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The systemic academic

The systemic academic

Dr. Upmanu Lall is a professor at Columbia University, a member of the Xylem Water Advisory Board and a leading expert on hydroclimatology. Here he offers us his take on flooding and the future.


Disastrous flooding in disparate areas of the globe seems to be all over the news. Is this impression accurate – has flooding increased in scale and frequency?

We expect mid-and high-latitude regions to experience more floods in a warmer climate, in part because a warmer atmosphere can hold a larger amount of water that can precipitate. However, it is not clear that there is an increasing trend in floods, at least in the last decade.

Last year there were several impressive floods – in Pakistan, Brazil and Australia – with significant impacts. While several of these were unprecedented in recent history, they were not extraordinary relative to what can be reconstructed from history and are most likely related to natural modes of climate variability.

However, many researchers use climate model simulations to show that the chance of floods in northern Europe is many times higher today than it was in 1900 or so. But these are subtle changes in rare events, so conclusive statements are hard to come by.

Even if we don’t have a climate-change-induced increase in flooding, natural climate variations that persist over decades often dramatically change the odds of floods. It is important to understand these mechanisms and translate them into prediction as the impacts of such events, especially in a highly urbanizing world, can be dramatic.

In terms of water resources, how can design and engineering help mitigate the effects of climate change?

One of the predictions of climate change is that the intermittence between precipitation events will increase and events may become more intense. This implies a greater need for storage – and more efficient use of it.

Water and wastewater treatment needs will also increase because such changes will most likely increase wash-off dynamics from the landscape. Combined with the persistence of non-point-source pollutants in water bodies, this will greatly degrade water quality. Treatment is energy intensive, so we need strategies for carbon capture and sequestration and to increase the use of renewables, especially solar heat in treatment processes.

What would you like to see water technology companies do to support the availability of clean water?

In urban settings, they should work with governments to promote an infrastructure model that best leverages centralized and decentralized systems while assuring lifeline water supply at an affordable price for all. Basic infrastructure is aging nearly everywhere, so we need innovations to bring costs down, raise reliability and improve energy resource utilization. We also need a smart water-wastewater-energy grid that is integrally managed; companies will need to lead the research and development to bring this to fruition.

As an academic, do you believe more can be done in the educational system to prepare the next generation for addressing its water-stressed future?

We need to generate excitement, rather than harp on the potential negatives of a water-stressed future. In basic science classes, we should introduce appropriate water technology content with a geographical context and tangible, relevant applications of physics, chemistry and math.

What projects are you working on now?

There are several. First, we wish to improve global water security through a better prediction of supplies and proactive demand management, especially in agriculture. Second, in the Global Flood Project, our hypothesis is that structured climate variations lead to persistent and coincident or clustered floods and droughts across the world. By looking globally, we hope to dramatically improve prediction. Our third major task is studying the Himalayan region to understand and quantify the potential impacts of climate variation on hydrology, ecology and hydropower development. We hope our findings will guide future regional development. Finally, a lot of our ongoing work focuses on climate risk management through better prediction.

by Simon