Papers by Adina Racoviteanu
Anecdotal evidence from glacier termini observations in the Himalayas suggest that these glaciers... more Anecdotal evidence from glacier termini observations in the Himalayas suggest that these glaciers have been in a state of general retreat since the last century, and point to "alarming" rates of retreat in the past decades. Concomitantly, local communities in the Western Himalayas have reported changes in glacier extents, snow cover and weather patterns. In response to "alarming" rates of glacial retreat, some indigenous cultures in the Himalayan area have begun a number of adaptive responses such as meltwater harvesting to construct "artificial" glaciers, which store the water during the dry season. There is urgency in: a) scientifically evaluating whether such practices of glacier regeneration can help provide water in a timely manner and 2) developing glacier datasets to assist such local efforts to ensure water supply in these data-scarce mountainous areas. Here we compare and contrast scientific and indigenous perspectives on spatial patterns of gl...
<p>Mountains are a critical source of water and home to a large proportion ... more <p>Mountains are a critical source of water and home to a large proportion of the world’s population. Cryospheric and hydrological changes combined with increasing water demand are impacting water availability, livelihoods and cultural values, threatening long-term water security of downstream populations. Here, we present a global systematic review in which 83 peer-reviewed articles were critically evaluated to unravel and assess different types of adaptation measures that have been undertaken to manage water stress. We observe that changes in glacier extent and snowfall amount are the main cryospheric changes motivating adaptations. However, changes in precipitation patterns, such as increasing extremes or alterations of the rain-snow line, which lead to both increasing water stress and seasonal flooding or glacier lake outburst floods (GLOFs), and are also observed to be important motivators of adaptive actions. The main sectors affected by hydrological and cryospheric changes are agriculture, tourism, hydropower generation and health and safety. To reduce risks of water scarcity and water-related disasters, and to enhance the resilience of human and natural systems, a broad set of adaptation measures have been implemented in the world’s mountain regions. Such adaptations include crop diversification, new irrigation practices, dams and water storage infrastructure, training programs and the establishment of Early Warning Systems, artificial snow making, shifts to non-snow-based tourism, and changes to cultural practices. We find that globally the most commonly used adaptation practices correspond to the improvement of water storage infrastructure, agricultural and irrigation practices, economic diversification and water governance and laws. However, our systematic review reveals these and other adaptation actions have strong regional variation. For example, adaptation in the agricultural sector is most prevalent in Africa, Asia and South America; while in Europe, Australia and New Zealand responses in the tourism sector are more common. Socio-ecological trade-offs associated with adaptations are often reported. For example, the promotion of snow-making reduces socio-economic vulnerability but adds pressure on water resources and environment.</p><p>However, successful implementation of adaptation measures are limited by a diverse set of factors. This includes reduced capacities and resources in infrastructure maintenance, mismanagement, conflicts and mistrust in government together with lack of funding and insufficient collaboration between stakeholders as well as delayed implementation of laws and mountain development programs. Moreover, extreme events and climate change impacts together with discontinuities and errors in climate data need to be considered. In order to address or overcome these limitations, it is important to raise awareness of local communities about climate change and to demonstrate the positive effects of adaptation measures and environmental laws; increase funding for mountain programs and motivate combined activities of governments and stakeholders to build their trust on each other.</p>
Climate Dynamics
Mountain glaciers are key indicators of climate change. Their response is revealed by the environ... more Mountain glaciers are key indicators of climate change. Their response is revealed by the environmental equilibrium-line altitude (ELA), i.e. the regional altitude of zero mass balance averaged over a long period of time. We introduce a simple approach for distributed modelling of the environmental ELA over the entire European Alps based on the parameterization of ELA in terms of summer temperature and annual precipitation at a glacier. We use 200 years of climate records and forecasts to model environmental ELA from 1901 to 2100 at 5 arcmin grid cell resolution. Historical environmental ELAs are reconstructed based on precipitation from the Long-term Alpine Precipitation reconstruction (LAPrec) dataset and temperature from the Historical Instrumental climatological Surface Time series of the greater Alpine region (HISTALP). The simulations of future environmental ELAs are forced with high-resolution EURO-CORDEX regional climate model projections for the European domain using three ...
