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Ragettli, S.; Pellicciotti, F.; Immerzeel, W. W.; Miles, E. S.; Petersen, L.; Heynen, M.; Shea, J. M.; Stumm, D.; Joshi, S.; Shrestha, A.
The hydrology of high-elevation watersheds of the Hindu Kush-Himalaya region (HKH) is poorly known
. The correct representation of internal states and process dynamics in glacio-hydrological models can often not be verified due to missing in situ measurements. We use a new set of detailed ground data from the upper Langtang valley in Nepal to systematically guide a state-of-the art glacio-hydrological model through a parameter assigning process with the aim to understand the hydrology of the catchment and contribution of snow and ice processes to runoff. 14 parameters are directly calculated on the basis of local data, and 13 parameters are calibrated against 5 different datasets of in situ or remote sensing data. Spatial fields of debris thickness are reconstructed through a novel approach that employs data from an Unmanned Aerial Vehicle (UAV), energy balance modeling and statistical techniques. The model is validated against measured catchment runoff (Nash-Sutcliffe efficiency 0.87) and modeled snow cover is compared to Landsat snow cover. The advanced representation of processes allowed assessing the role played by avalanching for runoff for the first time for a Himalayan catchment (5% of annual water inputs to the hydrological system are due to snow redistribution) and to quantify the hydrological significance of sub-debris ice melt (9% of annual water inputs). Snowmelt is the most important contributor to total runoff during the hydrological year 2012/2013 (representing 40% of all sources), followed by rainfall (34%) and ice melt (26%). A sensitivity analysis is used to assess the efficiency of the monitoring network and identify the timing and location of field measurements that constrain model uncertainty. The methodology to set up a glacio-hydrological model in high-elevation regions presented in this study can be regarded as a benchmark for modelers in the HKH seeking to evaluate their calibration approach, their experimental setup and thus to reduce the predictive model uncertainty
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The Irrawaddy and Salween rivers in Myanmar deliver water fluxes to the ocean equal to ~ 70% of the Ganges–Brahmaputra river system
. Together these systems are thought to deliver about half the dissolved load from the tectonically active Himalayan–Tibetan orogen. Previously very little data was available on the dissolved load and isotopic compositions of these major rivers. Here we present time series data of 171 samples collected fortnightly at intervals throughout 2004 to 2007 from the Irrawaddy and Salween at locations near both the river mouths, the up-stream Irrawaddy at Myitkyina, the Chindwin, a major tributary of the Irrawaddy and a set of 28 small tributaries which rise in the flood plain of the Irrawaddy between Yangon and Mandalay. The samples have been analysed for major cation, anion and 87Sr/86Sr ratios. The new data indicates that the Irrawaddy has an annual average Na concentration only a third of the widely quoted single previously published analysis. The Irrawaddy and Salween drain about 0.5% of global continental area and deliver about 3.3% of the global silicate-derived dissolved Ca + Mg fluxes and 2.6% of the global Sr riverine fluxes to the oceans. This compares with Ganges and Brahmaputra which deliver about 3.4% of the global silicate-derived dissolved Ca + Mg fluxes and 3.2% of the global Sr riverine fluxes to the oceans from about 1.1% of global continental area. The discharge-weighted mean 87Sr/86Sr ratio of the Irrawaddy is 0.71024 and the Salween 0.71466. The chemistry of the Salween and the Irrawaddy waters reflects their different bedrock geology. The catchment of the Salween extends across the Shan Plateau in Myanmar through the Eastern syntaxis of the Himalayas and into Tibet. The Irrawaddy flows over the Cretaceous and Tertiary magmatic and metamorphic rocks exposed along the western margin of the Shan Plateau and the Cretaceous to Neogene Indo-Burma ranges. The 87Sr/86Sr compositions of the Salween and Upper Irrawaddy (between 0.7128 and 0.7176) are significantly higher than the downstream Irrawaddy (0.7095 to 0.7108) and the Chindwin (0.7082 to 0.7095). The Irrawaddy and the Chindwin exhibit lower 87Sr/86Sr and Na/Ca ratios during and immediately post-monsoon, interpreted to reflect higher weathering of carbonate at high flow. The Salween exhibits higher 87Sr/86Sr ratios but lower Na/Ca ratios during the monsoon, interpreted to reflect higher inputs from the upper parts of the catchment in the Himalayas
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Himalayan communities live in marginal environments
