Moraine-dammed Lakes Research Articles

Evidence of climate change - Investigating glacial terminus and lake inventory using earth observation data for mountainous Bhutan

The mapping and monitoring of different types of Glacial lakes through the Geospatial techniques is vital to show the impact of climate changes on the Glacier and alleviate hazards that result from the bursting of Glacial Lakes and cause catastrophic consequences to human lives. The main goal of the present work was to map and analyze different types of glacial lakes in Bhutan during the years 1990, 2000, and 2017. Several sets of satellite images, Landsat-TM for 1990, Landsat ETM + for 2000, and Landsat 8-OLI satellite image for 2017, were used to estimate the changes in the glacial lakes and the inventory study. Several glacial lakes, i.e., moraine-dammed lake, supra glacial lake, lateral moraine lake, erosional lake, medial moraine lake, and end moraine lake, were mapped within these periods. It was found that there was a rapid increase in glacial lakes from 1990 to 2017. The number of glacial lakes in 1990 was increased from 213 to 436 in 2017. It was also observed that the spatial dimensions of some of the glacial lakes increased. The study revealed five end moraine lakes, 40 lateral moraine lakes, 50 supra glacial lakes, 239 erosional lakes, and 15 other moraines dammed lakes in 2017.

Infilled lakes (Pampas) of the Cordillera Blanca, Peru: Inventory, sediment storage, and paleo outbursts

Infilled lakes are a prevalent geomorphic feature in the intricate high mountain landscape of the Cordillera Blanca, Peru. Despite their apparent geomorphic, hydrological, and ecological importance, a systematic inventory of these areas has been lacking. This study presents an inventory of infilled lakes in the Cordillera Blanca. A total of 962 infilled lake polygons have been manually mapped, covering an area of nearly 90 km2 (the area of individual mapped polygons ranges from 0.001 km2 to 1.760 km2), more than double the area of existing lakes (40 km2) and the majority of flat areas (62% of areas with slope ≤5°). The study reveals that infilled bedrock-dammed lakes are the most common type (42%), while moraine-dammed lakes account for the majority of the infilled lake area (52%) and sediment volume (52% to 57%). Considering high uncertainty of infilled basins’ morphology, the estimated sediment volume of infilled lakes ranges between 0.9 km3 and 2.3 km3 (compared to 0.79 km3 to 1.15 km3 of water stored in existing lakes). The case study of Lake Aguascocha catchment reveals a mean sediment yield of 0.64 to 1.63∙106 m3∙km−2 during the past 10.7 ± 0.3 ka, that is, a mean annual sediment yield of 58.5 to 156.4 m3∙km−2∙yr−1. Furthermore, 65 locations where preserved geomorphic evidence indicates possible outburst floods in the past are identified. These areas are particularly important for understanding patterns of lake outburst occurrence on longer timescales than traditionally considered in lake outburst flood hazard studies. The dataset presented in this study is intended to serve as a basis for identifying sites suitable for further site-specific paleo-geographical, sedimentological, geochronological as well as broader mountain landscape evolution studies.

Features of the Level Regime of Periglacial Moraine-Dammed Lakes in the Growth Stage (Based on the Example of Lakes of the Tavan–Bogdo–Ola Mountain Range, South Eastern Altai)

Features of the Level Regime of Periglacial Moraine-Dammed Lakes in the Growth Stage (Based on the Example of Lakes of the Tavan–Bogdo–Ola Mountain Range, South Eastern Altai)

Geomorphologic evidences and hydrologic reconstruction of Holocene catastrophic flood events in the Yarlung Tsangpo Grand Canyon, Eastern Himalaya

