Periodic Reporting for period 4 - CAT (Climbing the Asian Water Tower)
Berichtszeitraum: 2020-08-01 bis 2021-07-31
The water cycle in the Himalaya is poorly understood because of its extreme topography that results in complex interactions between climate and water stored in snow and glaciers. Hydrological extremes in the greater Himalayas regularly cause great damage, e.g. the Pakistan floods in 2010, while the Himalayas also supply water to over 25% of the global population. So, the stakes are high and an accurate understanding of the Himalayan water cycle is imperative. The discovery of the monumental error on the future of the Himalayan glaciers in the fourth assessment report of the IPCC is exemplary for the scientific misconceptions which are associated to the Himalayan glaciers and its water supplying function. The underlying reason is the huge scale gap that exists between studies for individual glaciers that are not representative of the entire region and hydrological modelling studies that represent the variability in Himalayan climates. In CAT, I will bridge this knowledge gap and explain spatial differences in Himalayan glacio-hydrology at an unprecedented level of detail by combining high-altitude observations, the latest remote sensing technology and state-of-the-art atmospheric and hydrological models. I will generate a high-altitude meteorological observations and will employ drones to monitor glacier dynamics. The data will be used to parameterize key processes in hydro-meteorological models such as cloud resolving mechanisms, glacier dynamics and the ice and snow energy balance. The results will be integrated into atmospheric and glacio-hydrological models for two representative, but contrasting catchments using in combination with the systematic inclusion of the newly developed algorithms. CAT will unambiguously reveal spatial differences in Himalayan glacio-hydrology necessary to project future changes in water availability and extreme events. As such, CAT may provide the scientific base for climate change adaptation policies in this vulnerable region.
The overall aim of the CAT project is to identify and quantify regional differences in greater Himalayan glacio-hydrology and to elucidate climate change induced alterations in water availability and the occurrence of extreme precipitation events through three key objectives:
1. Advance the knowledge on high-altitude climate dynamics from valley to synoptic scales, with a special focus on high-altitude precipitation and the interaction between the atmosphere, the extreme topography, the land surface and the cryosphere
2. Understand how climate controls key glacio-hydrological processes in high-altitude catchments in particular ice flow and melt dynamics of debris covered glaciers, snow maturation and sublimation and routing of (sub-surface) runoff.
3. Explain regional differences and their consequences for accurate projections of future changes in greater Himalayan glacio-hydrology by implementing catchment scale glacial-hydrological models for two representative, but contrasting catchments at a resolution that allows inclusion of key local-scale glacio-hydrological processes and atmospheric dynamics.
The project was concluded very successfully and we have made great advances in understanding the glacio-hydrology of the Himalaya and how this may change in the future. This is evidenced by two successfully defended PhD theses, numerous publications and outreach activities and open access datasets with meteorological, glaciological and hydrological observations.
The project led to important insight into how climate change impacts the water supply from the mountain ranges in Asia. This has important societal consequences as millions of people depend on this water for irrigation, drinking water and industry. The results of the project have been covered widely in the media including international newspapers, IPCC reports and popular science magazines like National Geographic and the Scientific American.
1. Advance the knowledge on high-altitude climate dynamics from valley to synoptic scales, with a special focus on high-altitude precipitation and the interaction between the atmosphere, the extreme topography, the land surface and the cryosphere
2. Understand how climate controls key glacio-hydrological processes in high-altitude catchments in particular ice flow and melt dynamics of debris covered glaciers, snow maturation and sublimation and routing of (sub-surface) runoff.
3. Explain regional differences and their consequences for accurate projections of future changes in greater Himalayan glacio-hydrology by implementing catchment scale glacial-hydrological models for two representative, but contrasting catchments at a resolution that allows inclusion of key local-scale glacio-hydrological processes and atmospheric dynamics.
The project was concluded very successfully and we have made great advances in understanding the glacio-hydrology of the Himalaya and how this may change in the future. This is evidenced by two successfully defended PhD theses, numerous publications and outreach activities and open access datasets with meteorological, glaciological and hydrological observations.
The project led to important insight into how climate change impacts the water supply from the mountain ranges in Asia. This has important societal consequences as millions of people depend on this water for irrigation, drinking water and industry. The results of the project have been covered widely in the media including international newspapers, IPCC reports and popular science magazines like National Geographic and the Scientific American.
In the project we have developed a number of new and innovative methodologies. These included new drone measurements of high altitude glaciers, the development and applications of specific sensors to measure snow properties and turbulent fluxes at very high altitude in the Himalaya and high resolution atmospheric modelling at unprecedented resolution. This combination of new measurements, remote sensing and models led to important insights in the functioning and the impact of climate change on the hydrological cycle in high mountain Asia. This is of key importance to millions of people downstream who depend on its water resources. The project team consisted of glaciologists, meteorologists and hydrologists and was truly interdisciplinary. In the field we have worked together with Nepali colleagues of the International Center for Integrated Mountain Development in Nepal and we have transferred knowledge and technology to our Nepali counterparts.