even mangrove and corals. This impact is catastrophic on the corals and whereas not that catastrophic when compared to coral. However, mangroves were recorded the spatial decline on relatively gradual time scale (Figure 2A). The mangrove change study was continued till 2010 to get clear scenario. The results of the spatiotemporal changes in the mangrove reveal net spatial decline of mangrove cover was 4.48km2 in the Interview Island (Figure 3A). The rate of decrease in the mangrove cover was 0.3km2/y during 2000 to 2006. But, it was decreased by 0.67km2/y during 2006 to 2010 in a span of 4 years.

Fig3: The bar diagrams showing spatial changes in mangroves during 2000-2010 (A), changes in the coral eco-morphology classes during 2000-2006 (B)

Fig2: The plate showing the spatio-temporal changes in the mangrove cover (A) and coral eco-morphology (B)

The tectonic induced uplift in the parts of the Interview Island caused the degradation of the coral reefs in the area. Further corals in the area were further subjected to the bleaching during summer months of 2010 by the elevated temperatures (Krishnan et al. 2011; and INCOIS, 2011) indicating the threat imposed on the coral environs in the area. The whole Andaman experienced the uplift in the northwestern parts and subsidence in the southeastern parts. The coasts experienced up-lift resulted in the degradation of mangroves in the up-stream area at the distal ends (landward side) of the coast due to reduction of the saline influence. The tendency of the mangrove community might move towards the proximal end (seaward side) with young/new mangroves. Conversely,


Geospatial assessment of Coral and Mangrove Environs of the Andaman Islands

mangroves degraded at the proximal end in the land subsided coasts due to the increase in the saline condition might result in growth of young/new mangroves at distal end. 6.

Conclusions:

The present study aims at demonstrating the geospatial techniques such as remote sensing and GIS to quantify the impacts of natural disasters on the spatiotemporal changes in the coral and mangrove environs. The data and techniques used in the study are able to quantify spatial changes at enhanced accuracy. Such studies are useful in understanding the damage caused on the important eco-systems. Further the study gives input to the eco-system modeling to understand diversity index and the implications on production in the coastal marine environment. 7.

Aknowledgements:

The authors would like to thank Dr. Shailesh Nayak, Secretary, MoES for encouragement. Authors are thankful to Director, INCOIS for facility and support. Thanks to CARI Andaman for support during in-situ campaign. Thanks to Global Observatory for Ecosystem Services (GOES), Michigan State University for the Landsat data. This is INCOIS contribution number. 8.

Reference:

[1] Bahuguna, A. Nayak, S. and Roy, D. (2008) Impact of the tsunami and earthquake of 26th December 2004 on the vital coastal ecosystems of the Andaman and Nicobar Islands assessed using RESOURCESAT AWiFS data, International Journal of applied Observation and Geoinformation, Vol. 10, pp. 229-237. [2] Blasco F, Gauquelin T, Rasolofoharinoro M, Denis J, Aizpuru M, Caldairou V (1998) Recent advances in mangrove studies using remote sensing data. Marine and Freshwater Research Vol. 49, No. 4, pp. 287–296. [3] Brian G. Long and Timothy D. Skewes (1996) A Technique for Mapping Mangroves with Landsat TM Satellite Data and Geographic Information System. Estuar Coast Shelf Sci Vol. 43, pp. 373– 381. [4] Chauhan HB, Dwivedi RM (2007) Inter sensor comparison between RESOURCESAT LISS III, LISS IV and AWiFS with reference to coastal landuse/ landcover studies. Int J App Earth Obs Geoinfo Vol. 10, No. 2, pp. 181-185. [5] Danielsen, F., Sørensen, M.K., Olwig, M.F., Selvam, V., Parish, F., Burgess, N.D., Hiraishi, T., Karunagaran, V.M., Rasmussen, M.S., Hansen, L.B., Quarto, A., Suryadiputra, N. (2005). The Asian tsunami: a protective role for coastal vegetation. Science Vol.310, pp. 643.