Catastrophic floods from breaching of natural dams on the Namche Barwa and Giala Peri play an important role in shaping high-mountain landforms in the eastern Himalayan syntaxis. However, there is limited knowledge of geomorphologic evidences and magnitude of outburst flooding in the Yarlung Tsangpo Grand Canyon. In this paper, geomorphic impacts of high-magnitude outburst floods (104–106 m3/s) were analyzed using palaeoflood hydrology technology. Well-preserved 2018 Sedongpu (SDP) flood and 2000 Yigong (YG) flood sand bars are charactered by grey sands with parallel laminations, whereas megaflood geomorphic evidences in the Grand Canyon are dominated by massive slackwater deposits and lateral gravel bars. The palaeoflood events were dated to 4.3–2.4 ka, corresponding to the known Holocene megafloods in the lower Yarlung Tsangpo River. These flood ages are obviously younger than most of remnant lacustrine deposits during the late Pleistocene, but consistent with the ages in the top part of palaeolake and glacial moraines of the Namche Barwa. The chronological data help to confirm the highest probability phases of outburst floods from moraine-dammed lakes. The repeated megaflood peak discharges range from 0.5 to 1.1 × 106 m3/s, which are approximately 5–10 times greater than the maximum peak discharge of 2000 YG flood (9.5 × 104 m3/s) and 20–40 times than that of 2018 SDP flood (2.5 × 104 m3/s) in the Medog reach. Megaflood waters are always deepest (∼200 m) and fastest (∼50 m/s), which are at least twice times larger than 2000 YG flood. Higher shear stress (>3.3 kPa) and stream power per unit area (>168 kw/m2) occurred in narrower channel and sharp bend with higher velocity. Our model also predicts some potential erosion and deposition landscapes resulted from floodwaters routing through the Grand Canyon. These results address the geomorphic impacts of catastrophic flood events with magnitudes (104–106 m3/s) in the Yarlung Tsangpo Grand Canyon. Our new palaeoflood geomorphologic evidences provide a key constraint on the age and magnitude of Holocene megafloods in the largest Himalayan River.

Inventory methodology of periglacial lakes in Spitzbergen (Svalbard)

The paper discusses periglacial lakes, which were formed after the Little Ice Age due to the reduction of Spitzbergen (Svalbard) glaciation. A method for inventorying the periglacial lakes in Spitzbergen (Svalbard) is proposed based on the Norwegian Polar Institute cartographic materials and remote sensing methods. Such lakes have been formed due to deglaciation in Svalbard since the beginning of the 20th century after the Little Ice Age. Three morphological features of the periglacial lake were used as selection criteria: the lake is in contact with the glacier, the lake is located within the terminal moraine or borders on it, each of which is sufficient.As a result of the inventory, 705 periglacial lakes have been found in Spitzbergen (Svalbard). The largest number of lakes is located in the northeastern part of the archipelago, where the relief is poorly dissected. The largest clusters of lakes are found on the moraines of mountain-valley glaciers located on the warmer western coasts. The periglacial lakes were divided into 5 types: glacier-dammed lakes (19 %), lakes in contact with the glacier front (30 %), thermokarst lakes on the moraine (27 %), moraine-dammed lakes (15 %) and lakes in contact with the terminal moraine (9 %). The most numerous were periglacial lakes adjoining the glacier (about 50 %). Their total area is 162 km2 and accounts for 87 % of the total area of all periglacial lakes. The other half of the lakes have formed shores, and their transformation is likely to be much slower in the future. The quantitative ratio of lake types testifies to the active phase of the process of lake expansion in the archipelago. This ratio of lakes by groups can be a clear indicator of climate change in the archipelago.

Glacial lake outburst flood risk assessment using remote sensing and hydrodynamic modeling: a case study of Satluj basin, Western Himalayas, India.

Glacier-associated hazards are becoming a common and serious challenge to the high mountainous regions of the world. Glacial lake outburst floods (GLOFs) are one of the most serious unanticipated glacier hazards, with the potential to release a huge amount of water and debris in a short span of time, resulting in the loss of lives, property, and severe damage to downstream valleys. The present study used multi-temporal Landsat and Google earth imageries to analyze the spatio-temporal dynamism of the selected glacial lake (moraine-dammed) in the Satluj basin of Western Himalayas. Furthermore, GLOF susceptibility of the lake was assessed using a multi-criteria decision-based method. The results show that the lake area has increased from 0.11 to 0.26 km2 over the past 28years from 1990 to 2018. The susceptibility index value for the lake was calculated as 0.75, which indicates that the lake is highly susceptible to the GLOF. The depth and volume of the lake were estimated to be 16m and 57 × 105 m3, respectively, using an empirical formula. HEC-RAS, HECGeo-RAS, and Arc-GIS software were utilized in this study to perform unsteady flow analysis and to determine the GLOF impact on the downstream area. The worst-caseGLOF scenario(breach width of 75m) was revealed during an overtopping failure of the moraine dam, resulted in a peak discharge of 4060 m3/s and releasing a total watervolume of 57 × 105 m3. The breach hydrograph has been routed to calculate the spatial and temporal distribution of peak flood, inundation depth, velocity, water surface elevation, and flood peak arrival time along the river channel. The analysis further reveals that the routed flood waves reach the nearest settlement, i.e., Rajpur town, situated at a distance of 102km in the downstream valley of the lake at 6h after the beginning of the lake breach event with a peak discharge/flood of 1757 m3/s and maximum flow velocity of 1.5m/s. With the ongoing climate warming and glacier retreat, moraine-dammed lakes are becoming more hazardous and thus increasing the total threat. Therefore, it is mandatory to monitor and assess such lakes at regular intervals of time to lessen the disastrous impacts of GLOFs on the livelihood and infrastructure in the downstream valleys. The findings of this study will aid in the creation of risk management plans, preparatory tactics, and risk reduction techniques for GLOF hazards in the region.

