The World Environment day is an annual event observed all over the world on 5th June to conserve and restore our degrading environment. This year's theme is "Forest: Nature at your Service", which is linked with the declaration of the UN to observe 2011 as International Year of Forest with the theme "Forest for People", highlighting the link between quality of human life, the health of forests and forest eco-systems.
People all over the world continue to put pressure on forests especially in densely populated areas where people are cultivating on marginal lands polluting the area and the overgrazing is contributing to desertification.
Forests of all types are giving valuable services to human and the services provided by the mangroves are well understood. The mangroves provide many multiple benefits and services to mankind, including some important ones like sustaining shrimp fishery, preserving biodiversity, serving as a sink for greenhouse gases and bio-filter for industrial effluents and protecting coastal infrastructures from erosion and destruction by storms and tsunamis.
On the occasion of the World Environment Day, it is good opportunity to put forth the plight of the Pakistan's mangrove forests and the authorities concerned are requested to restore and manage them. A few decades ago, the Indus delta mangroves were regarded as the 5th largest mangrove forest of the world, with a cover of about 200,000 hectares, but now their cover has drastically reduced to about 78,000 hectares. The World Mangroves Atlas, published by FAO in 2007, explained that Pakistan has so far lost 196,000 hectares of Indus delta mangroves.
Many factors responsible for this sharp decline may be due to hyper-salinity because of regular cut in the Indus river flow into the Indus delta, overexploitation of mangroves for wood and fodder and urbanisation. However, the mangroves of Karachi and along Korangi Creek are facing heavy load of solid and liquid wastes along with cutting pressure and changed inland use pattern. This situation is extremely alarming and will bring catastrophe to the already stressed mangroves.
The mangroves of Karachi need special attention because they help keep the city clean by absorbing the greenhouse gases and also the toxic substances contained in its industrial effluents coming through Lyari drain. In case of a storm or tsunami, they will act like a shield and prevent both human casualties. It is estimated that approximately 70% sewage is entering into the KPT waters through 7 major drains and 13 small drains. Total 400 million gallons of untreated effluents ends up into the harbour water.
Karachi Harbour spreads over an area of 62 sq. km and have 1,000 ha of mangrove cover at eastern and western backwaters. Healthy mangrove stands can be observed at the western backwaters while the mangrove covers at eastern backwaters is facing stress from the siltation load coming through Nehr-e-Khyam, Soldier Bazaar Nallah and City Railway Station Drain. The heavy loads of silts in 60 mgd of waste water filled the shallow waters and change the natural composition of the mangrove soil. The new recruiters of the mangroves find difficulty to establish resulting senile population.
All is not lost. Karachi Port Trust has planned to do remedial dredging in the channels of the China Creek. For this, CSD beaver dredger has been procured and placed at the China Creek. Strategy has been formulated and areas have been marked to be dredged on priority basis. Environmental consideration has also been taken care of. The disposal of the dredged spoil will be collected at the designated transferred sites /areas having erected bunds. The dredge slurries will be reduced to dry solids via a process known as dewatering. These hard cakes will be later on used in the road constructions. The China Creek will be restored by having its well-hydraulics regime and mangrove vegetation will flourish in the area.