. They are dependent on ecosystem services and thus highly exposed to climate variability and change. This study aimed to help understand how mountain communities perceive change, how change impacts their livelihoods, and how they respond to change. Forty focus group discussions and 144 in-depth interviews at the household level were conducted in 20 villages in northwest India and across Nepal. Perceptions of change were compared with actual climate records where available. Respondents considered rainfall patterns to be less predictable and had experienced an overall reduction in water availability, severely affecting their harvests. Increased temperatures were also reported, particularly at higher elevations. People responded to the changing conditions with a wide range of coping and adaptation mechanisms. However, many of these mechanisms will not be sustainable in view of the likely magnitude of future climate change, and they are also restricted to social groups with appropriate assets. The poor, lower caste families, women, and other marginalized groups are particularly vulnerable and less able to adapt. Targeted efforts are required to move from coping to adapting and to avoid inequalities between social groups increasing due to the different adaptive capacities
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Mountains occupy 24% of the global land surface area and are home to 12% of the world’s population
. They have ecological, aesthetic, and socioeconomic significance, not only for those living in mountain areas, but also for people living beyond. The Hindu Kush-Himalayan region (HKH) expanding to over four million square kilometres is endowed with rich biodiversity, culture, and sources of varied goods and services that serve more than 200 million people living in the region and 1.3 billion people living in the river basins receive services from them. The countries sharing the HKH have set aside 39% of the biodiversity rich area for different systems of protection. However, in the recent years, the HKH is facing numerous drivers of environmental change including climate change. Various studies suggest that warming in the HKH has been much higher than the global average over the last 100 years and the HKH is already facing climate change threats at ecoregions, ecosystems and species levels. While climate change is a global problem requiring a global solution, the HKH countries have initiated various reconciling initiatives to link conservation with climate change for enhancing ecological and socio-economic resilience. However, there is serious paucity of expertise, capacity and data on climate change as well as biodiversity in the HKH bringing challenges in enhancing the resilience. Considering the significance of the HKH on local, regional, and global levels, it is imperative to close the gaps to meet the challenges arising from the consequences of climate change. International Centre for Integrated Mountain Development (ICIMOD), with its partners, has conceptualised a number of innovative conservation approaches with an objective to reconcile biodiversity conservation goals with climate change challenges. These conservation approaches have a huge potential for mutual benefits from the common good practices, resources and expertise and there is a need for more formal cooperative agreements between the various institutions and communities of the countries at the regional level for addressing regional issues of conservation in the changing climate. Conservation Science Vol.2(1) 2014: 17-27
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This report is an output of the Himalayan Climate Change Adaptation Programme (HICAP)
. The aim of this report is to present downscaled climate scenarios in a relevant, understandable and illustrative manner for a diverse group of end-users and stakeholders, including other HICAP research components decision-makers at different levels. This report is based on dynamically downscaled temperature and precipitation projections for 8 different domains in the Hindu-Kush Himalayas. It uses the HICAP model (the WRF model, driven by the NorESM GCM model) for the RCP4.5 and RCP8.5 scenarios. Comparing model results with local observations for a reference period (1996-2005, the output was corrected for various under- and overestimations. For each domain, projections for periods 1996-2005, 2010-2030, 2030-2050 and 2050-2080 are presented a) in figures relevant for local users and decision makers, b) in a simplified text summing up the projections, and briefly discussing them in relation to potential impacts. This report provides highly relevant, locally specific results for the HICAP region, and relates these to geographical variations within each domain across the Himalayas. No other models and projections have been used in this report, and the HICAP model results should be compared with other sources of information for a final assessment of local climate change and impacts. The usability of the report extends beyond the HICAP project: the model-adjustment method, aimed at showing how to make projections realistic and relevant at the local level, the ease of the calculations and the guided interpretations of the figures and projections can serve as a guide to model use and presentations anywhere, provided the availability of a minimal amount of observations to compare and adjust larger scale model outputs to local climate observations for a certain reference period
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Brown, M. E.; Racoviteanu, A. E.; Tarboton, D. G.; Gupta, A. S.; Nigro, J.; Policelli, F.; Habib, S.; Tokay, M.; Shrestha, M. S.; Bajracharya, S.; Hummel, P.; Gray, M.; Duda, P.; Zaitchik, B.; Mahat, V.; Artan, G.; Tokar, S.
