Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

C. P. Priju ¹, A. C. Narayana ¹

Affiliations
1 Department of Marine Geology & Geophysics, Cochin University of Science & Technology, Cochin -682 016, IN

Abstract

In this paper, we present the textural characteristics, and Tanner's bivariate plots of grain size parameters to understand the depositional processes in a lagoonal system during the Late Holocene. For this purpose, 16 core samples recovered from the Vembanad lagoon, the largest backwater system on the west coast of India, were investigated. In northern and southern sectors of the lagoon, sand is the dominant textural facies, while in the central sector mixed textural facies - muddy sand and sandy mud - are prevalent. Suite statistics suggest that open- and closed-basin conditions prevailed, which punctuated the high and low energy conditions. High-energy conditions prevailed in northern and southern parts of the lagoon, particularly in areas close to the river mouths. Other parts of the lagoon exhibit low to moderate energy regime and open-to-restricted estuarine conditions. The study emphasizes that the bivariate plot is an extremely useful tool in distinguishing between open- and closed basin conditions in coastal environments.

Keywords

Sedimentological studies, Depositional environments, Vembanad Lagoon, Kerala, Southwest coast of India.

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A. C. Narayana ¹, C. P. Priju ¹

Affiliations
1 Department of Marine Geology and Geophysics, Cochin University of Science & Technology, Lakeside Campus, Cochin - 682 0 1 6, IN

Abstract

The coastal landforms and land use/Land cover changes of central Kerala have been studied with the aid of topographic maps, satellite images and extensive field checks. The landforms identified are barrier islands, beach ridges and swales, strandlines, flood plains and marshy swamps. Several parallely positioned barrier islands and paleo-Beach ridges reveal that the central Kerala coast has been prograding. It is observed that the evolution of coastal landforms is influenced by the fall in sea level and/or uplift of the coast. Extensive occurrence of strandline/Chenier deposits supports the view that the rivers of central Kerala once have supplied enormous amount of sediments.

Land use/Land cover changes, which have occurred during 1966-1995 are quite alarming. The reduction of about 50% in both flood plain and river channel area is due to changes in the land use pattern. Significant changes in the shoreline and morphology of river mouths are recorded. Area of accretional shoreline is more than that of erosion-Prone shoreline. Major morphological changes are observed near the Cochin inlet. The factors affecting the shoreline and landform changes are natural as well as anthropogenic. The natural processes affecting the shoreline changes are sediment supply, coastal processes, and anthropogenic activities such as dredging. Important factors affecting the land use/Land cover changes are reclamation of land for agricultural and industrial purposes, and sand mining in riverbeds and paleostrandline areas.

Keywords

Coastal Landforms, Shoreline Changes, Paleostrandlines, Remote Sensing, Kerala Coast.

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A. C. Narayana ¹, C. P. Priju ¹, A. Chakrabarti ²

Affiliations
1 Department of Marine Geology and Geophysics, Cochin University of Science and Technology, Lakeside Campus, Kochi - 682 016, IN
2 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur - 721 302, IN

Abstract

No Abstract.

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