In our world, all major cities and human settlements are built around either rivers or coasts. Even most of the large settlements on the coast are built on or around the deltas of rivers. The reasons behind human settlements next to water channels are obvious: the availability of water for consumption and drainage, and for communication and transportation. However, Pakistan seems to defy logic, and this, in part, is the reason behind many of the ecological and economic problems the country faces. Going back in history, the outcome is not by some broader design. Most of the large human settlements, in what is now known as Pakistan, were built along the banks of the five rivers of Punjab or along the banks of River Kabul. This has been the pattern of the Indian subcontinent, just as it is across the world. Two important cities of the region, namely Delhi and Lahore, grew on the banks of the River Jumna and the River Ravi. There are other major human settlements along these river channels and coasts. But then came partition and with it an utter disregard for geographical and ecological considerations while dividing Punjab, and to a certain extent Bengal, which led to events that have disturbed the ecological balance of these lands.India, being situated upstream, started controlling the flow of the waters into Pakistan. This led to conflicts that invited international arbitration resulting in the Indus Waters Treaty (IWT): a treaty through which Pakistan was to cede complete control of the three rivers, namely Ravi, Sutlej and Beas along with partial control of River Chenab and River Jhelum to India. The impact, as it turns out, has been catastrophic.The treaty has deprived the hugely populated central Punjab of its lifeline, its flowing rivers. The mega city of Lahore has been deprived of its water channel Ravi. The creation of a large link-canal system has led to the emergence of new ecological realities within the region. It has led to the problem of salinity and waterlogging along the newly created channels. It has put pressure on the downstream water usage of the River Indus, the only channel Pakistan still fully controls. And, above all, it led to the sustaining of a region that has been deprived of its natural share of water through artificial means.Five decades into the IWT, central Punjab has become ecologically unsustainable. Between the cities of Gujrat and Okara, within less than a 100 kilometre radius, a population of around 60 million people lives without any indigenous source of water and in the absence of any indigenous energy source. The area serves as a source of Pakistan’s industrial and agricultural produce, in the absence of any natural water and energy source. This, as should be obvious to anyone, is unsustainable.Not for a lack of intention, but more for a lack of intellectual capacity, policymakers in Pakistan failed to realise that by signing the IWT, the focus of development and any population growth had to shift towards the west to the banks of the River Indus, the only river channel Pakistan still has control over. Rather than planning for that, they continued to focus on the existing settlements on Ravi, Sutlej and Chenab. Natural waterways have an inbuilt way of bringing settlements into harmony with the environment. In the absence of these natural waterways, the settlements began to display a sheer disregard for nature. This has led to a ballooning of human settlements in an area that has no natural water channels of its own, and the ground water is fast depleting. What makes matters worse is that this area has no indigenous energy source. Faced with these water and energy challenges, coupled with a population of close to 60 million, central Punjab is sitting on an ecological time bomb, a bomb that has to burst eventually. And the scariest thing is that there is no realisation on the part of any of the stakeholders of the challenge that awaits us. This ecological time bomb scenario is the biggest threat Pakistan and the region face. If nothing is done, it will lead to mass migration of large chunks of the 60 million people for their survival. An unplanned, impulse migration of this scale can make any state, economic system and political order crumble.Avoiding it requires a collaborative effort. The focus has to shift towards building and expanding new settlements along the banks of the Indus and closer to indigenous energy sources. For centuries, humans have moved settlements from where the rivers dried out and shifted to where they flowed. Unintentionally, with the IWT, we have made that choice too. It is time for us to see it through. Doing this in harmony and in collaboration will make everyone a beneficiary. The author can be reached on twitter at @aalimalik