&... more <p>Understanding the evolution of debris-covered glaciers, including their evolution over time, the distribution of surface features such as exposed ice walls and supraglacial lakes, and their contributions to glacier ice melt and to glacier-related hazards such as Glacier Lake Outburst Flood (GLOF) events requires an interdisciplinary approach, with a combination of remote sensing methods and collaborative fieldwork.</p><p>Since 2017, the IGCP 672 /UNESCO project led has been focussing on the transfer of scientific knowledge on monitoring debris-covered glaciers to local partner institutions in high Asia through trainings, workshops and field collaborations. Our long-term goal is to disseminate methodologies developed under this project to local institutions in high Asia and to embed scientific knowledge into local communities. Here we report on recent capacity building activities held within the context of this new project involved local participants from universities in Nepal and Sikkim. The training included remote sensing/GIS modules, temperature measurements, sediment logging and drone surveys of the ablation zone, which will allow us to better quantify the surface features and their evolution.</p><p> </p>
Regional Environmental Change
Across High Asia, the amount, timing, and spatial patterns of snow and ice melt play key roles in... more Across High Asia, the amount, timing, and spatial patterns of snow and ice melt play key roles in providing water for downstream irrigation, hydropower generation, and general consumption. The goal of this paper is to distinguish the specific contribution of seasonal snow versus glacier ice melt in the major basins of High Mountain Asia: Ganges, Brahmaputra, Indus, Amu Darya, and Syr Darya. Our methodology involves the application of MODIS-derived remote sensing products to separately calculate daily melt outputs from snow and glacier ice. Using an automated partitioning method, we generate daily maps of (1) snow over glacier ice, (2) exposed glacier ice, and (3) snow over land. These are inputs to a temperature index model that yields melt water volumes contributing to river flow. Results for the five major High Mountain Asia basins show that the western regions are heavily reliant on snow and ice melt sources for summer dry season flow when demand is at a peak, whereas monsoon rainfall dominates runoff during the summer period in the east. While uncertainty remains in the temperature index model applied here, our approach to partitioning melt from seasonal snow and glacier ice is both innovative and systematic and more constrained than previous efforts with similar goals.
The Journal of Asian Studies
Asia, a region grappling with the impacts of climate change, increasing natural disasters, and tr... more Asia, a region grappling with the impacts of climate change, increasing natural disasters, and transboundary water issues, faces major challenges to water security. Water resources there are closely tied to the dramatic Hindu-Kush Himalayan (HKH) mountain range, where over 46,000 glaciers hold some of the largest repositories of fresh water on earth (Qiu 2010). Often described as the water tower of Asia, the HKH harbors the snow and ice that form the headwaters of the continent's major rivers (Bandyopadhyay 2013). Downstream, this network of river systems sustains more than 1.3 billion people who depend on these freshwater sources for their consumption and agricultural production, and increasingly as a source of hydropower (Immerzeel, Van Beek, and Bierkens 2010; National Research Council 2012; Rasul 2014).
Egu General Assembly Conference Abstracts, Apr 1, 2009
Himalayan glaciers are representative indicators of climate fluctuations through their mass balan... more Himalayan glaciers are representative indicators of climate fluctuations through their mass balance variations. Mass balance is generally computed from field measurements but can also be estimated from remotely sensed images. One remote sensing method uses snow line altitudes observed from satellite images as a proxy of the equilibrium line altitude at the end of the hydrological year. This method allows
Egu General Assembly Conference Abstracts, Apr 1, 2009
The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier ou... more The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier outlines and related attributes, derived primarily from satellite imagery, such as from ASTER and Landsat. Each snapshot of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. The database currently contains outlines for approximately
With contradictory statements about "disappearing Himalayan glaciers" in the last few y... more With contradictory statements about "disappearing Himalayan glaciers" in the last few years, increasing concerns have been raised about the impact of snow and glacier changes on regional water supplies. Concomitantly, local communities in the western Himalaya report changes in glacier extents, snow cover and weather patterns. In response to perceived water scarcity, indigenous Himalayan cultures have begun a number of adaptive responses such as meltwater harvesting to construct "artificial" glaciers. This research addresses the need for a detailed assessment of glacier and climate parameters in the Himalaya, with the goal of identifying "at risk" glacierized areas and helping these local communities plan future water resources. The objectives of the research are threefold: 1) to review existing knowledge about glacier fluctuations and remote sensing methods for glacier mapping in the Himalaya; 3) to quantify spatio-temporal patterns of glacier changes i...
The delineation of debris-covered glaciers remains a challenge in optical remote sensing, due to ... more The delineation of debris-covered glaciers remains a challenge in optical remote sensing, due to the similarity of the spectral signature of debris-covered ice to surrounding lateral moraines, making it difficult to apply standard semi-automated algorithms commonly used for clean ice delineation. Furthermore, supraglacial debris exhibits considerable spatial variability in its characteristics such as debris cover thickness, particle size, thermal resistance and thermal conductivity. These properties are needed in order to map the extent of debris cover and to estimate ice melt under the debris cover or at the surface. In this study we evaluate the potential of texture analysis for detecting surface characteristics of debris-cover glacier tongues in the Khumbu Himalaya, using Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and high-resolution Ikonos data. We focus on mapping supra-glacier lakes and exposed ice walls using texture analysis algorithms such as gre...