Assessment of potential damage in case of Upper Akkol Lake outburst (South-Eastern Altai, Russia)

At present, due to the gradual reduction of glaciation area in high mountainous areas around the world, there is an active transformation of landscapes freed from ice. Namely, the number of glacial moraine-dammed lakes is increasing. Such lakes are often unstable, rapidly changing their morphometric characteristics, which require observation. It is also known that recently there have been more frequent cases of catastrophic outbursts of such lakes and flooding of the territories below. Populations living in such areas are exposed to significant and often uncontrollable risks. One of such lakes, representing a potential threat of breaching, is the Upper Akkol Lake, located on the slope of the South Chuysky Ridge in South-Eastern Altai (Russia, Altai Republic). In this article, we assessed the potential damage from a possible lake outburst, and the information was communicated to local administrations in order to take timely measures to minimize damage or avoid a catastrophe.

Quantitative susceptibility assessment of the breach of moraine-dammed lakes due to glacier avalanches

Glacial lake outburst floods (GLOFs) have caused tens of millions of dollars of damage to infrastructure and have killed thousands of people worldwide. The objective of this study was to quantify the hazard posed by the occurrence of a GLOF due to an ice avalanche into an ice-free moraine-dammed lake, producing a surge wave and raising the water level. This study was carried out in the Himalayan region and in the western cordillera of North America. Some simplifications and combinations of parameters were made to reduce the number of parameters as much as possible. We selected seven factors for the quantitative susceptibility assessment of the GLOF hazard: the dangerous glacier slope factor S, temperature factor T, aspect factor Y, glacier aspect factor X, runout factor of the dangerous glacier R, ratio of the volume factor of the dangerous glacier to the volume of the lake V, and the downstream slope factor of the dam D (lake parameter). A machine learning model (a support vector machine, SVM) was used to create a susceptibility assessment model. Data for 21 drained and 50 undrained ice-free moraine-dammed lakes in the Himalayan region were used for the training of the GLOF susceptibility assessment model. In addition, data for 19 drained and 43 undrained ice-free moraine-dammed lakes in the western cordillera of North America were used to test the GLOF susceptibility assessment model. The susceptibility assessment factor P1 is a combination of these seven factors. The probability of GLOF occurrence increases as the P1 value increases. Using three critical P1 values, we divided the GLOF occurrence probability into four grades: low, medium, high, and very high probability of occurrence. The threshold values for the western cordillera of North America were 6.1–15.4% lower than the corresponding critical values for the Himalayan region because the annual temperature variation is larger in Canada than in Tibet. Thus, this assessment model can be used to assess the susceptibility of other areas of the world to GLOFs when annual temperature variations are considered.

Improving the accuracy of glacial lake volume estimation: A case study in the Poiqu basin, central Himalayas

