STARTING in the 1850s, the development of the Indus river basin, primarily for large-scale irrigated agriculture, was motivated by colonial interests. After independence, the basin’s development involving damming, diverting and dividing the rivers, were motivated by political prejudices emerging from Partition, Cold War politics, and the interests of global financial/ construction businesses.

Post-independence water sector development interests overwhelmed science, society and the environment. The stage of unscientific buildout was set by David E. Lilienthal, who hypothesised that “rivers of the Indus Basin flow to the Arabian Sea unused” and suggested that the “urgent problem is how to store up … wasted waters … rather than permitted to flow to the sea unused”. This scientifically flawed hypothesis, was accepted by Pakistan and India; both began undertaking one mega project after another. The rivers dried up and water stopped flowing to the sea. On the one hand, it was a death sentence for the environment, but on the other, it created lucrative projects for financial and business interest groups at taxpayers’ expense; rulers on both sides gained political mileage and Cold War alliances flourished.

Until today, however, the countries sharing the basin had never been at peace with each other. Provinces within the countries still fight over water rights; water feuds among farmers are routine; irrigated areas are drowning in water logging and salinity; and, despite billions of projects, the majority of people within the irrigated areas live below the poverty line; while the basin remains in a state of malaise.

With colonialism gone, the prejudices of Partition fading, and the Cold War over, it’s time to rethink the system. For that we need to analyse, first, the scientific shortcomings in the earlier development, which began with Lilienthal’s idea. Flowing river waters carry dissolved salts and suspended silt. If the river is not permitted to enter the sea, water, salts and silt start accumulating in the landscape with devastating consequences.

Water: The water that is not allowed to flow into the sea evaporates but the rest seeps into the soil’s pores. Over decades of seepage, pore space in many areas was completely filled and water started oozing to the surface — this is called waterlogging. Today, around 43 per cent of the irrigated basin is classified as waterlogged. The problem is worst in Sindh.

It’s time to rethink the water system

Menace of salts: Natural salts in the Indus come from both high mountain ranges and deep saline formations in the plains. A continental collision some 50 million years ago led to the formation of the Karakoram and Himalayas mountain ranges which are still rising. The Indus existed even before the continental collision. For millions of years, the river kept dumping eroded debris into the ancient Tethys Sea until it was completely filled. On top of the filled-up sea, deposition continued forming the sweet alluvial plains that currently stretch from the foothills of the Himalayas to the Arabian Sea.

The creation of fertile alluvial plains on top of a highly saline filled-up sea is a delicately balanced miracle of the Indus, sustained by the meandering river for millions of years by draining out salts into the Arabian Sea. In recent times, the Indus had been dumping more than 50m tons of salts annually into the sea. But since the implementation of Lilienthal’s vision, over 50m tons of salts accumulate annually in the landscape, threatening the delicately balanced miracle of the Indus; 35pc to 40pc of the basin has already been impacted.

Fate of silt: The Indus happens to be the fifth most silt-laden river in the world with an annual silt load of between 250m and 490m tons a year. Geologically speaking, the eroding mountains in the north form the erosion-regime within the Indus Basin. The Tethys Sea, as it was being filled, was the depositional regime in earlier eons. In the current era, the Indus Delta has been the depositional regime of the basin, which, until the 1830s, was adding land in place of the sea. The silt supply in the river had been so consistent over millions of years that species like blind dolphin evolved to navigate its murky waters!

But today, instead of reaching the depositional environment of the river delta, the silt gets trapped behind dams; accumulates on riverbeds behind diversion barrages; and, is diverted towards irrigation canals. Hence, the sea is reclaiming the delta at an alarming rate of 96 acres per day.

Lilienthal’s vision overruled science. Today, the insurmountable problems of waterlogging, salinity, choking of riverbeds, delta erosion, and threatened biodiversity are hitting us in the face. People and the environment are paying the price of politics, prejudice, greed, and the ignorance of earlier planners. It’s time to rethink the system without ignoring science, before it is too late to turn things around.

The writers are experts on hydrology and water resources.

Published in Dawn, June 5th, 2021