This paper focuses on the contribution of annual glacier ice melt to streamflow in two watersheds... more This paper focuses on the contribution of annual glacier ice melt to streamflow in two watersheds situated in the monsoon-influenced part of the Nepal Himalaya (Trishuli and Dudh Kosi basins). We used a simple elevation-dependent ice ablation model to estimate the annual contribution of glacier ice melt to streamflow. Glacier area and hypsometry were extracted from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and IKONOS remote sensing data combined with elevations from the Shuttle Radar Topography Mission (SRTM) data. Long-term hydro-meteorological measurements from ground stations were used to calculate average discharge values at various elevations and distances from the glacier outlets, which we compared to glacier melt estimates from the ice ablation model. We found that glacier ice melt was positively correlated with the basin glacierized area and contributed 48.2% to annual flow in the Langtang Khola watershed (43.5 % glacierized area) and 14.5% in th...
ABSTRACT The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of g... more ABSTRACT The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier outlines and related attributes, derived primarily from satellite imagery, such as from ASTER and Landsat. Each snapshot of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. The database continues to expand both spatially and temporally: the number of glaciers represented, as well as the number of outlines from different times per glacier, are both increasing. As of August 2011, the database, located at NSIDC, contains outlines for approximately 95 000 glaciers, covering 290 000 km2. More datasets are expected soon, such as from GlobGlacier (e.g. all European Alps, western Greenland, Sweden, Baffin Island), and the Regional Centers for Svalbard, Argentina, Nepal, China, and others. Though the database does not yet cover the world's glaciers completely, approximately 670 glaciers have outlines from more than one time. This database increasingly enables analysis of global and regional glacier area and its distribution, glacier change, distribution of glaciers by different properties (e.g. morphology, debris-cover),and other yet-to-be imagined possibilities. In spite of steady progress, there remain some geographic areas that are not yet covered, including southernmost South America, Arctic Russia, the the periphery of most of Greenland and Antarctica. For applications such as sea level change studies that require complete global coverage of glaciers with at least moderate resolution, it is imperative that these gaps be filled soon. This will be addressed through adapting existing datasets to the GLIMS data model, using new satellite data and methods as they develop, and building analysis capacity worldwide to get more researchers involved in high accuracy glacier mapping.
ABSTRACT The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of g... more ABSTRACT The Global Land Ice Measurements from Space (GLIMS) initiative has built a database of glacier outlines and related attributes, derived primarily from satellite imagery, such as from ASTER and Landsat, and the number of glaciers represented there continues to grow. Each snapshot of a glacier is from a specific time, and the database is designed to store multiple snapshots representative of different times. These multiple snapshots are tied to each other through a common identifier, the GLIMS glacier ID. Where larger ice bodies are subsequently mapped as two or more ice bodies (due either to physical break-up of the ice body over time or to more detailed mapping), then the new pieces are assigned new IDs and ties back to the larger body are made through a "parent ID". When new data are contributed to GLIMS, datasets can cover hundreds or thousands of glaciers, and they increasingly cover glaciers that have been previously mapped and that have GLIMS IDs already assigned. For database integrity, a new glacier outline should be assigned the ID already assigned to the glacier from the previous mapping effort. This allows accurate automatic counting of glaciers, as well as computation of changes on a per-glacier basis, as all the multitemporal information about a glacier is tied together with a single ID. However, assignment of the appropriate IDs is challenging. Glaciers change size and extent over time, and even break into multiple pieces, requiring more sophisticated approaches to automatic assignment of IDs and parent IDs. This contribution discusses several cases where the difficulty of merging new data with old data ranges from easy to difficult. We discuss solutions to these cases, as well as a system we're developing to answer the need for automated ID matching and assignment.
