Goa's rich and dying ecosystem -ToI

Goa's rich and dying ecosystem Apr 3, 2013, 04.39 AM IST Freshwater environments have attracted mankind since time immemorial, which is evident from the historical fact that all ancient civilizations were situated on the banks of perennial rivers or were at least in places where freshwater was easily available. Historical evidence further shows that the inhabitants of the state were hunters-gatherers during the early Stone Age, who slowly evolved during the Neolithic Period into craftsmen, farmers and herdsmen. In Goa today the priorities are industrialization, tourism and mining, as a result of which there has been no consideration for the state's wetlands which are the legacy of the agrarian society of the past. This latter fact is the main reason why our wetlands, used earlier for paddy cultivation, have degraded or even disappeared totally in some places. Swamps with big benefits Wetlands have been defined as swamps and other damp areas of land. But in common parlance the word is used interchangeably with lakes and paddy fields which denote a large body of water surrounded by land. A wetland is a transition ecosystem characterized by poor drainage and the consequent presence of sluggishly moving or standing water that saturates the soil either all or most of the time. The direct benefits of wetlands to mankind are in terms of agriculture, water supply, fishing and power generation. Indirect benefits are flood control, food chain support and biodiversity. The aesthetic benefits are creative stimulus and mental relaxation. In addition to providing mankind with basic requirements of water for direct consumption and irrigation, wetlands also provide fodder, fibre, etc, on account of their high productivity and rich plant resources. Goa's freshwater wetlands where paddy is cultivated are located on the banks of the River Zuari in Ponda and Tiswadi talukas, on the banks of River Mandovi in Sattari taluka and a few in Ponda and Bicholim talukas, and along the Cumbharjua canal in parts of Tiswadi and Ponda talukas. The wetlands in the coastal belt cover the talukas of Salcete, Bardez and Mormugao. All these wetlands are highly productive and are home to a variety of plant, insect and animal species. They also serve as gene pools. The plants growing in these wetlands act as traps for soil particles and nutrients in the water, especially wherever the water flows into and out of the wetland. Wetlands also provide a spawning ground for small fish species, many of which are edible. The dirty picture But the ever-increasing population and its ever-increasing demands on natural resources have led to various threats on the productive ecosystem of wetlands as well. In Cacora, Mullem and Xeldem, because of the easy availability of canal water the sluice gates of the wetlands are not closed by bunding thus allowing the streams to flow out. This has resulted in the running water carving narrow channels on the bed of the wetlands. Elsewhere, the lack of proper drainage systems and sewage treatment facilities in settlements adjacent to or upstream of wetlands has led to sewage flowing into the latter. Examples are the patches of wetlands around Bicholim, Vasco and Margao, which have turned entirely into sewage drains. This has also happened to wetlands in the vicinity of industries which release effluents contaminated with toxic waste. It is also observed that the residential colonies and associated commercial complexes along the state's coastline have destroyed wetlands and ponds of natural origin in Bardez and Salcete talukas. Man-made dangers A major part of Goa is covered by laterite aquifers which in turn are covered by tree and bush species such as Carey, Eugenia, Carissa and Zizyphus. These have the capacity to retain rainwater by creating an obstruction to flowing water during heavy precipitation and consequently the retained rainwater seeps into the crust in larger quantities. During dry spells these species act as an umbrella holding the surface temperature of the crust at a lower level than it would otherwise be. This is beneficial as the crust surface remains porous, biologically active and water-friendly. The lower surface temperature also reduces evaporation leaving the water table higher. Thus the augmentation of water held by these aquifers is increased significantly. None of the plant species mentioned above have any significant value as timber but are cut for firewood, mainly by migrant labourers working in the organized sectors of construction and quarries, and by bakeries and local hooch distillers. The removal of the vegetation cover from the laterite crust makes it harder, less permeable to water seepage and reduces its capacity as an aquifer. There is further contamination by sewage and effluents from industries situated on some of the major aquifers in the state. Even if the goods manufacturing processes do not produce any liquid effluents, various metal treatment agents, lubricants used for machinery, packaging, printing materials and fuels, in the long run, cause seepage of heavy metals such as cadmium, lead, mercury, organic matter containing various aromatic compounds, sulphur, phosphorus and nitrogen compounds during the rainy season into the aquifers. Time to stem the apathy The conservation of this unique ecosystem is imperative, and certain methods could be followed such as periodic desilting, disinfecting and water testing. To augment their capacity, small ponds can be dug on top of plateaus. Indigenous plant species can also be cultivated on top of these ecological formations. The construction of check dams and watershed development will also go a long way in augmenting the capacity of these aquifers. For wetlands, on the other hand, since they are large open spaces and cannot be isolated, precautions to avoid contamination of the water at large should be adopted. This can be via the construction of garland channels for waste water or sewage around the wetlands. These channels would prevent the water from entering the wetlands and the waste water thus collected could be sent to the effluent treatment plant before being released into the environment. This would take care of both the sewage from residential colonies and the effluents from industrial and commercial establishments. Finally, to protect this unique, transitional and highly-productive ecosystem of Goa, we should make ourselves aware of the correlation of geology, hydrology and hygiene. The writer is an associate professor, department of botany, Ponda Education Society's SRSN College of Arts and Science, Farmagudi, Ponda. http://timesofindia.indiatimes.com/city/goa/Goas-rich-and-dyingecosystem/articleshow/19353895.cms