ECO-CHRONICLE 13

ECO CHRONICLE ISSN: 0973-4155 Vol. 12, No. 1, March, 2017 PP: 13 - 16

GEOSPATIAL STUDY OF SASTHAMKOTTA RAMSAR , , SOUTH WEST

Prijilal K.G1, Revathy Das2, Krishnakumar A2* and Dhanya T. Dharan3

1Ministry of Environment, Forest and Climate Change, . 2ESSO- National Centre for Earth Science Studies (NCESS), Ministry of Earth Sciences (Govt of India), Akkulam, -695011, Kerala. 3Scientific Response to Environmental Developmental and Human Arenas (SREDHA), Palayam, Thiruvananthapuram-695033, Kerala Corresponding author: [email protected]

ABSTRACT

The present study confines to the variation in the areal extension of the different land use/land cover categories during the period from 1966 to 2004 in Sasthamkotta wetland region, as a wetland of International Importance (Ramsar site). Temporal land use changes are delineated with the help of remote sensing and GIS techniques. Survey of India toposheets [1966 - scale 1:50,000 and 1988- scale: 25,000] and IRS LISS III images are used in this study for deriving the temporal changes. The toposheets and imagery are digitized and maps for the concerned periods are prepared. The three maps are brought into uniform scale and overlaid in GIS software for detailed analysis in order to understand the land-use/land cover changes over the years. From the analysis, it is found that the land use/land cover pattern of the study area showed a marked difference in areal extension of different categories. The field survey also indicated that large scale conversion of paddy fields took place in this area. There is a drastic decline of paddy fields from 9.13 Km2 to 2.89 Km2 during the past 40 years and such a change is due to the reclamation for various needs. Since the rubber cultivation has increased over the years, the area under plantation category also increased. Population pressure imparted tremendous changes in the land use pattern of the surrounding regions of the wetland ecosystem, especially due to house and other constructions, as part of various developmental activities taking place in the area. The need for adopting sustainable agricultural and developmental activities, in order to conserve the wetland region is also discussed.

Keywords: Land use, Spatio-temporal changes, Sasthamkotta , Wetland, Conservation

INTRODUCTION

Wetlands, the transitional zones between permanently resources (Ruchira et al., 2007). Sasthamkotta lake and aquatic and dry terrestrial ecosystems, are among the its surroundings are under severe environmental stress world’s most productive environment (MoEF, 2010). A wide especially due to large-scale land use/land cover variety of like marshes, swamps, open water conversions that is occurring in and around for the past bodies, mangroves, tidal flats, salt marshes etc. exists in several decades (The Hindu, April 9, 2013). Hence this our country. Wetlands are considered life support systems study has been undertaken to identify the extent of and provide a wide range of services critical to human changes took over in the wetland region over the past 40 development and well-being, and functions as the ‘Kidneys years and to suggest future sustainable conservation of the landscapes’. measures.

Wetlands of Kerala are considered as sites of exceptional STUDY AREA biodiversity in the country and are characterized by several endemic species. Sasthamkotta, -kol Sasthamkotta lake is the largest fresh water lake of Kerala and Ashtamudi are the three designated Ramsar sites of and is located in the outskirts of town, approximately Kerala. But wetlands of Kerala are subjected to 29 km North-East (Fig.1). This lake covers an area of anthropogenic pressure through mining activities, water around 375 hectares and physiographically in the midland abstraction, changes in the natural flood regime, land region between 9 0’- 9 5’N latitude and 76 35’-76 reclamation, pollution and over-utilization of natural 46’E longitude. p p p p 14 ECO-CHRONICLE

