Scientists, environmentalists and fishing communities agree that the impact of Asian tsunami was considerably worsened by shrimp farms and other industrial developments which destroyed or degraded mangrove forests and other natural sea defences. With the loss of mangroves, the potential of damage from tsunami is maximized.

The tsunamigenic earthquakes in Indian ocean occur mostly at the three locations (1) Andaman sea; (2) An area measuring about 400-500 km SSW of Sri Lanka; 3) Arabian Sea- about 70-100 km south of Pakistan, off Karachi and Balochistan.

The tsunami record dates back to November 326 BC earthquake near the Indus delta/Kutch region. At that time, Alexander the Great while returning to Greece after his conquests, adopted a sea route. But an earthquake of large magnitude destroyed the mighty Macedonian fleet. There are seven records of tsunamis set off by earthquakes near Indonesia, Pakistan and one at the Bay of Bengal in the last century. Though rare and relatively unheard of, tsunamis have also struck the shores of South Asia in the past.

The last major tsunami-generating earthquake in the Arabian Sea was on November 28th, 1945. More than 4000 people were killed on the Makran Coast by earthquakes and the tsunami.

The magnitude of earthquake on Richter was 7.8. Its epicenter was at 24.5 N 63.0 E in the northern Arabian Sea, 87.1 km SSW of Churi (Balochistan), 97.6 km SSW of Pasni (Balochistan), 98.5 km SE of Gwadar (Balochistan), and 408 km west of Karachi (Sindh).

The tsunami reached a height of 40 feet in Makran and caused great damage to the entire coastal region. Waves completely destroyed and killed all the people of the fishing village of Khudi, some 30 miles west of Karachi.

At Dabo creek, 12 fishermen were swept into the sea. The towns of Pasni and Ormara were badly affected. Both were reportedly "underwater". Pasni's, postal and telegraph offices, government buildings and the rest houses were destroyed. Number of people were washed away. The tsunami was also recorded at Muscat and Gwadar.

At Karachi, the tsunami arrived from the direction of Clifton and Ghizri. It ran along the oil installations at Keamari and flooded a couple of compounds. The waves were 6.5 feet high in Karachi. There was no damage either to the port or to boats in Karachi Harbour.

Pakistan was also hit by Tsunami on May 20, 1999, unimaginatively code named as, "Tropical Cyclone 2A". Tsunami that submerged 600 coastal villages in Thatta and Badin district, was responsible for the death of at least 400 people.

Cyclone 2A reached the coast of the Arabian Sea causing the sea water to gush 10km inland of the coast. The Cyclone 2A is said to be the biggest cyclone to have hit this area in this century. At least 164 bodies were found from Raj Malik village in Thatta district. Another 100 fishermen or more were caught on their boat.

The infrastructure for water and power supply was completely destroyed. Also the road and telecommunications were cut. The coastal area was completely cut off from other areas.

The damages to crops and livestock were tremendous. The officials said as many as 60,000 hectares of farmland were destroyed. In the Shah Bunder and Ketty area alone, 152,000 acres of farmland were lost. Environmentalists said that such the devastation would have been minimized, had there been a fully developed mangrove to act as a barrier.

When the British, under Sir Charles Napier, annexed Sindh in 1843 Karachi was a fishing village with a small-gated fort and a ditch or moat called Kalachi-jo-Kun. It had two gates, Kharadar (salt water gate) facing the sea and the other called Mithadar (sweet water gate) facing the Lyari River.

Karachi's location on a backwater opening south between Cape Monze and the Indus delta was designed to be protected from the sea. The natural harbor formed by a sand spit was mainly responsible for Karachi's evolution as a seaport. The city was bounded by what was once the island of Kiamari but which, as a result of reclamation, is now joined to the coast.

After British occupation and prior to improvements, the backwater filled and emptied with every tide and at low water there was a stretch of mud flats and mangrove swamps.

The backwater currents were a real asset on a coast prone to severe silting and it is to this that the port owes its early development by Hindu merchants at the beginning of the 18th century.

Over the past five decades, many of the wetlands has been reclaimed by disrupting water sources or by drainage. The reclaimed lands are used for agriculture or urban/industrial developments.

The inter-tidal areas at Clifton Beach have been reclaimed for city expansion. The posh residential area of Karachi is now located on the coastline. Additional coastal areas are being reclaimed for new residential schemes. Whereas, these reclamations are being carried out without giving due consideration to the implications of reclamations on the coastal dynamics.

Pakistan's second largest port, Port Qasim, has been established in the Korangi Creek area is spread over thousands of acres of mangrove forest. Both, the port and a nearby steel mills, are flanked by a new town, which houses people working in the two giant complexes. Thermal pollution and solid wastes originating from these sources are degrading the mangroves ecosystem.

Similarly dredging operations in the channels and creeks leading to the port, and needed for navigation, have a detrimental effect on the young seedlings and pneumatophores of mangroves as sediment cover cuts off their oxygen supply.

The deepening and widening of a 45km long navigational channel in the Phitti Creek that connects the port with the open Arabian Sea, has apparently created a coastal erosion problem in the area and so far resulted in the massive destruction of barrier islands which used to act as the nature's first line of defence against coastal erosion.

Indus delta area is considered as very important due to the presence of arid mangrove ecosystem which is the seventh largest mangrove forest in the world. The area covered by the mangrove is about 129,000 ha, 97 percent of the total mangrove area.

The major species in the delta is the Avicennia marina, with 95 per cent of the total mangrove population. Other threatened species of mangroves in the area are Rhizophora mucronata, Ceriops tagal, Aegiceras corniculata.

The delta area supports the large stand of mangrove forest to maintain the delta habitat. The estuarine creeks and mangrove area are the nursery ground for many species of fish and shrimps.

They spend critical time of their life in these habitat till they reached at certain age. Mangroves also provide shelter to many aquatic as well as terrestrial species. They are also important staging ground for migratory birds.

The delta area regularly support more then 60,000 migratory waterfowl each year including some threatened species. The estuarine creeks, and mangrove area are the main nursery ground of fish and shrimps and all these species spent their early stages of their life and depend on these habitat.

Due to the reduction in the mangrove cover, loss to fishery production is significant. About five to six thousand families of fishermen are associated with fishing profession. Estuarine system (coastal area), supports most important activity of commercial fishing.

After independence, more and more land was converted to agriculture use. In this process of transformation, natural vegetation, which originally occupied that land, was destroyed/grazed for cultivation of agriculture crops.

Expansion of agriculture and subsequent industrial development led to the need for conserving water for agriculture purpose and power generation through construction of reservoir on Indus and its tributaries.

The economic priorities over ruled ecological consequences that were bound to follow in years to come. An intricate system of canals, barrages and reservoirs was constructed to transfer supplies from Indus, Jhelum and Chenab rivers to the areas formerly fed by eastern rivers, to compensate for water supplies lost to India under the Indus Water Treaty signed between India and Pakistan in September 1960.

As a consequence, the river below Kotri shows increased braiding and sand bar development. Sediment passing down the system tends to be deposited in the section south of Kotri, rather than maintaining the growth of the delta. As a result the Indus Delta that once used to occupy an area of about 6,180 km2 consisting of creeks, mudflats and mangrove forest is now reduced to 1,192 km2. These constructions have affected water flow reaching Sindh.