• We present a new volume-scaling law specific to moraine-dammed lakes. • The new equation shows a more robust performance than other published formulas. • The total lake volume in the Poiqu basin has increased by 148% from 1974 to 2020. Lake volume is a critical parameter in the prediction of potential flood volume and peak discharge in the risk assessment of glacial lake outburst flood (GLOF). As existing volume–area scaling relationships often blur the complexity of lake geometry, we presented a new volume-scaling law specific to moraine-dammed lakes, derived from a large lake bathymetry dataset. The relationship was based on the premise that lake geometry parameters (i.e., area, volume, width/length ratio) scale predictably. We then critically evaluated the performance of the new approach and compared it with 19 existing empirical relationships by examining a database of glacial lake bathymetry obtained without repeated measurements. Overall, the new volume-scaling relationship showed a more robust performance than other published formulas. In addition, an intriguing result was that regional differences were not always controlled by the predictability of lake volumes, that is, there were no regional restrictions on the use of the new method, at least not in the Himalayas. Finally, using the new approach and high-resolution Landsat imagery, our results of sequential mapping of all lakes in the Poiqu basin indicated that the total lake volume has increased by 148% from 1974 to 2020. Compared with other formulas, the lake volume estimation approach proposed in this paper provides an approximate mean value, which provides a key input parameter for flood simulation and a new alternative for estimating lake volume.

Rapidly Expanding Glacial Lakes in Nepal Himalaya

The retreat and shrinkage of glaciers due to climate change are the causes for the formation and expansion of glacial lakes in the Himalayas. This study presents the rapidly expanding glacial lakes in Nepal Himalayas between 1988 and 2018 based on the published glacial lake inventories produced from Landsat imageries (30 m). Glacier-fed end moraine-dammed glacial lakes whose surface area was?0.1 km2 in 2018 with an expansion rate of more than 30% in 1988-2018 were regarded as rapidly expanding glacial lakes. The results show that 19 rapidly expanding glacial lakes are heterogeneously distributed in different sub-basins of Nepal. Among the sub-basins, Dudh Koshi sub-basin has a maximum (5) number of rapidly expanding glacial lakes. The total surface area of these 19 glacial lakes expanded by ~133%, from 4.12±0.61 km2 in 1988 to 9.62±1.04 km2 in 2018. Regular monitoring of rapidly expanding glacial lakes is required because the rapid expansion heightens the risk of GLOF by developing more potential flood volume and the expanding lakes can reach sites of possible avalanches.

Assessing climate change impacts on Pacific salmon and trout using bioenergetics and spatiotemporal explicit river temperature predictions under varying riparian conditions.

Pacific salmon and trout populations are affected by timber harvest, the removal and alteration of riparian vegetation, and the resulting physical changes to water quality, temperature, and associated delivery of high-quality terrestrial prey. Juvenile salmon and trout growth, a key predictor of survival, is poorly understood in the context of current and future (climate-change mediated) conditions, with resource managers needing information on how land use will impact future river conditions for these commercially and culturally important species. We used the Heat Source water temperature modeling framework to develop a spatiotemporal model to assess how riparian canopy and vegetation preservation and addition could influence river temperatures under future climate predictions in a coastal river fed by a moraine-dammed lake: the Quinault River in Washington State. The model predicted higher water temperatures under future carbon emission projections, representative concentration pathway (RCP) 4.5 and 8.5, with varying magnitude based on different riparian vegetation scenarios. We used the daily average temperature output from these scenarios to predict potential juvenile fish growth using the Wisconsin bioenergetics model. A combination of riparian vegetation removal and continued high carbon emissions resulted in a predicted seven-day average daily maximum temperature (7DADM) increase of 1.7°C in the lower river by 2080; increases in riparian shading mitigate this 7DADM increase to only 0.9°C. Under the current thermal regime, bioenergetics modeling predicts juvenile fish lose weight in the lower river; this loss of potential growth worsens by an average of 20–83% in the lower river by 2080, increasing with the loss of riparian shading. This study assess the impact of riparian vegetation management on future thermal habitat for Pacific salmon and trout under warming climates and provide a useful spatially explicit modeling framework that managers can use to make decisions regarding riparian vegetation management and its mechanistic impact to water temperature and rearing juvenile fish.

Simulation of Glacial Lake Outburst Flood in Southeastern Qinghai-Tibet Plateau—A Case Study of JiwenCo Glacial Lake

