Seawater Intrusion in the Indus Delta and Associated Hazards

Seawater intrusion into the once-fertile Indus Delta has unfortunately become a way of life, simply because almost everyone not directly impacted by this phenomenon has started taking it for granted and very few are willing to do anything about it. This has resulted in substantial damage to the ecology and biodiversity of the environment, as well as the regional economy and more specifically, the livelihood of the local inhabitants.

The Indus Delta, which is 150 kms wide at its mouth and covers almost 85% of Sindh’s coastal belt, is the most prominent ecological feature of the coast east of Karachi. It comprises of 17 major creeks and numerous minor creeks, all intermingling with mangrove forests in the creek pockets, as well as expansive mudflats.

Cash crops like rice and wheat used to be grown here in abundance and though the percentage of people deriving income from farming has dwindled to barely 20%, this source is coming under increasing strain from the twin scourges of water-logging and salinity, exacerbated by the influx of seawater.

This degradation has been precipitated, amongst other associated factors, by the gradual ingress of seawater, some 70 kms inland by some estimates, during the past 30 yrs. The reasons for this are threefold: drastically reduced waterflows downstrem of Kotri, dwindling mangrove cover and overall seawater rise due to global warming.

Although the Water Apportionment Accord of 1991 guarantees the release of 10 MAF of Indus water into the delta, the same could not be implemented in practice, simply because this requirement has been relegated to the lowest possible priority. For nine months of the year, hardly any waterflow can be seen in the delta. During the 6 month long Rabi season in particular, there is virtually zero flow below Kotri for five-sixths of the time. The problem is aggravated by the fact that hardly 10% of the 12000-plus watercourses that constitute the irrigation infrastructure downstream of Kotri are lined, which enables water seepage to further deplete the availability of water at the tail end.

The coast of Sindh, notably the Indus Delta, hosts the largest arid climate mangroves in the world. It ia a sad commentary on our part that these mangrove forests, which are beneficial on many counts, are being deforested at an alarming rate, despite the best efforts of certain concerned organisations to arrest this trend by planting more saplings. The reasons are not hard to find: negligible supply of fresh water to the delta, ever-increasing volumes of untreated sewage and industrial effluents into the sea and extensive land reclamation and clearance projects, as well as its attendant construction work. Unless these root causes are addressed, simply planting more saplings may not work to any appreciable extent.

A mangrove forest is nature’s gift to the coastal environment. Apart from acting as a bulwark against natural disasters, it serves as a life-sustaining eco-system for nourishing all types of flora and fauna. It is also a valuable source of nutrients as well, for both freshwater and marine fisheries. Their roots provide a natural protection against coastal erosion, retarding the process through their ability to hold the soil together by trapping suspended particles. The lack of a natural seawater flushing mechanism, so vital for preserving their health, has resulted in wiping out all the less salt-tolerant species. 98% of whatever mangroves remain in the Indus Delta constitutes of the most salt-tolerant variety, referred to as Avicennia Marina. Even this variety cannot flourish for long without being regaled by freshwater inputs. Freshwater flushing serves the added purpose of removing pollutants from the industrial effluents being discharged untreated into the sea, without which they toxify the coastal environment.

The ever-increasing global carbon emissions have given rise to global warming and an alarming rise in sea levels. In the last hundred years or so, sea levels have risen more than during the past 2000 years and, if carbon emissions are not capped, could rise to double as much within just the next two decades. The harmful impact of this rise is most felt along the flat topography of the Indus Delta, which is hardly in a position to keep it at bay.

The Indus Delta used to be historically interspersed with natural river courses, which, braided with smaller tributaries, formed a natural drainage system. Over time, most of these waterways now stand abandoned, afflicted by the ravages of time, nature and plain outright neglect. The construction work, inclusive of an irrigation canal network, that we indulged in, and the unauthorised settlements that we tolerated, played no small part in the obstruction of these dhoras, as they are locally referred to. Such obstructions, along with an attendant lack of drainage capacity, have made it vulnerable to the multiple scourges of sea intrusion, salinity, water-logging and flooding.

These calamities combined have laid waste nearly 3.5 million acres of prime agricultural land since 1956, forcing around 800,000 families to migrate from their ancestral lands. Nearly 65% of the coastal folk who used to depend on fishing for their livelihood are in dire straits. Freshwater fisheries have almost become a thing of the past, abetted in great part by land-based pollution, with such fishermen forced to move inland in search of alternate livelihood. Those who depended on agriculture for sustenance were equally impacted. This coastal region, where plantations of wheat, rice, sugarcane, fruits and vegetables once flourished, now stands devastated through soil erosion. Shah Bandar and Keti Bandar talukas, which were once thriving agricultural and commercial communities, now stand reduced to the status of small fishing settlements.

Floods and water-logging have likewise generated severe health problems for the inhabitants and their livestock. Diarrhoea, dysentery and respiratory infections, as well as climate-sensitive diseases like malaria and dengue are taking a severe toll on the already-weary denizens. Malnutrition adds an incendiary component to the mix by lowering resistance and immunity levels. Badly-damaged roads, through which patients have to make their way to hospitals and clinics, needlessly cause further loss of lives.

