We discuss here (in a series of notes) about developing viable strategy for sustainable development of coastal regions. The planning, though, expected to be seriously handicapped by considerations of prospective climate and ecological changes, still has viability by adopting dynamic strategies, where the broad-based ecological information is holistically integrated with development goals and execution decisions. Satellite data plays a very important role in evolving the decision support system.

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Since time immemorial, most of the population concentration has been either in the coastal regions or on banks of river primarily because of easy water source to support life and commercial activities. Hence, developmental efforts in these regions have played very important role in economics. The resultant pollution has been routinely disposed off directly or indirectly in to the seas. This contribution together with the natural contribution due to natural decay in the biotic system, and sediments from rivers & coastal erosion (caused by storm & tidal surges and wave action) has reached enormous proportions in recent times to, the extent that this global built-up of coastal pollution has become very serious threat to very existence of our planet.

The coastal pollution is routinely being neutralized by the ocean, called ocean   resilience, whereby the ocean does an active self purification through dilution of pollutants (because of naturally occurring mixing processes), fixing of some of the pollutants (by conversion to inorganic salts which are later on deposited at ocean bed) as well as re-distribution by ocean currents. Though, nutrition and oxygen deficiency is produced locally as a result, the rate of self-purification has been larger than the rate at which pollution was added to it and over a period (say a decade) the oxygen and nutrients too are redistributed ensuring a complete revival. This process of resilience, obviously, has a limit beyond which any overburdening is expected to weaken the natural filter. The transport of pollution elsewhere by ocean dynamics makes local pollution built-up a global concern.

In this self-purification process, coastal eco-system (encompassing a large bio-diversity) acts as an eco-scavenger. Even a partial loss of this bio-diversity, will have a cascading impact on the health of the coastal environment and ultimately impact economy. Let us take mangroves and coral reefs as example. The mangroves show a remarkable preference for low salinity (salinity <10 ppt) and coral reefs prefer relatively cooler waters. A rise in temperature will tend to shorten the life span of coral reefs, while increase in salinity will push mangroves inland and eventually a complete loss. These sub eco-systems are also home to a variety of bio-diversity which will also disappear eventually. This disappearance (or even a reduction), in turn, will reduce its capacity to protect the shores and hence accelerate coastal erosion. The erosion, in turn, might endanger human settlements, enforcing migration of human population inland and also lead to salinity ingress inland. This cascading impact of environment degradation, therefore, should be a major concern while planning and executing development along the coast.

 A concerted global effort for conserving environment was made in 1992, when world leaders met for Earth Summit at Rio-de-Janiero (Brazil). Since then, IPCC has been very aggressively active to prepare global scenario of environmental degradation at all levels, prepare primary recommendations to mitigate it. Many countries have subsequently framed and enacted regulations to mitigate the alarmingly deteriorating situation. India too has taken a lead by enacting coastal regulatory act (1991) amended in 2001 and reframed in 2011 supplementing the pollution control act of 1974. The coastal regulations are enforced for up to 500m inland from High Tide Line (HTL) and it stipulates that pollution further inland is controlled by Control of Pollution Act 1974 (section 6 of 1974 referring to water effluent treatment and discharge to rivers). These regulations are still not adequate and a large amount of untreated water and air pollution is added unceremoniously. Ganga pollution is a glaring example, where the pollution concentration in its estuarine zone has rendered the largest estuarine eco-system of world, Sundervans, a very sick area.

Pollution Causes Degradation in Water Quality

The degree of pollution in the coasts is best estimated in terms of water quality. The coastal water quality is a function of mixing of sediments and pollution (both chemical and biological) in it. The water quality degradation not only endangers eco-system, but also has very large impact on human life. It compromises the natural food chain and promotes build-up of harmful organism (like algae), fish breeding is lost, and the water cannot be purified for human use. The coastal settlements are threatened as the inhabitants loose livelihood opportunities and may have considerable public health threat. This aspect has been found to be a strong reason for large scale migration many times in past leading to socio-economic catastrophe to the extent that whole civilizations have been wiped out (loss of Indus civilization is one example). Interestingly, the very industries and commercial activities which are chiefly responsible for pollution, are also threatened by a colossal loss to the establishments, in turn, impacting the economy severely.

