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.

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.’

Fanny, Patrick, Etienne Berthier and colleagues from Oslo University (Andreas Kääb and Désirée Treichler) have just published the study “A spatially resolved estimate of High Mountain Asia glacier mass balances from 2000 to 2016” in Nature Geoscience. They used more than 50,000 ASTER satellite images to derive digital elevation models and to track glacier thickness changes over High Mountain Asia. They provide the first consistent estimate of volume change for ~90 000 km² of glaciers.
 
Their study confirms the existence of the so called “Karakoram anomaly” and, following a 2015 study by Andreas Kääb et al. refines its location: glaciers located in the West Kunlun, Karakoram and Eastern Pamir have balanced or slightly positive mass changes. The most negative mass changes are found in the Eastern Himalaya, where glaciers loose mass at rates similar to the ones in the European Alps (up to 0.62 ± 0.23 m w.e. yr^-1).
 

Rate of glacier elevation change (in m/yr) for the period 2000-2016. Red dots represent area where glaciers are thinning and blue dots area where glaciers are thickening.