Rainfall in the region is scanty, but when the skies really open up once in a while, or to be a bit more precise, every few years or so, it catches everyone unprepared, which maximises the damage inflicted. As I mentioned earlier, this area is already soggy with water-logging, and being without a proper drainage system, the excess rainfall adds to the misery of the locals.

The construction of many large dams upstream, as a counterfoil to the fallout of the World Bank sponsored Indus Water Treaty with India, the upper riparian, was expected to result in better water management, by not only conserving water, but also by releasing it in desired doses and at the right time. This still didn’t translate into a boon for the tailenders because of rising consumption and other causes. Apart from major dams, many smaller ones, along with numerous barrages, main and link canals, have all conspired to deprive the once-thriving Indus Delta of even the minimum amount of its share of water as guaranteed under the inter-provincial Water Distribution accord.

Pakistan’s irrigation system, which also furnishes a way to drain saline water into the sea, was designed and executed by the British. It still retains its basic structure. Recognising the importance of a sound drainage system for sustaining agriculture in Sindh, experts from the World Bank came up with the idea of the Left Bank Outfall Drain to clear away the saline water from four of Sindh’s districts, either into the sea or into the shallow Shakoor Lake bordering India. The 41 km long Tidal Link Canal meant to drain this water into the sea proved to be a failure, being washed away within an year of its inauguration, for the simple reason that its level was lower than that of the sea it was supposed to drain into: a simple yet fatal flaw that, when pointed out in advance by the local community, was scoffed at. The adjoining lands are thus at the receiving end of this saline water and pollutants being pushed back by the sea.

Although the LBOD still serves a useful purpose in clearing Central Sindh of its excess water, including saline water and industrial-cum-municipal wastes, it creates in turn insurmountable problems for those living further downstream. Waste products from a number of sugar mills set up in and around Badin, have further polluted the once flourishing fresh water lakes in the area, depriving the locals of their livelihood as well as their source of precious drinking water. Apart from the faulty design of the Tidal Link Canal, other problems have to do with a lack of capacity, when needed, and lack of round-the-year maintenance.

As far as measures for restricting the impact of offshore floods and seawater intrusion is concerned, one may do well to turn to the Dutch, the past masters in the field of water management. Their philosophy: ‘Live with water, don’t fight it!’ After devastating floods wracked the countryside in 1953, Dutch engineers set about devising a near foolproof dyke system, one that would even cater to a once in a blue moon sort of eventuality. Instead of merely relying on floodwalls, they sought to absorb floodwaters in marshy plains and specially constructed rivers, setting back in some cases, the dykes further away from the water. They also developed tough synthetic textiles to better anchor earthen levees for preventing soil movement and water penetration. The engineering marvel that they created can rightfully be counted amongst the seven wonders of the modern world, as it effectively shields almost 27% of the country that is below sea level and yet houses 60% of its population. The agency that was set up subsequently in 2006 to minimse the risk of flooding from Netherland’s four main rivers set about their task by lowering floodplains, widening rivers and side channels, in essence giving the river space to cope with the extra water.

If the Americans can turn to the Dutch for technical assistance in the wake of Storm Katerina, there is no reason why we can’t! The only roadblock is a mental one. We can happily dish out inordinate sums of money nearly every year, or every alternate year, on providing succour to those wracked by recurring floods, but cannot convince ourselves to devote due attention to preventive measures to stop it from occurring in the first place.

Similarly, our mindset is such that we’d rather overuse water on land rather than let even a drop trickle down into the sea, which we deem to be a colossal waste. Endowed with such a linear line of thinking, its no wonder that the lustrous ecology of the Indus Delta is close to ruination. Everywhere else in the civilised world, dams serve as a means of water management; we use them to prevent water going down into the sea.

Sea intrusion, water-logging, salinity, pollution, floods and cyclones, are all inter-related problems. Dense mangrove forests are vital for preserving the ecology and biodiversity of the region and which also serve as a bulwark against natural calamities. For them to flourish, a minimum supply of freshwater as agreed under the inter-provincial water distribution accord has to flow down to the sea round the year. The region’s drainage capacity needs to be enhanced and the tidal link canal re-invented to ensure that this water flows into the sea. Untreated sewage or industrial wastes should be prevented from being dumped into the river. Watercourses need to be lined to stop the seepage of pollutants and saline elements into the soil. In addition, innovative technical solutions have to be devised to keep the seawater out.

Just imagine a future where sea levels keep rising; where the sea keeps intruding and devastating the ecology of an environmentally rich region; where it prevents land-based impurities and saline-laden water from draining out into the sea; where the life-sustaining force of the mangroves, deprived of its freshwater nourishment, becomes too feeble to resist the onslaught of the sea and its attendant storms; where water-logging, salinity and pollutants swamp the breadbasket of Karachi, Malir, and where a rich, natural, biodiverse environment is lost to the forces of nature and neglect. Unless we are willing to do something about it, then, as the tagline of a horror film goes, ‘Be afraid, be very, very afraid!’

Note: This constitutes the text of my keynote address at an international workshop organised by the National Institute of Oceanography on 20 October 2015 on the subject of ‘Seawater Intrusion affecting Coasts, Ecosystems and Livelihoods’. This was also published in the July 2016 edition of the monthly magazine ‘Global Age’.

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