The anthropogenic sources for the non-sedimentary pollution in the coastal water can arise from coastal zone itself in terms of treated and un-treated waste discharges from municipal sewage system, industrial & commercial activities, direct dumping of waste in sea by local populace and ships, waste disposal from cargo handling at ports and jetties, waste generated from the exploration and exploitation of marine resources, accidental pollution due to oil spills etc.  There are diffuse sources too like precipitation of pollution in air, runoff from agricultural field containing remnants of fertilizers and pesticides, pollution in the estuarine zone through inadequate waste management upstream etc. The sedimentary pollution arises from dumping of silts in ocean, dredging to deepen the harbours and indirectly by accelerating coastal erosion by coastal deforestation and coastal mining.

To top the local effects, the degradation of coastal eco-system is further compromised due to global warming. Studies have shown that global warming of about 0.5°C will lead to a global sea level rise of about 50 cm, increase the intensity of sea waves and the storm surges. Consequently, the mangroves will be pushed inland, lose the bio-diversity and thereby all the coastal defences against erosion. Apart from threatened inundation of lower regions on the coast, the erosion severely redefines the coast line and cause further threat to the coastal settlements, industrial and commercial establishments.

Planning Needs to Ensure Integrity of Coastal Water Quality

It has been proved through many experiments that a dynamically measured integration of environment with the pace of development might be the solution to lessen the impacts. The key is to get a dynamic estimate of the ocean revival process which keeps on changing with time (as pollution builds up) and keep the pollution concentration at a lower rate than it. The strategy could also encompass inclusion of “selective rejuvenation”. Let me illustrate it. We know that the mangroves, coral reefs and mud-flats act as breeding places for marine life supported by a complex food chain with in the bio-diversity. The overfishing in these regions will upset natural food chain, and the economic output will decrease over time. In fact, excessive fishing returns poor gain any where over a period. In an effort to reverse the losses, the local government could decide to divide the fishing area in blocks, permitting fishing in alternate blocks rather than random as is generally the practice. This selective period of rejuvenation will provided crucial time for nature to regenerate and improve quality and quantity of marine fish.

The understanding of ocean dynamics and associated self-purification processes needs systematic analysis of timely environmental information in conjunction with predictions from geo-bio-chemo-physical modelling on continuous basis. Thereafter, the development planning responsibly uses these estimates to design controls on the pollution released to coastal waters. The ocean information system (like COMAPS in India), thus, becomes an integral component of the development planning and monitoring process. A complete decision support system for such purpose will comprise the following components:

1. Synoptic information of pollution emanating from potential point sources in coastal region (e.g. industrial and municipal waste discharge systems in coastal regions),

2. Synoptic information on commercial activities (like coastal fishing, marine harvesting and other commercial activities) having potential to cause environmental degradation.

3. Synoptic information on far off diffuse pollution sources to facilitate estimates for net pollution build-up in estuarine zones
4. Synoptic information of air-borne pollution dispersal to the coastal regions and its interaction with marine atmosphere through precipitation and direct mixing in sea water,
5. Assessment of degradation in water quality and coastal bio-diversity
6. Modelling of bio-physical state of ocean including sediment transport to assess the impact of net pollution load on the bio-physical environment of the coastal region.
7. Assessment of coastal climate changes and impacts on the environment with projected scenario for a proposed development initiative.
8. Integration of mitigation schemes together with continuous monitoring to ensure minimum degradation to the coastal & marine environment.

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There will be subsequent parts of this note containing information on:

Part II: Illustrative examples of construction of coastal goodness indices as quantitative assessment of the impact factors

Part III: Illustrative decision support system for coastal application