Author Archives: Walter Immerzeel

Glacier-dammed lake outburst modelling in Shimshal valley

Recent observations show that the surging tongue of Khurdopin glacier in Shimshal catchment in Northern Pakistan has caused a lake to form in 2017 (Steiner et al. 2018), which might return annually in subsequent years following the melt season. Ongoing monitoring has shown that the lake expanded since November 2017 reaching a constant area of ca 350 000 m2 in March of 2018 and it has remained stable since. As the ice masses from the surge will take many more months to melt the lake is likely to remain or reappear even after drainage events. As the melt season starts the lake may drain and this may cause flooding downstream, in particular close to the village of Shimshal, the adjacent agricultural areas and lake Attabad located further downstream.

Shimshal model area

The mountain hydrology team of Utrecht University is supporting the Aga Khan Foundation for Habitat. The National Disaster Management Authority (NDMA) in Pakistan is coordinating the effort and is dealing with the emerging issue and have put together a team of experts. Our results may support this process.

To assess potential damage from a lake burst an initial BASEMENT hydrodynamic model was constructed for the area using available elevation models , estimated lake water volumes and dam breach scenarios from literature and an initial model simulation assuming a lake volume of 7 million m3 and a short breach period was conducted. The movie below shows the maximum inundation depth as the wave travels through the valley.

Subsequent work will focus on the following:

  • Improve the cross profiles using field data or high resolution DEMs (e.g. ALOS-PRISM)
  • Extend the model run until Attabad lake and assess the potential flood wave there.
  • Include multiple volume and lake growth scenarios
  • Include multiple breach scenarios ranging from a catastrophic, near instantaneous breach to a more gradual scenario
  • Include more detailed exposure data such as infrastructure, houses, agricultural areas

For more information please contact Jakob Steiner or Walter Immerzeel.

Increasing irrigation may lead to growing glaciers

It has been a mystery for years: while glaciers are shrinking all over the world, there is an area in the Asian high mountains where the glaciers are actually growing. New research from our group shows that humans might be responsible for this. The increasing agricultural activity in the region is resulting in more snow and less sunlight in the mountains, precisely in the areas where the glaciers are growing.

The vast majority of glaciers in the high mountains of Asia are partially melting away due to global warming. But there’s an area to the northwest of the Tibetan Plateau where the glaciers are actually growing. ‘Because the region is difficult to access, little has been known about these glaciers for quite some time’, says first author Remco de Kok, a physical geographer at Utrecht University. ‘But with the help of weather models we have shown that these glaciers can expand because local land use has changed. The fact that human activity can have such an immediate impact on the growth of glaciers is new information, and extremely important to know for the many people who depend on the meltwater from glaciers.’ The results of the study are published in the journal Geophysical Research Letters.

More snow, less sunlight
The increasing irrigation in the region is the cause of this remarkable glacier growth. Research leader Walter Immerzeel explains: ‘In the lowlands of China, Pakistan and India, river and groundwater are increasingly being used to irrigate agricultural areas. Much of the irrigation water is eventually “sweated out” by the plants and absorbed into the atmosphere. Using a special weather model, we have shown that the increasing water vapour later comes down as additional snow – precisely in the places where the growing glaciers are found. The additional clouds also allow less sunlight to pass through, causing the glaciers underneath to melt at a slower rate.’

The ice supply in the Asian high mountains is crucial to the many millions of people who depend on the meltwater. The results of this study are primarily good news, although the research group, which also consists of Pleun Bonekamp and ObbeTuinenberg, warns against too much optimism. ‘Due to the limited amount of river and groundwater, the question is to what extent agriculture in Asia can continue to grow in the future. If irrigation decreases, the effect will be undone and it is likely that – in combination with the further warming of the earth – the glaciers will retreat at an accelerated pace.’

 

 

Walter Immerzeel presents Himalayan research on the 10th anniversary of the ERC

Have you always wondered what these prestigious, multi-million euro research grants from the European Research Council (ERC) are all about? Are you interested how ERC research projects relate to your daily life? Together with nine other ERC laureates from Utrecht University, Walter Immerzeel presented his ERC research during the ERC Day ‘Utrecht Inspires’ on 28 March, which was part of celebrations of the 10th Anniversary of the ERC.

 

Martian crater officially named Langtang

To honor Langtang, the village that was tragically destroyed by an avalanche triggered by the Nepal earthquake of April 2015, we proposed to name a Martian crater after Langtang. The idea was initiated by colleague Tjalling de Haas, who investigates debris flows and land-forms on Mars. The request was officially approved by the International Astronomical Union and Langtang will now forever be remembered, even on Mars. The crater has a diameter of 12 km and interesting enough contains glacial land-forms and the moraines of the Last Mars Glacial Maximum and the debris fans formed after the glaciers melted are clearly visible.

 

The Langtang Crater

The Langtang Crater

 

 

 

 

 

 

 

 

 

 

 

Debris flows in the Langtang Crater

Debris flows in the Langtang Crater

 

 

 

 

New 3D visualisation of Langtang glacier

Using the software SketchFab we have produced a 3D visualisation of a part of the Langtang glacier in Nepal. The model allows an interactive inspection of the surface features of the glacier. It shows the huge variation on the surafce of the glacier including different types of lakes, ice cliffs, boulders and bare ice. It is also possible to view this 3D model using VR glasses and a Google Cardbox on your smart phone. Enjoy!

Explore Langtang Glacier on SketchFab

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