Glacial lake outburst floods (GLOFs) is one of the main natural disasters in alpine areas, which can cause extreme destruction to downstream settlements and infrastructures. A moraine-dammed lake named JiwenCo glacial lake (JGL) in the southeastern Qinghai-Tibetan Plateau failed on 26 June 2020, destroying many buildings, roads, bridges, and farmlands along the flow path. We reconstructed the process of this GLOF event by the Hydrological Engineering Center’s River Analysis System (HEC-RAS) and examined the JGL’s evolution (area, length, and volume) before its outburst, based on the measured cross sections and hydrological data, videos, and pictures taken by inhabitants, DEM data, and Landsat Thematic Mapper (TM)/Enhanced Thematic Mapper (ETM+)/Operational Land Imager (OLI) images. The result showed that area, length, and volume of the JGL increased by 0.20 ± 0.07 km2, 0.66 ± 0.03 km, and 0.03 ± 0.001 km3 from 1988 to 2020 (before the outburst), respectively. Approximately 0.05 km3 of water volume was discharged with the dropped water level of 15.63 m after the outburst. The peak flow was 534.4 m3/s at breach and increased to 1,408.11 m3/s at Zhongyu town. The difference between the simulated and measured peak flows in Zhongyu town was 41.88 m3/s (3.53%), showing the high accuracy of the modeling results. For villages along the river-channel, the highest velocity was found in Yiga village (14.23 m/s) and the lowest was in Gongwa village (1.22 m/s). The maximum depth was gradually increased as the river reached downstream, 8.03 m in Yiga village and 50.96 m in Duiba village. The combination of landslide, high temperature, and extremely heavy precipitation resulted in this GLOF disaster. An integrated disaster prevention and mitigation plan needs to be developed for susceptible areas such as Niduzangbo basin that experienced two GLOFs in recent 10 years.

Dam type and lake location characterize ice-marginal lake area change in Alaska and NW Canada between 1984 and 2019

Abstract. Ice-marginal lakes impact glacier mass balance, water resources, and ecosystem dynamics and can produce catastrophic glacial lake outburst floods (GLOFs) via sudden drainage. Multitemporal inventories of ice-marginal lakes are a critical first step in understanding the drivers of historic change, predicting future lake evolution, and assessing GLOF hazards. Here, we use Landsat-era satellite imagery and supervised classification to semi-automatically delineate lake outlines for four ∼5-year time periods between 1984 and 2019 in Alaska and northwest Canada. Overall, ice-marginal lakes in the region have grown in total number (+183 lakes, 38 % increase) and area (+483 km2, 59 % increase) between the time periods of 1984–1988 and 2016–2019. However, changes in lake numbers and area were notably unsteady and nonuniform. We demonstrate that lake area changes are connected to dam type (moraine, bedrock, ice, or supraglacial) and topological position (proglacial, detached, unconnected, ice, or supraglacial), with important differences in lake behavior between the sub-groups. In strong contrast to all other dam types, ice-dammed lakes decreased in number (six fewer, 9 % decrease) and area (−51 km2, 40 % decrease), while moraine-dammed lakes increased (56 more, 26 % and +479 km2, 87 % increase for number and area, respectively) at a faster rate than the average when considering all dam types together. Proglacial lakes experienced the largest area changes and rate of change out of any lake position throughout the period of study and moraine-dammed lakes which experienced the largest increases are associated with clean-ice glaciers (<19 % debris cover). By tracking individual lakes through time and categorizing lakes by dam type, subregion, and topological position, we are able to parse trends that would otherwise be aliased if these characteristics were not considered. This work highlights the importance of such lake characterization when performing ice-marginal lake inventories and provides insight into the physical processes driving recent ice-marginal lake evolution.

Climate change-induced high-altitude lake: Hydrochemistry and area changes of a moraine-dammed lake in Leh-Ladakh

Climate change-induced high-altitude lake: Hydrochemistry and area changes of a moraine-dammed lake in Leh-Ladakh

Controls of outbursts of moraine-dammed lakes in the greater Himalayan region

Abstract. Glacial lakes in the Hindu Kush–Karakoram–Himalayas–Nyainqentanglha (HKKHN) region have grown rapidly in number and area in past decades, and some dozens have drained in catastrophic glacial lake outburst floods (GLOFs). Estimating regional susceptibility of glacial lakes has largely relied on qualitative assessments by experts, thus motivating a more systematic and quantitative appraisal. Before the backdrop of current climate-change projections and the potential of elevation-dependent warming, an objective and regionally consistent assessment is urgently needed. We use an inventory of 3390 moraine-dammed lakes and their documented outburst history in the past four decades to test whether elevation, lake area and its rate of change, glacier-mass balance, and monsoonality are useful inputs to a probabilistic classification model. We implement these candidate predictors in four Bayesian multi-level logistic regression models to estimate the posterior susceptibility to GLOFs. We find that mostly larger lakes have been more prone to GLOFs in the past four decades regardless of the elevation band in which they occurred. We also find that including the regional average glacier-mass balance improves the model classification. In contrast, changes in lake area and monsoonality play ambiguous roles. Our study provides first quantitative evidence that GLOF susceptibility in the HKKHN scales with lake area, though less so with its dynamics. Our probabilistic prognoses offer improvement compared to a random classification based on average GLOF frequency. Yet they also reveal some major uncertainties that have remained largely unquantified previously and that challenge the applicability of single models. Ensembles of multiple models could be a viable alternative for more accurately classifying the susceptibility of moraine-dammed lakes to GLOFs.

