https://pure.aber.ac.uk/portal/files/4916016/Westoby_et_al._GEOMORPH_2012_Accepted.pdf

‘Structure-from-Motion’ photogrammetry: A low-cost, effective tool for geoscience applications

Glacial melting in the Tibetan Plateau affects the water resources of millions of people. This study finds that—partly owing to changes in atmospheric circulations and precipitation patterns—the most intensive glacier shrinkage is in the Himalayan region, whereas glacial retreat in the Pamir Plateau region is less apparent.

/pdf/different-glacier-status-with-atmospheric-circulations-in-9xtro65rsi.pdf

Different glacier status with atmospheric circulations in Tibetan Plateau and surroundings

Changes in climate extremes and their impacts on the natural physical environment: An overview of the IPCC SREX report

Himalayan glaciers are a focus of public and scientific debate. Prevailing uncertainties are of major concern because some projections of their future have serious implications for water resources. Most Himalayan glaciers are losing mass at rates similar to glaciers elsewhere, except for emerging indications of stability or mass gain in the Karakoram. A poor understanding of the processes affecting them, combined with the diversity of climatic conditions and the extremes of topographical relief within the region, makes projections speculative. Nevertheless, it is unlikely that dramatic changes in total runoff will occur soon, although continuing shrinkage outside the Karakoram will increase the seasonality of runoff, affect irrigation and hydropower, and alter hazards.

https://www.zora.uzh.ch/id/eprint/72075/1/2012_BolchT_BolchAl12_science_GlacHimal_supplm_subm_Kopie_.pdf

The state and fate of Himalayan glaciers

An overview of glacial hazards in the Himalayas

Glacier recession in high-Himalayan catchments leads to the formation of moraine-dammed lakes on many debris-covered glacier tongues.Suchlakesarehazardoustocommunitiesandinfrastructuredownstreambecauseoftheirpotentialtobreachcatastrophically, and their early recognition is required if remedial efforts are to be timely and cost-effective. Whilst the development of supraglacial lakes is known to begin as a series of ponds that subsequently coalesce into a larger lake, the relationship between glacier dynamics and lake formation is not well understood. Using ERS-1 and ERS-2 Synthetic Aperture Radar (SAR) data, SPOT-5 optical imagery and historical aerial photography, information is presented on the dynamics and structure of glaciers in Tibet (China) and Nepal that drain the southern side of the Himalaya. Glacier velocity data derived from interferometry show that where lakes are developing on debris-covered tongues the ice is virtually stagnant (displacements b 5ma −1 ). Furthermore, elevation data from Digital Elevation Models (DEMs) derived from aerial photography and SPOT-5 HRS data reveal that supraglacial lake formation is prevalent where glacier surface gradients are less than 2° from the glacier terminus, supporting empirical observations from previous work. The resolutionofferedbytheDEMsandSARdataallowsvariationsintransverse glacierelevations andvelocitiestobedetected,suchthat the pattern of lake development on an individual glacier can be identified. Whilst the glacier surface gradient provides the boundary conditions favourable for lake formation, local variations in glacier velocity and surface morphology between flow units control the precise location of lake growth. Integrating the surface gradient and velocity information into a single analysis highlights those glaciers that are particularly vulnerable to lake development over an expected decadal timescale. The wider application of these techniques,basedonremote sensing data,isparticularly suitablefor ‘first-pass’hazardassessments andfor regionswhere field access is difficult due to severe terrain, political sensitivity or financial constraints.

Early recognition of glacial lake hazards in the Himalaya using remote sensing datasets

Original abstract: Moraines that dam proglacial lakes pose an increasing hazard to communities in the Andes and other mountain ranges. The moraines are prone to failure through collapse, overtopping by lake waters or the effect of displacement waves resulting from ice and rock avalanches. Resulting floods have led to the loss of thousands of lives in the Cordillera Blanca mountains of Peru alone in the last 100 years. On 22 April 2002 a rock avalanche occurred immediately to the south-west of Laguna Safuna Alta, in the Cordillera Blanca. The geomorphic evidence for the nature, magnitude and consequences of this event was investigated in August 2002. Field mapping indicated that the avalanche deposited 8–20 × 106 m3 of rock into the lake and onto the surface of the frontal region of Glaciar Pucajirca, which flows into the lake. Repeated bathymetric surveying indicated that ~5 × 106 m3 of this material was deposited directly into the lake. The immediate effect of this event was to create a displacement wave that gained in height as it travelled along the lake basin, overtopping the impounding moraine at the lake’s northern end. To achieve overtopping, the maximum wave height must have been greater than 100 m. This, and subsequent seiche waves, caused extensive erosion of both the proximal and distal faces of the impounding terminal moraine. Further deep gullying of the distal face of this moraine resulted from the supply of pressurized water to the face via a relief overflow tunnel constructed in 1978. Two-dimensional, steady-state analysis of the stability of the post-avalanche moraine rampart indicates that its proximal face remains susceptible to major large-scale rotational failure.

Impact of a rock avalanche on a moraine‐dammed proglacial lake: Laguna Safuna Alta, Cordillera Blanca, Peru

Remote sensing studies have shown that glaciers and their proximal environments exhibit unique temporal, spatial and spectral characteristics that can be analysed to better quantify glacial hazard potential. In this review, the optical remote sensing data sources available to glacial hazard assessors are considered and the range of information on glacial environments that can be derived is analysed. The review shows that the integration of a variety of data sources can provide geoscientists with information regarding glacial lakes and lake development, glacier dynamics, avalanche sources and ice-marginal fluctuations. Such data can be used to complement and, in many cases, improve field-based glacial hazard assessments. The review concludes that aerial photography still remains the main source of data for measuring a number of glacier characteristics, but that fine to moderate spatial resolution satellite sensors (e.g., ASTER, SPOT 5 HRVIR, Landsat ETM) also provide useful information that can be used to ...

Optical remote sensing techniques in high-mountain environments: application to glacial hazards

Field and geophysical studies have allowed us to identify processes leading to ice-cored moraine degradation for three natural dams investigated in Peru and Nepal. As potentially hazardous lakes form on the snouts of debris-covered glaciers they may separate a stagnant ice body from the upper reaches of the glacier to form an ice-cored end-moraine complex. The ice-cored moraines appear to degrade through ablation beneath the debris cover, by localized thermokarst development, and by associated mass movement. Relict glacier structures serve as a focal point for the onset of accelerated thermokarst degradation. Once exposed, the ice core then undergoes accelerated wastage through the combined affects of solar radiation and mechanical failure due to the rheological response of the ice to deepening kettle forms. Continuing degradation reduces the lake freeboard, weakens the moraine dam, and can lead to its catastrophic failure.

Shaun D. Richardson

Papers

An overview of glacial hazards in the Himalayas

Early recognition of glacial lake hazards in the Himalaya using remote sensing datasets

Impact of a rock avalanche on a moraine‐dammed proglacial lake: Laguna Safuna Alta, Cordillera Blanca, Peru

Optical remote sensing techniques in high-mountain environments: application to glacial hazards

Degradation of ice-cored moraine dams : implications for hazard development