The intrusion of the Arabian Sea into the mouth of the Indus River on Pakistan's southern coast is eroding land, forcing whole villages to relocate inland, and threatening fishing livelihoods, residents and environment. As sea levels rise globally, low-lying coastal areas become vulnerable to the incoming saltwater.
The Senate's Standing Committee on Science and Technology issued a letter to Prime Minister Nawaz Sharif in March 2015, expressing fears of the seriousness of sea intrusion along the coastal areas of Sindh and Balochistan which can result in the sinking of Badin and Thatta in a period of 30 years, followed by Karachi.
The sea’s intrusion into the once-thriving Indus Delta in the coastal Thatta district occurs mainly because the Indus River does not carry enough water below the Kotri Barrage, a major dam 190 miles north of the coast, to hold back the saltwater from the river and its network of creeks and mudflats. The seawater intrusion turns fields and underground drinking water saline, makes land waterlogged and reduces fish catch.
Current rate of erosion, the 6,700-square-mile district of Thatta, with its population of 1.1 million, could be gone by 2025.
Over the past 30 years, the Arabian Sea has devoured about 1.2 million acres (1,875 square miles) of land from the coasts of both districts. According to Pakistan’s National Institute of Oceanography (NIO) nearly 3.5 million acres of agricultural land in Sindh had been eroded since 1956.
"The Sindh Development Review 2008-2009,” a provincial Planning and Development Department report, cites a study estimating Keti Bunder mudflat erosion at 66 feet per year with the rate in one of the four major creeks near the town was as high as 5,500 feet per year.
Though no official records exist, 34 of the sub-district's 42 settlements have disappeared under the sea.
Since water reserves have been destroyed by salinity and the land is too barren to grow anything, more than 90 percent of the population rely on fishing as their main source of income.
The Sindh Development Review states freshwater discharge from the Indus River into the delta has plunged from 49 trillion gallons 60 years ago to 235 billion gallons in 2006.
Although the International Union for the Conservation of Nature, an international environmental organization, has calculated the required flow at the delta to be 8.8 trillion gallons, the flow has been less than 3.3 trillion gallons for the past two decades.
The effects of saltwater intrusion can be felt up to 40 miles upstream, the Sindh Development Review report found.
A 2012 report by the Pakistan Meteorological Department, “Climate Change in Pakistan Focused on Sindh Province,” states about 5,300 glaciers in northern Pakistan are on a steady retreat, while in coastal areas, especially in the Indus Delta region, temperatures are on a constant climb.
Sea intrusion had inundated more than 2.2 million acres of farm land in Thatta and Badin districts. Mangrove forests were being steadily depleted, leaving the region vulnerable to greater damage from storm flooding. Forests, agriculture lands and the entire eco system of the Indus delta were being damaged. Thousands of people who were surviving on water of the Indus delta have migrated from area.