Study on Earthquake-Induced Sloshing Waves in Moraine-Dammed Lakes

Large surface water waves can be triggered in moraine-dammed lakes during earthquakes and may lead to the overtopping failure of moraine dams. In the earthquake-prone Himalayas, there are thousands of moraine-dammed lakes; their outburst may lead to catastrophic disasters (e.g. floods and debris flow), posing severe threats to humans and infrastructures downstream. This paper experimentally studied earthquake-induced water waves (EWWs) in moraine-dammed lakes and examined the effects of several factors (e.g. water depth, earthquake parameters, and uneven lake basin). The experimental results suggest that the EWWs positively correlate to the earthquake wave, and the maximum height of the EWWs increases by 10%–15% when the effect of the uneven lake basin is considered. Based on the experiment data, we derived a calculation equation to estimate the maximum amplitude of EWWs considering the basin effect, and proposed a fast risk assessment method for moraine lakes due to overtopping EWWs. Finally, based on the method, we assessed the failure risk of the moraine lakes located in the Gyirong river basin where the China–Nepal corridor crosses. The study broadens understandings of the risk source of moraine-dammed lakes.

Spatiotemporal supraglacial pond and ice cliff changes in the Bhutan–Tibet border region from 2016 to 2018

AbstractSupraglacial ponds and ice cliffs can dramatically enhance ablation rates on debris-covered glaciers. Supraglacial ponds can also coalesce, forming moraine-dammed lakes at risk of glacial lake outburst flood (GLOF). Given Bhutanese glaciers have some of the highest ice loss rates in the Himalaya and GLOF vulnerability is high, we seek to advance our understanding of the spatial distribution and evolution of supraglacial ponds and ice cliffs. Here, we use high-resolution (3 m) Planet Labs satellite imagery to provide the first short-term, high-resolution dataset of supraglacial pond and ice cliff evolution for three glaciers along the Bhutan–Tibet border from 2016 to 2018. A total of 5754 ponds and 2088 ice cliffs were identified. Large intra-annual changes were observed, with ponded area changes and drainage events coinciding with the seasonality of the Indian Summer Monsoon. On average, ~19% of the total number of ponds had a coincident ice cliff. Pond spatial distribution was driven by ice-surface velocities, with higher numbers of ponds found in areas of low velocity (<8 m a−1). Our study provides the first detailed, quantitative investigation of supraglacial ponds and ice cliffs in Bhutan, providing a framework for further monitoring in this understudied, yet important, region of the Himalaya.

A Review of Glacial Lake Expansion and Associated Glacial Lake Outburst Floods in the Himalayan Region

Climate change is strongly affecting the Himalayas. Geologically young and fragile, the Himalayas are sensitive to even minor changes in the climate. Regional warming in Himalayas has been observed between 0.15 and 0.60 °C per decade, which is higher than the mean global warming rate of 0.74 °C per 100 years. Consequent to this warming trend, the glaciological changes in Himalayas are obvious, which has resulted in the formation, expansion and disappearance of various types of glacial lakes. The dangerous lakes among these pose threat to downstream community and infrastructure. In this study, an attempt has been made to critically analyze the progress in Glacier Lake Outburst Floods (GLOF) research and understand its dynamism from multiple approaches through a meta-analysis of peer-reviewed scholarly literature for a period of 2001–2020. The study has found that the glacial lakes in the study region are increasing in number and expanding rapidly owing to the climate change and anthropogenic causes as the Glacier Lake Outburst Floods (GLOFs) are becoming common. The expansion rates of pro-glacial lakes connected to glaciers and moraine-dammed lakes are faster than other type of lakes. Findings from the studies on area change analysis in the region reveal that a number of expanding glacial lakes can emerge as potential sites for future GLOFs, hence need immediate monitoring and observation. Geospatial tools and techniques coupled with field investigations have been found as a potent tool for mapping the evolution and propagation of GLOF hazards resulting from accelerated shrinking and thinning of glaciers and continued lake expansion. Further, the satellite-based remote sensing and modeling has been found as an excellent tool for GLOF management as well as reconstruction of previous GLOF events and prediction of future outburst potential. The idea of this study is linked to the increased incidence of GLOF events in the Himalayan region. This study will help in better understanding of glacial lake expansion and provide scope for future research in devising risk management action plans of potential GLOFs by selecting expanding glacial lakes as case studies.

