Int. J. of Geology & Earth Sci., 2015 Arunkumar K S and Sabu Joseph, 2015 ISSN 2395-647X www.ijges.com Vol. 1, No. 2, September 2015 Research Paper © 2015 IJGES. All Rights Reserved LAND USE/LAND COVER AND SHORELINE CHANGES ALONG THE SOUTHERN KERALA COAST, SW COAST OF INDIA Arunkumar K S1* and Sabu Joseph2 *Corresponding Author: Arunkumar K S [email protected] Shoreline represents the dynamic boundary that separates beaches from the continual impact of waves, winds, surge, and tides. This boundary evolves over timescales of hours (e.g., changing tides or wave conditions) to decades. The term land use refers to the human activity or economic function associated with a specific piece of land, while the term land cover refers to the type of feature present on the surface of the earth. An attempt is made to study the land use / land cover and shoreline changes along the coastal tract of Thiruvananthapuram district (length = 70 km) which accounts 12% of the total shoreline of Kerala, confined between N. Lat. 8017' 33" and E. Long. 760 40' 18" to 770 5' 45". Survey of India top sheets of 1967 and 1989, digital data products of IRS-P6 of 2005 and IKONOS of 2005 are used for the study. The major land use/land cover categories identified in the decreasing order of abundance are coconut plantation (60%), followed by mixed plantation (25.5%), sandy area (12.37%), water bodies (8.27%) and paddy (2.9%). From the analysis of the shoreline, it has been found that the Kovalam-Poonthura sector (L= 5 km) is highly eroding (-130 m), followed by Vettur-Edava sector (L= 4.5 km) moderately eroding (-90 m) and Mudalapozhi-Mampalli sector (L= 5.15 km), moderately eroding (-50 m).High accretion (+140 m) is observed in the Karumkulam-Chowara sector (=6.19 km) followed by moderate accretion in the Pudukurichi-Mudalapozhi sector (3.0 km). Keywords: Shoreline, Land use/land cover, Thiruvananthapuram, IRS, GIS INTRODUCTION economic function associated with a specific An environmentally sound Coastal Zone piece of land, while the term land cover refers to Management (CZM) program heavily leans on a the type of feature present on the surface of the precise archival database or sets of baseline data earth (Lillesand and Kiefer, 2000). Both the land on land use/land cover and shoreline, and their use and land cover are closely related and are past changes as well as the state-of-the-art. The interchangeable. The interpretation of land use- term land use refers to the human activity or land cover can be directly used for the 1 Assistant Professor, Department of PG Studies & Research in Geology, MES Ponnani College, South Ponnani, Malappuram-679586. 2 Associate Professor, Department of Environmental Sciences, University of Kerala, Kariavattom, Thiruvananthapuram-695581. This article can be downloaded from http://www.ijges.com/current-issue.php 7 Int. J. of Geology & Earth Sci., 2015 Arunkumar K S and Sabu Joseph, 2015 development of the area through land use planning sensing data, which have proved to be of great (Sahi et al., 1985). utility in all fields of earth sciences, including the study of coastal processes, coastal zone Shoreline comprises a major element of the regulation, coastal zone management and urban earth’s landscape and the procedures that shape and land information system, due to the rapid, it are exceptionally complex (Pethick, 1984). repetitive, synoptic and multispectral coverage. Again, it is one of the most rapidly changing Usefulness of remote sensing as a very important landforms of the coastal zone. Geologic tool for gathering land use/land cover changes is processes such as erosion, deposition, well known and well documented (Luque, 2000; sedimentation, periodic storms, flooding and sea Yang and Lo, 2002). Satellite images have been level changes continuously tend to modify the effectively used for monitoring shoreline changes shoreline. The accurate demarcation of shoreline in different parts of India (De Solan et al., 2001). is therefore very important for planning conservation measures. Spatial data analysis, comparison of changes from multi-temporal data and presentation of According to Vink (1975) human activities results have become handy with the advent of stand out as the single largest force causing land Geographic Information System (GIS). Major use/land cover changes, and further Singh (1989) advantage of GIS is that it allows identification of suggested that this may occur due to both human the spatial relationships between features and action and change in environmental condition. temporal changes within an area over a period of These changes perturb the existing coastal time. ecosystem and play an important role in controlling the climate of that region. Again, these The coastal tract of Thiruvananthapuram changes have a key role in carbon cycling through district (Length = 70 km; Width = ~10.0 km, Area emission of greenhouse gases affecting = 700 km2) has been selected for the present