Walter Immerzeel

In Moving Mountains



Moving Mountains

To map the effects of climate change, mountain hydrologist Walter Immerzeel and his team venture to remote altitudes where other scientists do not go. From his tent base camp in the Himalayas, he collects data on precipitation, temperature, atmospheric pressure, solar irradiance, windspeed and more using over 200 measuring instruments.


These data must be extremely accurate in order to reliably predict changes in the region’s water cycle – which is of crucial importance for the millions of people who live in the climate-sensitive areas downstream. In Moving Mountains, filmmaker and mountaineer Renko Douze follows Immerzeel on one of his mountain expeditions.


Walter Immerzeel
Renko Douze
15 min
Walter Immerzeel is one of the few scientists to research climate change above 5.000 meters in altitude.
Portret Walter Immerzeel


Walter Immerzeel

Mountain hydrologist Walter Immerzeel (1975) studied Environmental Sciences at Utrecht University where he also gained his PhD at the Physical Geography department in 2008. He has a passion for mountainous areas and lived and worked as a researcher in Nepal for two years.

He is now Professor of Mountain Hydrology at Utrecht University, where he leads a young team of scientists. Immerzeel has led numerous research expeditions to the Himalayas. His research focuses on the interaction between climate change and the cycle of snow, ice and water in the high mountains and what makes his research unique is that he investigates this at different levels of scale.


  • Leading scientist on mountain hydrology, climate change and agriculture
  • Fellow of the American Geophysical Union
  • Winner of various prestigious grants such as NWO Veni (2011), the ERC Starting Grant (2015) and NWO Vidi (2016)
Still Moving Mountains

Essential research

There are 78 water systems worldwide that primarily rely on glaciers and snow as their freshwater source. These systems are therefore known as the world’s water towers. Around 1.9 billion people, approximately a quarter of the world’s population, depend on them.

A large international research team led by Walter Immerzeel has mapped out which water towers are most important for the people living downstream, and how vulnerable they are to changes in climate and socio-economic factors.

In 2021, Walter Immerzeel wrote in Scientific American about the insights his data collection have produced so far and the challenges we’re faced with right now.

national geographic

Discover the world's watertowers in this interactive tool

Walter Immerzeel also collaborated with National Geographic to create an interactive map of the world’s most important water towers’. Discover them yourself here. 

“In the past, mountains were not seen as one of the key parts of the earth system, like tropical forests or oceans, but now we are recognizing them as just as important.”

How to make a model out of data?

The Faculty of Geosciences Utrecht University made a series of videos about data modelling watercycles. Watch them here. 


  • Renko Douze

    Renko Douze (1986) is a producer and filmmaker who in 2011 founded the production company Een van de jongens together with Hasse van Nunen. Douze has worked as a writer, director and editor for documentary films and series such as the children’s programme Het Klokhuis. He is an avid mountaineer, which proved useful during the filming of Moving Mountains.