Coastal processes

          Quaternary Coastal Evolution

          Sea Level Changes

          Coastal dynamics

          Estuarine dynamics   

Quaternary Coastal Evolution and Sea Level Changes

The Quaternary period was characterised by exceptional climatic oscillations and sea level changes. Quaternary studies, ranging from modern process studies to mapping, dating and analysis of Pleistocene and Holocene deposits, are in progress in many countries.

Geologists have sought to determine the episodes of marine transgression and regression and worldwide efforts are currently on to achieve precision in establishing the sea level curve. Since long, consequences of oscillating sea level on the coastal region have been recognised. Only limited scientific information on Quaternary coastal evolution and sea level changes is obtained in India.

To further Quaternary research, a well co-ordinated integrated multi-institutional programme with optimum objectives and financial support from premier departments is highly essential

In association with Cochin University of Science and Technology, CESS is investigating the evolution of the Kerala coast during the late Quaternary period in terms of sea level changes, palaeooceanography and palaeo-climate.

The studies are being carried out in the northern Kerala coast (Kannur and Kasaragod districts) along two EW trending transects. Based on the study of the nature of the litho-units, chronostratigraphic disposition of the coastal land deposits has been attempted. An indicative sea level curve was derived for the last 33,000 years based on biotic bathometers, which stretch beyond the LGM. The bottom sediments of the innermost ridge may belong to the 5e oxygen isotope stage representing the last interglacial maximum. A derivative model of the evolution of this coast is being attempted based on the results.

Sediment dynamics:

Multi-date sequences of images show very distinct differences in the distribution pattern of chlorophyll and suspended sediment concentration (SSC). High concentration tongues of SSC extending into offshore, characterize nearshore regions of some of the inlets, viz., Valapatnam, Beypore and Kochi. Precluding a few locations for brief spells, the drift and dispersion is essentially southerly irrespective of seasons. Chromaticity transformation for mapping SSC using the LISS III data has been shown to be promising but needs improvisation
with extensive sea truth data.

Prediction of shoreline changes:

Long-term changes in shoreline position were mapped using the 1982 toposheets, IRS 1A LISS II data of 1990 and IRS IC LISS III of 1999. Striking changes are observed around the inlets. Several of the inlets have shown an accreting tendency along the northern spit and erosion along the southern spit. The net southerly drift (as identified from the OCM data) obstructed by the inlet flow might have resulted in the growth of northern spit in many cases. Coasts away from the inlets appear to be relatively stable, but localized erosion/accretion are not uncommon. A model for prediction of shoreline changes is being developed.

Dynamics of tidal inlets:

Studies on temporal and spatial migration and offset of Valapatnam, Ponnani and Munambam inlets were carried out. In the case of Ponnani inlet, the southern spit shows northward drift of the northern arm with a consequent withdrawal of southern spit. Considerable estuarine-ward drift is also noticed for both the spits. Width of the inlet mouth has drastically reduced over a period of time, since 1966-67. The role of flood/ebb tidal deltas in modulating the inlet migration is being examined.

IRS P4 OCM Utilisation Programme

The high spectral and temporal resolution of IRS-P4 satellite with Ocean Colour Monitor (OCM) onboard provides an opportunity to study the coastal rocesses of Kerala. CESS with its vast field knowledge in coastal oceanography is a natural partner in this group endeavour of sensor validation, algorithm development and study of coastal processes. The main objectives of the project are:
a) Study of transport and dispersal of suspended sediments in the coastal zone

b) Detection and mapping of coastal currents and sedimentation

c) Estimation of seasonal and long-term changes in beach morphology

d) Mapping and monitoring of accreting, eroding and stable areas

e) Study of the impact of dumping dredged material on the coastal zone

f ) Development of numerical model to simulate shoreline positions

g) Monitoring of tidally controlled estuarine areas for sediment concentration and dispersion

h) Study of historical development of coastal inlets and understanding of the temporal/spatial migration and offset of the tidal inlets in varied geomorph-ological set-up and development of a simulation/prediction model.