Present state of the coastal environment in India
Elrich de Sa
The definition by the Land Ocean Inter. In the Coastal Zone [LOICZ] Science plan: "the coastal zone as extending from the coastal plains to the outer edge of the continental shelves, approximately matching the region that has been alternately flooded and exposed during the region that has been alternately flooded and exposed during the sea-level fluctuations of the late Quaternary period". This second definition is of the coastal domain from 200m above to 200m below sea levels which:
Most pollution in India arises from land-based sources - industrial & domestic wastes and agricultural run-off. Shipping and associated ship-building, breaking and port activities are becoming increasingly significant. The crop of recently started coastally located industries use sea-water as a resource and the coastal domain as a sink of altered sea-water [temperature and density]. These pose newer, more direct threats to sensitive eco areas.
Translating the table of cummulative discharges in the coastal seas to hot-spot locales, we have in:
A first compilation of the type and quantum of pollutants into the coastal ecosystem of India are given below:
Mumbai and around
The data, to date, indicated that the Indian
coasts have well circulated oxygenated waters, and that hot-spots remain contained within
Coastal Seas and Global impacts
What are we putting in?
What do we need to know and do?
We need to be able to predict the evolution of the coastal ecosystems for different global change scenarios and the effects of these changing coastal systems on social and economic activities and how we can improvise strategies for the sustainable management of coastal resources.
What are the problems in the way?
The coastal seas on the other hand undergo cumulative changes which though localised have global impact. An example is the entrophication of coastal waters leading to changes in carbon flow and its sequestration and the effect on the global carbon cycle.
The other major problem is the complexity of biological systems. Even in a localised environment, the species are numerous, the numbers are large, there are different metabolic rates, life styles and life expectancies. Environmental changes will affect species differently and thus their effect on the biogeochemical cycles will alter. Biological systems have a slowness of response to chronic a low levels of external forcing, and this buffering capacity delays or in some cases masks the eco-system response.
Coastal seas - regional & local
Physical processes operating along
Large-scale currents along the outer shelf and beyond, around India, reverse seasonally with the monsoon winds. The currents forming a continuum from the northern Bay of Bengal to the northern Arabian Sea.
What influences currents on the inner shelf ? It is expected that large scale currents, tides, winds and river run off play important roles. Tides, inds in season (and sea-breezes) , and river run-off would be the major influences nearest the coast. In the few instances of direct current measurements, the cross-shore components are tidal (towards shore on flow and away on ebb). The along shore component would vary with season and location and could be due to the seasonal coastal currents.
What is clear is the beneficial effect that the tidal currents have on the coasts of India. The along shore component that can carry pollutants coastally may never be significantly strong enough to counter the dilution effects during transport.
This seems to be consistent with the COMAPS data sets which indicate that India coastal waters are clean and well oxygenated with no detectable spread of "hot-spot" influence. The large rivers on the east coast also play a role in confining along shore pollutant transport. Their large run-offs acting as barriers to close to coast transport of pollutants & sediments. The movement and spread of the fresh waters of the Ganga and Brahmaputra however still needs detailed study.
It is important to understand shelf and estuarine (of which there are a very large number of varying sizes) circulation, so that through effective modelling pertinent information is available to decision makers on movement of pollutants, sediments and offshore hazards (oil spills).
Pollution on Indian Coasts
Metals, being a conservative pollutant, needs careful monitoring since they remain indefinitely in the environment without break-down. As yet our waters are clear.
DDT which has been banned in most Western countries had been widely used in Indian agriculture. It was responsible for increase in agricultural output and eradicating of several vector borne diseases. Its high toxicity nullifies its benefits. DDT and its somers, residues of Gama BHC, Aldrine and Dieldrine have been recorded in sediments in several coastal locations. Especially high concentrations have been recorded at the river mouths of the major east coast rivers.
Recent mining of organisms from the tidal and inter-tidal zone have revealed large numbers of molecules with obvious application for human health and industrial applications. This could be the most commercially important aspect of the Coastal Zone. Molecules that show bioactivity from one ecosystem may not show the same activity, or level of activity, when mined from a different locale or different season. This feature alone should be reason enough for the protection of all such ecosystems, and not only representative isolated units in protected areas / parks.
Considering that Indian waters are of a good quality and that pollutant sources remain relatively confined, the protection of sensitive environments, with adjacent buffer zones should be promptly notified and enforced. Losses of such areas are losses to the common good and future generations.
Sand dunes seem to be ecosystems that are most often destroyed, probably because their place in the scheme of dynamic coastal morphology, is not obvious. Suffice to say that dunes are the reserves that nature stores, dissipates energy on, and moves when needed.
The modelling approach
All these should, provide inputs to a future Earth System model.
As of date it needs to be appreciated, that the complexity of biological systems makes modeling difficult, and prediction of responses to changes more difficult. We cannot for instance say, if the present decline in tele-cast of biomass in the coastal seas does not feedback on global geochemical cycles, nor can we say that it does not. The fact that marine organisms occupy a true 3D world (compared to the 2D would of terrestrial organisms] compounds the modeling complexity.
Measurement and monitoring
The scheme for what parameters should be measured where, when and how often, is complex. It requires careful planning to maximise the data collected per unit of cost and effort. Monitoring schemes in sentinel organisms or choice of bio-makers, have to be carefully considered to ensure the natural availability of the same species along the Indian coasts. Choice of different species for different areas has to be carefully evaluated in the lab and in-situ.
Synoptic monitoring tools of moored buoys & remote sensing by satellites and by acoustics should be used where possible. They are some of the most cost effective monitoring tools of modern technology. Quality control through validation and calibration protocols and experiments, becomes an important aspect in this context. Geographic Information System, various data bases, rapid communication of alarms are other tools for successful monitoring, along with risk analysis and disaster management plans.
The business of models - new
perspective of an R&D Lab
Where do the social sciences come in?
These two aspects are complementary halves of a feedback loop that must be constructed, analysed and understood together.
Thus the anthropocentric, systemic, social science view of global change compliments the geocentric, cumulative, natural sciences view of bio-geochemical cycling. The coastal zones are important for both.
It is sometimes suggested that models of these 2 very different sciences can be proceed in one of 2 ways. Either the output of social science models feed as inputs to bio-geochemical models of coastal change [varying scenarios and projections] ; or vice-versa.
This is untenable. The space and time scales are so different that integration of the outputs of one model type as inputs to the other model type, is impossible.
The challenge therefore is to engage both
sciences simultaneously to get the scales right and to get the models right.
We began this talk with definitions and descriptions of the coastal zone, and then presented the case of India's coastal zone. Some hot spot locations were mentioned, but overall we conclude that our coastal waters are still in good condition. The activities of the Institute in the coasts, and the adoption of the LOICZ Science Plan were mentioned. A brief mention of our earth system was made, which was followed by the aspects of the global impact of the coastal seas. These were questions of what are we putting in, what do we need to know, what are the problems in the way, and the modelling approach.
The regional and local impact of the coastal seas was next discussed in terms of the physical processes operating, the pollution in our coasts and sensitive environments.
We then addressed the issues of modelling from the measurement and monitoring angle to the new perspective of an oceanographic laboratory that accepts that the state of the coastal environment has to be seen from 2 sides - the natural sciences and the social sciences.
Perhaps the Brundtland Reports sum it up best.
Sustainable development can be described as "the proper use and care of the coastal environment borrowed from future generations".
SD was defined a that which "meets the needs of the present without compromising the ability of future generations to meet their own needs".