Summary Quantification of the contribution of the hydrologic components (snow, ice and rain) to river discharge in the Hindu Kush Himalayan (HKH) region is important for decision-making in water sensitive sectors, and for water resources management and flood risk reduction
. In this area, access to and monitoring of the glaciers and their melt outflow is challenging due to difficult access, thus modeling based on remote sensing offers the potential for providing information to improve water resources management and decision making. This paper describes an integrated modeling system developed using downscaled NASA satellite based and earth system data products coupled with in-situ hydrologic data to assess the contribution of snow and glaciers to the flows of the rivers in the HKH region. Snow and glacier melt was estimated using the Utah Energy Balance (UEB) model, further enhanced to accommodate glacier ice melt over clean and debris-covered tongues, then meltwater was input into the USGS Geospatial Stream Flow Model (GeoSFM). The two model components were integrated into Better Assessment Science Integrating point and Nonpoint Sources modeling framework (BASINS) as a user-friendly open source system and was made available to countries in high Asia. Here we present a case study from the Langtang Khola watershed in the monsoon-influenced Nepal Himalaya, used to validate our energy balance approach and to test the applicability of our modeling system. The snow and glacier melt model predicts that for the eight years used for model evaluation (October 2003–September 2010), the total surface water input over the basin was 9.43 m, originating as 62% from glacier melt, 30% from snowmelt and 8% from rainfall. Measured streamflow for those years were 5.02 m, reflecting a runoff coefficient of 0.53. GeoSFM simulated streamflow was 5.31 m indicating reasonable correspondence between measured and model confirming the capability of the integrated system to provide a quantification of water availability
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We analysed the variability of equivalent black carbon (BC) and ozone (O3) at the global WMO/GAW station Nepal Climate Observatory-Pyramid (NCO-P, 5079 m a
.s.l.) in the southern Himalayas, for evaluating the possible contribution of open vegetation fires to the variability of these short-lived climate forcers/pollutants (SLCF/SLCP) in the Himalayan region. We found that 162 days (9% of the data-set) were characterised by acute pollution events with enhanced BC and O3 in respect to the climatological values. By using satellite observations (MODIS fire products and the USGS Land Use Cover Characterization) and air mass back-trajectories, we deduced that 56% of these events were likely to be affected by emissions from open fires along the Himalayas foothills, the Indian Subcontinent and the Northern Indo-Gangetic Plain. These results suggest that open fire emissions are likely to play an important role in modulating seasonal and inter-annual BC and O3 variability over south Himalayas
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Water has been identified as a key resource for Nepal's economic growth
. Although the country has 225 billion cubic meters of water available annually, less than 7% has been utilized. Climate change is a frequent topic in national development discussions in part because of its possible impact on future water availability. This study assessed the likely impact of climate change on water resources development in the Koshi River basin, Nepal, using the Soil and Water Assessment Tool to generate projections for the 2030s and 2050s. Results suggested that the impacts are likely to be scale dependent. Little impact is projected at annual, full-basin scales; but at sub-basin scale, under both the IPCC's A2 and B1 scenarios, precipitation is projected to increase in the upper transmountain subwatersheds in the 2030s and in most of the basin in the 2050s and to decrease in the lower sub-basins in the 2030s. Water yield is projected to increase in most of the basin except for the A2 scenario for the 2030s. Flow volumes are projected to increase during the monsoon and postmonsoon but decrease during the winter and premonsoon seasons. The impacts of climate change are likely to be higher during certain seasons and in some sub-basins. Thus, if infrastructure is in place that makes it possible to store and transfer water as needed, the water deficit due to any changes in rainfall or flow patterns could be managed and would not be a constraint on water resources development. The risks associated with extreme events such as floods and droughts should, however, also be considered during planning
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