Simulation and Assessment of Future Glacial Lake Outburst Floods in the Poiqu River Basin, Central Himalayas

A glacial lake outburst flood (GLOF) is a typical glacier-related hazard in high mountain regions. In recent decades, glacial lakes in the Himalayas have expanded rapidly due to climate warming and glacial retreat. Some of these lakes are unstable, and may suddenly burst under different triggering factors, thus draining large amounts of water and impacting downstream social and economic development. Glacial lakes in the Poiqu River basin, Central Himalayas, have attracted great attention since GLOFs originating there could have a transboundary impact on both China and Nepal, as occurred during the Cirenmaco GLOF in 1981 and the Gongbatongshaco GLOF in 2016. Based on previous studies of this basin, we selected seven very high-risk moraine-dammed lakes (Gangxico, Galongco, Jialongco, Cirenmaco, Taraco, Beihu, and Cawuqudenco) to simulate GLOF propagation at different drainage percentage scenarios (i.e., 25%, 50%, 75%, and 100%), and to conduct hazard assessment. The results show that, when any glacial lake is drained completely or partly, most of the floods will enter Nepal after raging in China, and will continue to cause damage. In summary, 57.5 km of roads, 754 buildings, 3.3 km2 of farmland, and 25 bridges are at risk of damage due to GLOFs. The potentially inundated area within the Chinese part of the Poiqu River basin exceeds 45 km2. Due to the destructive impacts of GLOFs on downstream areas, appropriate and effective measures should be implemented to adapt to GLOF risk. We finally present a paradigm for conducting hazard assessment and risk management. It uses only freely available data and thus is easy to apply.

Impact of glacier changes in the Himalayan Plateau disaster

Excluding the polar areas, the Hindu Kush–Himalayan (HKH) Plateau and its surroundings have the most glaciers. The Himalayan Plateau and its surroundings have declined gradually over the past 100 years. However, unexpected shifts have taken place since the 1990s in the condition of the glaciers. The massive loss of the small glaciers, in particular, was more extreme than the failures of the gigantic glaciers with an area about a km2. The approximate decay calculated through the Remote Sensing techniques has shown that from 1989 to 2009, the longitudinal region of Siachen Glacier decreased by 5.9 km in total area. To measure their potential strength to average surface runoff, a variety of standardized land cover climatic variables is being used to describe the spatiotemporal distribution of snow storms, and evaporation. The spatial trend primarily represents an irregular shift in the Himalayan glaciers and the surrounding areas. This research examined and disclosed the spatiotemporal distribution and development of Moraine-Dammed (MD) lakes and Likely Hazardous Glacier Changes (LHGC) in the Himalayan Plateau (HP). A unified degree of disaster for county-based Glacier Eruption Floods (GEFs) by integrating LHGC risks, geographic visibility, susceptibility, and using the hierarchical analytic process and comprehensive weighted method. The comparison between current and proposed methods is made by using the analysis hierarchical process, a proposal methodology in dynamic environments where several factors are taken into consideration in prioritization and selection of alternatives. GEF are types of outbursts that are triggered by a system that has a glacial lake collapse. An occurrence like the one in which a glacier is melting or overflowing in a water body is known as glacier run. The findings show that in the Himalayan plateau, there are 662 MD lakes, covering a complete range of 198.6 km2, of which 301 lakes covering a total area of 80.21 km2 are identified as LHGCs. The number of lakes declined by just 3.13% relative to 1989–1999, although the overall lake region has increased by 19%. The GEF disaster frequency regionalization findings show the distribution of historical GEF disaster sites.