hydrological and other earth system processes study, and this accounts 12% of the total shoreline (Mcconnel, 2001). of Kerala. It is confined between N. Lat. 80 17’ 33’’ to 80 46’ 43’’ and E. Long. 760 40’ 18’’ to 770 5’ 45’’ Another major problem faced by the coastal (Figure 1). Riverine zones, estuarine systems zone is shoreline recession due to coastal and canals are the major ecosystems; while erosion. This causes severe damages to coastal beaches and cliffs are the prominent geomorphic properties and ecosystems. It requires a detailed units in the study area. understanding of the nature and rate of shoreline changes, modifications to coastal ecosystems MATERIALS AND METHODS and changes in coastal land use/land cover to initiate interventions through shoreline Data sets on land use/landcover and shoreline changes within the 500.0 m landward of the management plans to contain the damages due shoreline of Thiruvananthapuram coast have to coastal erosion and land use changes. been identified and gathered from Survey of India The studies of coastal land use/land cover and toposheets 1: 50,000 (in 1967), 1: 25,000 (in shoreline changes have become easier with the 1989), aerial photographs on 1: 50,000 (in 1990) availability of high-resolution satellite remote This article can be downloaded from http://www.ijges.com/current-issue.php 8 Int. J. of Geology & Earth Sci., 2015 Arunkumar K S and Sabu Joseph, 2015 Figure 1: Location Map of the Study Area and satellite imageries of IRS-P6 LISS-IV and color with lighter tone. Thick vegetation and IKONOS-MS (in 2005) for analysis in a GIS plantation crops appear in dark red color. Since platform.The study comprises the interpretation the FCC are produced by the combination of of individual bands (B2, B3 & B4) and the False visible (B2 & B3) and near-IR (B4) band, the Color Composite (FCC), which is made by the spectral signatures of the earth surface features combination of different bands through digital are enhanced on FCC. Thus, FCC are extensively image processing techniques (Lillesand and used in the study, along with conventional digital Kiefer, 2000). processing techniques (Lillesand and Kiefer, INTERPRETATION OF FCC 2000). The turbid water bodies appear as blue patches, Land use/land cover study comprises the while the deep water appears as black. The digital processing of the data products of IRS-P6 brightest features in the FCC are the sandy areas. and IKONOS to extract terrain features. The Agricultural fields, urban areas, settlements, ERDAS 8.7 software on Windows XP roads and railway tracks appear in light yellowish professional operating system was used for the gray tone. The moist sand and the wet coastal digital processing of the data investigation. The structures like jetties exhibit light greenish yellow following steps, viz., image rectification, image This article can be downloaded from http://www.ijges.com/current-issue.php 9 Int. J. of Geology & Earth Sci., 2015 Arunkumar K S and Sabu Joseph, 2015 enhancement based on Fourier transforms and for geocorrection. The shoreline of 2005 was contrast stretching and image classification have digitized in ERDAS using Satellite imageries, IR been used in the digital image processing band that is suitable for the delineation of land- (Lillesand and Kiefer, 2000; Venkatachary et al., water boundary. Then these vector layers were 2001). brought to same projection and merged polygon topology was constructed for these merged METHODS FOR SHORELINE layers. Then area (erosion, accretion) was CHANGES obtained from the vector attribute table. Several methods have been suggested to RESULTS AND DISCUSSION accurately measure the position of shoreline from aerial photographs and satellite imageries with Land Use / Land Cover Study low error factors (Hequelte and Ruz, 1991; Chen The land use/land cover aspects of the and Ruz, 1998). Sea level data have been used Thiruvananthapuram coast are given in the Table as a surrogate data for the development of 1 and Figure 2 and 3. The coastal villages like shoreline position estimations for the ancient and Poovar, Karumkulam, Vizhinjam, Kulathur, projected shorelines (Crowell et al., 1997). Chirayinkizh and Anjengo are thickly populated However, among all the methods suggested, the leading to large-scale socio-economic problems. technique of Thieler and Danforth (1994) invokes Among these, Karumkulam is the most densely populated village (population= 11508/km2) in the the entire range of cartographic techniques State. The study area is generally constituted by required for the precise mapping of shoreline and settlement with vegetation and clustered associated geomorphic entities. This method has settlements in certain locations (Baba et al., been adopted in this study in respect of both 1998). The study area has a fishing harbour at satellite data and toposheet data. Vizhinjam and an international airport at The key aspects of the methods includes Shankhumugam.