The present study quantifies the changes in the areal as dumping of human wastes, soil erosion due to extension of different land use/land cover categories of destruction of vegetation, changes in land use pattern etc., Sasthamkotta Lake and its adjoining regions from 1966 leading to the deterioration of environmental quality (Salin to 2004 and its effects in the wetland environment. et al., 2013). Preliminary field survey showed that there are changes in the land use patterns. A region encompassing a total area Sustainable management of Sasthamkotta wetland of 55 sq.km in and around Sasthamkotta wetland region ecosystem is necessary as it serves the important functions has been taken for this study. The present work is carried such as food storage, water quality maintenance and out using remote sensing and GIS techniques for the providing habitat for different species of flora and fauna. identification of spatio-temporal land use changes in the Since wetlands are regarded as one of the threatened Sasthamkotta wetland region. ecosystems, an analysis of the nature and rate of environmental changes over the past several decades are MATERIALS AND METHODS essential for proper understanding of the present environmental set up and to determine the problems in To derive temporal changes, thematic maps depicting the various attributes. In this respect, information on the existing spatial distribution of previously existed land-use are land use/land cover pattern is a pre-requisite for planning, prepared from the Survey of India toposheets (1966 having utilisation and formulation of policies and programmes for scale 1:50,000). The land-use areas are delineated from making any micro and macro-level development plan. the toposheet and brought together in corresponding scale and the recent data (2004) pertaining to this area is The above shows the trend in land-use changes of prepared from the LISS 111 satellite imageries. All the Sasthamkotta wetland region during the period 1966 to maps are digitized following uniform scale and overlaid in 2004. The spatial distribution of land-use pattern of the GIS software for the detailed analysis of the variation in study area shows marked difference in the areal extent of areal extension of wetlands over the years. The extent of different classes from 1966 to 2004. land use changes during the period of 1966 and 2004 are calculated and shown in Table.1. Fig.2 and Fig.3 shows In 1966, mixed crops covered an area of about 52.12% the various land use categories during the period 1986 and have come down to 30.52% in 2004. Rubber and 2004 respectively. plantations and built-up area replaced the mixed crops with RESULTS AND DISCUSSION an increase from 3.22% to 16.6% and 1.76% to 17.18% from 1966 to 2004. Studies by Suraj et al. (2013) reported Sasthamkotta wetland is facing severe environmental that the replacement of mixed crops to plantation crops is degradation due to various anthropogenic activities such mainly due to the profit gained by the cultivation of plantation crops. Fig. 1 Location Map of the study area Population pressure and other developmental activities imparted tremendous changes in the land use pattern of the surrounding regions of the wetland ecosystem, especially due to housing and other constructional activities taking place in the area. Similar studies by Krishnakumar (2002) in and basins reported that the encroachment of local people residing nearby areas and planters aggravated the rate of destruction of wetlands. Cropland category ECO-CHRONICLE 15

Fig. 2 Land-use categories in Sasthamkotta Wetland Fig: 3 Land-use categories in Sasthamkotta Wetland region during the period of 1996 region during the period of 2004

Table1. Area and percentage of various land-use catego- these activities are taking place without any consent by ries of Sasthamkotta wetland region during 1966 and 2004 the concerned authorities, the wetland area has drastically and the changes observed during the periods. diminished and hence the built-up area shows a remarkable increase with that of 1966. Land use 1966 2004 Changes types (Km2) Area % Area % CONCLUSION (Km2) (Km2) Addition (+) Depletion The present study focussed on land-use changes of (-) Sasthamkotta wetland region during 1966-2004 period Mixed 28.67 52.12 16.79 30.52 -41.44 with the help of Remote sensing and GIS. Increase in Crops population density and reclamation are the main factors Plantation 1.72 3.22 9.13 16.6 +81.16 triggering the land use conversion in this wetland region. Spatio-temporal analysis reveals that the peripheral Built-up 0.97 1.76 9.45 17.18 +89.93 areas of the Sasthamkotta Lake have been drastically Cropland 8.09 9.13 3.33 2.89 -14.29 changed over the years. The study calls for the need for sustainable agricultural and developmental activities in mainly consisting of paddy fields showed a decline in their order to conserve the Sasthamkotta wetland region, and area from 9.13% to 2.89%. Reclamation of paddy fields thereby the conservation of the precious fresh water for settlements and conversion of paddy fields for the body. cultivation of plantation crops are the main reasons behind these remarkable changes. ACKNOWLEDGMENTS

Owing to the demand existing for new lands for constructing The authors thank Director, NCESS for encouragement new buildings, the wetlands/paddy fields are reclaiming at and support. Facilities provided in Centre for Geo- an alarming rates in the Sasthamkotta wetland region. After information Science and technology, University of Kerala, reclamation, the lands are selling at higher prices. Since is gratefully acknowledged. 16 ECO-CHRONICLE

REFERENCES Krishnakumar, A. 2002. Environmental degradation of Neyyar and basins of Southern Kerala. MoEF, 2010. Draft Regulatory Frame work for Wetlands Ph.D. thesis (unpublished) University of Kerala. Conservation for Comments, Govt. of India. Suraj and Neelakantan, 2013. Detection of land-use pattern Ruchira Chaudhary and Rachna S. Pillai, 2008. Studies changes and management priorities for Thrissur District. on the physico-chemical characteristics of International journal of Remote Sensing. Vol. 2. Sasthamkotta Lake with reference to suitability with aquaculture. Journal of Environmental Research and Salin Peter and Sreedevi, 2013.Qualitative evaluation of Development. Vol. 2. Sasthamkotta Lake by using GIS. Vol. 3.