278

[6] Giri, C., Bruce, P., Zhiliang, Z., Ashbindu, S. and Tieszen, L.L. (2007) Monitoring mangrove forest dynamics of the Sundarbans in Bangladesh and India using multi-temporal satellite data from 1973 to 2000. Estuar Coast Shelf Sci Vol. 73, pp. 91-100. [7] Green, E.P., Clark, C.D., Mumby, P.J., Edwards, A.J. and Ellis, A.C. (1998) Remote sensing techniques for mangrove mapping. Int. J. Remote Sens Vol.19, No.5, pp.935-956. [8] INCOIS, (2011) Coral Bleaching Alert System, WWW.http://www.incois.gov.in/Incois/coralwarnin g.jsp, Accessed on 10 May 2011. [9] Jin, J., Shenghong, R. and Lingjie, Z. (2002). A study on the cost of coastal zone resources (in Chinese with English abstract). Marine Environment Science, Vol.21, No.1, pp.63-67 [10] Kathiresan, K. and Rajendran, N. (2005) Coastal mangrove forests mitigated tsunami, Estuar Coast Shelf Sci Vol.65, pp.601-606. [11] Krishnan P, Dam Roy S, Grinson George, Srivastava RC, Anand A, Murugesan S, Kaliyamoorthy M, Vikas N, Soundararajan R (2011) Elevated sea surface temperature during May 2010 induces mass bleaching of corals in the Andaman. Current Science, 100 (1): 111-117. [12] Lunetta, R.S. (1999) Remote Sensing Change Detection; Environmental Monitoring Methods and Applications. In: R.S. Lunetta and C.D. Elvidge (Eds), Taylor & Francis, London, pp 318. [13] Mahendra, R. S., Bisoyi, H., Prakash, C. M., Velloth, S., Sinivasa Kumar T., Bahuguna, A. and Nayak, S., 2008. Spatio-temporal Variations in the Coral Environs of North Reef Island, Andaman: A Remote Sensing and GIS approach, ISRS Symposium, Ahemedabad, India. [14] Mahendra, R. S., Bisoyi, H., Prakash, C. M., Velloth, S., Sinivasa Kumar T. and Nayak, S. (2010) Applications of the Multi-spectral Satellite data from IRS-P6 LISS-III and IRS-P4 OCM to Decipher Submerged Coral Beds around Andaman Islands. International Journal of Earth Sciences and Engineering, 3(5), 626-631. [15] Rajendran, K., Rajendran, K., Earnest, C.P., Ravi Prasad, A., Dutta, G.V.K., Ray, D. K. and Anu, R. (2008). Age estimates of coastal terraces in the Andaman and Nicobar Islands and their tectonic implications. Tectonophysics, Vol.45, pp.53–60. [16] Selvam, V., Ravichandran, K, K., Gnanappazham, L. and Navamuniyammal-Taramani, M. (2003) Assessment of community-based restoration of Pichavaram mangrove wetland using remote sensing data. Current Science, Vol.85, No.6, pp.795-797. [17] Singh A (1989) Review article—digital change detection techniques using remotely sensed data, Int J Remote Sens., Vol.10, No.6, pp989–1003.


279

MAHENDRA R S, MOHANTY P C, B ISOYI H AND SRINIVASA KUMAR T

[18] Srinivasa Kumar, T., Mahendra, R.S., Nayak, S., Radhakrishnan, K.R. and Sahu, K.C. (2012) Identification of hot spots and well managed areas of Pichavaram mangrove using Landsat TM and Resourcesat – 1 LISS IV: An example of coastal resource conservation along Tamil Nadu Coast, India. Journal of Costal Conservation, 26(3), 523534. [19] Tobita, M., Suito, H., Imakiire, T., Kato, M., Fujiwara, S. and Murakami, M. (2006) Outline of

vertical displacement of the 2004 and 2005 Sumatra earthquakes revealed by satellite radar imagery, Earth Planets Space, Vol.58, e1-e4. [20] Walters, J.S., Maragos, J., Siar, S. and White, A.T. (1998) Participatory Coastal Resource Assessment: A Handbook for Community Workers and Coastal Resource Managers. Coastal Resource Management Project and Silliman University, Cebu City, Philippines.