Global Land Ice Measurements from Space, 2014
ABSTRACT This chapter summarizes the current state of remote sensing of glaciers in the India, Ne... more ABSTRACT This chapter summarizes the current state of remote sensing of glaciers in the India, Nepal, and Bhutan regions of the Himalaya, and focuses on new methods for assessing glacier change. Glaciers in these Himalaya regions exhibit complex patterns of changes due to the unique and variable climatic, topographic, and glaciological parameters present in this region. The theoretical understanding of glaciers in the Himalaya is limited by lack of sufficient observations due to terrain breadth and complexity, severe weather conditions, logistic difficulties, and geopolitics. Mapping and assessing these glaciers with satellite imagery is also challenging due to inherent sensor limitations and information extraction issues. Thus, we still lack a complete understanding of the magnitude of feedbacks, and in some places even their sign, between climate changes and glacier response in this region. In this chapter we present the current status of glaciers in various climatic regimes of the Himalaya, ranging from the monsoon-influenced regions of the central–eastern Himalaya (Nepal, Garhwal, Sikkim, and Bhutan) through the monsoon transition zone of Himachal Pradesh (India), to the dry areas of Ladakh (western Himalaya). The case studies presented here illustrate the use of remote sensing and elevation data coupled with glaciermapping techniques for glacier area and elevation change detection and ice flow modeling in the context of the Himalaya.
Frontiers in Earth Science
The separation of fresh snow, exposed glacier ice and debris covered ice on glacier surfaces is n... more The separation of fresh snow, exposed glacier ice and debris covered ice on glacier surfaces is needed for hydrologic applications and for understanding the response of glaciers to climate variability. The end-of-season snowline altitude (SLA) is an indicator of the equilibrium line altitude (ELA) of a glacier and is often used to infer the mass balance of a glacier. Regional snowline estimates are generally missing from glacier inventories for remote, high-altitude glacierized areas such as High Mountain Asia. In this study, we present an automated, decision-based image classification algorithm implemented in Python to separate snow, ice and debris surfaces on glaciers and to extract glacier snowlines at monthly and annual time steps and regional scales. The method was applied in the Hunza basin in the Karakoram and the Trishuli basin in eastern Himalaya. We automatically partitioned the various types of surfaces on glaciers at each time step using image band ratios combined with topographic criteria based on two versions of the Shuttle Radar Topography Mission elevation dataset. SLAs were extracted on a pixel-by-pixel basis using a "buffer" method adapted for each elevation dataset. Over the period studied (2000-2016), end-of-the-ablation season annual ELAs fluctuated from 4,917 to 5,336 m a.s.l. for the Hunza, with a 16-year average of 5,177 ± 108 m a.s.l., and 5,395-5,565 m a.s.l. for the Trishuli, with an average of 5,444 ± 63 m a.s.l. Snowlines were sensitive to the manual corrections of the partition, the topographic slope, the elevation dataset and the band ratio thresholds particularly during the spring and winter months, and were not sensitive to the size of the buffer used to extract the snowlines. With further refinement and calibration with field measurements, this method can be easily applied to higher resolution Sentinel-2 data (5 days temporal resolution) as well as daily PlanetScope to derive sub-monthly snowlines.
Himalayan J. of Science, 2012
There is urgency in developing and testing remote sensing tools for developing extensive glacier ... more There is urgency in developing and testing remote sensing tools for developing extensive glacier datasets in high altitude areas of the Himalayas. Detailed information about glacier parameters is missing in many areas of the Himalayas, limiting our understanding of glacier fluctuations in this area. One of the biggest challenges in glacier mapping from spaceborne imagery is the delineation of debris-covered glacial tongues. The high Himalayas provide interesting challenges and unique opportunities for testing glacier mapping algorithms including debris cover. This research exploits the potential of visible, infrared and thermal ASTER data combined with SRTM elevation datasets for mapping glacier parameters (glacier area, elevations and snow lines) in the Himalayas. Multi-spectral classification techniques (ASTER ¾ band ratios and normalized differences NDSI and NDVI), single band thresholds, topographic characteristics (elevation and slope) and thermal information were combined in a decision tree to map clean ice and debris-covered ice. Snow lines were mapped from ASTER imagery acquired at the end of the ablation season, with instrument gains suitable for snow and ice. Ground control points (GCPs) collected in the field were used to assess the accuracy of the remote sensing-derived elevations. Changes in glacier parameters were derived by comparison with glacier datasets from older topographic maps and were linked with changes in climate parameters (precipitation and temperature).
... Tundra; Moist Dwarf-shrub, Tussock-graminoid Tundra; Shrublands; Wet Tundra; Water; and Ice, ... more ... Tundra; Moist Dwarf-shrub, Tussock-graminoid Tundra; Shrublands; Wet Tundra; Water; and Ice, Snow and Clouds ... NA-AVHRR), pixels that were the same on both land-cover maps were portrayed as ... that were di erent were portrayed as they were coded on the NA-MSS map. ...
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Papers by Adina Racoviteanu